Nonisothermal Crystallization Kinetics of Polylactic Acid under the Influence of Polyolefin Elastomers

Abstract

Crystallization kinetics of various blends of poly(lactic acid) (PLA)/polyolefin elastomer (POE) was studied through nonisothermal experimental investigations and theoretical approaches. The PLA/POE blends were prepared in a melt mixing process by using two types of POEs and compatibilizers. The rubber phases used were adopted on the basis of polyethylene (PE) and polypropylene (PP) type olefin elastomers. The effects of two kinds of compatibilizers containing ethylene vinyl acetate copolymer (EVA) and ethylene acrylic ester-glycidyl methacrylate terpolymer (EGMA) on the morphology and various parameters of crystallization of PLA were investigated using scanning electron microscopy (SEM) and differential scanning calorimeter (DSC) measurements, respectively. The morphology investigations on PLA blends containing PP based olefin elastomers showed that the introduction of EGMA compatibilizer into the matrix led to a more than 100% reduction in the size of the rubber droplets. The experimental measurements of crystallization behavior of various PLA/POE blends showed that the POEs and compatibilizers could cause a fall in the initial crystallization temperature more than 13 °C. The theoretical approaches used for studying the kinetics of crystallization of PLA in the presence of various POEs and compatibilizers indicated a decrease in the crystallinity of PLA and a 64% reduction in the activation energy compared to the neat PLA. The results suggest that the largest variation in the crystallization kinetic parameters of PLA was resulted from the PP based olefin elastomer and EGMA compatibilizer.

Tuning the mechanical and thermomechanical properties through the combined effect of crosslinking and annealing in poly(lactic acid)/acrylonitrile‐EPDM‐styrene blends

“…19,20 Researchers are trying to improve PLA's mechanical and thermomechanical performance in this context, primarily through polymer blends. [21][22][23][24] There are scientific reports on the development of PLA blends with ethylene-propylene-diene (EPDM), 25,26 polycaprolactone (PCL), 27,28 polyolefin elastomers, 29,30 poly(butylene adipate-co-terephthalate) (PBAT), 7,31 poly(butylene succinate) (PBS), 32,33 and natural rubber (NR), 34,35 exploring their mechanical, thermal, rheological, and morphological properties. Although the polymer blends of PLA showed improved impact strength and elongation at break, the main setback has been severe losses in elastic modulus, tensile strength, and heat deflection temperature (HDT).…”