Effect of Thermo–Oxidative Aging on the Tensile and Morphological Properties of PP/NR and PP/RRP Blends

Abstract

Kesan penuaan termo-oksidatif ke atas sifat tensil dan morfologi untuk adunan polipropilena (PP)/getah asli (NR) dan PP/serbuk getah kitar semula (RRP) menggunakan pelbagai kandungan getah (80/20, 50/50 dan 40/60 berat/berat) telah dikaji. Adunan dicampur menggunakan Brabender Plasticorder pada suhu 190°C dan kelajuan 50 rpm. Keputusan menunjukkan bahawa pada kandungan getah yang sama, adunan PP/RRP mempunyai peratus retensi kekuatan tensil yang lebih tinggi (91–99% berbanding 85–93% untuk adunan PP/NR) dan juga modulus Young (71–86% berbanding 55–80% untuk adunan PP/NR) tetapi pemanjangan pada takat putus yang lebih rendah (72–85% berbanding 75–87% untuk adunan PP/NR). Mikrograf elektron penskanan menunjukkan permukaan rekahan selepas penuaan termo–oksidatif adunan PP/NR adalah lebih licin berbanding permukaan rekahan adunan PP/RRP. Pemerhatian ini menyokong keputusan retensi kekuatan tensil selepas penuaan termo–oksidatif bagi adunan PP/RRP yang lebih baik berbanding adunan PP/NR. Kata kunci: termo-oksidatif; polipropilena; getah asli; serbuk getah kitar semula The effect of thermo–oxidative aging on the tensile and morphological properties of polypropylene (PP)/natural rubber (NR) and PP/recycled rubber powder (RRP) blends at different rubber content (80/20, 50/50 and 40/60 wt./wt.) were studied. The blends were melt mixed using a Brabender Plasticorder torque rheometer at a temperature of 190°C and rotor speed of 50 rpm. The results indicated that at a similar rubber content, PP/RRP blends exhibited higher degree of retention of tensile strength (91–99% compared with 85–93% for PP/NR blend) and Young´s modulus (71–86% compared with 55–80% for PP/NR blend) but exhibited lower elongation at break (72–85% compared with 75–87% for PP/NR blend). Scanning electron microscopy (SEM) examination of the tensile fractured surface of PP/NR blends showed a more smooth fractured surface than PP/RRP blends after thermo–oxidative aging. This observation supported the higher tensile strength retention after thermo–oxidative aging of PP/RRP blends compared with the PP/NR blends. Key words: thermo-oxcidative; polypropylene; natural rubber; recyled rubber powder