Preparations and Applications of Polymers

8/3/2019 Preparations and Applications of Polymers

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Plastics and Resins : Plastics are the basic materials, those show

property of plasticity and can be moulded byapplying heat /pressure. Resins are the binding materials of polymers

which form major part of polymer. Plastic have advantages over metals and other

materials, because they have :1. Light weight and high strength.2. good thermal and electrical insulation3. high corrosion resistance4. easy workability (casting, moulding etc.)5. High chemical intertness6. Decorative7. Law maintenance cost.





T hermo Plastics : T he polymers which are softened on heating

and hardened on cooling.,

Repeated heating or cooling do not alter anychemical change. T hese are prepared by addition reaction. T hese are made of long chains attached by

weak vander waal¶s fames of attraction. T hese are soft, weak and less brittle. T hese are reclaimed from waste. T hese solvable in some organic solvents.

Resins and plastics are synonomous in thiscase.Ex : PVC, PE, PS, etc.,



T hermo setting Resins : T he polymers which are hardened during their moulding

process. Once they are hardened they cannot be softened. Hence

these are called permanent setting resins. T hese acquire cross ± linked, 3D, Network structure. T he bonds retain their structure. Prolongated heating causes charring of the polymer. T hese are produced by condensation polymerization. T hese are hard, strong and more brittle. T hese cannot be reclaimed from waste. T hese are not soluble in organic solvents.

Ex : Bekalite, Novalac, etc.,







Asbestos : heat & chemical resistanceCatalyst and accelerators : T o increase the

polymerizationEx: Ag, cu, ZnO, etc.,

Stabilizer : T o improve thermal stability

Ex: Lead, Barium, etc.,Lubricants : T o get glossy finishing, to make the mouldingsmoother

Ex: Wax, oils,Anti oxidants : T o prevent chemical oxidation.

EX: Phenol diphenyl aminesColourants : to get desired colour.

Ex: Ferro cynates, Al silicates.



P olyvinyl Chlor ide

T he monomer used for the manufacture of PVC is Vinyl chloride.

PreparationT here are two ways of producing the monomer

Vinyl chloride.One method is by cracking ethylene dichloride

in vapor phase at a temperature of 500oC .

500 oC

CH 2Cl-CH 2Cl H2C=CHCl + HCl



The other me thod is by re acting ac e tyle newith h ydr og e n chlor ide in pre s e nc e of

catalyst . 150o

C

HCl + CH CH H2C=CHClcatalyst

Polyvinyl chloride is obtained by heating awater emulsion of vinyl chloride in presenceof small amount of benzoyl peroxide or hydrogen peroxide in an autoclave under

pressure.H2C=CHCl polymer ization ---[H2C=CHCl-- ]n



PVC is a chemically inert andnonflammable powder having a highsoftening point of 148 oC. T here are twokinds of PVC plastics

1. Plasticised PVC and2. Rigid PVC



P lasticis e d PV C is pr oduc e d by mixing plasticis er s like dibutyl pthalat e, tr icre syl

ph os ph at e e tc .,w ithPV

C re sin unifo rm ly.Us e s:-Us e d for m aking r ain coats ,ta ble clot hs ,

cu r tains , coatings for e le ct r ic wire and ca ble s ,toile t a r ticle s ,tool handl e s , r adio ,T. V co mp on e nts ,conv e yer be lts ,p ipe s ,be nds ,cou pling,valv e s e tc .





Te flon or P olyte tr a fluor oe thyle ne

Eg: n F 2C=CF 2 -(-CF 2-CF 2-)n -T etra flouroethylene P T FE

T etra flouroethylene Polymerizes athigher temperature and pressure in

the presence of free radical initiatorsor catalysts like persulfate or

hydrogen peroxide in aqueous media.Redox initiators such as ferroussulphate and hydrogen peroxide can

also be used.



P T FE is commercially known as T eflon. It is highly crystalline(93-98%) material.

It is a linear with very little branching. T he density of T eflon is 2.3 g/cm 2. It is highly chemical resistant. It has a very good insulating property .



