Lab 6 MATE 210

chemical makeup of polymers

composed mostly of carbon (C) and hydrogen (H). Other elements, like oxygen(O), nitrogen (N), chlorine (Cl), fluorine (F), phosphorus (P), and sulfur (S) are added to obtain certain properties.

Carbon backbone

a long chain made up of C atoms

Polymers are thus molecular chains, and do not have an ordered and periodic atomic arrangement in a unit cell like metals or ceramics. Therefore, polymers tend to be amorphous materials without a crystalline structure

3 Polymer Categories

1. Thermoplastic (TP) polymers - long molecular chains held together bysecondary bonds.

2. Thermoset (TS) polymers - long molecular chains held together by primarybonds.

3. Elastomers - long molecular chains held together by few, isolated primarybonds

What is a polymer

A long string of mers

What type of bond is responsible for determing the mechanical properties of TP Polymers

secondary bonds (based on weak molecular dipole)

what are the two major types of secondary bonds

1. Hydrogen bonds: formed from permanent dipoles between molecules.

2. Van der Waals bonds: those formed from nonpermanent dipoles betweenmolecules.

What is the most commonly used test for structural materials like polymers

tensile test

what are the three main mechanical properties measured in a typical tensile test

1. Modulus of elasticity (E) - also known as Young's modulus (measure of thestiffness of a material)

2. Yield strength (Y) - also known as the elastic limit (amount of stress the material can withstand before it permanentlydeforms)

3. Percent elongation (% Elong.) - also known as ductility (amount of plastic deformation thatcan occur in a given polymer)

How many tensile properties will be test

three common polymers: polyethylene (PE), polycarbonate (PC), and polystyrene (PS).