atom transfer radical polymerization (atrp) of styrene was carried out at 105°c and a monte carlo simulation was employed to model the system. the variations of monomer conversion, the initiator concentration, average molecular weight, and molecular weight distribution were evaluated as the reaction proceeded. according to the results obtained, for similar reaction time, monomer conversion is h...

A method is presented for estimating relative mutation rates or relative effective population sizes, under the hypothesis of adaptively neutral allelic variation. This method was applied to seven surveys of electrophoretic variation. It was observed that electrophoretic mutation rates so obtained follow the gamma distribution and, in Drosophila, are positively correlated with the molecular weig...

fourier transform infrared (ftir) and gel permeation chromatography (gpc) wre respectively utilized in determining the changes in isocyanate (nco) concentration and molecular weight (mw) and its distribution (mwd) in polyurethanes during their cure and postcure stages. samples, originally cured at 45°c, were taken through accelerate aging tests at various temperatures. the ftir and gpc analytic...

ethylene was homopolymerized over ziegler-natta catalyst and the homopolymerization was modeled using moment equations. mechanism was modeled according to five different reaction centers of catalyst. for each center, there are different reaction rate coefficients; therefore the final product of each center would be expected to be different. modeling results showed good conformity to the experim...

This work investigates the possibility of obtaining molecular weight distribution (MWD) linear ultrahigh (UHMW) polypropylene (PP) through rheology. To this end, viscoelastic response a set UHMWPP samples is measured over largest possible frequency range. The terminal relaxation achieved by running creep experiments and converting compliance in dynamic moduli. A time–temperature concentration p...