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...

In this study, the relationship between skin structure and shear strength distribution of thin-wall injection molded polypropylene (PP) molded at different molecular weight and molecular distribution was investigated. Skin-core structure, cross-sectional morphology, crystallinity, crystal orientation, crystal morphology and molecular orientation were evaluated by using polarized optical microsc...

A novel method is presented for the calculation of weight chain length distribution in free radical polymerization of vinyl monomers. In the proposed method, polymerization kinetic equations and molecular weight moment equations are used in conjunction with a function that defines the weight fraction of polymer in a finite chain length interval. The entire range of molecular weight is divided i...

in current work a comprehensive mechanism based on intermediate radical termination theory is assumed for raft polymerization of styrene over cumyl dithiobenzoate as raft agent. rate constants for addition (ka) and fragmentation reactions (kf) are set to 6×106 and 5×104 respectively, which lead to an equilibrium constant value of k = ka/kf = 1.2 x 102. moment equations method was used to model ...

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 anal...