U SESIt is used to make insulation of

motors,transformers,coils,capacitors etc.U sed to make self lubricating ball bearings.T eflon is used to make articles like pumpvalves, pipes, tanks etc.U sed for storage chemicals.T eflon is the coating material used in nonsticking frying pans.



B ak e liteIt is forme d by cond e nsation r xn of phe nol & form ald eh yde in pre s e nc e of acid or alkali catalyst at pr oper temper atu re

pr oduc e s bak e lite or phe nol formald eh ydere sin .Intial r xns of phe nol & form ald eh ydepr oduc e s mono ,di,tr i-me thylol phe nols .



CH 2OHOH OH

OHOH

CH 2OH CH 2OH

HCH O

CH 2OH CH 2OH



CH 2OHOH OH

OHHCH O

CH 2

+

OH

M ethylene linkage



CH 2OHOH OH

OHCH 2-O-CH 2

OH

Ether linkage

+



CH 2OHOH OH

OHCH 2

OH

+

CH 2C

OH

HCHO

Acid (Catalyst )

Alkali(Catalyst)

OHCH 2-O-CH 2

OH

A Stage Resin

OHCH 2OH

CH 2 OH

B Stage Resin

C



P/F ratio Less than 1P/F ratio greater than 1

AlkaliCatalyst¨

Reaction interruptedat an earlystage

Acid Catalyst¨

A-stage resin+

B-stage resin

B-stage resin(Novolac)

Powdered resinsHexamethylene diamine andadditive

M oulding & Curing

Bakelite resin

M oulding & Curing



CH 2

C-Stage Resin or Cross linked bakelite Resin

OH

CH 2-O-CH 2

OH

CH 2

CH 2

CH 2

OH

CH 2

CH 2 O

OH

CH 2

CH 2



Properties:S e t to r igid, h a r d, sc r atc h re sistant , in solu ble,wat er re sistant .The y poss e s e xce lle nt e le ct r ical insulating cha r act er.

U ses:F or m aking e le ctr ic insulato r p a r ts like s witcher plugs , s witch b oa r ds , he at er h andl e s e tc ..,F or impre gnating fabr ics , wood and pa per,

ad e nin e s for gr inding whee ls .F or m aking be a r ings , us e d in pr ope ller s hafts for p a per indust r y and r olling mills.



N ylonN

ylon 6:6 is prep a re d by the cond e nsation polymer ization of adi pic acid and he xa me thyle nedia mine in the a bs e nc e of air.

n[(CH 2)6(NH 2)2 + (CH 2)6(COOH) 2]adipic acid

N

H

H

C

H

H

N

H

C

O

C

H

H

C

O

n6 4

NYLON 6,6

+ 2n H20

polymerization



Properties:It has rem a r ka bly low e fficie nt of f r iction against many me talsS e lf e xtinguis hing whe n it co me s in contact with a flame.Low wat er a bso rption and good st re ngt h wh ich

do e s not de ter ior at e e ve n whe n us e d for a long per iod .



P olye st er : Hav e e st er linkag e s in main chain Us e d e xclusiv e ly for m aking te xtile s S ynthe sis of polye st er s by poly cond e nsation of

pur ifie d tereph lthalic acid and mono e thyle ne glycols

2HC

H 2 C

O H

O H

+

C OO H

C OO H

C OO *OO CH 2 C2

O* + 2 H2O



Dacron Tr ad e na me for P olye thyle ne Tereph thalat e

aka P ET, P ETE, P ET P

P olye thyle ne Tereph thalat e is a re sin of thepolye st er family that is us e d to mak e be ver ag e,food and other liquid contain er s , synt he tic fiber s

Cle a r, toug h p lastic with good gas and moistu reba rr ier pr oper tie s





Tr ans e st er ification is us e d in the synt he sis of polye st er, in wh ich die st er s und er go tr ans e st er ification with diols to formmac r omole cul e s . In ou r cas e, dime thyl tereph thalat e and e thyle ne glycol re act to form p olye thyle ne tereph thalat e and me thanol , wh ich is e va por at e d to dr ive the

re action forwa r d.



C atalysts Tr ans e st er ification re actions a re ofte n catalyz e d by the addition of an acid or b as e.

