Thermal Diffusivity of Injection-molded Polpropylene Plate Filled with Glass Fiber

Abstract

Anisotropy in composition structure of injection-molded polypropylene plate filled with glass fiber was studied by means of measuring that thermal diffusivity. Two types of test films, whose thickness direction was vertical to melt flow direction (MD) or transverse direction to the melt flow (TD), were cut from the injection-molded plates, with a diamond cutter and a microtome. Glass fiber contents in the test films were 0, 5, 10 and 20 weight percent. Those thermal diffsivity was measured by a simple non-steady state method, using AC Joule heating, which had been developed in our laboratory. Then, the thermal diffsivity of injection-molded plate was evaluated as anisotropic in the place near the gate. Further, it was clarified by the obervation of dispersion and orientation states of glass fiber with polarizing light microscopy, that the orientation of glass fiber caused the anisotropy in the thermal diffusivity, rather than weight percent of the glass fiber.