橡胶/液晶复合膜的形态结构与透气性能

Permeability and morphology of poly(cis-butadiene)/ ester-ether liquid crystal composite membranes

以顺丁橡胶 (PB)和具有双重液晶相的液晶化合物双 - 4 - (4′ -乙氧基苯甲酰氧基 )苯甲酸一缩乙二醇酯 (DEBEB)制成了不同液晶含量的高分子复合膜 ,并研究了其气体透过性能 .复合膜具有两个明显的特征 :1)室温下 ,所有复合膜的透气系数均大于纯PB膜 .其中PB/DEBEB(质量比为 90 /10 )的复合膜具有比纯PB膜大 6倍的透过系数 (PO2 =54.7、PN2 =17和PCO2 =4 32Barrer ,1Barrer=7.6× 10 - 8cm3·cm/cm2 ·s·MPa)及好的分离系数 (αO2 /N2 =3.2、αCO2 /N2 =2 5.4和αCO2 /O2 =7.9) .2 )O2 、N2 、CO2 透气系数 -温度关系曲线都呈现“N”型特征 .复合膜形态结构的研究表明 :复合膜中DEBEB的质量分数在 10 %以上时 ,液晶不是以分子分散状态而是以晶畴的方式被分散包裹在橡胶基质膜中 .因此提出了晶畴与基质膜之间存在界面微隙的设想 ,并结合液晶的相行为 ,对上述现象进行了合理的解释 .

Polymer/liquid crystal composite membranes,with several mass ratios,composed of poly( cis -butadiene)(PB)and diethylene glycol bis(4-(4′-ethoxybenzoyloxy)benzoate)(DEBEB) with a dualmesophase were prepared in order to improve their gas permeation properties.There were two obvious characteristics in gas permeation behavior through the composite membranes:(1) At room temperature,the permeability coefficients to O 2,N 2 and CO 2 through the composite membranes were higher than that of PB membrane.For example,a PB/DEBEB(90/10) membrane gave a result( P O2 =54.7, P N 2 =17 and P CO 2 =432 Barrer) which was about six times higher than a PB membrane,and good separation factors( α O 2/N 2 =3.2、 α CO 2/N 2 =25.4 and α CO 2/O 2 =7.9).(2) All relationships between temperature and the permeability coefficient to the three gases were characterized by the N-shape method.Morphology studies by DSC,SEM and OPM demonstrated that the DEBEB content in the composite membranes at above 10% was not molecularly dispersed,but spherically embedded in the PB matrix in a crystal domain state.It is suggested that microvoids probably occur on interfaces between the crystal domains and the PB matrix.Gas permeation characteristics of the composite membranes were appropriately interpreted as results of together influence of DEBEB phase transition behavior and morphology of the composite membranes.