A cids can catalys e the re action by donating a pr oton to the alkoxy gr ou p, thus making it m orere activ e, wh ile b as e s can catalys e the re action by rem oving a pr oton f r om the alco hol, thus making it more re activ e.



P oly me r



M e c h an i s m of P oly me r iz at i on



H i story of Dacron P ET : or iginally pat e nte d by B r itish chem ists

± John Re x Wh infie ld and Ja me s Te nnant Dickson in 1941 aft er e a r ly re s e a r ch b y Wallac e Ca r other s

D upont us e d its nylon te chnology to impr ove thepolye st er fiber that was pat e nte d by the B r itish

D ac r on was cre at e d in 1950 b y Dupont



W h at IS Dacron?

A p olye st er fiber us e d in clot hing .A ya r n us e d in:

cu r tains

dre ss fabr ics high pre ssu re fire h os e s me n¶s s hir ts thre ads .



Dacron P roducts B oat sailsA nte nna r ope

Climb ing r ope sF oa m cov er sCa rpe ts and te xtile s

F ur nitu reLuggag e



W he r e can w e f i nd i t?



Dacron i n M e d i c i n e Ca r diot hor acic and V ascula r gr afts and imp lants ± Ane ur ys m rep air (Th or acic and Abdo minal Aor ta)

±P

atc h Angio plasty ± V ascula r gr aftsS tr ong , fle xible and tre at e d

with collag e n to keep b lood

f r om soaking thr oug hChem ically iner t and thus we ll

toler at e d insid e the b ody



Dacron- T he n and Now D ac r on has co me a long way sinc e 1950M ore co mm only us e d today thanks to newte chnologyP r ice r ang e va r ie s depe nding on the pr oduct it as bee n mad e intoIntr insic viscosity (thickn e ss) of ~0.60 ( fiber s)

±P

ET can r ang e up to ~0.85 for tire co r d



H e alt h Eff e cts O ne study s howe d that aft er imbe dding polymer films of Dac r on in r od e nts there w as e vide nc e of so me m alignant tum or form ation , study was lat er deeme d inad e quat eF ur ther re s e a r ch s hows no s hor t term or long term toxicity with us e of Dac r onHo we ver, st r ong e vide nc e of naus e a , vomiting ,ce ntr al ner vous syst em p a r alysis and kidn e y da mag e w ith pr olong e d e xposu re to e thyle neglycol



Dacron P rop e rt ie s High te nsil e st re ngt h, h igh re sistanc e to st re tching , b othwe t and dr y, and good re sistanc e to de gr adation by chem ical ble ac he s and to a br asion which is why it is pre f erre d for su r gical us eHigh me lting temper atu re of 496 de gree s F a hre nhe it (256 de gree s Ce lsius) , du e to cr oss-linkag e in synt he sis of the fiber.





which have been doped with appropriate impurities .

These polymers may be made either n-type or p-typedepend upon type of dopant used.

H3C-CH=CH- (CH=CH) n-CH=CH-CH 3

N N N *

n

poly anilene

N N N *

n

poly anilene



Doping:

the conductivity of a polymer can be increased bycreating either +ve or -ve charges on polymer backbone oxi·n or red·n is calleddoping.it is two types

1. n-type doping2.p-type doping



1)p-DO P ING :Tre ating an intr insically conducting polymer

with a lew is acid there b y oxi¶n pr oc e ss tak e s plac e and +ve cha r ge s on polymer a re cre at e d.P olymer + lew is acid = (polymer )n+ + (L. a) n-

Co mon p-do pants a re I2,B r 2,As F 5,P F 6 e tc«

Ex:

(C2H2)n + 2 F e Cl3 (C2H2)n+F e Cl4- +F e Cl2



2) n- DO P ING :Tre ating an int r insically conducting polymer with a lew is bas e there b y re d¶n pr oc e sstak e s plac e and -v e cha r ge s on polymer a recre at e d.

P olymer + lew is bas e = (polymer )n- +(L.b )n+

Co mm on n-do pants a re L i, N a , N H3 e tc ..,

Ex:(C2H2)n + N H3 (C2H2)n-N H3

+



Applications: Wir ing in ai r cr afts and a er os pac e co mp on e nts In te le co mm unication syst em s In antistatic coatings for clot hing In e le ct r o magn e tic sc ree ning mat er ials In e le ct r onic de vice s suc h as tr ansisto r s and diod e s In sola r ce lls, dr ug de liver y syst em for h uman body In ph oto voltaic de vice s e g: Al / p olymer / A u, ph oto

voltaic ce lls.

