1979 Volume 36 Issue 9 Pages 575-580
The high-melting-point crystal (HC) in high-molecular-weight polyethylene fibril (Mw=6×105-1×105) crystallized under stretching above the melting point were investigated by means of differential scanning calorimetry (DSC) and wide angle X-ray measurements. The HC appeared in these fibrils by stretching ratios of 8-15 at 138-150°C. For the sample stretched at stretching ratio of 15 at 150°C, the amount of the HC measured by DSC method was 10% of the fibril. Lattice constants of the HC measured with wide angle X-ray at 137°C or 140°C coinside with those of orthorhombic polyethylene crystal. This suggests an extended-chain crystal growth of the HC. Its melting point determined with DSC at the heating rate of 0.625°C/min was 150.5°C.
