The effect of molecular structure on the properties of biomedical polymers - Durability and Reliability of Medical Polymers - page 40

1.02

0.98

0.94

0.90

-160 -120 -80 -40 0

Temperature T (°C)

2.24 Dilatometric diagram of a hypothetic polymer, obtainable in
crystalline and amorphous state.

C p

D C p

￿ ￿ ￿ ￿ ￿ ￿

T
2.25 Schematic differential scanning calorimetry (DSC) graph
showing D C p for amorphous polymers.

Ê
Ê

ˆ

= ∂
∂

H
T

[2.7] C

P

Ë

P

Polymers containing polar groups (-Cl, -F, -CN, -OCH 3 , -COOCH 3 ),
either in the main structure or in lateral chains, show higher transition points
than similar non-polar structures (Fig. 2.25).
this is because the polarity allows the augmentation of intermolecular
forces by electrostatic effects or hydrogen bonds. thus, comparing the