Preparation of highly biodegradable and electron beam crosslinkable linear low-density polyethylene - based biocomposites with unique mechanical performance

Abstract

Preparation of high starch containing LLDPE (linear low-density polyethylene)/starch composite with a considerable degree of mechanical properties has always been a challenge for a long time. These challenges are low thermal stability of starch, difficulties in processability of high starch containing LLDPE, inability of polymers to contain large quantities of starch and compromised mechanical properties of prepared composites. To overcome these difficulties, 20 wt% ENGAGE (ethylene-octene copolymer), a polyolefin elastomer, was blended with 80 wt% LLDPE followed by composites preparation with modified starch-pistachio shell powder (SPSP). ENGAGE, due to its unique processability, improved the processability of high SPSP-containing LLDPE composite. And due to the generation of extra space by amorphous ENGAGE, the LLDPE/ENGAGE blends could accommodate up to 70 wt% SPSP without any degradation during high-temperature processing. Mechanical properties were also considerably enhanced due to the reinforcement of the polymer matrix by pistachio shell powder (PSP). SEM and dynamic mechanical analysis (DMA) confirmed the structural integrity of processed composites and uniform dispersion of SPSP into LLDPE/ENGAGE blends. The obtained LLDPE-based composites with 70% biodegradability and around 240% elongation are unique and useful. It is also revealed that the presence of 20 wt% PSP inhibits electron beam-initiated degradation of starch instead leading to crosslinked network in composites, thus further enhancing properties.