Comparative data Roller

Sedimentation methods are also useful in determining particle size distribution. Webb (28) describes the techniques employed in liquid sedimentation and gives data comparing the results with those obtained in mechanical screening. Sedimentation methods are particularly useful in measuring sub-sieve sizes. Air-elutriation methods (Roller, 29) are also useful, especially when used in connection with microscopic examination (Wiley, Deloney, and Denton, 30 Matheson, 31). 

Zhang and Xu [1993] blended EVAc and CPE (chlorinated-polyethylene) with PE (Table 11.9), because crosslinked PE has low flexibility for use as cable insulation. They mixed 30-70% HDPE with 70-30% EVAc or CPE, along with 0.5-1.0% of the antioxidant 1010 and 0.5-1.0% of zinc stearate in a SK-160B double roller mixer at 130-140°C. The blends so made were either hot-pressed into sheets or extruded into tubes, and irradiated with 1.5-MeV electrons to a dose of 100 kGy. Some properties of the irradiated blends and PE are compared in Table 11.21. As the data in this Table show, the flexibility and the elongation of the HDPE/EVAc and HDPE/CPE blends are better than those of the PE but their hardness and softening points are lower. The two blends also show the memory effect better than that shown by the PE. Moreover, the heat-shrunk tubes of the PE/EVAc and PE/CPE blends were more flexible than those of the heat-shmnk PE. 

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