聚乙烯醇分子结构对聚乙烯醇/氧化石墨烯复合材料吸水保水性能的影响

Microstructure and Water Absorption Properties of Polyvinyl Alcoholand Preparation of Polyvinyl Alcohol /Graphene Oxide Composites with High Water Absorbing Properties

对4种聚乙烯醇(PVA)的相对分子质量、醇解度、VAc单元嵌段度进行了定量表征,并制备了PVA/氧化石墨烯(GO)复合材料,对其结晶度、结晶及熔融行为、吸水和保水性能进行研究,试图揭示PVA分子结构与PVA/GO复合材料吸水及保水性能之间的深层联系。结果表明,PVA醇解度越高,VAc单元嵌段度越低,其PVA/GO复合材料的结晶和熔融温度就越高、结晶度越高,而相对分子质量的影响很小;另一方面,醇解度过低、疏水乙酰基含量高、氢键含量少时,则吸水性能和保水性能较差;醇解度过高则会导致结晶度过高,对吸水和保水性能有抑制作用。只有醇解度及结晶度适中时,PVA/GO吸水及保水性能最优。

In this study,the molecular weight and distribution,hydrolysis degree,VAc unitdistributionof four kinds of polyvinyl alcohol(PVA)were characterized.The PVA/graphene oxide(PVA/GO)composites were prepared,and the crystallinity,crystallization behavior,water absorption/water retention property were studied to elucidate the relationship between PVA molecular structures and water absorption/water retention properties of PVA/GO.The results suggest that with the higher hydrolysis degree and the lower VAc unit distribution,the crystallization and melting temperature is higher,and the crystallinity increases;meanwhile,the molecular weight of PVA is not important.A low hydrolysis degree leads to a high content of hydrophobic ethanoyl group and a low content of hydrogen bond and finally undesirable water absorption/water retention properties,while the high hydrolysis degree results in too high crystallinity,playing a depressive effect to water absorption/water retention properties of the composites.Only sample PVA-2 with the medium hydrolysis degree can provide the highest water absorption/water retention properties.