AMORPHOUS LINEAR POLYETHYLENE

A technique was developed which is capable of quenching thin linear polyethylene films (100-1000 Å) to an apparently amorphous state. Electron microscopy of samples kept at liquid nitrogen temperature before and during platinum-carbon shadowing indicated that the glass has a morphology consisting of nodules approximately 100 Å in size superimposed upon irregularities 1000 Å or more in diameter. This morphology did not rearrange to form lamellae as the sample was warmed rapidly and recrystallized; instead the chains seemed to reorganize locally to develop three-dimensional crystallinity. In most of the quenched samples some localized areas of varying sizes and numbers were seen which had a lamellar or spherulitic morphology which seemed to have formed during cooling due to local variations in the quench rate. Electron diffraction from well-quenched areas of samples inserted into the microscope without warming them sufficiently that they crystallized showed only amorphous halos. Upon warming, crystallinity in the orthorhombic unit cell form appeared at temperatures above 180 - 190K. Differential scanning calorimetry revealed a broad exotherm between 160 and 180 or 200K from samples that were kept under liquid nitrogen before and during insertion into the d.s.o. © 1979.