Central Academy Senior Secondary School

7/24/2019 Central Academy Senior Secondary School

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POLYMERIZATION

CENTRAL ACADEMY SENIORSECONDARY SCHOOL

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TOPIC : POLYMERIZATION

SUBMITTED BY :

ARCHIT KAPOORCLASS: 11

CELL NO: 20041

SESSION : 2015-16

UNDER UIDANCE O!:

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POLYMERIZATION

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Mr Chandan Singh, Mrs Mala Saxena

Project Coordinator, Principal,

Department of Chemistry, Central Academy,

Central Academy, Lucknow

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POLYMERIZATION

Lucknow

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POLYMERIZATION

ARCHIT KAPOOR

Class 11

OBJECTIVE

THE OAL O! THIS PRO?ECT ISTO STUDY ABOUT

POLMERIZATION AND

DI!!ERENT KINDS O!

POLYMERS94 | P a g e


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POLYMERIZATION

PolymerizationIUPAC definition

Polymerization: The process of converting amonomeror a mixture of monomers into a polymer.

An example of alkene polymerization, in which each styrenemonomer's double bond reforms as a single

bond plus a bond to another styrene monomer. The product ispolystyrene.

n polymer chemistry, polymerizationis a process of reactingmonomer moleculestogether ina chemical reactionto form polymerchains or three!dimensional networ"s. There are manyforms of polymerization and different systems exist to categorize them.

Introduction

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https://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Polymerhttps://en.wikipedia.org/wiki/Styrenehttps://en.wikipedia.org/wiki/Polystyrenehttps://en.wikipedia.org/wiki/Polystyrenehttps://en.wikipedia.org/wiki/Polymer_chemistryhttps://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Chemical_reactionhttps://en.wikipedia.org/wiki/Polymerhttps://en.wikipedia.org/wiki/Polymerhttps://en.wikipedia.org/wiki/Polymerhttps://en.wikipedia.org/wiki/Styrenehttps://en.wikipedia.org/wiki/Polystyrenehttps://en.wikipedia.org/wiki/Polymer_chemistryhttps://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Chemical_reactionhttps://en.wikipedia.org/wiki/Polymerhttps://en.wikipedia.org/wiki/Monomer


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POLYMERIZATION

n chemical compounds, polymerization occurs via a variety of reaction mechanisms that vary incomplexity due tofunctional groupspresent in reacting compounds#$%and their inherent stericeffects. n more straightforward polymerization, al"enes,which are relatively stable due tobondingbetween carbon atoms, form polymers through relatively simple radical reactions& incontrast, more complex reactions such as those that involve substitution at thecarbonylgroupreuire more complex synthesis due to the way in which reacting molecules polymerize.

As al"enes can be formed in somewhat straightforward reaction mechanisms, they form usefulcompounds such as polyethyleneand polyvinyl chloride(P)*+ when undergoing radicalreactions,#$%which are produced in high tonnages each year%due to their usefulness inmanufacturing processes of commercial products, such as piping, insulation and pac"aging. ngeneral, polymers such as P)* are referred to as homopolymers, as they consist of repeated

long chains or structures of the same monomer unit, whereas polymers that consist of more thanone molecule are referred to as copolymers(or co!polymers+.#-%

ther monomer units, such as formaldehyde hydrates or simple aldehydes, are able topolymerize themselves at uite low temperatures (ca. /01 2*+ to formtrimers&%moleculesconsisting of 3 monomer units, which can cyclize to form ring cyclic structures, or undergo furtherreactions to form tetramers,#$%or $ monomer!unit compounds. 4urther compounds either beingreferred to asoligomers #$%in smaller molecules. 5enerally, because formaldehyde is anexceptionally reactive electrophile it allows nucleophillicaddition of hemiacetal intermediates,which are in general short!lived and relatively unstable mid!stage compounds that react withother molecules present to form more stable polymeric compounds.

Polymerization that is not sufficiently moderated and proceeds at a fast rate can be very

hazardous. This phenomenon is "nown ashazardous polymerizationand can cause fires andexplosions.

Step-growth#.%

6tep!growth polymers are defined as polymers formed by the stepwise reaction betweenfunctional groups of monomers, usually containingheteroatomssuch as nitrogen or oxygen.7ost step!growth polymers are also classified ascondensation polymers, but not all step!growthpolymers (li"e polyurethanesformed fromisocyanateand alcohol bifunctional monomers+ releasecondensates& in this case, we tal" aboutaddition polymers. 6tep!growth polymers increase inmolecular weight at a very slow rate at lower conversions and reach moderately high molecularweights only at very high conversion (i.e., 89-+.

To alleviate inconsistencies in these naming methods, ad;usted definitions for condensation andaddition polymers have been developed. A condensation polymer is defined as a polymer thatinvolves loss of small molecules during its synthesis, or contains heteroatoms as part ofitsbac"bone chain, or itsrepeat unitdoes not contain all the atoms present in the hypotheticalmonomer to which it can be degraded.

Chain-growth

*hain!growth polymerization (or addition polymerization+ involves the lin"ing together ofmolecules incorporating double or triple carbon!carbon bonds. Theseunsaturated monomers(the identical molecules that ma"e up the polymers+ have extra internalbonds that are able to brea" and lin" up with other monomers to form a repeating chain, whose

bac"bone typically contains only carbon atoms. *hain!growth polymerization is involved in the

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Homopolymers

Copolymers
https://en.wikipedia.org/wiki/Functional_grouphttps://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Steric_effectshttps://en.wikipedia.org/wiki/Steric_effectshttps://en.wikipedia.org/wiki/Alkeneshttps://en.wikipedia.org/wiki/Alkeneshttps://en.wikipedia.org/wiki/Sigma_bondhttps://en.wikipedia.org/wiki/Sigma_bondhttps://en.wikipedia.org/wiki/Sigma_bondhttps://en.wikipedia.org/wiki/Free-radical_reactionhttps://en.wikipedia.org/wiki/Carbonyl_grouphttps://en.wikipedia.org/wiki/Carbonyl_grouphttps://en.wikipedia.org/wiki/Polyethylenehttps://en.wikipedia.org/wiki/Polyethylenehttps://en.wikipedia.org/wiki/Polyvinyl_chloridehttps://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Polymerization#cite_note-5https://en.wikipedia.org/wiki/Trimer_(chemistry)https://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Tetramerhttps://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Oligomerhttps://en.wikipedia.org/wiki/Oligomerhttps://en.wikipedia.org/wiki/Oligomerhttps://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Nucleophilehttps://en.wikipedia.org/wiki/Nucleophilehttps://en.wikipedia.org/wiki/Hazardous_polymerizationhttps://en.wikipedia.org/wiki/Hazardous_polymerizationhttps://en.wikipedia.org/wiki/Hazardous_polymerizationhttps://en.wikipedia.org/w/index.php?title=Polymerization&action=edit&section=2https://en.wikipedia.org/wiki/Heteroatomshttps://en.wikipedia.org/wiki/Heteroatomshttps://en.wikipedia.org/wiki/Condensation_polymerhttps://en.wikipedia.org/wiki/Condensation_polymerhttps://en.wikipedia.org/wiki/Polyurethanehttps://en.wikipedia.org/wiki/Isocyanatehttps://en.wikipedia.org/wiki/Addition_polymerhttps://en.wikipedia.org/wiki/Addition_polymerhttps://en.wikipedia.org/wiki/Backbone_chainhttps://en.wikipedia.org/wiki/Backbone_chainhttps://en.wikipedia.org/wiki/Structural_unithttps://en.wikipedia.org/wiki/Structural_unithttps://en.wikipedia.org/wiki/Chemical_bondhttps://en.wikipedia.org/wiki/Functional_grouphttps://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Steric_effectshttps://en.wikipedia.org/wiki/Steric_effectshttps://en.wikipedia.org/wiki/Alkeneshttps://en.wikipedia.org/wiki/Sigma_bondhttps://en.wikipedia.org/wiki/Sigma_bondhttps://en.wikipedia.org/wiki/Free-radical_reactionhttps://en.wikipedia.org/wiki/Carbonyl_grouphttps://en.wikipedia.org/wiki/Carbonyl_grouphttps://en.wikipedia.org/wiki/Polyethylenehttps://en.wikipedia.org/wiki/Polyvinyl_chloridehttps://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Polymerization#cite_note-5https://en.wikipedia.org/wiki/Trimer_(chemistry)https://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Tetramerhttps://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Oligomerhttps://en.wikipedia.org/wiki/Polymerization#cite_note-clayden_organic-4https://en.wikipedia.org/wiki/Nucleophilehttps://en.wikipedia.org/wiki/Hazardous_polymerizationhttps://en.wikipedia.org/w/index.php?title=Polymerization&action=edit&section=2https://en.wikipedia.org/wiki/Heteroatomshttps://en.wikipedia.org/wiki/Condensation_polymerhttps://en.wikipedia.org/wiki/Polyurethanehttps://en.wikipedia.org/wiki/Isocyanatehttps://en.wikipedia.org/wiki/Addition_polymerhttps://en.wikipedia.org/wiki/Backbone_chainhttps://en.wikipedia.org/wiki/Structural_unithttps://en.wikipedia.org/wiki/Chemical_bond


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POLYMERIZATION

manufacture of polymers such aspolyethylene,polypropylene, and polyvinyl chloride(P)*+. Aspecial case of chain!growth polymerization leads to living polymerization.

n the radical polymerizationofethylene, its < bondis bro"en, and the two electrons rearrange tocreate a new propagating centerli"e the one that attac"ed it. The form this propagating centerta"es depends on the specific type of addition mechanism. There are several mechanisms

through which this can be initiated. The free radicalmechanism is one of the first methods to beused. 4ree radicals are very reactive atoms or molecules that have unpaired electrons. Ta"ingthe polymerization of ethylene as an example, the free radical mechanism can be divided intothree stages:chain initiation, chain propagation, and chain termination.

