有機および無機繊維強化ポリプロピレンの破壊・衝撃特性

Abstract

ガラス繊維や有機繊維(アラミドおよびポリビニールアルコール繊維)のような種々の長繊維で強化されたポリプロピレンにおける破壊および衝撃特性を研究した。繊維の長さが特性におよぼす影響を調べるために、種々の長さに切断したガラス繊維もまた使用した。濃度を変えた種々のシラン系カップリング剤による表面処理をガラス繊維にほどこした。強化繊維とポリプロピレン繊維の混合マットを分繊飛動装置と呼ばれている混合装置で調整し、圧縮成形した。破壊および衝撃特性はアイゾット衝撃、高速衝撃および破断靭性で評価し、結果を短ガラス繊維強化ポリプロピレンの結果と比較した。衝撃特性が強化繊維の体積率で改良されるが改良の程度は強化繊維により異なること、またガラス繊維強化ポリプロピレンの衝撃特性が繊維の表面処理でかなり改良されることが分かった。アイゾット衝撃強度と破断面との関係が明瞭に観察できた。ガラス繊維充填系の破壊靭性は繊維の臨界体積率でピークを示すが、有機繊維系においては繊維の体積率と共に直線的に増加した。

Fracture and impact properties for various long fibers such as glass fiber and organic fibers (aramid and polyvinyl alcohol fiber) reinforced polypropylenes were investigated. Chopped glass fibers in various lengths were also used in order to investigate in the influence of fiber length on the properties. Surface treatment by different kinds of silane coupling agents with different concentrations was performed on glass fiber. Reinforcement fiber and polypropylene fiber mixed mats were prepared by a mixing machine which is called 'fiber separating/flying machine' and then compression molded. Fracture and impact properties were evaluated by Izod impact, high rate impact and fracture toughness, and results were compared with those of short glass fiber reinforced polypropylenes. It was found that impact properties increase with volume fraction of reinforcement fibers although these improvement rates were different with reinforcement fibers, and that the impact properties of glass fiber reinforced polypropylenes were significantly improved by surface treatment of fibers. Correlation between Izot impact strength and fracture surface was observed clearly. Fracture toughness of glass fiber filled systems showed the peak at a critical volume fraction of fiber, but that of organic fiber filled systems increased linearly with volume fraction of fiber.