Chemistry Reference
In-Depth Information
Table 4.2
Glass Transition and Crystal Melting Temperatures of Polymers (
C)
T
m
a
T
m
a
T
g
T
g
Poly(dimethyl siloxane)
2
127
Poly(ethyl methacrylate)
65
—
—
120
b
Polyethylene
2
140
Poly(propyl
methacrylate)
35
—
Polypropylene(isotactic)
2
8
176
Poly(n-butyl
methacrylate)
21
—
Poly(1-butene) (isotactic)
2
24
132
Poly(n-hexyl
methacrylate)
2
5
—
Polyisobutene
2
73
Poly(phenyl
methacrylate)
110
—
—
Poly(4-methyl-1-penetene)
(isotactic)
29
250
Poly(acrylic acid)
106
—
cis-1,4-Polybutadiene
2
102
Polyacrylonitrile
97
—
—
58
b
96
b
trans-1,4-Polybutadiene
2
Poly(vinyl chloride)
87
—
(conventional)
cis-1,4-Polyisoprene
273
—
Poly(vinyl fluoride)
41
200
282
b
Polyformaldehyde
175
Poly(vinylidene chloride)
218
200
Polystyrene (atactic)
100
—
Poly(vinyl acetate)
32
—
Poly(alpha-methyl styrene)
168
—
Poly(vinyl alcohol)
85
—
Poly(methyl acrylate)
10
—
Polycarbonate of
bisphenol A
157
—
Poly(ethyl acrylate)
2
24
Poly(ethylene
terephthalate)
69
267
—
(unoriented)
50
b
Poly(propyl acrylate)
2
37
Nylon-6,6 (unoriented)
265
—
Poly(phenyl acrylate)
57
Poly(p-xylene)
375
—
—
Poly(methyl methacrylate)
(atactic)
105
—
a
T
m
is not listed for vinyl polymers in which the most common forms are attactic nor for elastomers,
which are not crystalline in the unstretched state.
b
Conflicting data are reported.
The kinetic flexibility of a macromolecule is directly related to the ease with
which conformational changes between
trans
and
gauche
states can take place.
The lower the energy barrier
E
in Fig. 1.6, the greater the ease of rotation about
main chain bonds. Polymers with low chain stiffnesses will have low
T
g
's in the
absence of complications from interchain forces. Chain backbones with
Δ
Si
O
or
C
O
