膜科学与技术

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Research on alkali resistance of PVDF and its copolymer membranes

Authors： YE Can, ZHOU Yue, LIU Fei, WANG Xiaozu, WANG Zhaohui, CUI Zhaoliang

Units： State Key Laboratory of Materials-Oriented Chemical Engineering , College of Chemical Engineering, Nanjing Tech University ,Nanjing 211816, China

KeyWords： PVDF；PVDF-HFP；PVDF-CTFE；Alkali resistance

ClassificationCode：TQ031.4

year,volume(issue):pagination： 2022,42(1):72-79

Abstract：

In this paper, polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropene (PVDF-HFP) and polyvinylidene fluoride-trifluoroethylene chloride (PVDF-CTFE) were used as membrane materials to prepare ultrafiltration and microfiltration membranes by Non-solvent induced phase separation (NIPS) method. The formula contains 20 wt% polymer, 6 wt% additive and 74 wt% solvent DMAC. Field emission scanning electron microscopy (FESEM), Fourier infrared spectroscopy (FTIR) and whiteness meter were used to characterize the three kinds of films prepared. Concentrations of 0.01, 0.1, 1, 3 and 5 mol/L sodium hydroxide solution was used to construct the alkaline environment. The alkali resistance of the three polymer membranes was investigated after immersion for 50 h. After soaking in 5 mol/L NaOH solution for 50 h, the elongation at break of PVDF, PVDF-HFP and PVDF-CTFE films respectively decreased by 95.3%, 30.7% and 22.6%. The strength of PVDF membrane and PVDF-HFP membrane respectively decreased by 34.5% and 11.5%, while PVDF-CTFE membrane did not decrease significantly. The results show that the mechanical properties and plasticity of the two copolymer membranes were better than that of PVDF membranes in the same alkaline environment. The results of Raman test show that the polymer defluorinated hydrogen formed carbon-carbon double bond, the defluorinated hydrogen resulted in the darkening of the film color and the degradation of the film in alkali solution, but the degradation degree of the two copolymer films was much lower than homopolymer films.

Funds：

国家重点研发计划（2017YFC0403702）；国家自然科学基金（22078146）；江苏省人力资源和社会保障厅六大人才高峰（JNHB-036）

AuthorIntro：

叶灿（1994,，10），硕士，江苏泰州，主要研究方向为膜分离

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