Morphology and Properties of Polylactic Acid Composites with Butenediol Vinyl Alcohol Copolymer Formed by Melt Blending

Due to its poor toughness and hydrophilicity, the application of polylactic acid (PLA) in the field of absorbent sanitary materials is restricted. A butenediol vinyl alcohol copolymer (BVOH) was used to improve PLA via melt blending. The morphology, molecular structure, crystallization, thermal stability, tensile property, and hydrophilicity of PLA/BVOH composites with different mass ratios were investigated. The results show that the PLA/BVOH composites possessed a two-phase structure with good interfacial adhesion. The BVOH could effectively blend into PLA without a chemical reaction. The addition of the BVOH promoted the crystallization of PLA, improved the perfection of the crystalline region, and increased the glass transition temperature and melting temperature of PLA in the heating process. Moreover, the thermal stability of PLA was markedly improved by adding the BVOH. The addition of the BVOH also had a significant effect on the tensile property of the PLA/BVOH composites. When the content of the BVOH was 5 wt.%, the elongation at the break of the PLA/BVOH composites could reach 9.06% (increased by 76.3%). In addition, the hydrophilicity of PLA was also significantly improved, and the water contact angles decreased with the increase in the BVOH content and time. When the content of the BVOH was 10 wt.%, the water contact angle could reach 37.3° at 60 s, suggesting good hydrophilicity.