The crystalline textures of a blend of linear polyethylene with low density polyethylene and a blend of deuterated linear polyethylene with low density polyethylene have been investigated as a function of rate of cooling from the melt. Differential scanning calorimetry, transmission electron microscopy and Fourier transform infrared spectroscopy have been used to study co-crystallization and phase segregation. On the basis of previous studies, the blend compositions were chosen so that the melt contained a single phase. Segregation between components was found to occur, as a result of crystallization, during cooling at all rates other than rapid quenching. The degree of segregation was found to increase with decreasing cooling rate. The morphologies resulting from this phase segregation during crystallization, have been compared with morphologies, previously determined, of blends of other compositions rapidly quenched from what was believed to be a phase separated melt. The scale of phase segregation is found to differ by more than an order of magnitude between the two types of morphology. The results support the argument that those rapidly quenched samples, which contain two crystal types, do so because of phase separation in the melt and not because of phase separation on crystallization. A comparison is made between two methods of sample preparation for transmission electron microscopy: permanganic etching/replication and chlorosulfonic fixation/sectioning. We have found the latter method better for revealing detailed morphological features between large lamellae
Посилання на статтю:
Morphology, melting behaviour and co-crystallization in polyethylene blends: the effect of cooling rate on two homogeneously mixed blends / R. L. Morgan, M. J. Hill, P. J. Barham // Polymer. – 1999. – N 40. – P. 337–348.