Abstract: There is provided a process for producing a styrenic polymer having a weight average molecular weight (Mw) of 200,000-500,000, a number average molecular weight (Mn) of 100,000-450,000 and a molecular weight distribution (Mw/Mn) of from 1.1 to 2 by free radical polymerization.There is also provided a styrenic polymer, a styrenic resin composition comprising such polymer and a molded article comprising such composition.Said styrenic polymer and said resin composition have excellent flowability during molding and also excellent mechanical strength.

Abstract: A process for producing a styrenic polymer having a wide-spread molecular weight distribution, which comprises polymerizing a styrenic monomer or a styrenic monomer and a monomer copolymerizable with the styrenic monomer in the presence of 50 to 5000 ppm by weight of at least one compound selected from compounds having a dithiocarbamate group and sulfide compounds having at least one of an aryl group, an arylalkyl group and a thiazole group based on the total monomer to a final conversion of 40% by weight or more in the absence or presence of a radical initiator subjecting to a suspension polymerization, a batchwise bulk polymerization or a continuous bulk polymerization using a plug flow type polymerization reactor. According to the present invention, there can be provided a simplified process for preparing a styrenic polymer having a wide-spread molecular weight distribution.

Abstract: Disclosed are a rubber-modified polystyrene resin composition which comprises a polystyrene resin serving as a matrix and soft component particles as dispersed therein, the composition fulfilling the following requirements (a) to (d):(a) the polystyrene resin as the matrix satisfies the following requirements:150,000.ltoreq.Mw.ltoreq.500,000wherein Mw is the weight average molecular weight, and2.ltoreq.Bn(Mz).ltoreq.20wherein Bn(Mz) is the branch count or the number of branching points in the Z-average molecular weight (Mz),(b) the soft component particles in the composition have an average particle diameter (Dp) of 0.1 to 10 .mu.m,(c) the soft component particles in the composition have a swelling index in the range of 3 to 30, and(d) the proportion of the soft component particles in the composition is in the range of 5 to 30% by weight, as well as an injection-molded article formed from the composition.

Abstract: Disclosed are a rubber-modified polystyrene resin composition which comprises a polystyrene resin serving as a matrix and soft component particles as dispersed therein, the composition fulfilling the following requirements (a) to (d):(a) the polystyrene resin as the matrix satisfies the following requirements:150,000.ltoreq.Mw.ltoreq.500,000wherein Mw is the weight average molecular weight, and2.ltoreq.Bn(Mz).ltoreq.20wherein Bn(Mz) is the branch count or the number of branching points in the Z-average molecular weight (Mz),(b) the soft component particles in the composition have an average particle diameter (Dp) of 0.1 to 10 .mu.m,(c) the soft component particles in the composition have a swelling index in the range of 3 to 30, and(d) the proportion of the soft component particles in the composition is in the range of 5 to 30% by weight, as well as an injection-molded article formed from the composition.

Abstract: A new polymeric compound, MF-300, is provided, which possesses a specific protective activity against bacterial infections caused particularly by Pseudomonas aeruginosa. The compound is derived from the reaction of ribostamycin with crotonoyl chloride followed by concentration of the reaction product and by subsequent recovery therefrom of a fraction having a range of molecular weights of 10,000.about.100,000 when measured by ultrafiltration method.