On the glass transition temperature of polyethylene as revealed by microhardness measurements

There is no consensus among researchers about the glass transistion temperature of polyethylene. This is due to the fact that polyethylene is not commonly accessible in the completely amorphous state. It is concluded on the basis of transmission electron microscopy, electron diffraction, and differential scanning calorimetry that the concept of two values of glass transition temperature is acceptable. The lower value of glass transition temperature corresponds to the onset of a large-scale segmental motion in completely amorphous materials. The upper value corresponds to motion in segments constrained by crystalline regions.