Handbook of Solvents - George Wypych - ChemTech - Ventech!

260 Nobuyuki Tanaka
Table 5.2.4 shows the numerical values of δ p for aPP, together with T g,h g,h x, and h 0,
which give the concave type curves against1-X A, respectively. Where X A is the mole fraction
of meso dyads. As h u of crystals or quasi-crystals in aPP, 1900 cal/mol was used, because
h u(=1900 cal/mol) of iPP 28 should be almost equal to that of syndiotactic PP (sPP);
h conf +h int ≈1900 cal/mol at each T m for both PP, where h conf = 579.7 cal/mol at T m = 457K 28
for iPP, h conf = 536.8 cal/mol at T m = 449K 34 for sPP, and h int = 1360 cal/mol for both PP.
Here quasi-crystals are ordered parts in aPP with1-X A≈0.30 ~ 0.75, which do not satisfy
the requirements of any crystal cell. As T g of iPP and sPP, 270K was used for both PP. 12,35
The experimental values of T g for aPP are less than 270K. 36-41 In this calculation, for aPP
with1-X A= 0.4, the minimum of T g, 254K, was obtained. δ p in T>T g showed the minimum,
8.22 (cal/cm 3 ) 1/2 ,at1-X A= 0.3, which is 0.20 less than 8.42 (cal/cm 3 ) 1/2 of iPP, and
δ p in T