Two models are used to predict the expected molecular weight distribution for polyethylene and polypropylene formed through Ziegler-Natta catalysis. Realistic values of kinetic and physical parameters, taken from experimental studies, are used to provide quantitative results. The simple core model, which neglects catalyst particle breakup, does not allow significant MWD broadening due to diffusion effects. On the other hand, a more realistic multigrain model shows that significant MWD broadening could arise due to intraparticle monomer diffusion limitations.

SynopsisPoly(viny1 chloride)/poly(butadiene-co-acrylonitrile) interpenetrating polymer networks (IPN's) were synthesized in latex form. Dynamic mechanical spectroscopy as.a function of temperature revealed that the glass transitions of the individual networks were broadened and in some cases spanned the entire temperature range between the two individual polymer transitions. This was interpreted to indicate extensive but incomplete mixing between the two networks. Depending on overall composition, the cast or molded films were either plastic or tough elastomers at room temperature. Some aspects of phase continuity and structure, including a graded core-shell model, are discussed.

The addition of unsaturated organic halides during the metathesis polymerization reaction of cyclooctene, using a WC16/diisobutylaluminium chloride/2,6-di-tert-butyl-4-methylphenol catalyst, was found to cause instantaneous conversion of the unreacted monomer to polymer. Both 1 ,Zdichloroethene and 1 ,6-dibromo-3-hexene were found to be very effective for this purpose. When 1,4-dichlor0-2-butene was added during the reaction, unusual and unexplained products were obtained, but when it was added to the catalyst before the start of the reaction a very fast polymerization occurred yielding high molecular weight polymers. Changes in polymer melting points with reaction time suggested that isomerization occurred after polymerization and that the initial polymers formed had slightly blocky, trow unit sequences. Y l n B E. g J