The effect of molecular weight and hydrolysis degree of poly(vinyl alcohol)(PVA) on the thermal and mechanical properties of poly(lactic acid)/PVA blends

Abstract The effect of molecular weights and hydrolysis degrees (HD) of polyvinyl alcohol (PVA) on thermal and mechanical properties and crystallinity of polylactic acid (PLA)/PVA blends was investigated. Blends were prepared by the melt blending method using PLA/PVA ratios: 80/20, 90/10 and 97/3 wt. %. A single glass transition temperatures was observed for all PLA/PVA blends, suggesting the formation of binary compatible blends at concentration range studied. Thermogravimetric analysis results showed a better thermal stability for PLA/PVA blends containing PVA of higher Mw and HD. According to mechanical properties, low quantities of PVA (3 wt. %) do not affect the tensile strength of blends (irrespective of Mw and HD). However, as the PVA content increases, tensile strength tends to lower values, especially for blends with 20 wt.% of PVA, with 98% of HD.

摘要 本研究考察了聚乙烯醇（polyvinyl alcohol, PVA）的分子量与水解度（HD）对聚乳酸（polylactic acid, PLA）/PVA共混物的热学、力学性能及结晶度的影响。采用熔融共混法制备共混物，PLA与PVA的质量配比设置为80/20、90/10及97/3。所有PLA/PVA共混物均仅呈现单一玻璃化转变温度，表明在本次研究的浓度范围内形成了二元相容共混体系。热重分析结果显示，含有高分子量、高水解度PVA的PLA/PVA共混物具备更优异的热稳定性。从力学性能来看，低添加量（3 wt.%）的PVA不会对共混物的拉伸强度产生影响（无论PVA的分子量与水解度如何）。然而，随着PVA添加量的提升，共混物的拉伸强度呈降低趋势，尤其在PVA添加量为20 wt.%且水解度为98%的共混物中表现最为显著。