将聚乙烯醇/纳米纤维素(PVA/NCC)复合膜应用于乙醇-水混合溶液的渗透汽化脱水过程,探讨了纳米纤维素对膜的溶胀性能、机械性能和渗透汽化性能的影响; 利用原子力显微镜(AFM)探测了纳米纤维素的形貌特征; 采用傅里叶变换红外光谱仪(FTIR)、扫描电镜(SEM)、差示扫描量热仪(DSC)和热重分析仪(TGA)对膜结构和热性能进行了表征.研究结果表明,棒状的纳米纤维素与PVA基体间形成了强烈的氢键作用且均匀分散在PVA基质中; 纳米纤维素的加入提高了膜的熔融温度,增加了膜的热稳定性,有效地抑制了膜的溶胀,并提高了膜的机械性能; 在PVA中添加纳米纤维素可以提高膜的渗透汽化分离性能,用纳米纤维素含量为2%的复合膜在80 ℃时分离体积分数为90%的乙醇水溶液,膜的分离因子达到347,比未加入纳米纤维素时提高24%; 而渗透通量为288 g/(m2·h),比未加入纳米纤维素时下降11%.%Poly ( vinyl alcohol ) ( PVA )/cellulose nanocrystal ( NCC ) composite membranes were used in the pervaporation separation of water-ethanol feed mixtures, and characterized by Fourier transform infrared spectroscopy( lTIR), scanning electron microscopy( SEM), differential scanning calorimetric(DSC) and thermogravimetry(TG). Atomic force microscope (AFM) was used to characterize the cellulose nanocrystal. The characterization results demonstrated that NCC displayed slender rods and dispersed homogeneously within the PVA matrix, which could be assigned to the hydrogen bonds formed between PVA and NCC. The DSC and TG analysis demonstrated that the nanocomposite membranes exhibited an increase in melting temperature and higher thermal resistance. With the addition of NCC, the mechanical properties of the nanocomposite membranes were improved. Moreover, the nanocomposite membranes had good pervaporation properties. Among all the prepared membranes, PVA/NCC nanocomposite membrane containing 2％ NCC exhibited the best separation factor, whose averaged separation factor was 347 for aqueous solution of ethanol(90％ ) at 80 ℃ and 24％ higher than that of crosslinked PVA membrane, but its permeation flux was 288 g/( m2 · h), 11％ lower than crosslinked PVA membrane.
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