Crystallization kinetical and morphological peculiarities in binary crystalline/crystalline polymer blends

A survey is presented on the crystallization kinetics and the morphology of miscible cry stalline/crystalline polymer blends. There are only few corresponding systems. In them, however, a number of strange kinetic and structural phenomena can be observed: (i) spherulitic crystallization of the components side-by-side, (ii) "interpenetrating crystallization," (iii) "interlocking spherulitic, crystallization," and (iv) "interfilling crystallization." Cocrystallization is forbidden for crystallographic reasons. The blend partners grow instead in their own lamellar stacks, and mixed lamellar stacks are a seldom and questionable exception. They crystallize also usually stepwise and not simultaneously. Upon step crystallization, the crystallization of the second component is determined by its redistribution with crystallization of the former. Those composition inhomogeneities are an independent issue that arises also with the development of the morphology in crystalline/amorphous blends, and a corresponding survey is yielded, too. The blend poly (vinylidene fluoride)/poly-beta-hydroxybutyrate is a convenient model system as it can show all of these morphological and kinetic features after suitable thermal treatment. Some of them are demonstrated in the present publication. (c) 2007 Wiley Periodicals, Inc.