Files
Abstract
Recently, the development of bio-based polymers has attracted considerable attention, due to their composability or biological degradability. In this study, poly(lactic acid) (PLA) and poly(hydroxyalkanoate) (PHA) were modified with three functional additives for improving their thermal, mechanical, and rheological properties for industrial application. A plasticizer, a processing aid, and a nucleating agent used as additives were blended with PLA or PHA in various concentrations using a solution casting technique or a melt blending process. Poly(butylene glutarate) (PBG) was explored due to its potential to be used as a plasticizer and processing aid for PLA and PHA, respectively. The nucleation effect of poly(3-hydroxybutyrate) (PHB) was investigated on PHA. Differential scanning calorimetry (DSC), tensile testing, dynamic mechanical analysis (DMA), and melt flow index (MFI) were used to determined thermal, mechanical, and rheological properties of these blends. Atomic force microscopy (AFM), scanning electron microscope (SEM), and polarized optical microscope (POM) were used to determine the morphology of the blends. The rates of composting biodegradation for the selected blends were evaluated in a respirometer under aerobic conditions at 58 °C. The results suggested that PBG is a useful plasticizer for PLA and an effective processing aid for PHA. PBG improved the % elongation at break and accelerated the rate of degradation of PLA. Besides the melt fracture on the surface of extruded PHA can be eliminated by adding PBG to the blend in a commercial extruder. It was found that PHB is an effective nucleating agent for PHA, and since PHB is a biologically degradable material, blending of PHB with PHA is still route to an environmentally friendly product.