Polymerization ofethylene

4ree radical addition polymerization of ethylene must ta"e place at high temperatures andpressures, approximately 311 2* and =111 atm. >hile most other free radical polymerizations donot reuire such extreme temperatures and pressures, they do tend to lac" control. ne effect ofthis lac" of control is a high degree of branching. Also, as termination occurs randomly, when two

chains collide, it is impossible to control the length of individual chains. A newer method ofpolymerization similar to free radical, but allowing more control involves the?iegler!@attacatalyst, especially with respect to polymer branching.

ther forms of chain growth polymerization includecationic addition polymerizationand anionicaddition polymerization. >hile not used to a large extent in industry yet due to stringent reactionconditions such as lac" of water and oxygen, these methods provide ways to polymerize somemonomers that cannot be polymerized by free radical methods such as polypropylene.*ationicand anionic mechanisms are also more ideally suited forliving polymerizations,although freeradical living polymerizations have also been developed.

stersof acrylic acidcontain a carbon!carbon double bond which iscon;ugatedto an estergroup. This allows the possibility of both types of polymerization mechanism. An acrylic ester by

itself can undergo chain!growth polymerization to form a homopolymerwith a carbon!carbonbac"bone, such aspoly(methyl methacrylate+. Also, however, certain acrylic esters can reactwithdiaminemonomers by nucleophilic con;ugate additionof amine groups to acrylic *B*bonds. n this case the polymerization proceeds by step!growth and the products are poly(beta!amino ester+ copolymers, with bac"bones containing nitrogen (as amine+ and oxygen (as ester+as well as carbon.#C%

Physical polymer reaction engineering

To produce a high!molecular!weight, uniform product, various methods are employed to bettercontrol the initiation, propagation, and termination rates during chain polymerization and also toremove excess concentrated heat during these exothermic reactions compared to polymerizationof the pure monomer (also referred to as bul" polymerization+. These include emulsion

polymerization,solution polymerization,suspension polymerization, and precipitationpolymerization. Although the polymer polydispersity and molecular weight may be improved,these methods may introduce additional processing reuirements to isolate the product from asolvent.

Photopolymerization#.%

7ost photopolymerizationreactions are chain!growth polymerizations which are initiated by theabsorption of visible or ultraviolet light. The light may be absorbed either directly by the reactantmonomer (directphotopolymerization+, or else by aphotosensitizerwhich absorbs the light andthen transfers energy to the monomer. n general only the initiation step differs from that of theordinary thermal polymerization of the same monomer& subseuent propagation, termination andchain transfer steps are unchanged.#D%n step!growth photopolymerization, absorption of light

triggers an addition (or condensation+ reaction between two comonomers that do not reactwithout light. A propagation cycle is not initiated because each growth step reuires theassistance of light.#0%

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https://en.wikipedia.org/wiki/Polyethylenehttps://en.wikipedia.org/wiki/Polypropylenehttps://en.wikipedia.org/wiki/Polypropylenehttps://en.wikipedia.org/wiki/Polyvinyl_chloridehttps://en.wikipedia.org/wiki/Polyvinyl_chloridehttps://en.wikipedia.org/wiki/Living_polymerizationhttps://en.wikipedia.org/wiki/Living_polymerizationhttps://en.wikipedia.org/wiki/Radical_polymerizationhttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Pi_bondhttps://en.wikipedia.org/wiki/Reactive_centerhttps://en.wikipedia.org/wiki/Free_radicalhttps://en.wikipedia.org/wiki/Chain_initiationhttps://en.wikipedia.org/wiki/Chain_initiationhttps://en.wikipedia.org/wiki/Chain_propagationhttps://en.wikipedia.org/wiki/Chain_terminationhttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Branching_(chemistry)https://en.wikipedia.org/wiki/Cationic_addition_polymerizationhttps://en.wikipedia.org/wiki/Cationic_addition_polymerizationhttps://en.wikipedia.org/wiki/Cationic_addition_polymerizationhttps://en.wikipedia.org/wiki/Anionic_addition_polymerizationhttps://en.wikipedia.org/wiki/Anionic_addition_polymerizationhttps://en.wikipedia.org/wiki/Polypropylenehttps://en.wikipedia.org/wiki/Polypropylenehttps://en.wikipedia.org/wiki/Living_polymerizationhttps://en.wikipedia.org/wiki/Living_polymerizationhttps://en.wikipedia.org/wiki/Living_polymerizationhttps://en.wikipedia.org/wiki/Esterhttps://en.wikipedia.org/wiki/Acrylic_acidhttps://en.wikipedia.org/wiki/Acrylic_acidhttps://en.wikipedia.org/wiki/Conjugated_systemhttps://en.wikipedia.org/wiki/Conjugated_systemhttps://en.wikipedia.org/wiki/Homopolymerhttps://en.wikipedia.org/wiki/Poly(methyl_methacrylate)https://en.wikipedia.org/wiki/Poly(methyl_methacrylate)https://en.wikipedia.org/wiki/Diaminehttps://en.wikipedia.org/wiki/Diaminehttps://en.wikipedia.org/wiki/Diaminehttps://en.wikipedia.org/wiki/Nucleophilic_conjugate_additionhttps://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Polymerization#cite_note-6https://en.wikipedia.org/wiki/Emulsion_polymerizationhttps://en.wikipedia.org/wiki/Emulsion_polymerizationhttps://en.wikipedia.org/wiki/Solution_polymerizationhttps://en.wikipedia.org/wiki/Solution_polymerizationhttps://en.wikipedia.org/wiki/Solution_polymerizationhttps://en.wikipedia.org/wiki/Suspension_polymerizationhttps://en.wikipedia.org/wiki/Precipitation_polymerizationhttps://en.wikipedia.org/wiki/Precipitation_polymerizationhttps://en.wikipedia.org/w/index.php?title=Polymerization&action=edit&section=5https://en.wikipedia.org/wiki/Polymerization#cite_note-ALM-7https://en.wikipedia.org/wiki/Polymerization#cite_note-Soto_2014-8https://en.wikipedia.org/wiki/Polyethylenehttps://en.wikipedia.org/wiki/Polypropylenehttps://en.wikipedia.org/wiki/Polyvinyl_chloridehttps://en.wikipedia.org/wiki/Living_polymerizationhttps://en.wikipedia.org/wiki/Radical_polymerizationhttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Pi_bondhttps://en.wikipedia.org/wiki/Reactive_centerhttps://en.wikipedia.org/wiki/Free_radicalhttps://en.wikipedia.org/wiki/Chain_initiationhttps://en.wikipedia.org/wiki/Chain_propagationhttps://en.wikipedia.org/wiki/Chain_terminationhttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Branching_(chemistry)https://en.wikipedia.org/wiki/Cationic_addition_polymerizationhttps://en.wikipedia.org/wiki/Anionic_addition_polymerizationhttps://en.wikipedia.org/wiki/Anionic_addition_polymerizationhttps://en.wikipedia.org/wiki/Polypropylenehttps://en.wikipedia.org/wiki/Living_polymerizationhttps://en.wikipedia.org/wiki/Esterhttps://en.wikipedia.org/wiki/Acrylic_acidhttps://en.wikipedia.org/wiki/Conjugated_systemhttps://en.wikipedia.org/wiki/Homopolymerhttps://en.wikipedia.org/wiki/Poly(methyl_methacrylate)https://en.wikipedia.org/wiki/Diaminehttps://en.wikipedia.org/wiki/Nucleophilic_conjugate_additionhttps://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Polymerization#cite_note-6https://en.wikipedia.org/wiki/Emulsion_polymerizationhttps://en.wikipedia.org/wiki/Emulsion_polymerizationhttps://en.wikipedia.org/wiki/Solution_polymerizationhttps://en.wikipedia.org/wiki/Suspension_polymerizationhttps://en.wikipedia.org/wiki/Precipitation_polymerizationhttps://en.wikipedia.org/wiki/Precipitation_polymerizationhttps://en.wikipedia.org/w/index.php?title=Polymerization&action=edit&section=5https://en.wikipedia.org/wiki/Polymerization#cite_note-ALM-7https://en.wikipedia.org/wiki/Polymerization#cite_note-Soto_2014-8


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POLYMERIZATION

Photopolymerization can be used as a photographic or printing process, because polymerization

only occurs in regions which have been exposed to light. Enreacted monomer can be removed

from unexposed regions, leaving a relief polymeric image. #D%6everal forms of 3F printing!!including layer!by!layerstereolithographyand two!photon absorption 3F photopolymerization!!

use photopolymerization.

Polyethylene

Polyethylene

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https://en.wikipedia.org/wiki/Polymerization#cite_note-ALM-7https://en.wikipedia.org/wiki/3D_printing#Photopolymerizationhttps://en.wikipedia.org/wiki/Stereolithographyhttps://en.wikipedia.org/wiki/Two-photon_absorption#3D_photopolymerizationhttps://en.wikipedia.org/wiki/Two-photon_absorption#3D_photopolymerizationhttps://en.wikipedia.org/wiki/Polymerization#cite_note-ALM-7https://en.wikipedia.org/wiki/3D_printing#Photopolymerizationhttps://en.wikipedia.org/wiki/Stereolithographyhttps://en.wikipedia.org/wiki/Two-photon_absorption#3D_photopolymerization


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POLYMERIZATION

Names

IUPAC name

Polyethene or poly(methylene)

Other names

Polyethene

Identifiers

CAS Number 9002-88-4

Abbre!at!ons P"

#"$$ C%9&0'

eS Polyethylene

Properties

Chem!*al +ormula (C24)n

,ens!ty 09%.09/ 1*m'%3

elt!n po!nt %%&.%'& C (2'9.25& 67 '88.408 #) %3(2'9.25& 6)

"*ept here other!se note:; :ata are !en +or mater!als !n the!rstan:ar: state(at 2& C 55 63; %00


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POLYMERIZATION

The repeating unit of polyethylenein the most stable staggered conformation.

Polyethylene(abbreviated PE+ or polyethene(EPA*name polyetheneor poly(methylene)+is the most commonplastic. The annual global production is around 01 million tonnes.#=%ts

primary use is inpac"aging(plastic bags, plastic films,geomembranes, containersincludingbottles,etc.+. 7any "inds of polyethylene are "nown, with most having thechemicalformula(*=G$+n. Thus, P is usually a mixture of similar polymersofethylenewith various valuesof n.

