Miscibility of linear and branched polyethylene in the liquid state

Abstract

HDPE/LDPE blends and the pure components were crosslinked either by irradiation or by di-tert-butyl peroxide in the liquid state. The degree of crosslinkage was characterized by the reciprocal degree of swelling Q -1 (xylene, 2 h, 140°C). Above a critical degree of crosslinkage corresponding to Q -l = 0,2 the DSC curves of HDPE/LDPE blends show only one single crystallization peak on cooling from the melt and only one single melting peak on subsequent heating. This is an unequivocal proof for the single phase structure of HDPE/LDPE blends in the liquid state. Crosslinking with Q-I 2 0,2 prohibits fractional crystallization and forces the unbranched CH, sequences of both components between the crosslinks into one crystal lattice.

Flow instability in capillary extrusion of plasticized poly(vinyl chloride)

“…The endothermic shoulder, denoted by the arrows in the figure, is observed at a temperature just above the T a , which is ascribed to the fusion of the PVC crystallites. According to previous studies, 6,13,23,25,26 the DSC pattern of PVC fusion does not appear as a sharp peak but as one or two shoulders like those in the figure. The results in Figure 6 show that the PVC used in this study crystallizes during the annealing, even at the processing temperature.…”