探討無機填料/聚丙烯複合材料之機械性質

Abstract

本研究主要目的係探討無機填料含量對聚丙烯複合材料機械性質之影響，兩種無機填料分別為硫酸鎂晶鬚(Magnesium oxysulfate whisker)及矽灰石(Wollastonite)，分別以10wt%、20wt%及30wt%的含量與聚丙烯混合，透過掃描式電子顯微鏡(SEM)分析無機填料於聚丙烯之方向性及無機填料之形貌。無機填料對聚丙烯複合材料機械性質影響的探討，包括拉伸實驗及破壞韌性實驗。拉伸實驗結果顯示複合材料之楊氏模數隨著無機填料含量增加而遞增，透過微觀力學模型(Mori-Tanaka model)並考慮無機填料長徑比分布，預估無機填料複合材料之楊氏模數。破壞韌性實驗結果顯示兩種無機填料之複合材料破壞韌性皆於添加10wt%時達到峰值，含量增加逐漸降低，透過掃描式電子顯微鏡分析破壞韌性試片之破壞表面，探討其破壞機制。敲擊實驗藉由力量感測器及雷射位移計分析20wt%硫酸鎂晶鬚/聚丙烯複合材料板承受衝擊之受力及變形情況，觀察其破壞模式，此外，透過有限元素分析軟體LS-DYNA模擬板材之動態行為。

The study aims to investigate the mechanical properties of polypropylene (ethylene-methacrylic acid copolymers modified) composites containing there different loadings of inorganic fillers, i.e., 10wt%, 20wt% and 30wt%. Two kinds of inorganic fillers were considered, one is magnesium oxysulfate whisker and the other is acicular wollastonite crystal. The morphology of the inorganic filler dispersed within polypropylene was examined through the scanning electron microscope (SEM). The mechanical property of polypropylene composites with inorganic filler, including tensile property and fracture toughness. Tensile testes demonstrated that when the loading of the inorganic filler increases, the moduli of the polypropylene composites increase accordingly. The incremental tendency of the moduli in terms of inorganic filler loading was appropriately characterized using Mori-Tanaka micromechanical model with the consideration of aspect ratio distribution of inorganic filler. From fracture tests it was found that for both composite material systems, the fracture toughness achieves the peak value when the inorganic filler loading is 10wt% and then declines with the increment of the inorganic filler. Based on the SEM observation on the fracture surfaces, the decrement of the fracture toughness could be attributed to the severe aggregation of the inorganic fillers in the composites. The magnesium oxysulfate whisker/polypropylene composites plate with the filler loading 20wt% was analyzed by load cell and laser sensor for displacement to investigate the dynamic behavior and the failure mode of the composites. Furthermore, the dynamic behavior of hammer impact test was simulated by finite element software LS-DYNA.