Polyethylene was first synthesized by the 5erman chemist Gans von Pechmann,whoprepared it by accident in H090 while investigating diazomethane.#3%#$%>hen his colleagues ugen

Iambergerand 4riedrich Tschirnercharacterized the white, waxy substance that he had created,

they recognized that it contained long !*G =! chains and termed itpolymethylene.#-%

A pill boxpresented to a technician at * in H93C made from the first pound of polyethylene

The first industrially practical polyethylene synthesis (diazomethane is a notoriously unstable

substance that is generally avoided in industrial application+ was discovered in H933 by ric4awcett and Jeginald 5ibson, again by accident, at themperial *hemical ndustries(*+ wor"sin @orthwich, ngland.#C%Epon applying extremely high pressure (several hundred atmospheres+to a mixture of ethylene andbenzaldehydethey again produced a white, waxy, material. Iecausethe reaction had been initiated by trace oxygencontamination in their apparatus, the experimentwas, at first, difficult to reproduce. t was not until H93- that another * chemist, 7ichael Perrin,developed this accident into a reproducible high!pressure synthesis for polyethylene that becamethe basis for industrial KFP production beginning in H939. Iecause polyethylene was found tohave very low!loss properties at very high freuency radio waves, commercial distribution inIritain was suspended on the outbrea" of >orld >ar , secrecy imposed and the new processwas used to produce insulation for EG4 and 6G4 coaxial cablesof radarsets. Furing >orld >ar, further research was done on the * process and in H9$$ Ia"elite *orporation at 6abine,

Texas, and Fu Pont at *harleston, >est )irginia, began large scale commercial productionunder license from *.#D%

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https://en.wikipedia.org/wiki/Staggered_conformationhttps://en.wikipedia.org/wiki/IUPAChttps://en.wikipedia.org/wiki/Plastichttps://en.wikipedia.org/wiki/Tonnehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-2https://en.wikipedia.org/wiki/Packaginghttps://en.wikipedia.org/wiki/Packaginghttps://en.wikipedia.org/wiki/Packaginghttps://en.wikipedia.org/wiki/Plastic_baghttps://en.wikipedia.org/wiki/Plastic_filmhttps://en.wikipedia.org/wiki/Plastic_filmhttps://en.wikipedia.org/wiki/Geomembraneshttps://en.wikipedia.org/wiki/Bottlehttps://en.wikipedia.org/wiki/Bottlehttps://en.wikipedia.org/wiki/Bottlehttps://en.wikipedia.org/wiki/Chemical_formulahttps://en.wikipedia.org/wiki/Chemical_formulahttps://en.wikipedia.org/wiki/Polymerhttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Hans_von_Pechmannhttps://en.wikipedia.org/wiki/Hans_von_Pechmannhttps://en.wikipedia.org/wiki/Diazomethanehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-3https://en.wikipedia.org/wiki/Polyethylene#cite_note-3https://en.wikipedia.org/wiki/Polyethylene#cite_note-3https://en.wikipedia.org/wiki/Polyethylene#cite_note-4https://en.wikipedia.org/wiki/Eugen_Bambergerhttps://en.wikipedia.org/wiki/Eugen_Bambergerhttps://en.wikipedia.org/w/index.php?title=Friedrich_Tschirner&action=edit&redlink=1https://en.wikipedia.org/wiki/Polyethylene#cite_note-5https://en.wikipedia.org/wiki/Pill_organizerhttps://en.wikipedia.org/wiki/Imperial_Chemical_Industrieshttps://en.wikipedia.org/wiki/Northwichhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-6https://en.wikipedia.org/wiki/Benzaldehydehttps://en.wikipedia.org/wiki/Benzaldehydehttps://en.wikipedia.org/wiki/Oxygenhttps://en.wikipedia.org/wiki/Michael_Perrinhttps://en.wikipedia.org/wiki/Coaxial_cablehttps://en.wikipedia.org/wiki/Radarhttps://en.wikipedia.org/wiki/Radarhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-7https://en.wikipedia.org/wiki/Staggered_conformationhttps://en.wikipedia.org/wiki/IUPAChttps://en.wikipedia.org/wiki/Plastichttps://en.wikipedia.org/wiki/Tonnehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-2https://en.wikipedia.org/wiki/Packaginghttps://en.wikipedia.org/wiki/Plastic_baghttps://en.wikipedia.org/wiki/Plastic_filmhttps://en.wikipedia.org/wiki/Geomembraneshttps://en.wikipedia.org/wiki/Bottlehttps://en.wikipedia.org/wiki/Chemical_formulahttps://en.wikipedia.org/wiki/Chemical_formulahttps://en.wikipedia.org/wiki/Polymerhttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/Hans_von_Pechmannhttps://en.wikipedia.org/wiki/Diazomethanehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-3https://en.wikipedia.org/wiki/Polyethylene#cite_note-4https://en.wikipedia.org/wiki/Eugen_Bambergerhttps://en.wikipedia.org/wiki/Eugen_Bambergerhttps://en.wikipedia.org/w/index.php?title=Friedrich_Tschirner&action=edit&redlink=1https://en.wikipedia.org/wiki/Polyethylene#cite_note-5https://en.wikipedia.org/wiki/Pill_organizerhttps://en.wikipedia.org/wiki/Imperial_Chemical_Industrieshttps://en.wikipedia.org/wiki/Northwichhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-6https://en.wikipedia.org/wiki/Benzaldehydehttps://en.wikipedia.org/wiki/Oxygenhttps://en.wikipedia.org/wiki/Michael_Perrinhttps://en.wikipedia.org/wiki/Coaxial_cablehttps://en.wikipedia.org/wiki/Radarhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-7


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POLYMERIZATION

The brea"through landmar" in the commercial production of polyethylene began with thedevelopment of catalystthat promote the polymerization at mild temperatures and pressures.The first of these was achromium trioxideLbased catalyst discovered in H9-H byJobertIan"sandM. Paul Goganat Phillips Petroleum.#0%n H9-3 the 5erman chemist Narl?ieglerdeveloped a catalytic system based ontitaniumhalidesand organoaluminium compoundsthat wor"ed at even milder conditions than the Phillips catalyst. The Phillips catalyst is less

expensive and easier to wor" with, however, and both methods are heavily used industrially. Iythe end of the H9-1s both the Phillips! and ?iegler!type catalysts were being used for GFPproduction. n the H9D1s, the ?iegler system was improved by the incorporation of magnesiumchloride. *atalytic systems based on soluble catalysts, themetallocenes, were reported in H9DCby >alter Namins"yand Gans;Org 6inn. The ?iegler! and metallocene!based catalysts familieshave proven to be very flexible at copolymerizing ethylene with other olefinsand have becomethe basis for the wide range of polyethyleneresinsavailable today, including very low densitypolyethyleneandlinear low!density polyethylene.6uch resins, in the form of EG7>P fibers,have (as of =11-+ begun to replace aramidsin many high!strength applications.

Properties#.%

The properties of polyethylene can be divided into mechanical, chemical, electrical, optical andthermal properties.#9%

Mechanical properties#.%

Polyethylene is of low strength, hardnessand rigidity, but has a highductilityand impactstrengthas well as low friction. t shows strong creepunder persistent force, which can bereduced by addition of short fibers. t feels waxy when touched.

Thermal properties#.%

The usefulness of polyethylene is limited by its softening point of 01 2* (HDC 24+ (GFP, types oflow crystalline softens earlier+. 4or common commercial grades of medium! and high!density

polyethylene the melting point is typically in the range H=1 to H01 2* (=$0 to 3-C 24+. The meltingpoint for average, commercial, low!density polyethylene is typically H1- to HH- 2* (==H to=39 24+. These temperatures varies strongly with the type of polyethylene.

Chemical properties#.%

Polyethylene consists of nonpolar, saturated, high molecular weight hydrocarbons. Therefore, itschemical behavior is similar to paraffin. The individual macromolecules are not covalentlylin"ed.Iecause of their symmetric molecular structure, they tend to crystallize& overall polyethyleneispartially crystalline.Gighercrystallinityincrease densityand mechanical and chemical stability.

7ost KFP, 7FP,andGFPgrades have excellent chemical resistance, meaning they are notattac"ed by strong acids or strong bases, and are resistant to gentle oxidants and reducingagents. *rystalline samples do not dissolve at room temperature. Polyethylene (other than cross!

lin"ed polyethylene+ usually can be dissolved at elevated temperatures in aromatichydrocarbonssuch as tolueneor xylene, or in chlorinated solvents suchas trichloroethaneor trichlorobenzene.#H1%

Polyethylene absorbs almost no water. The gas and water vapor permeability (only polar gases+is lower than for most plastics&oxygen,carbon dioxideandflavoringson the other hand can passit easily.

P can become brittle when exposed to sunlight, carbon blac"is usually used as a E) stabilizer.

Polyethylene burns slowly with a blue flame having a yellow tip and gives off an odour of paraffin(similar tocandleflame+. The material continues burning on removal of the flame source andproduces a drip.#HH%

Polyethylene can not be imprinted or stuc" together without pretreatment.

