聚乙烯醇基高透湿高阻隔三元混合基质全热交换膜制备和性能

Polyvinyl alcohol(PVA)based ternary mixed matrix total heat exchange membranes(THEM)comprising montmorillonite(MMT)and CaCl_(2):preparation and characterization

探讨了通过蒙脱土(MMT)和无水氯化钙(CaCl_(2))共混掺杂改性,来打破透湿和阻气性之间的博弈(trade-off)效应,全面提升聚乙烯醇(PVA)全热交换膜性能的可行性。本文系统研究了氯化钙和蒙脱土的含量对膜的形态、接触角、热稳定性、力学性能、气体透过率和总换热效率的影响。实验数据表明,适量氯化钙的杂化可以引入水传导通道,提升膜的水蒸气透过率和焓交换效率,适量蒙脱土掺杂可以提升膜的高CO_(2)气体阻隔性能、改善其热稳定性和机械性能,同时提升粗糙度、提高湿度和焓交换效率;但是当无水氯化钙和蒙脱土含量过高时,膜的机械性能、透湿度和CO_(2)气体阻隔性能又会变差。综合考虑,PVA∶CaCl_(2)∶MMT的质量比为8∶1.6∶0.8的三元混合基质膜不仅具有高的透湿性和焓交换效率(68%),而且保持了聚乙烯醇膜的极高CO_(2)气体阻隔性,有望作为节能通风系统中全热交换膜的优化选项。

The feasibility of breaking the trade-off between the heat exchange ratio and waste gas barrier property of polyvinyl alcohol(PVA)based total heat exchange membranes were investigated using montmorillonite(MMT)and CaCl_(2) as co-additives.The morphology,water contact angle,thermal stability,mechanical properties,gas transmission permeability and total heat exchange efficiency of the ternary hybrid matrix membranes developed from solution-cast method were investigated at varied content of CaCl_(2) and MMT.It was observed that addition of suitable amount of CaCl_(2) hybrid can be introduced into the water conduction channel to improve the water vapor permeability and enthalpy exchange efficiency of the membrane.The addition of suitable amount of MMT could improve not only CO_(2)gas barrier property,but also surface roughness,thermal stability and mechanical properties of the THEM.However,excess MMT or CaCl_(2) content had both shown negative effects.Considering the requirements of low CO_(2)gas transmission permeability,good water vapor and heat exchange efficiency and mechanical properties,the hybrid matrix membranes with the mass ratio of PVA∶CaCl_(2)∶MMT of 8∶1.6∶0.8 was most likely to be used as total heat exchange membranes with improved performance in energy-saving ventilation systems.