甲醛交联麦草碱木质素--聚乙烯醇反应膜的制备及其性能研究

Preparation and properties of alkali lignin-poly (vinylalcohol) (PVA) reaction membrane with formaldehyde crosslinker

通过甲醛交联麦草碱木质素与聚乙烯醇（PVA）后采用流延法制备了麦草碱木质素-PVA反应膜，考察甲醛用量对反应膜力学性能的影响，并采用SEM、TG、DTG等方法予以表征，检测膜的力学性能、热性能、对紫外光的吸收性能、透气性能和耐溶剂性能。结果表明：甲醛加入量为3．0％时，麦草碱木质素-PVA反应膜的拉伸强度为21．81MPa，断裂伸长率为682％；表面和断面较为均匀平整；最剧烈分解温度约为300℃，465℃时残重率约为7．8％，均比PVA膜高，热稳定性增强；麦草碱木质素-PVA反应膜对200～500nm光有较强的吸收，具有抗紫外线辐射性能；氮气透气率为2．696×10^-7m^3／（m^2·d·kPa），远高于PVA膜；溶于水和乙酸等极性溶剂，几乎不溶于异丙醇、四氯化碳和石油醚等弱极性溶剂。

The wheat straw alkaline lignin-poly （vinytalcohol） （PVA） chemical reaction membranes were prepared on the basis of wheat straw alkaline lignin by crosslinking reaction of formaldehyde and PVA by the film casting method. The effects of formaldehyde content on mechanical properties of membranes were investigated. And the mechanical properties, thermal properties, absorbability of ultraviolet light, gas permeability and solvent resistance were measured. The results showed that the tensile strength and elongation at break of membranes were 21.81 MPa and 682% when the mass ratio of formaldehyde was 3.0%. The surface and fracture surface of membranes were well-distributed and smooth. The most violent decomposition temperature of the membranes was 300 ℃ and the residue of membranes was 7.8% at 465 ℃, both of which were higher than PVA membrane, indicating a better thermal stability of membranes. Also the membranes exhibited anti-UV according to the strong absorption capacity of light between 200 -500 nm. The nitrogen permeability of membranes was 1. 580 × 10^-8 m^3/（ m^2·day·kPa） , which was much lower than PVA membrane 2. 696 × 10^-7 m^3/（ m^2·day· kPa）. Besides, the membranes were soluble in water and acetic acid, and insoluble in isopropanol, carbon tetrachloride and petroleum ether.