Electrical Properties#.%

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https://en.wikipedia.org/wiki/Catalysthttps://en.wikipedia.org/wiki/Catalysthttps://en.wikipedia.org/wiki/Chromium_trioxidehttps://en.wikipedia.org/wiki/Chromium_trioxidehttps://en.wikipedia.org/wiki/Robert_Banks_(chemist)https://en.wikipedia.org/wiki/Robert_Banks_(chemist)https://en.wikipedia.org/wiki/Robert_Banks_(chemist)https://en.wikipedia.org/wiki/Robert_Banks_(chemist)https://en.wikipedia.org/wiki/J._Paul_Hoganhttps://en.wikipedia.org/wiki/J._Paul_Hoganhttps://en.wikipedia.org/wiki/Phillips_Petroleumhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-8https://en.wikipedia.org/wiki/Karl_Zieglerhttps://en.wikipedia.org/wiki/Karl_Zieglerhttps://en.wikipedia.org/wiki/Titaniumhttps://en.wikipedia.org/wiki/Titaniumhttps://en.wikipedia.org/wiki/Halidehttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Magnesium_chloridehttps://en.wikipedia.org/wiki/Magnesium_chloridehttps://en.wikipedia.org/wiki/Metallocenehttps://en.wikipedia.org/wiki/Walter_Kaminskyhttps://en.wikipedia.org/wiki/Walter_Kaminskyhttps://en.wikipedia.org/w/index.php?title=Hansj%C3%B6rg_Sinn&action=edit&redlink=1https://en.wikipedia.org/wiki/Olefinhttps://en.wikipedia.org/wiki/Resinhttps://en.wikipedia.org/wiki/Resinhttps://en.wikipedia.org/w/index.php?title=Very_low_density_polyethylene&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Very_low_density_polyethylene&action=edit&redlink=1https://en.wikipedia.org/wiki/Linear_low-density_polyethylenehttps://en.wikipedia.org/wiki/Linear_low-density_polyethylenehttps://en.wikipedia.org/wiki/Linear_low-density_polyethylenehttps://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene#UHMWfiberhttps://en.wikipedia.org/wiki/Aramidhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=2https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=2https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=3https://en.wikipedia.org/wiki/Hardnesshttps://en.wikipedia.org/wiki/Ductilityhttps://en.wikipedia.org/wiki/Ductilityhttps://en.wikipedia.org/wiki/Impact_strengthhttps://en.wikipedia.org/wiki/Impact_strengthhttps://en.wikipedia.org/wiki/Creep_(deformation)https://en.wikipedia.org/wiki/Creep_(deformation)https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=4https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=4https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=5https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=5https://en.wikipedia.org/wiki/Kerosenehttps://en.wikipedia.org/wiki/Covalent_bondhttps://en.wikipedia.org/wiki/Crystallization_of_polymershttps://en.wikipedia.org/wiki/Crystallization_of_polymershttps://en.wikipedia.org/wiki/Crystallization_of_polymershttps://en.wikipedia.org/wiki/Crystallinityhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/LDPEhttps://en.wikipedia.org/wiki/MDPEhttps://en.wikipedia.org/wiki/MDPEhttps://en.wikipedia.org/wiki/HDPEhttps://en.wikipedia.org/wiki/HDPEhttps://en.wikipedia.org/wiki/Aromatic_hydrocarbonhttps://en.wikipedia.org/wiki/Aromatic_hydrocarbonhttps://en.wikipedia.org/wiki/Toluenehttps://en.wikipedia.org/wiki/Xylenehttps://en.wikipedia.org/wiki/Trichloroethanehttps://en.wikipedia.org/wiki/Trichlorobenzenehttps://en.wikipedia.org/wiki/Trichlorobenzenehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Ullmann-10https://en.wikipedia.org/wiki/Waterhttps://en.wikipedia.org/wiki/Oxygenhttps://en.wikipedia.org/wiki/Oxygenhttps://en.wikipedia.org/wiki/Oxygenhttps://en.wikipedia.org/wiki/Carbon_dioxidehttps://en.wikipedia.org/wiki/Flavoringshttps://en.wikipedia.org/wiki/Carbon_blackhttps://en.wikipedia.org/wiki/Candlehttps://en.wikipedia.org/wiki/Candlehttps://en.wikipedia.org/wiki/Candlehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-11https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=6https://en.wikipedia.org/wiki/Catalysthttps://en.wikipedia.org/wiki/Chromium_trioxidehttps://en.wikipedia.org/wiki/Robert_Banks_(chemist)https://en.wikipedia.org/wiki/Robert_Banks_(chemist)https://en.wikipedia.org/wiki/J._Paul_Hoganhttps://en.wikipedia.org/wiki/Phillips_Petroleumhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-8https://en.wikipedia.org/wiki/Karl_Zieglerhttps://en.wikipedia.org/wiki/Karl_Zieglerhttps://en.wikipedia.org/wiki/Titaniumhttps://en.wikipedia.org/wiki/Halidehttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Magnesium_chloridehttps://en.wikipedia.org/wiki/Magnesium_chloridehttps://en.wikipedia.org/wiki/Metallocenehttps://en.wikipedia.org/wiki/Walter_Kaminskyhttps://en.wikipedia.org/w/index.php?title=Hansj%C3%B6rg_Sinn&action=edit&redlink=1https://en.wikipedia.org/wiki/Olefinhttps://en.wikipedia.org/wiki/Resinhttps://en.wikipedia.org/w/index.php?title=Very_low_density_polyethylene&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Very_low_density_polyethylene&action=edit&redlink=1https://en.wikipedia.org/wiki/Linear_low-density_polyethylenehttps://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene#UHMWfiberhttps://en.wikipedia.org/wiki/Aramidhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=2https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=3https://en.wikipedia.org/wiki/Hardnesshttps://en.wikipedia.org/wiki/Ductilityhttps://en.wikipedia.org/wiki/Impact_strengthhttps://en.wikipedia.org/wiki/Impact_strengthhttps://en.wikipedia.org/wiki/Creep_(deformation)https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=4https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=5https://en.wikipedia.org/wiki/Kerosenehttps://en.wikipedia.org/wiki/Covalent_bondhttps://en.wikipedia.org/wiki/Crystallization_of_polymershttps://en.wikipedia.org/wiki/Crystallinityhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/LDPEhttps://en.wikipedia.org/wiki/MDPEhttps://en.wikipedia.org/wiki/HDPEhttps://en.wikipedia.org/wiki/Aromatic_hydrocarbonhttps://en.wikipedia.org/wiki/Aromatic_hydrocarbonhttps://en.wikipedia.org/wiki/Toluenehttps://en.wikipedia.org/wiki/Xylenehttps://en.wikipedia.org/wiki/Trichloroethanehttps://en.wikipedia.org/wiki/Trichlorobenzenehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Ullmann-10https://en.wikipedia.org/wiki/Waterhttps://en.wikipedia.org/wiki/Oxygenhttps://en.wikipedia.org/wiki/Carbon_dioxidehttps://en.wikipedia.org/wiki/Flavoringshttps://en.wikipedia.org/wiki/Carbon_blackhttps://en.wikipedia.org/wiki/Candlehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-11https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=6


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POLYMERIZATION

Polyethylene is a goodelectrical insulator. t offers good trac"ing resistance, however, itbecomes easily electrostatically charged (which can be reduced by additions of graphite, carbonblac"or antistatic agents+.

Optical Properties#.%

Fepending on thermal history and film thic"ness P can vary between almost clear(transparent+, mil"y!opaue (translucent+ or opaue. P!KF thereby owns the largest, P!KKFslightly lower and P!GF the least transparency. Transparency is reduced bycrystallites, if theyare larger than the wavelength of light. #H=%

Manufacturing Process#

Monomer#.%

thylene (ethene+

The ingredient or monomeris ethylene(EPA*name ethene+, a gaseoushydrocarbonwith theformula *=G$, which can be viewed as a pair of methylene groups(B*G=+ connected to each other. Iecause the compound is highly reactive, the ethylene must be ofhigh purity. Typical specifications are - ppm for water, oxygen, and other al"enes. Acceptablecontaminants include @=, ethane (common precursor to ethylene+, and methane. thylene isusually produced from petrochemical sources, but also is generated by dehydration of ethanol. #H1%

Polymerization#.%

thylene is a rather stable molecule that polymerizes only upon contact with catalysts. Theconversion is highlyexothermic. *oordination polymerizationis the most pervasive technology,which means that metal chlorides or metal oxides are used. The most common catalysts consistof titanium(+ chloride, the so!called ?iegler!@atta catalysts. Another common catalyst isthePhillips catalyst,prepared by depositing chromium()+ oxideon silica.#H1%Polythylene can beproduced through radical polymerization, but this route has only limited utility and typicallyreuires high!pressure apparatus.

Joining

*ommonly used methods for ;oining polyethylene parts together include:#H3%

Got gas welding

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https://en.wikipedia.org/wiki/Electrical_insulatorhttps://en.wikipedia.org/wiki/Electrical_insulatorhttps://en.wikipedia.org/wiki/Carbon_blackhttps://en.wikipedia.org/wiki/Carbon_blackhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=7https://en.wikipedia.org/wiki/Transparency_and_translucencyhttps://en.wikipedia.org/wiki/Translucenthttps://en.wikipedia.org/wiki/Opacity_(optics)https://en.wikipedia.org/wiki/Crystallitehttps://en.wikipedia.org/wiki/Crystallitehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-12https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=9https://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/IUPAChttps://en.wikipedia.org/wiki/Gashttps://en.wikipedia.org/wiki/Hydrocarbonhttps://en.wikipedia.org/wiki/Hydrocarbonhttps://en.wikipedia.org/wiki/Methylene_grouphttps://en.wikipedia.org/wiki/Alkenehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Ullmann-10https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=10https://en.wikipedia.org/wiki/Exothermichttps://en.wikipedia.org/wiki/Exothermichttps://en.wikipedia.org/wiki/Coordination_polymerizationhttps://en.wikipedia.org/wiki/Titanium(III)_chloridehttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Phillips_catalysthttps://en.wikipedia.org/wiki/Phillips_catalysthttps://en.wikipedia.org/wiki/Phillips_catalysthttps://en.wikipedia.org/wiki/Chromium_trioxidehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Ullmann-10https://en.wikipedia.org/wiki/Radical_polymerizationhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-pdl-13https://en.wikipedia.org/wiki/Hot_gas_weldinghttps://en.wikipedia.org/wiki/Electrical_insulatorhttps://en.wikipedia.org/wiki/Carbon_blackhttps://en.wikipedia.org/wiki/Carbon_blackhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=7https://en.wikipedia.org/wiki/Transparency_and_translucencyhttps://en.wikipedia.org/wiki/Translucenthttps://en.wikipedia.org/wiki/Opacity_(optics)https://en.wikipedia.org/wiki/Crystallitehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-12https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=9https://en.wikipedia.org/wiki/Monomerhttps://en.wikipedia.org/wiki/Ethylenehttps://en.wikipedia.org/wiki/IUPAChttps://en.wikipedia.org/wiki/Gashttps://en.wikipedia.org/wiki/Hydrocarbonhttps://en.wikipedia.org/wiki/Methylene_grouphttps://en.wikipedia.org/wiki/Alkenehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Ullmann-10https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=10https://en.wikipedia.org/wiki/Exothermichttps://en.wikipedia.org/wiki/Coordination_polymerizationhttps://en.wikipedia.org/wiki/Titanium(III)_chloridehttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Phillips_catalysthttps://en.wikipedia.org/wiki/Chromium_trioxidehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Ullmann-10https://en.wikipedia.org/wiki/Radical_polymerizationhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-pdl-13https://en.wikipedia.org/wiki/Hot_gas_welding


