Various mixing methods (①PP→Talc/CaCO₃ mixing, ②PP→Talc→CaCO₃ mixing, ③PP→CaCO₃→Talc mixing) on the mechanical, thermal properties have been characterized by scanning electron microscopy (or acoustic exploration) and differential scanning calorimeter (DSC) .Stearic acid was used as a modifier for CaCO₃. PP and Talc (or CaCO₃) were mixed on a two-roll mill and thin films were prepared by compressing the mixed compound in a heated press.
For mixing method① or ②, the impact strength, tensile strength, tensile elongation at break were more than those of mixing method③. The heterogeneous structure such as aggregation or agglomeration of filled particles and presumably voids at polymer-filler interface for mixing method① or ②, which is calculated by ultra-sonic images, was less than that of mixing method③. In these experiments, impact strength of PP/Talc/CaCO₃ composites could roughly be expressed as a function of aggregation or agglomeration fraction.
DSC properties (crystallization temperature, melting point, melting enthalpy, etc.) were not remarkably dependent on each mixing method, except for crystallization enthalpy under a cooling crystallization process.

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Thermal diffusion behaviors of molten polyethylene molecules in thermal gradient fields were investigated by using conventional rotational rheometers. When a thermal gradient was given to the sample between parallel plates of a rotational rheometer, the absolute value of the complex viscosity of polyethylene having broad molecular weight distribution decreased with time. The decrease was enhanced at larger temperature gradient. It was confirmed by size exclusion chromatography that the decrease in apparent viscosity is attributed to the diffusion of lower molecular weight fraction to the higher temperature plate. This segregation hardly occurred in polyethylene with narrow molecular weight distribution. The applied oscillatory strain to measure the complex viscosity did not affect this phenomenon.

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