HIGH-MELTING-POINT CRYSTAL IN HIGH-MOLECULAR-WEIGHT POLYETHYLENE FIBRIL

The high-melting-point crystal (HC) in high-molecular-weight polyethylene fibril (MW=6×108~1×108) 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 138~150ͦC. For the sample stretched at stretching ratio of 15 at 150ͦC, 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 137ͦC or 140ͦC 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 0.625ͦC/min was 150.5ͦC. © 1979, The Society of Polymer Science, Japan. All rights reserved.