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POLYMERIZATION

4astening

nfrared welding

Kaser welding

Eltrasonic welding

Geat sealing

Geat fusion

Adhesivesand solventsare rarely used because polyethylene is nonpolarand has a highresistance to solvents. Pressure!sensitive adhesives(P6A+ are feasible if the surface is flametreatedor corona treated. *ommonly used adhesives include: #H3%

Fispersion of solvent!type P6As

Polyurethane contact adhesives

Two!part polyurethaneor epoxy adhesives

)inyl acetatecopolymerhot melt adhesives

Classification

Polyethylene is classified by its densityand branching. ts mechanical properties dependsignificantly on variables such as the extent and type of branching, the crystal structure, and

themolecular weight.There are several types of polyethylene:

Eltra!high!molecular!weight polyethylene(EG7>P+

Eltra!low!molecular!weight polyethylene (EK7>P or P!>AQ+

Gigh!molecular!weight polyethylene (G7>P+

Gigh!density polyethylene(GFP+

Gigh!density cross!lin"ed polyethylene (GFQKP+

*ross!lin"ed polyethylene(PQ or QKP+

7edium!density polyethylene(7FP+

Kinear low!density polyethylene(KKFP+

Kow!density polyethylene(KFP+

)ery!low!density polyethylene ()KFP+

*hlorinated polyethylene (*P+

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https://en.wikipedia.org/wiki/Fastenershttps://en.wikipedia.org/w/index.php?title=Infrared_welding&action=edit&redlink=1https://en.wikipedia.org/wiki/Laser_weldinghttps://en.wikipedia.org/wiki/Ultrasonic_weldinghttps://en.wikipedia.org/wiki/Heat_sealhttps://en.wikipedia.org/wiki/Heat_fusionhttps://en.wikipedia.org/wiki/Adhesivehttps://en.wikipedia.org/wiki/Solventhttps://en.wikipedia.org/wiki/Solventhttps://en.wikipedia.org/wiki/Nonpolarhttps://en.wikipedia.org/wiki/Nonpolarhttps://en.wikipedia.org/wiki/Pressure-sensitive_adhesivehttps://en.wikipedia.org/wiki/Pressure-sensitive_adhesivehttps://en.wikipedia.org/w/index.php?title=Flame_treatment&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Flame_treatment&action=edit&redlink=1https://en.wikipedia.org/wiki/Corona_treatmenthttps://en.wikipedia.org/wiki/Polyethylene#cite_note-pdl-13https://en.wikipedia.org/wiki/Polyurethane_adhesivehttps://en.wikipedia.org/wiki/Epoxy_adhesivehttps://en.wikipedia.org/wiki/Vinyl_acetatehttps://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Hot_melt_adhesivehttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/Branching_(chemistry)https://en.wikipedia.org/wiki/Molecular_weighthttps://en.wikipedia.org/wiki/Molecular_weighthttps://en.wikipedia.org/wiki/Molecular_weighthttps://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylenehttps://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylenehttps://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/Cross-linked_polyethylenehttps://en.wikipedia.org/wiki/Cross-linked_polyethylenehttps://en.wikipedia.org/wiki/Medium-density_polyethylenehttps://en.wikipedia.org/wiki/Linear_low-density_polyethylenehttps://en.wikipedia.org/wiki/Low-density_polyethylenehttps://en.wikipedia.org/wiki/Fastenershttps://en.wikipedia.org/w/index.php?title=Infrared_welding&action=edit&redlink=1https://en.wikipedia.org/wiki/Laser_weldinghttps://en.wikipedia.org/wiki/Ultrasonic_weldinghttps://en.wikipedia.org/wiki/Heat_sealhttps://en.wikipedia.org/wiki/Heat_fusionhttps://en.wikipedia.org/wiki/Adhesivehttps://en.wikipedia.org/wiki/Solventhttps://en.wikipedia.org/wiki/Nonpolarhttps://en.wikipedia.org/wiki/Pressure-sensitive_adhesivehttps://en.wikipedia.org/w/index.php?title=Flame_treatment&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Flame_treatment&action=edit&redlink=1https://en.wikipedia.org/wiki/Corona_treatmenthttps://en.wikipedia.org/wiki/Polyethylene#cite_note-pdl-13https://en.wikipedia.org/wiki/Polyurethane_adhesivehttps://en.wikipedia.org/wiki/Epoxy_adhesivehttps://en.wikipedia.org/wiki/Vinyl_acetatehttps://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Hot_melt_adhesivehttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/Branching_(chemistry)https://en.wikipedia.org/wiki/Molecular_weighthttps://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylenehttps://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/Cross-linked_polyethylenehttps://en.wikipedia.org/wiki/Medium-density_polyethylenehttps://en.wikipedia.org/wiki/Linear_low-density_polyethylenehttps://en.wikipedia.org/wiki/Low-density_polyethylene


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POLYMERIZATION

>ith regard to sold volumes, the most important polyethylene grades are GFP, KKFP, andKFP.

Ultrahighmolec!lar"eight polyethylene (U#M$PE)#.%

6tainless steel and ultra high molecular weight polythene hip replacement

EG7>P is polyethylene with a molecular weight numbering in the millions, usually between 3.Hand -.CD million. The high molecular weight ma"es it a very toughmaterial, but results in lessefficient pac"ing of the chains into the crystal structureas evidenced by densities of less thanhigh density polyethylene (for example, 1.931L1.93- gRcm3+. EG7>P can be made through anycatalyst technology, although ?iegler catalysts are most common. Iecause of its outstandingtoughness and its cut, wear, and excellent chemical resistance, EG7>P is used in a diverserange of applications. These include can! andbottle!handling machine parts, moving parts onweaving machines, bearings, gears, artificial ;oints, edge protection on ice rin"s, and butchers'chopping boards. t is commonly used for the construction of articular portions ofimplantsusedfor hipand"nee replacements.As fiber,it competes with aramidinbulletproof vests.

#ighdensity polyethylene (#%PE)#.%Main article:High-density polyethylene

GFPpipe installation in storm drain pro;ect in7exico.

GFP is defined by a density of greater or eual to 1.9$H gRcm 3. GFP has a low degree ofbranching. The mostly linear molecules pac" together well, so intermolecular forces are strongerthan in highly branched polymers. GFP can be produced by chromiumRsilica catalysts, ?iegler!@atta catalystsor metallocenecatalysts& by choosing catalysts and reaction conditions, the smallamount of branching that does occur can be controlled. These catalysts prefer the formationof free radicalsat the ends of the growing polyethylene molecules. They cause new ethylenemonomers to add to the ends of the molecules, rather than along the middle, causing the growthof a linear chain.

GFP has high tensile strength. t is used in products and pac"aging such as mil" ;ugs,

detergent bottles, butter tubs, garbage containers, and water pipes. ne!third of all toys are

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https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=13https://en.wikipedia.org/wiki/Toughnesshttps://en.wikipedia.org/wiki/Crystal_structurehttps://en.wikipedia.org/wiki/Bottlehttps://en.wikipedia.org/wiki/Implant_(medicine)https://en.wikipedia.org/wiki/Implant_(medicine)https://en.wikipedia.org/wiki/Hip_replacementhttps://en.wikipedia.org/wiki/Knee_replacementhttps://en.wikipedia.org/wiki/Knee_replacementhttps://en.wikipedia.org/wiki/Knee_replacementhttps://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene#UHMWfiberhttps://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene#UHMWfiberhttps://en.wikipedia.org/wiki/Aramidhttps://en.wikipedia.org/wiki/Aramidhttps://en.wikipedia.org/wiki/Bulletproof_vestshttps://en.wikipedia.org/wiki/Bulletproof_vestshttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=14https://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/Mexicohttps://en.wikipedia.org/wiki/Mexicohttps://en.wikipedia.org/wiki/Chromiumhttps://en.wikipedia.org/wiki/Chromiumhttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Metallocenehttps://en.wikipedia.org/wiki/Free_radicalshttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=13https://en.wikipedia.org/wiki/Toughnesshttps://en.wikipedia.org/wiki/Crystal_structurehttps://en.wikipedia.org/wiki/Bottlehttps://en.wikipedia.org/wiki/Implant_(medicine)https://en.wikipedia.org/wiki/Hip_replacementhttps://en.wikipedia.org/wiki/Knee_replacementhttps://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene#UHMWfiberhttps://en.wikipedia.org/wiki/Aramidhttps://en.wikipedia.org/wiki/Bulletproof_vestshttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=14https://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/High-density_polyethylenehttps://en.wikipedia.org/wiki/Mexicohttps://en.wikipedia.org/wiki/Chromiumhttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Ziegler-Natta_catalysthttps://en.wikipedia.org/wiki/Metallocenehttps://en.wikipedia.org/wiki/Free_radicals


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POLYMERIZATION

manufactured from GFP. n =11D, the global GFP consumption reached a volume of morethan 31 million tons.#H$%

Crosslinked polyethylene (PE& or &'PE)

PQ is a medium! to high!density polyethylene containing cross!lin"bonds introduced into the

polymer structure, changing the thermoplastic into a thermoset. The high!temperature propertiesof the polymer are improved, its flow is reduced, and its chemical resistance is enhanced. PQ isused in some potable!water plumbing systems because tubes made of the material can beexpanded to fit over a metal nipple and it will slowly return to its original shape, forming apermanent, water!tight connection.

