TIT# Investigation of secondary crystallization of polymers by means of
     microbeam X-ray scattering
AUT# Kolb, R.; Wutz, C.; Stribeck, N.; v. Krosigk, G.; Riekel, C.;
SOU# Polymer (2001), 42(12), 5257-5266
LOC# xv067
CLA#
COM#
APP#
MAT#
ABS# The kinetics of secondary crystallization during spherulite growth of isotactic poly(propylene)
     (iPP) and poly(vinylidene fluoride) (PVF) is studied using a novel technique that employs a micron size
     X-ray beam. The data are combined with separate conventional simultaneous on-line SAXS WAXS
     measurements and optical microscopy studies. In our experiments, crystallization takes place at low
     undercooling so that slowly growing large single spherulites are obtained. The data reveal that the main
     mechanism of secondary crystallization is the growth of new lamellae stacks within remaining amorphous
     regions. It is shown that a substantial amount of crystallites form as a result of secondary crystallization
     while the spherulite is growing. Furthermore, secondary crystallization is strongest directly behind the
     boundary of the spherulite and is independent of its size or growth state. A separate, off-line microfocus
     study on a quenched spherulite sample confirms this observation; the crystallinity is higher in the main
     body of the spherulite and lower near the boundary, where crystallization progressed to a lesser degree.