タルク・ゴムを含有するポリプロピレン射出成形品におけるゴム含有量の角部閉じ変形への影響

抄録

The most popular resin material for automotive plastic parts is polypropylene, which includes talc for stiffness and heat-resistance and rubber for impact-resistance. The anisotropic thermal expansion coefficient is well documented for talc reinforced polypropylene, but there are very few technical papers for warpage. Therefore, using this kind of material and molding with an L-shaped cross section, the influence of rubber concentration on corner deformation was discussed in this study.
The results of this study are as follows;
1) L-shaped cross section specimens show that the corner deformation increases linearly in proportion to the increase of rubber concentration.
2) Plane shape specimens show that the shrinkage rates in the planar direction decrease linearly and the shrinkage rates in the thickness direction increase linearly.
3) The strains in each rubber concentration are calculated using Hooke's Law. This force that induces corner deformation is assumed as the shrinkage difference between the planar and thickness directions. The tendencies of calculated strains are qualitatively consistent with measured corner deformations.
4) The reason why corner deformation decreases linearly to rubber concentration is due to the fact that the shrinkage difference between the planar and thickness directions increases and the fact that the flexural modulus decreases linearly.