Medi!mdensity polyethylene (M%PE)#.%

7FP is defined by a density range of 1.9=CL1.9$1 gRcm 3. 7FP can be produced bychromiumRsilica catalysts, ?iegler!@atta catalysts, or metallocene catalysts. 7FP has goodshoc" and drop resistance properties. t also is less notch!sensitive than GFP& stress!crac"ingresistance is better than GFP. 7FP is typically used in gas pipes and fittings, sac"s, shrin"film, pac"aging film, carrier bags, and screw closures.

'inear lo"density polyethylene (''%PE

KKFP is defined by a density range of 1.9H-L1.9=- gRcm 3. KKFP is a substantially linearpolymer with significant numbers of short branches, commonly made bycopolymerizationofethylene with short!chain alpha!olefins(for example, H!butene,H!hexene, and H!octene+. KKFPhas higher tensile strength than KFP, and it exhibits higher impact and puncture resistancethanKFP. Kower thic"ness (gauge+ films can be blown, compared with KFP, with betterenvironmental stress!crac"ing resistance, but is not as easy to process. KKFP is used inpac"aging, particularly film for bags and sheets. Kower thic"ness may be used compared toKFP. t is used for cable coverings, toys, lids, buc"ets, containers, and pipe. >hile otherapplications are available, KKFP is used predominantly in film applications due to its toughness,

flexibility, and relative transparency. Product examples range from agricultural films, 6aran wrap,and bubble wrap, to multilayer and composite films. n =1H3, the world KKFP mar"et reached avolume of E6S$1 billion.#H-%

'o"density polyethylene ('%PE)#.%

KFP is defined by a density range of 1.9H1L1.9$1 gRcm 3. KFP has a high degree of short! andlong!chain branching, which means that the chains do not pac" into the crystal structureas well.t has, therefore, less strong intermolecular forces as the instantaneous!dipole induced!dipoleattractionis less. This results in a lowertensile strengthand increasedductility. KFP is createdby free!radical polymerization.The high degree of branching with long chains gives molten KFPuniue and desirable flow properties. KFP is used for both rigid containers and plastic film

applications such as plastic bags and film wrap. n =1H3, the global KFP mar"et had a volumeof almost E6S33 billion.#HC%

The radical polymerization process used to ma"e KFP does not include a catalyst thatsupervises the radical sites on the growing P chains. (n GFP synthesis, the radical sites areat the ends of the P chains, because the catalyst stabilizes their formation at the ends.+6econdary radicals(in the middle of a chain+ are more stable than primary radicals (at the end ofthe chain+, and tertiary radicals (at a branch point+ are more stable yet. ach time an ethylenemonomer is added, it creates a primary radical, but often these will rearrange to form more stablesecondary or tertiary radicals. Addition of ethylene monomers to the secondary or tertiary sitescreates branching.

erylo"density polyethylene ('%PE)#.%

)KFP is defined by a density range of 1.001L1.9H- gRcm 3. )KFP is a substantially linearpolymer with high levels of short!chain branches, commonly made by copolymerization of

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https://en.wikipedia.org/wiki/Polyethylene#cite_note-14https://en.wikipedia.org/wiki/Cross-linkhttps://en.wikipedia.org/wiki/Cross-linkhttps://en.wikipedia.org/wiki/Thermosethttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=16https://en.wikipedia.org/wiki/Copolymerizationhttps://en.wikipedia.org/wiki/Copolymerizationhttps://en.wikipedia.org/wiki/Alpha-olefinhttps://en.wikipedia.org/wiki/1-butenehttps://en.wikipedia.org/wiki/1-butenehttps://en.wikipedia.org/wiki/1-hexenehttps://en.wikipedia.org/wiki/1-octenehttps://en.wikipedia.org/wiki/Puncture_resistancehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-15https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=18https://en.wikipedia.org/wiki/Crystal_structurehttps://en.wikipedia.org/wiki/Crystal_structurehttps://en.wikipedia.org/wiki/Instantaneous-dipole_induced-dipole_attractionhttps://en.wikipedia.org/wiki/Instantaneous-dipole_induced-dipole_attractionhttps://en.wikipedia.org/wiki/Instantaneous-dipole_induced-dipole_attractionhttps://en.wikipedia.org/wiki/Tensile_strengthhttps://en.wikipedia.org/wiki/Tensile_strengthhttps://en.wikipedia.org/wiki/Ductilityhttps://en.wikipedia.org/wiki/Ductilityhttps://en.wikipedia.org/wiki/Radical_polymerizationhttps://en.wikipedia.org/wiki/Radical_polymerizationhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-16https://en.wikipedia.org/wiki/Free_radicalhttps://en.wikipedia.org/wiki/Free_radicalhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=19https://en.wikipedia.org/wiki/Polyethylene#cite_note-14https://en.wikipedia.org/wiki/Cross-linkhttps://en.wikipedia.org/wiki/Thermosethttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=16https://en.wikipedia.org/wiki/Copolymerizationhttps://en.wikipedia.org/wiki/Alpha-olefinhttps://en.wikipedia.org/wiki/1-butenehttps://en.wikipedia.org/wiki/1-hexenehttps://en.wikipedia.org/wiki/1-octenehttps://en.wikipedia.org/wiki/Puncture_resistancehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-15https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=18https://en.wikipedia.org/wiki/Crystal_structurehttps://en.wikipedia.org/wiki/Instantaneous-dipole_induced-dipole_attractionhttps://en.wikipedia.org/wiki/Instantaneous-dipole_induced-dipole_attractionhttps://en.wikipedia.org/wiki/Tensile_strengthhttps://en.wikipedia.org/wiki/Ductilityhttps://en.wikipedia.org/wiki/Radical_polymerizationhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-16https://en.wikipedia.org/wiki/Free_radicalhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=19


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POLYMERIZATION

ethylene with short!chain alpha!olefins (for example, H!butene, H!hexene and H!octene+. )KFPis most commonly produced using metallocene catalysts due to the greater co!monomerincorporation exhibited by these catalysts. )KFPs are used for hose and tubing, ice and frozenfood bags, food pac"aging and stretch wrap as well as impact modifiers when blended with otherpolymers.

Jecently, much research activity has focused on the nature and distribution of long chainbranches in polyethylene. n GFP, a relatively small number of these branches, perhaps one inH11 or H,111 branches per bac"bone carbon, can significantly affect therheologicalproperties ofthe polymer.

Copolymers#.%

n addition to copolymerizationwith alpha!olefins, ethylene can also be copolymerized with awide range of other monomers and ionic composition that creates ionized free radicals. *ommonexamples include vinyl acetate(the resulting product isethylene!vinyl acetatecopolymer, or )A,widely used in athletic!shoe sole foams+ and a variety of acrylates.Applicationsof acryliccopolymerinclude pac"aging and sporting goods, and superplasticizer,used forcement production.

Molec!lar str!ct!re of different PE types#.%

The diverse material behavior of different types of polyethylene can be explained by theirmolecular structure. 7olecular weight and crystallinity are having the biggest impact, thecrystallinity in turn depends on molecular weight and degree of branching. The less the polymerchains are branched, and the smaller the molecular weight, the higher the crystallinity ofpolyethylene. The crystallinity is between 3- (P!KFRP!KKF+ and 01 (P!GF+. >ithincrystallites polyethylene has a density of H.1 gcm !3, in the amorphous regions of 1.0C gcm !3.Thus, an almost linear relationship exists between density and crystallinity.#9%

The degree of branching of the different types of polyethylene can be schematically representedas follows:#9%

P"-,

P"-==,

P"-=,

The figure shows polyethylene bac"bones, short!chain branches and side chain branches. The polymer chains are represented linearly.

Chain ranches#.%

The properties of polyethylene are highly dependent on type and number of chain branches. Thechain branches in turn depend on the process used: either the high!pressure process (only P!KF+ or the low!pressure process (all other P grades+. Kow!density polyethylene is produced bythe high!pressure process by radical polymerization, thereby numerous short chain branches aswell as long chain branches are formed. 6hort chain branches are formed by intramolecularchain

transferreactions, they are always butylor ethylchain branches because the reaction proceedsafter the following mechanism:

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https://en.wikipedia.org/wiki/Rheologyhttps://en.wikipedia.org/wiki/Rheologyhttps://en.wikipedia.org/wiki/Rheologyhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=20https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=20https://en.wikipedia.org/wiki/Copolymerizationhttps://en.wikipedia.org/wiki/Vinyl_acetatehttps://en.wikipedia.org/wiki/Ethylene-vinyl_acetatehttps://en.wikipedia.org/wiki/Ethylene-vinyl_acetatehttps://en.wikipedia.org/wiki/Acrylatehttps://en.wikipedia.org/wiki/Acrylatehttps://en.wikipedia.org/wiki/Acrylic_resinhttps://en.wikipedia.org/wiki/Acrylic_resinhttps://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Superplasticizerhttps://en.wikipedia.org/wiki/Superplasticizerhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=21https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=22https://en.wikipedia.org/wiki/Intramolecularhttps://en.wikipedia.org/wiki/Intramolecularhttps://en.wikipedia.org/wiki/Chain_transferhttps://en.wikipedia.org/wiki/Chain_transferhttps://en.wikipedia.org/wiki/Butyl_grouphttps://en.wikipedia.org/wiki/Ethyl_grouphttps://en.wikipedia.org/wiki/Ethyl_grouphttps://en.wikipedia.org/wiki/Rheologyhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=20https://en.wikipedia.org/wiki/Copolymerizationhttps://en.wikipedia.org/wiki/Vinyl_acetatehttps://en.wikipedia.org/wiki/Ethylene-vinyl_acetatehttps://en.wikipedia.org/wiki/Acrylatehttps://en.wikipedia.org/wiki/Acrylic_resinhttps://en.wikipedia.org/wiki/Copolymerhttps://en.wikipedia.org/wiki/Superplasticizerhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=21https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=22https://en.wikipedia.org/wiki/Intramolecularhttps://en.wikipedia.org/wiki/Chain_transferhttps://en.wikipedia.org/wiki/Chain_transferhttps://en.wikipedia.org/wiki/Butyl_grouphttps://en.wikipedia.org/wiki/Ethyl_group


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POLYMERIZATION

Environmental issues#.%

A bag manufactured from polyethylene.

