Ch. 14 Polymer Structures Flashcards
General Properties of Plastics
Low density, ez molding, low cost, noise reducing, corrosion resistant, low friction, insulating
Old Polymers
Wood, rubber, cotton, wool, leather, silk
Mers
Basic polymer unit
Isomerism
2 compounds w same formula can look different
Common Hydrocarbons
Alcohols, Ethers, Acids, Aldehydes, Aromatics
Alcohol
R - OH
Ethers
R - O - R’
Acids
R - C - OH and C = O
Aldehydes
R - C - H and C = O
Aromatics
Benzene ring and R
Bulk Polymers
Polyethelene, PVC, PTEE, Polypropylene, Polystytrine, PMAA, Bakelite, Nylon, PET, PC,
Molecular weight methods
No. Avg. Molecular weight, Weight Avg. Molecular weight
No. Avg. Molecular Weight Formula (Mn)
Sum of Number fraction of chains * Mean molecular weight
Weight Avg. Molecular Weight Formula (Mw)
Sum of weight fraction of chains * Mean moleculat weight
Degree of Polymerization
DP = Mn / m (mer molecular weight)
Double bonds restrict…
rotation
Bulky side groups…
hinder rotation
Molecular structure types (from least to most strong)
Linear, Branched, Crosslined, Network
Stereoisomerism
Stereo Regularity of chain
Isotactic
One sided groups
Syndiotactic
Alternating sided groups
Atactic
Random sided groups
Thermoplastic
Plastc when heated, long chains w HON side groups
Thermoset
Plastic until set by chem reaction,rigid network
Homopolymers
Polymers of only 1 mer
Copolymers
Polymers of 1+ mer
Types of copolymers
Random, alernating, block, graft
Crystal structure of thermoplastics
Chain folded struct.
% Crystallinity is proportional to
E, TS, Annealing
Spherulites
Layered struct of natural rubber
% Crystallinity (measure)
= Pc ( Ps - Pa ) / Ps ( Pc - Pa ) * 100
Crystallinity depends on
Cooling rate, chain config.
