THE INFLUENCE OF CROSS-LINKING ON ISOTHERMAL CRYSTALLIZATION OF LDPE FILLED WITH SILICA

The effect of crosslinking on the isothermal crystallization of low density polyethylene filled with three types of silica was investigated at 375 K. The crosslinking initiated by thermal decomposition of peroxide leads to overall retardation of crystallization. The presence of a filler in the polymer matrix results in the two opposing effects of nucleation and retardation. Crosslinking in the presence of a filler leads to the formation of substantial amounts of an immobile phase resulting in rather unexpected effects, explained by combination of nucleation, retardation and pre-ordering of chains. Comparison of the three types of fillers shows that those with large surface area affect the crystallization to the greatest extent.