Although ethylene can be produced from renewables, polyethylene is mainly made frompetroleum or natural gas.

*iodegrading plastics#.%

ne of the main problems of polyethylene is that without special treatment it is not readilybiodegradable, and thus accumulates. n Mapan, getting rid of plastics in an environmentallyfriendly way was the ma;or problem discussed until the4u"ushima disasterin =1HH. t waslisted as a S91 billion mar"et for solutions. 6ince =110, Mapan has rapidly increased therecycling of plastics, but still has a large amount of plastic wrapping which goes to waste. #HD%

n 7ay =110, Faniel Iurd, a HC!year!old *anadian, won the *anada!>ide 6cience 4airinttawa after discovering thatPseudomonas fluorescens, with the help of Sphingomonas,candegrade over $1 of the weight of plastic bags in less than three months. #H0%

The thermophilic bacterium Brevibacillus borstelensis(strain D1D+ was isolated from a soilsample and found to use low!density polyethylene as a sole carbon source& when incubatedtogether at -1 2*. Iiodegradation increased with time exposed to ultravioletradiation.#H9%

n =1H1, a Mapanese researcher, A"inori to, released the prototype of a machine whichcreates oil from polyethylene using a small, self!contained vapor distillation process. #=1%

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https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=23https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=24https://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disasterhttps://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disasterhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-prideaux2007-17https://en.wikipedia.org/wiki/Canada-Wide_Science_Fairhttps://en.wikipedia.org/wiki/Canada-Wide_Science_Fairhttps://en.wikipedia.org/wiki/Pseudomonas_fluorescenshttps://en.wikipedia.org/wiki/Sphingomonashttps://en.wikipedia.org/wiki/Sphingomonashttps://en.wikipedia.org/wiki/Polyethylene#cite_note-18https://en.wikipedia.org/wiki/Brevibacillus_borstelensishttps://en.wikipedia.org/wiki/Ultraviolethttps://en.wikipedia.org/wiki/Polyethylene#cite_note-19https://en.wikipedia.org/wiki/Polyethylene#cite_note-20https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=23https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=24https://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disasterhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-prideaux2007-17https://en.wikipedia.org/wiki/Canada-Wide_Science_Fairhttps://en.wikipedia.org/wiki/Pseudomonas_fluorescenshttps://en.wikipedia.org/wiki/Sphingomonashttps://en.wikipedia.org/wiki/Polyethylene#cite_note-18https://en.wikipedia.org/wiki/Brevibacillus_borstelensishttps://en.wikipedia.org/wiki/Ultraviolethttps://en.wikipedia.org/wiki/Polyethylene#cite_note-19https://en.wikipedia.org/wiki/Polyethylene#cite_note-20


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POLYMERIZATION

Acinetobactersp. 3-H can degrade lower molecular!weight P oligomers. >hen P issub;ected to thermo! and photo!oxidization, products including al"anes, al"enes, "etones,aldehydes, alcohols, carboxylic acid, "eto!acids, dicarboxylic acids, lactones, and esters arereleased.#=H%

n =1H$, a *hinese researcher discovered thatndian mealmothlarvae could metabolize

polyethylene from observing that plastic bags at his home had small holes in them. Feducingthat the hungry larvae must have digested the plastic somehow, he and his team analyzedtheir gut bacteria and found a few that could use plastic as their only carbon source. @ot onlycould the bacteria from the guts of the Plodia interpunctellamoth larvae metabolizepolyethylene, they degraded it significantly, dropping its tensile strength by -1, its mass byH1 and the molecular weights of its polymeric chains by H3. #==%#=3%

Chemically modified polyethylene#.%

Polyethylene may either be modified in the polymerization by polaror non!polarcomonomersor after polymerization through polymer!analogous reactions. *ommonpolymer!analogous reactions are in case of

polyethylene crosslin"ing, chlorinationand sulfochlorination.

+onpolar ethylene copolymers#.%

,olefins#.%

n the low pressure processU!olefins(eg.H!buteneor H!hexene+ may be added, which areincorporated in the polymer chain during polymerization. These copolymers introduce shortside chains, thuscrystallinityand densityare reduced. As explained above, mechanical andthermal properties are changed thereby. n particular, P!KKF is produced this way.

Metallocene polyethylene (PEMC)#.%

7etallocene polyethylene (P!7+ is prepared by means ofmetallocene catalysts, usuallyincluding copolymers (z. I. ethene R hexene+. 7etallocene polyethylene has a relatively

narrow molecular weight distribution, exceptionally high toughness, excellent opticalproperties and a uniform comonomer content. Iecause of the narrow molecular weightdistribution it behaves less pseudoplastic (especially under larger shear rates+. 7etallocenepolyethylene has a low proportion of low molecular weight (extractable+ components and alow welding and sealing temperature. Thus, it is particularly suitable for the food industry.#9%:=30#=$%:H9

Polyethylene "ith m!ltimodal molec!lar "eight distri!tion#.%

Polyethylene with multimodal molecular weight distribution consists of several polymerfractions, which are homogeneously mixed. 6uch polyethylene types offer extremely highstiffness, toughness, strength, stress crac" resistance and an increased crac" propagationresistance. They consist of eual proportions higher and lower mole"ularerer polymer

fractions. The lower molecular weight units crystallize easier and relax faster. The highermolecular weight fractions form lin"ing molecules between crystallites, thereby increasingtoughness and stress crac" resistance. Polyethylene with multimodal molecular weightdistribution can be prepared either in two!stage reactors, by catalysts with two differentactive centers on a carrier or by blending in extruders. #9%:=30

Cyclic olefin copolymers (COC)#.%

*yclic olefin copolymersare prepared by copolymerization of etheneand cycloolefins(usually norbornene+ produced by using metallocene catalysts. Theresulting polymers are amorphous polymers and particularly transparent and heat resistant.#9%:=39#=$%:=D

Polar ethylene copolymers#.%

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https://en.wikipedia.org/wiki/Polyethylene#cite_note-21https://en.wikipedia.org/wiki/Polyethylene#cite_note-21https://en.wikipedia.org/wiki/Indian_mealmothhttps://en.wikipedia.org/wiki/Indian_mealmothhttps://en.wikipedia.org/wiki/Indian_mealmothhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-22https://en.wikipedia.org/wiki/Polyethylene#cite_note-23https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=25https://en.wikipedia.org/wiki/Chemical_polarityhttps://en.wikipedia.org/wiki/Comonomerhttps://en.wikipedia.org/wiki/Comonomerhttps://en.wikipedia.org/wiki/Comonomerhttps://en.wikipedia.org/wiki/Cross-linkhttps://en.wikipedia.org/wiki/Chlorination_reactionhttps://en.wikipedia.org/wiki/Sulfochlorinationhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=26https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=27https://en.wikipedia.org/wiki/Alpha-olefinhttps://en.wikipedia.org/wiki/Alpha-olefinhttps://en.wikipedia.org/wiki/1-Butenehttps://en.wikipedia.org/wiki/1-Butenehttps://en.wikipedia.org/wiki/1-Hexenehttps://en.wikipedia.org/wiki/Crystallinityhttps://en.wikipedia.org/wiki/Crystallinityhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=28https://en.wikipedia.org/wiki/Metallocene_catalystshttps://en.wikipedia.org/wiki/Metallocene_catalystshttps://en.wikipedia.org/wiki/Molecular_weight_distributionhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Vasile-24https://en.wikipedia.org/wiki/Polyethylene#cite_note-Vasile-24https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=29https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=30https://en.wikipedia.org/wiki/Cyclic_olefin_copolymerhttps://en.wikipedia.org/wiki/Cycloolefinhttps://en.wikipedia.org/wiki/Norbornenehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Vasile-24https://en.wikipedia.org/wiki/Polyethylene#cite_note-Vasile-24https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=31https://en.wikipedia.org/wiki/Polyethylene#cite_note-21https://en.wikipedia.org/wiki/Indian_mealmothhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-22https://en.wikipedia.org/wiki/Polyethylene#cite_note-23https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=25https://en.wikipedia.org/wiki/Chemical_polarityhttps://en.wikipedia.org/wiki/Comonomerhttps://en.wikipedia.org/wiki/Cross-linkhttps://en.wikipedia.org/wiki/Chlorination_reactionhttps://en.wikipedia.org/wiki/Sulfochlorinationhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=26https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=27https://en.wikipedia.org/wiki/Alpha-olefinhttps://en.wikipedia.org/wiki/1-Butenehttps://en.wikipedia.org/wiki/1-Hexenehttps://en.wikipedia.org/wiki/Crystallinityhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=28https://en.wikipedia.org/wiki/Metallocene_catalystshttps://en.wikipedia.org/wiki/Molecular_weight_distributionhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Vasile-24https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=29https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=30https://en.wikipedia.org/wiki/Cyclic_olefin_copolymerhttps://en.wikipedia.org/wiki/Cycloolefinhttps://en.wikipedia.org/wiki/Norbornenehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Vasile-24https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=31


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POLYMERIZATION

The basic compounds used as polar comonomers are vinyl alcohol (thenol, an unsaturatedalcohol+, acrylic acid (propenoic acid, an unsaturated acid+ andesterscontaining one of thetwo compounds.

