Rheology catalysed

Blends of ethylene-vinyl acetate (EVA) copolymer with metallocene-catalysed elastomeric ethylene-alpha-olefin copolymer were investigated and were found to be immiscible in the melt and solid state but mechanically compatible. The morphology (SEM), thermal (DSC), rheological (viscosity), mechanical (including tensile, shear thinning and elastic behaviour) and optical properties of EVA-rich and ethylene-alpha-olefin copolymer-rich blends were studied and the results are discussed in terms of processibility in film applications. 24 refs. 

Transition metal prooxidants cause problems during both the manufacture and use of plastics products. Firstly they catalyse rheological changes in the polymer during processing and reduce shelf-life before use. Secondly it is difficult to control the induction time to photooxidation. It will be seen below that control of peroxidation is essential to the application of degradable plastics in agriculture. 

Cellulose pretreated in the presense of TMAC failed to exhibit enhanced activity toward sodium trichloroacetate in an isopropanol slurry. Products with essentially identical D.S. s were isolated from "catalysed and control experiments. However, solutions of catalysed CMC, (D.S.=0.7), appeared more fiber free than those prepared from controls with similar D.S.. The catalysed solutions (1%) exhibited slightly higher viscosities (500 cp vs 325 cp) and were less thixotropic than standard CMC. Efforts to ascertain if this difference in rheological behavior can be attributed to a more homogeneous distribution of substituents are in progress. 

High molar mass epoxy prepolymers containing rabber dispersions based on carboxyl-terminated butadiene-acrylonitrile copolymer were prepared from initially miscible solution of low molar mass epoxy prepolymers, bisphenol A and carboxyl-terminated NBR. During chain extension inside a twin screw extruder due to epoxy-phenoxy and epoxy-carboxy reactions, a phase separation process occurs. Epoxy-phenoxy and epoxy-carboxy reactions were catalysed by triphenylphosphine. The effect of reaction parameters (temperature, catalyst, reactant stoichiometry) on the reactive extrasion process were analysed. The structure of the prepolymers showed low branching reactions (2-5%). Low molar mass prepolymers had a Newtonian rheological behaviour. Cloud-point temperatures of different reactive liquid butadiene aciylonitrile random copolymer/epoxy resin blends were measured for different rubber concentrations. Rubber... 

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