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CHEG380: Introduction to Polymer Science and Engineering

Lecture #1General Introduction to Polymers

Fall 2013

Tuesday, August 27th, 2013

Dr. Saeed Alhassan

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Importance of Polymers

• Polymers are useful materials for plethora of applications and

are found in every corner of our daily life• Polymers are found in the following applications:

• Eyeglass frames

• Upholstery

• Packaging

• Car parts

• Clothes

• TV displays

• CDs

• Films

• Tableware• Silverware

• Adhesives

• Food industry

• Sports

• Tires

• Bottles

• Containers

• Safety helmets

• Valves and fittings

• Coatings

• Synthetic oils

• Additives• Piping

• Toys

• Pharmaceutical

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History of Polymers

• The first thermoset was developed by Charles Goodyear 

when he “vulcanized” natural rubber with sulfur in 1839.• The first plastic , cellulose nitrate was synthesized by

 Alexander Parkes in 1862. Cellulose (natural polymer)was mixed with nitric acid to produce cellulose nitrate

• John Wesley Hyatt improved on Parkes’s invention andduped it “Celluloid”, which was later used in photographyand motion pictures and revolutionized the world of cinema.

• The first “true” synthetic polymer was developed in 1909 by Leo Baekland , which was synthesized fromformaldehyde-phenol (called “phenolics”, trade name:Baeklite)

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History of Polymers

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History of Polymers

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Definitions• Mer: one part

• Mono-mer: (mono=alone) is a simple molecular unit which can react to

form polymer• Di-mer (Di= two) is a small molecule made of two similar units

• Tri-mer (Tri= three) is a small molecule made of three similar units

• Tetra-mer (Tetra= four) is a small molecule made of four similar units

• Oliogo-mer: (oligo= few) is a molecule made of few similar units(usually 10-20)

• Poly-mer: (poly = many) A molecule of high relative molecular weight,the structure of which essentially comprises the multiple repetition of units derived from monomers (also known as Macromolecules)(International Union of Pure and Applied Chemistry Gold Book p. 870and 1151).

Note: the repeating unit in polymers are usually linked through covalent

bonds.• Polymerization: a process to convert monomers into polymers

• Plastics: common name for synthetic polymers and used frequently inpublic domain

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Polymer Classification

1) Natural vs. Synthetic: if available from natural

source then it is natural. If made in the lab, then synthetic.Examples: Poly(styrene) is synthetic while Cellulose

(polysaccharide) is natural polymer.

2) Thermoplastic vs. Thermoset: Thermoplastics are

defined as the materials that can be formed repeatedly intoany required shape by the use of heat. Thermosets are

materials that cannot be reformed into other shapes by the

use of heat after they have been formed. Example of 

thermoplastic polyethylene, polypropylene, polystyrene,poly(methyl methacrylate)…etc. Examples of thermoset is

epoxies, polyurethane, unsaturated polyesters..etc

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Polymer Classification

3) Addition vs. condensation: if a polymer is

synthesized from addition polymerization, then it iscalled addition polymer. If synthesized from

condensation polymerization, then it is called

condensation polymer.

4) Structure:

1. Linear, branched, crosslinked…etc

2. Homopolymer vs. copolymer

3. Amorphous vs semi-crystalline

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Molecular Structure of Polymers

• Majority of polymers are made of the following atoms in

the backbone:1) Carbon (forms 4 bonds)

2) Silicon (forms 4 bonds)

3) Nitrogen (forms 3 bonds)

4) Oxygen (forms 2 bonds)

• Carbon is the most common element in polymer becauseit form more than two bonds, which is necessary toproduce polymer with varying chemistry since carbon

can bond to four atoms. In addition, carbon has smalleratomic weight than silicon, and that makes moredesirable as building blocks for polymers. In addition,carbon is more compatible for human usage.