Handbook of Solvents - George Wypych - ChemTech - Ventech!

258 Nobuyuki Tanaka
as shown in the fourth column, hx(eq.[5.2.17]) - hu is almost equal to hx (≈hu) from equation
[5.2.18] or δp (=13.6 (cal/cm 3 ) 1/2 ). For iPP, hx(eq.[5.2.17]) is a little more than hx from equation
[5.2.18] or δp (=8.2 (cal/cm 3 ) 1/2 ), suggesting that the ordered parts in glasses seem to be
related closely to the helical structure. For iPS, hx(eq.[5.2.17]) and hx(eq.[5.2.17]) - hu are in
the upper and lower ranges of hx from δp (=8.5~10.3 (cal/cm 3 ) 1/2 ), respectively. For PET,
hx(eq.[5.2.17]) is almost equal to hu, but hx from equation [5.2.18] or δp (=10.7 (cal/cm 3 ) 1/2 )
is a little more than hu, resulting from glycol bonds in bulk crystals distorted more than in ordered
parts. 10,25,30
5.2.3 δp PREDICTION FROM THERMAL TRANSITION ENTHALPIES
Table 5.2.3 shows the numerical values of δp predicted from equations [5.2.1] ~ [5.2.4] us-
r
ing the results of Tables 5.2.1 and 5.2.2, together with hx,hu,hg,h0, and δp (reference values)
7,8 r
for several polymers. The predicted values of δp for each polymer are close to δp .
Table 5.2.3
N6
Polymer
N66
iPP
iPS
PET
hx
cal/mol
9590*
(10070)
4830**
19300*
(20280)
9580**
1600*
(1780)
1470**
5030*
(5550)
5380*
(5670)
6600**
hu
cal/mol
-
-
5100
-
-
10300
1900
1900
1900
-
-
5500
5500
5500
hg
cal/mol
8980
8980
8980
17980
17980
17980
-
-
-
4820
4820
4180
4180
4180
h0
cal/mol
18570
(19050)
18910
37280
(38260)
37860
3500
(3680)
3370
9850
(10370)
15060
(15350)
16280
δ p
(cal/cm 3 ) 1/2
13.4
(13.6)
13.5
13.4
(13.6)
13.5
8.4
(8.6)
8.3
9.9
(10.2)
10.2
(10.3)
10.6
r
δp (cal/cm 3 ) 1/2
-
-
-
13.6
13.6
13.6
8.2 7
8.2 7
8.2 7
8.5 - 10.3
8.5 - 10.3
10.7
10.7
10.7
The numerical values attached * and ** are h x from equations [5.2.17] and [5.2.18], respectively. The numerical
values in parentheses were calculated using equation [5.2.17] with the second term of T g{s g conf - (RlnZ0)/x}.
For atactic polypropylene (aPP) that could be treated as a binary random copolymer
composed of meso and racemi dyads, 26,27,31 δ p is predicted as follows.
For binary random copolymers, h g is given by:
int conf
h = h + h ( X ) [5.2.19]
g g g
A
with h g int =hg int (1)-(hg int (1)-hg int (0))(1 - XA)
where:
h g conf (XA) the conformational enthalpy per molar structural unit for a copolymer
with X A at T g
h g int (1) the intermolecular cohesive enthalpy per molar structural unit for a
homopolymer of component A (X A=1) at T g