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High levels of minerals (clay, CaC03, Ai203*3H20) can be Incorporated homogeneously into ultrahigh molecular weight polyethylene by polymerizing ethylene onto catalytically activated mlneral surfaces. The homogeneity is achieved by deaggregating the mineral prior to polymerization and by the use of combination of R, Zr and RSAI as catalysts which are uniformly and Irreversibly attached to the mineral surface. The process leads to no uncoated mineral or polymer free of mineral, both of which can have a deleterious effect on mechanical properties. In contrast to most filed plastics which are brittle, these composites retain the ductile faUure characteristics of the unfilled ultrahigh molecular polyethylene, providing a unique combination of reinforcement and impact toughness in a mineral-filled polyolefin. Polymer molecular weight must be in excess of 10' for optimum properties.

A wide compositional range of copolymers of 1‐cyclobutene carbonitrile (CBCN) and 1‐bicyclobutance carbonitrile (BBCN) with common vinyl monomers was prepared in order to study systematically the effect of cyclobutane carbonitrile ring incorporation on the glass transition temperature (Tg). In general, the Tg's of the copolymers are increased in proportion to the weight percent of the small‐ring monomer incorporated, but the 1,2‐mode of incorporation raises Tg more than the 1,3‐mode. Attempts were made to correlate data with quantitative Tg–composition relationships (Fox–Johnston equations). Prediction for nitrile homopolymer Tg's are compared with literature values.

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