Mechanical Properties of Blends of High Density Polyethylene and Polypropylene

HDPE/PP Blends의 역학적 성질

The mechanical properties of blends of high density polyethylene(HDPE) and isotatic polyproylene(iPP) was examined testing temperature, strain rate, and the composition. Initial Young's modulus increases monotonically with increasing PP content 70wt% above which it reaches a maximum at about 80wt% PP contents under the testing condition of up to 90℃ and all stain rates. At a given PP content, composite curves for the yield stress plotted against log of the strain rate at a certain temperature could be drawn by shifting the curves obtained at different temperature along the axis of strain rate. The shift factor for the composition of a master curve could be expressed by the Arrhenius plot. These master curves for the different PP contents could be further reduced into a composite curve by shifting them along the axis of strain rate. These results show the effects of temperature, rate of strain, and of PP contents on the yield stress can be convertible to each other by simple laws. The necking stress increases linearly with increasing PP contents, and decreases monotonously with increasing the testing temperature. And the yield elongation decreases with increasing PP contents, but at about 80wt% PP contents it shows a minimum value. The crystallinity and the melting point of blends were also measured by DSC.