INFLUENCE OF CALCIUM-BASED FILLERS AND VEGETABLE OIL ON THE PROCESSABILITY AND YIELD BEHAVIOR OF POLYOLEFINS

The mixing of different polyolefins, several calcium-based fillers, an d a type of vegetable oil was investigated. The effect of viscosity an d type of polyolefin on Young's modulus, yield stress, and elongation at yield has been determined. Tensile and machine torque properties ha ve been studied for both mixing at 180 degrees C and at 250 degrees C as a function of the content of several types of calcium carbonate or calcium hydroxide filler. The influence of the addition of a sunflower oil as a lubricant has also been characterized. SEM micrographs indic ate some problems of the formation of agglomerates and the influence o f particle size on matrix morphology and filler/matrix adhesion. Physi cal and chemical interactions among high-density polyethylene (HDPE), vegetable oil, and calcium hydroxide was noticed. Spectra from infrare d spectroscopy illustrate the formation of structures similar to metal lic soaps, which integrate well within HDPE. Compared to calcium carbo nate, results reveal excellent possibilities for the use of calcium hy droxide as a filler for polyolefins. (C) 1997 John Wiley & Sons, Inc.