No abstract

Thermal and microwave-activated ring-opening polymerization at 180 "C in the presence of titanium tetrabutylate at different c-caprolactone/titanium tetrabutylate molar ratios were compared. A special equipment was developed to control polymerization in the microwave field and to simultaneously monitor viscosity build-up as well as changes in microwave powers corresponding to input, reflection and transmission. Conversion, measured by means of viscosity build-up, and number-average molecular weight of poly(e-caprolactone) were similar for both processes and did not indicate advantages relating to the use of microwave irradiation.

Thermal and microwave-induced free-radical non-aqueous dispersion polymerization of methyl methacrylate (MMA) in the presence of poly(styrene)-block-poly(ethene-alt-propene) dispersing agent were compared. For controlled polymerization in the microwave field, a new microwave polymerization reactor was built to afford uniform heating and to control temperature via microwave power variation. At identical MMA concentration and polymerization temperature of70 "C no special effect of the microwave field on conversions, molecular weights and particle sizes of PMMA was detected with respect to conventional thermal free radical dispersion polymerization.

No abstract

A novel class of liquid rubber comprises bis(4-hydroxybenzoate)-terminated poly(tetrahydrofuran), which reacts with bisphenol A diglycidyl ether to form segmented liquid rubbers with poly(tetrahydr0furan) and poly(hydroxyether) segments. In anhydride-cured epoxy resins such segmented liquid rubbers afford improved toughness. Dioland bis(hydroxybenzoate)-terminated poly(tetrahydr0furan)-based liquid rubbers are compared. It is possible to control the polymer morphology by the variation of the molecular architecture of segmented poly(tetrahydr0furan)-based liquid rubbers.The average size ofthe dispersed rubber phases depends on the molecularweight ofthe segmented liquid rubbers and correlates with impact strength and stiffness.