1. Rotation of bonds

2. Viscous flow Occurs only by shear  z   xy Describe deformation under shear by angle  tan       z z     xy       ˙ ˙  

3. Most polymer melts are shear-thinning (pseudoplastic) - i.e., become thinner at high shear rates Zero Shear Rate Viscosity 5 4 3 2 1 0 0 1 234-2 -3 Log  a (Pa) Log  sec -1 ). Compression Molding Calendering Extrusion Injection Molding Spin Drawing 10 0 SHEAR RATES ENCOUNTERED IN PROCESSING 10 1 10 2 10 3 10 4 10 5 Strain Rate (sec -1 ) Viscous flow

4. Viscosity increases with MW Plot is for zero shear rate values Viscosity increases with MW Plot is for zero shear rate values Viscous flow 54321 Poly(di-methylsiloxane) Poly(iso-butylene) Poly(ethylene) Poly(butadiene) Poly(tetra-methyl p-silphenyl siloxane) Poly(methyl methacrylate) Poly(ethylene glycol) Poly(vinyl acetate) Poly(styrene) Log M + constant Log  m + constant

5. Creep Relaxation

6. Creep of cellulose acetate

7. Relaxation in PMMA 10 9 8 7 0.0010.010.11101001000 Stress relaxation of PMMA Time (hours) 40 0 C Log E(t), (dynes/cm 2 ) 60 0 C 80 0 C 92 0 C 100 0 C 110 0 C 112 0 C 115 0 C 120 0 C 125 0 C 135 0 C

8. Creep & recovery

9. Some specific polymers Polyvinyl chloride (PVC) {-C-C-} n Cl H H – – – – – – – – Very rigid and strong, T g = 60-80 C siding, pipe, conduit, usw. Very rigid and strong, T g = 60-80 C siding, pipe, conduit, usw. Presence of Cl gives rise to solubility in various organic solvents - allows "solvent welding"

10. Some specific polymers Polyvinyl chloride (PVC) {-C-C-} n Cl H H – – – – – – – – Presence of Cl gives rise to solubility in various organic solvents Rigid PVC difficult to form by some techniques (e.g., calendaring)……so add solvent as "plasticizer" Presence of Cl gives rise to solubility in various organic solvents Rigid PVC difficult to form by some techniques (e.g., calendaring)……so add solvent as "plasticizer" PVC sheet then roll-formed onto fabric backing and - voilá - "vinyl"!

11. Some specific polymers Rigid PVC difficult to form by some techniques (e.g., calendaring)……so add solvent as "plasticizer" PVC sheet then roll-formed onto fabric backing and - voilá - "vinyl"! Problem: solvent slowly evaporates, esp. when (auto) vinyl seats & fascia heated by sun Armorall to the rescue! Periodically put solvent back into polymer

12. Oils - Low MW……liquids lubricants, hydraulic fluids, water repellants, usw. Oils - Low MW……liquids lubricants, hydraulic fluids, water repellants, usw. Elastomers - intermediate MW, crosslinked waterproofing, caulk, prostheses, usw. Elastomers - intermediate MW, crosslinked waterproofing, caulk, prostheses, usw. Molding compds - high MW, crosslinked non-structural parts, insulation, usw. Molding compds - high MW, crosslinked non-structural parts, insulation, usw. Crosslinking – moisture reacts w/parts of chain to crosslink……acetic acid is byproduct of rxn Crosslinking – moisture reacts w/parts of chain to crosslink……acetic acid is byproduct of rxn silicones Some specific polymers

13. High T M – form at elevated temps Non-crystalline, nearly as strong as highly crystalline nylon, but tougher (stiff chain, pendant groups, H bonding betwn chains) {-O-C-O- -C- -} n O H-C-H H H polycarbonate Some specific polymers

14. Nylon cousin, but far stronger (very stiff chain) {-C- -C-N- -N-} n O H aramid O H Non-burning, very high T M, solvent resistant When made into fibers ––> Kevlar Some specific polymers

15. H 2 C-C-C{-O- -C- -O-} n C-C-CH 2 H-C-H H H epoxy H HOO H H hardenerH 2 N-R-NH 2 Prepregs Some specific polymers