MICROPHASE STRUCTURES AND C-13 NMR RELAXATION PARAMETERS ULTRAHIGH MOLECULAR-WEIGHT POLYETHYLENE

The phase transformations in ultrahigh molecular weight polyethylene ( UHMWPE) gel-films upon superdrawing have been studied by X-ray diffrac tion and high resolution solid state C-13 NMR, The morphological chang e and molecular motions in the crystalline phase, amorphous phase and interphase are discussed according to the C-13 nuclear relaxation time (T-1c, T-2c) results. A brief interpretation to the three or four T-1 c values in the crystalline phase is presented. It is found,that the c omponent with the highest T-1c (T-1c(alpha)) plays a key role in the f orming of 'Shish-Kebab' microfibril which determines the sample streng th and modulus, namely, the greater the T-1c(alpha), the higher the mo dulus and strength of the drawn UHMWPE gel-film. These results support the 'Shish-Kebabs' model in crystalline polymers.