T. Hugel et al., Building lamellae from blocks: The pathway followed in the formation of crystallites of syndiotactic polypropylene, ACT POLYM, 50(5-6), 1999, pp. 214-217
AFM images of isothermally crystallized samples of syndiotactic polypropyle
ne and poly(propene-co-octene) show that the lamellar crystallites are comp
osed of blocks. Upon heating the granular structure vanishes. Observations
support the view recently established by SAXS experiments that polymer crys
tallization is a two-step process, with the block. formation near the growt
h front as a first and their fusion into a lamella as a second step. it is
proposed that the blocks. have the minimum size necessary to remain intrins
ically stable. This could explain the observed invariability of the crystal
thickness with changing co-unit content.