Molecular weight and distribution of crystalline polymers by non-isothermal crystallization kinetics

Tri-block copolymer poly(styrene)-b-poly(ethylene oxide)-b-poly(styrene) (SEOS) and homopolymer poly(ethylene oxide) (PEO) with almost the same molecular weight as PEO block were studied comparatively under non-isothermal conditions on differential scanning calorimetry (DSC) . From final degree of crystalline X_c and given degree of polymerization N, relative degree of crystalline X_t at nucleation stage was changed to be monomer unit numbers involved in crystallization process. Based on well recognized model of PEO crystalline structure, X_t can be used to calculate the scales of PEO crystalline. These results indicate that the degree of polymerization can be calculated by DSC. By using two type of polypropylene (PP) of industrial grade as model polymers, we present and corfirm a novel method to test the molecular weight and distribution of crystalline polymers through non-isothermal crystallization kinetics from cooling and heating curves. The method is low cost，easy and environmental due to lack of solvent.