The effect of poly(ethylene-octene) grafted maleic anhydride elastomer (poegma) and liquid epoxidised natural rubber (lenr) on mechanical properties of poly(hydroxyl-3-butyrate) (phb)

Abstract

Poly(hydroxyl-3-butyrate) (PHB) has a great potential in many applications due to its biodegradable and biocompatible properties. However, PHB is considered as a stiff material since it has high brittleness and narrow processing windows which limit the use of PHB. In order to improve the brittleness of PHB, poly(ethylene-octene) grafted maleic anhydride elastomer (POEgMA) and liquid epoxidized natural rubber (LENR) were incorporated into PHB using internal mixer. The blends were melt blended at temperature of 165 °C and rotor speed of 60 rpm for 8 min. The concentration of POEgMA and LENR were varied from 5, 10, 15 and 20 wt%. The mechanical and morphological properties were determined using tensile testing, Izod impact testing and scanning electron microscopy (SEM). Addition of 5 wt% POEgMA decreased the elongation at break and impact strength of PHB. The tensile strength and tensile modulus showed no significant changes with increasing amount of elastomers added to the blends. SEM micrograph revealed smaller rubber particles in the PHB/LENR system in comparison to the PHB/POEgMA blends at the same rubber concentration. The impact strength of PHB/LENR blends decreased significantly with the addition of elastomer. Thus based on this observation, it is suggested that the presence of LENR improves the plasticizing effect of the blends and not acting as an impact modifier.