ポリプロピレン/エチレンプロピレンゴム混合系の線膨張とモルフォロジーの関係
Linear Thermal Expansion and Morphology of Polypropylene/Ethylene-Propylene Rubber Blends
小泉順二・奥本忠興・水谷治靖・七田裕章
Koizumi, Junji / Okumoto, Tadaoki / Mizutani, Haruyasu / Shichida, Yoshiaki
Ethylene-propylene rubber modified polypropylene (R-PP) has been often used for automotive exterior parts, but it has been difficult to apply R-PP to large size parts because of the poor dimensional stability. Recently a low coefficient of linear thermal expansion (CLTE) is required to reduce the gap between exterior parts.
In PP/EPR/Talc blends, a reduction of the CLTE in the flow direction of injection molding was tried by changing the flowability of both PP and EPR and the PP/EPR ratio. The flowability showed small effect on CLTE. The lowest CLTE was obtained around a PP/EPR ratio of 30/45 at which the blend showed a co-continuous two-phase structure of EPR and PP phases highly elongated in the flow direction.
Key words: Coefficient of linear thermal expansion / Blend / PP / EPR / Morphology / Dimensional stability / Co-continuous two-phase structure