In re cha r ge a ble light we ight batt er ie s In optically dis play de vice s bas e d on poly thiophe ne .



Rubber High p olymer s with e lastic pr oper tie s in e xce ss of

300%. Is not st r aig ht chain e d but in form of a coil and

st re tche d like a s pr ing .Natural rubber : Consist of a basic mat er ial lat e x which is a polymer

of iso pre ne. M.Wt is a r ound 10,000 ± 1,50,000

CC

C

C

H

H

C

CH 3

H

C

H

HH

CH 3

H

HC

H

H



V ulcanization : To impr ove the pr oper tie s of r ubber it is

co mp ound e d with so me chem icals like sul ph ur,H2S , B e nzoyl chlor ide e tc . is call e d V ULC AN IZ AT ION .

The pr oc e ss consist in he ating the r a w r ubber w ithsul ph ur at 100 -140 oc.

The sul ph ur is add e d on mono mer dou ble b onds . Th us s er ve s to stiff e n the m at er ial by a so r t of

anc hor ing and cons e qu e ntly, pre ve nting inter m ole cula r m oveme nt of r ubber s pr ings .

V ulcanit e r ubber contains a bout 32% sul ph ur.

CH 3 CH



CH 2 C

3

CH CH 2 C

CH 3

CH CH 2

+

CH 2 C

CH 3

CH CH 2 C

CH 3

CH CH 2

CH 2 C

CH 3

HC CH 2 C

CH 3

CH CH 2

CH 2 C CH

CH 2 C CH CH 2

CH 3 CH 3

S SS S

S

VULCANIZATION OF RUBBER WITH SULPHUR



ELAS TOMER S : An e lasto mer / a r tificial r ubber is any vulcanisa ble m an mad e r ubber like p olymer,st re tche d to at le ast twice its le ngt h b ut it re tur ns to its or iginal s ha pe and dime nsions as

soon as st re tching for ce is re le as e d.B UNN A-S / S TYRE N E RU BB ER : Wh ich is pr oduc e d by co polymer ization of

butadi e ne & sty re ne.U SES: Manufactu re m oto r tire s , floor tile s , s hoe -sol e s ,

gask e ts , ad he siv e s e tc ..,



H

C

H

C

H

C

H

C

H

H

+ C

H

H

C

H

n

C C

H

C

H

C C

H

H

CH

HH

H

H

H

x

nx

butadiene 75 parts styrene 25 parts

styrene-butadiene rubber

co polymerization



Nitrile rubber or Buna N is prepared bypolymerisation of 1,3butadiene andacrylonitrile. :N itr ile r ubber or B una N is prep a re d by polymer isation of 1,3b utadi e ne and ac r ylonit r ile.n CH2=CH-CH=CH 2+ n CH 2=CH-C N

[-CH 2-CH=CH-CH 2-CH 2-CH--]- n

CN



B UTYL RU BB ER : P r oduc e d by co polymer ization of iso bute ne w ith

s mall a mounts of iso pre ne.U SES: F or m aking cycl e & auto mobile tube s , Auto mobile p a r ts Conv e yor be lts for food Tank linings e tc .,



CH2 C

CH 3

CH 3

m + CH2 C CH

CH 3

CH 2n

CH 2 C

CH 3

CH 3

CH 2 C CH CH 2 *

mn

isobutene isoprene

butyl rubber



Th iokol r ubber : P r oduc e d by the re action b/w sodiu m

polysul ph ide & e thyle ne dichlor ide.

Na S

SNa

Cl CH 2

CH 2Cl

S

S

H2C*

H2C S S

S S

*

n

+ 2n NaCl

ethylene di chloride sod. tetra sulphidethiokol

n n+

U ses: The y a re che a p & can e asily be s ha pe d but hav e an un ple asant s me ll. Making hos e p ipe and tank linings

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Preparations and Applications of Polymers