Mechanical and Morphological Study of Talc/calcium Carbonate Filled Polypropylene Hybrid Composites Weathered in Tropical Climates

Abstract

Dua jenis komposit, iaitu komposit polipropilena (PP) terisi–tunggal (diisi dengan talkum atau kalsium karbonat) dan komposit PP terisi–hibrid (diisi campuran talkum dan kalsium karbonat) yang telah diacuan–suntikkan kepada bentuk ‘dumbbell’. Spesimen tersebut didedahkan kepada pencuacaan semulajadi, iaitu iklim tropika di Pulau Pinang, Malaysia selama 6 bulan. Selepas tempoh pendedahan, sifat mekanikal PP terisi–tunggal telah merosot akibat degradasi fizikal dan kimia yang teruk. Kajian yang lebih mendalam ke atas aspek struktur komposit telah dijalankan untuk mendapatkan kepastian tentang keadaan degradasi tersebut. Walau bagaimanapun, komposit PP–terisi hibrid menunjukkan keupayaan untuk mengekalkan sifat tegangan dan lenturan yang lebih baik walaupun terdapat kesan degradasi pada permukaan spesimen. Didapati bahawa kesan ‘hibridisasi’ telah berjaya meningkatkan ketahanan komposit hibrid terhadap degradasi pencuacaan yang teruk, sehingga struktur–struktur di dalam komposit tersebut dapat dilindungi daripada kesan degradasi, sedangkan permukaan komposit telah mengalami degradasi yang teruk. Kata kunci: Polipropilena; komposit hibrid; pengoksidaan foto; pengguntingan rantai; degradasi terma; pencuacaan semula jadi Two kinds of composites, namely single–filler polypropylene (PP) composites (contain either talc or calcium carbonate) and hybrid–filler PP composites (consist of a mixture of talc and calcium carbonate) were injection moulded into dumbbells. These specimens were subjected to natural weathering i.e. tropical climate in Penang, Malaysia for 6 months. After 6 months of exposure, the mechanical properties of single–filler PP composites deteriorated due to severe physical and chemical degradation. This was confirmed after studies were made on the structure aspects of the composite. However, the hybrid–filler PP composites were found to show better retention in both tensile and flexural strength albeit have undergone some degree of degradation as well. It was found that the ‘hybridization’ effect has successfully increased the resistance of the hybrid composite to severe environmental degradation to the extent that it protects the internal structure of the composite from environmental damage, while the surface of the composite gets severely degraded. Key words: Polypropylene; hybrid composite; photooxidation; chain scission; thermal degradation; natural weathering