Polylactide/polyvinyl acetate blends containing different molecular weights of poly(ethylene glycol)

Polylactide (PLA)/polyvinyl acetate (PVAc)/poly(ethylene glycol) (PEG) blends with different molecular weights of PEG (4000, 10000, and 20000 g/mol) were prepared, and the weight ratio was fixed at 72/18/10 (g/g/g) after the tensile analysis of PLA/PVAc and PLA/PEG blends, and finally the samples were characterized by various methods. The tensile and impact results showed that all the ternary blends were well toughened by PEG, and with the increase of PEG molecular weight, the tensile strength and impact strength increased. Scanning electron microscopy and energy-dispersive X-ray spectroscopy results indicated that 20% (by weight) of PVAc exceeded its solubility limit with PLA, and therefore the excess PVAc was dispersed as nanoparticles in the matrix. When PEG was added, the insoluble amount of PVAc decreased, indicating that the miscibility between PLA and PVAc could be increased by PEG. Differential Scanning Calorimetry results showed that T_m optical microscopy results showed that the number and size of PLA spherulites was peak areas of PLA in PLA/PVAc/PEG blends were smaller than that in PLA/PVAc blend, showing that the crystallinity of PLA was decreased with the addition of PEG in the presence of PVAc, which was confirmed by X-ray diffraction results. Polarization was the smallest in PLA/PVAc/PEG blends. All the ternary blends were transparent and had better visible light transmissions than PLA/PVAc blend. Thermal gravimetric analysis results showed that PLA and its blends had similar thermal stability. Overall, a low-cost PLA-modified material that combined high toughness, strength, and transparency without the need for customization was provided.

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