Ethylene copolymers "ith !nsat!rated alcohols#.%

thyleneRvinyl alcohol copolymer ()G+ is (formally+ a copolymer of P and vinyl alcohol(ethenol+, which is prepared by (partial+ hydrolysis of ethylene!vinyl acetate copolymer (asvinyl alcohol itself is not stable+. Gowever, typically )G has a higher comonomer contentthan the )A* commonly used.#=-%:=39

)G is used in multilayer films for pac"aging as a barrier layer (barrier plastic+. As )G ishygroscopic (water!attracting+, it absorbs water from the environment, whereby it loses itsbarrier effect. Therefore, it must be used as a core layer surrounded by other plastics (li"eKFP, PP, PA or PT+. )G is also used as a coating agent against corrosion at streetlights, traffic light poles and noise protection walls.#=-%:=39

Ethylene-acrylic acid copolymers (EAA)#.%

*opolymer of ethylene and unsaturated carboxylic acids (such as acrylic acid+ are

characterized by good adhesion to different materials, by resistance to staress crac"ing andhigh flexibility.#=C%Gowever, they are more sensitive to heat and oxidation than ethylenehomopolymers. thyleneRacrylic acid copolymers are used asadhesion promoters.#9%

f salts of an unsaturated carboxylic acid are present in the polymer, thermo!reversible ionnetwor"s are formed, they are called ionomers.onomers are highly transparentthermoplastics which are characterized by high adhesion to metals, high abrasion resistanceand high water absorption.#9%

Ethylene copolymers "ith !nsat!rated esters#.%

f unsaturated esters are copolymerized with ethylene, either the alcohol moiety may be inthe polymer bac"bone (as it is the case in ethylene!vinyl acetate copolymer+ or of the acidmoiety (e. g. in ethylene!ethyl acrylate copolymer+. thylene!vinyl acetatecopolymers are

prepared similarly to KF!P by high pressure polymerization. The proportion of comonomerhas a decisive influence on the behaviour of the polymer.

The density decreases up to a comonomer share of H1 because of the disturbed crystalformation. >ith higher proportions it approaches to the one ofpolyvinyl acetate(H.HD gRcm3+.#=-%:=3-Fue to decreasing crystallinity ethylene vinyl acetate copolymers are getting softer withincreasing comonomer content. The polar side groups change the chemical propertiessignificantly (compared to polyethylene+:#9%:==$weather resistance, adhesiveness andweldability rise with comonomer content, while the chemical resistance decreases. Alsomechanical properties are changed: stress crac"ing resistance and toughness in the coldrise, whereas yield stress and heat resistance decrease. >ith a very high proportion ofcomonomers (about -1+ rubbery thermoplastics are produced (thermoplastic elastomers+.#=-%:=3-

thylene!ethyl acrylate copolymers behave similarly to ethylene!vinyl acetate copolymers. #9%:=$1

Crosslinking#.%

)arious methods can used to preparecross!lin"ed polyethylene(P!Q+ from thermoplasticpolyethylene (P!KF, P!KKF or P!GF+. Iy crosslin"ing low!temperature impactstrength, abrasion resistanceand environmental stress crac"ing resistance can be increasedsignificantly, whereas hardnessand rigidity are somewhat reduced. P!Q does not meltanymore (analogous to elastomers+ and is thermally resistant (over longer periods of up toH=1 2*, for short periods without mechanical load up to =-1 2*+. >ith increasing crosslin"ingdensity also the maximum shear modulus increases (even at higher temperatures+. #=D%#=-%P!Qhas significantly enhanced properties compared with ordinary P.#=0%As P!Q is infusible,

always the final pre!products or the mold part are cross!lin"ed.

Applications#.%

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https://en.wikipedia.org/wiki/Vinyl_alcoholhttps://en.wikipedia.org/wiki/Propenoic_acidhttps://en.wikipedia.org/wiki/Esterhttps://en.wikipedia.org/wiki/Esterhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=32https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=33https://en.wikipedia.org/wiki/Polyethylene#cite_note-26https://en.wikipedia.org/w/index.php?title=Adhesion_promoter&action=edit&redlink=1https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Ionomerhttps://en.wikipedia.org/wiki/Ionomerhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=34https://en.wikipedia.org/wiki/Ethylene-vinyl_acetatehttps://en.wikipedia.org/wiki/Polyvinyl_acetatehttps://en.wikipedia.org/wiki/Polyvinyl_acetatehttps://en.wikipedia.org/wiki/Polyvinyl_acetatehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Thermoplastic_elastomerhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=35https://en.wikipedia.org/wiki/Cross-linked_polyethylenehttps://en.wikipedia.org/wiki/Cross-linked_polyethylenehttps://en.wikipedia.org/wiki/Abrasion_resistancehttps://en.wikipedia.org/wiki/Hardnesshttps://en.wikipedia.org/wiki/Hardnesshttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Saechtling-27https://en.wikipedia.org/wiki/Polyethylene#cite_note-Saechtling-27https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Koltzenburg-28https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=36https://en.wikipedia.org/wiki/Vinyl_alcoholhttps://en.wikipedia.org/wiki/Propenoic_acidhttps://en.wikipedia.org/wiki/Esterhttps://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=32https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=33https://en.wikipedia.org/wiki/Polyethylene#cite_note-26https://en.wikipedia.org/w/index.php?title=Adhesion_promoter&action=edit&redlink=1https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Ionomerhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=34https://en.wikipedia.org/wiki/Ethylene-vinyl_acetatehttps://en.wikipedia.org/wiki/Polyvinyl_acetatehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Thermoplastic_elastomerhttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=35https://en.wikipedia.org/wiki/Cross-linked_polyethylenehttps://en.wikipedia.org/wiki/Abrasion_resistancehttps://en.wikipedia.org/wiki/Hardnesshttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Saechtling-27https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Koltzenburg-28https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=36


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POLYMERIZATION

P!Q is used as insulating material for medium and high voltagecable insulation,for hotwater pipes and molded parts in electrical engineering, plant engineering and in automotiveindustry.

Types of crosslinking#.%

A basic distinction is made between peroxide crosslin"ing (P!Qa+, silane crosslin"ing (P!Qb+, electron beam crosslin"ing (P!Qc+ and azo crosslin"ing (P!Qd+. #=D%

Chlorination and s!lfochlorination#.%

*hlorinated Polyethylene(P!*+ is an inexpensive material having a chlorine content from3$ to $$. t is used in blends with P)*because the soft, rubbery chloropolyethylene isembedded in the P)* matrix, thereby increasing theimpact resistance.n addition, it alsoincreases the weather resistance. 4urthermore, it is used for softening P)* foils, withoutris"ing the migrate of plasticizers. *hlorinated polyethylene can be crosslin"ed peroxidicallyto form an elastomer which is used in cable and rubber industry. #=-%>hen chlorinatedpolyethylene is added to other polyolefins, it reduces the flammability.#9%:=$-

*hlorosulfonated P (*67+ is used as starting material for ozone resistant synthetic rubber.#=9%

*ioased polyethylene#.%Main articles: BioplasticsandReneable Polyethylene

Iras"emand Toyota Tsusho *orporationstarted ;oint mar"eting activities to producepolyethylene from sugarcane. Iras"em will build a new facility at their existing industrial unitin Triunfo, J6, Irazil with an annual production capacity of =11,111 short tons(H01,111,111 "g+, and will produce high!density and low!density polyethylenefrom bioethanolderived from sugarcane.#31%

Polyethylene can also be made from other feedstoc"s, including wheat grainand sugar beet.Jetrieved from cane sugar, i.e. plant biomass renewable feedstoc", Irazil is the first countryto develop the product.#citation needed%These developments are using renewable resources rather

than fossil fuel, although the issue of plastic source is currently negligible in the wa"e ofplastic waste and in particular polyethylene waste as shown above.

Nomenclature and general description of the process#.%

The name polyethylene comes from the ingredient and not the resulting chemical compound,which contains no double bonds. The scientific namepolyetheneis systematically derivedfrom the scientific name of the monomer.#3H%#3=%The al"ene monomer converts to a long,sometimes verylong, al"ane in the polymerization process. #3=%n certain circumstances it isuseful to use a structure!based nomenclature& in such casesEPA*recommendspoly(methylene+ (poly(methanediyl+ is a non!preferred alternative+.#3H%The difference in namesbetween the two systems is due to the opening upof the monomer's double bond upon

polymerization.#33%The name is abbreviated to PE. n a similarmanner polypropyleneandpolystyreneare shortened to PP and P6, respectively. n theEnited Ningdom the polymer is commonly called polythene, from the *trade name,although this is not recognized scientifically.

a

+at!ral r!er, also called India r!eror caoutchouc, as initially produced, consists

of polymersof theorganic compoundisoprene, with minor impurities of other organic compounds

plus water. 7alaysia is a leading producer of rubber. 4orms ofpolyisoprenethat are used as

natural rubbers are classified as elastomers.@atural rubber is used by many manufacturing

companies for the production of rubber products. *urrently, rubber is harvested mainly in the

form of the latexfrom certain trees. The latex is a stic"y, mil"y colloiddrawn off by ma"ing

incisions into the bar" and collecting the fluid in vessels in a process called tapping. The latexthen is refined into rubber ready for commercial processing. @atural rubber is used extensively in

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https://en.wikipedia.org/wiki/High_voltagehttps://en.wikipedia.org/wiki/Insulator_(electricity)https://en.wikipedia.org/wiki/Insulator_(electricity)https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=37https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=37https://en.wikipedia.org/wiki/Polyethylene#cite_note-Saechtling-27https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=38https://en.wikipedia.org/w/index.php?title=Chlorinated_Polyethylene&action=edit&redlink=1https://en.wikipedia.org/wiki/Polyvinyl_chloridehttps://en.wikipedia.org/wiki/Polyvinyl_chloridehttps://en.wikipedia.org/wiki/Impact_resistancehttps://en.wikipedia.org/wiki/Impact_resistancehttps://en.wikipedia.org/wiki/Impact_resistancehttps://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Domininghaus-25https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-Kaiser-9https://en.wikipedia.org/wiki/Polyethylene#cite_note-29https://en.wikipedia.org/w/index.php?title=Polyethylene&action=edit&section=39https://en.wikipedia.org/wiki/Bioplasticshttps://en.wikipedia.org/wiki/Bioplasticshttps://en.wikipedia.org/wiki/Renewable_Polyethylenehttps://en.wikipedia.org/wiki/Renewable_Polyethylenehttps://en.wikipedia.org/wiki/Braskemhttps://en.wikipedia.org/wiki/Toyota_Tsusho_Corporationhttps://en.wikipedia.org/wiki/Sugarcanehttps://en.wiki

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