R. Russo et V. Vittoria, DETERMINATION OF INTRINSIC BIREFRINGENCE OF SMECTIC PHASE IN ISOTACTIC POLYPROPYLENE, Journal of applied polymer science, 60(7), 1996, pp. 955-961
When isotactic polypropylene is quenched at 0 degrees C from the molte
n state, a biphasic material, amorphous-smectic, is obtained. The smec
tic phase has an intermediate order between the amorphous and the crys
talline. In this study the intrinsic birefringence of the smectic phas
e was determined. Tapes with different draw ratio were prepared at roo
m temperature, at which the smectic phase does not transform into the
crystalline phase. The amount of the smectic phase was determined with
measurements of density and sorption of vapors of dichloromethane. Th
e value of the intrinsic birefringence for the smectic phase is: Delta
degrees n(sm) = 40 . 10(-3). This value is in good agreement with the
values proposed by Samuels for the intrinsic birefringence of the amo
rphous and the crystalline phases. (C) 1996 John Wiley & Sons, Inc.