INTERCHAIN PACKING AND UNIT CELL OF SYNDIOTACTIC POLYPROPYLENE.

We have examined the general validity and applicability of our newly proposed interchain packing and unit cell for syndiotactic polypropylene, in view of the general acceptance for 30 years of the original structural model. Whereas our initial evidence arose from single crystals in ultra-thin films, we now demonstrate the correctness of our structure for polycrystalline thick films, for bulk specimens obtained directly from the polymerization, and for uniaxially oriented specimens. This removes any possible ambiguity that our structure might represent a special case arising from thin-film, substrate or epitaxial effects, or from thermal or mechanical treatments. We remove any questions about chemical defects as originators of our alternative structure by demonstrating that our specimens are among the very highest in the literature in terms of syndiotactic content, ordered- sequence distribution, melting temperature, heat of fusion, and crystallinity.