Research On Gas Permeability Of PEBA Gel Membranes Via Thermally Induced Phase Separation

With the development of modern industry, the threats of global warming to human lifehave received worldwide attention. As the main greenhouse gas, CO2separation to mitigategreenhouse effect, energy efficiency and carbon resource recycling are important researchsubjects at present.Gel membrane in membrane gas-separation technology has attracted people’s attentionsfor its advantages of outstanding gas permeability, high selectivity and stability. Solvent castmethod has been widely used to prepare gel membrane, unfortunately solvent pollution wascaused during the preparation. Thermally induced phase separation(TIPS), which ischaracteristic of miscible in high temperature and thermal reversible in low temperaturebetween polymer and solvent, have a distinct advantages compared with solvent cast method.In this paper, ethylene glycol monophenyl ether (EPH) and polyether block amide(PEBA) were selected as the functional carrier and polymer to prepare a series of gelmembranes using thermally induced phase separation (TIPS) method. The effect ofcompatibility, stability mechanical properties and gas permeability of the gel membranesaccording to the change of EPH content, proportion of triblock copolymers PEBA and EPH-IPDI content were studied. The main conclusions are listed below:1. EPH/PEBA (PEBA:PEBA2533, PEBA3533, PEBA4033, PEBA6333) gel membraneswere prepared to research the impact of different ration of block segments in PEBA on thecompatibility of PEBA and EPH, thermal performance, mechanical properties and gaspermeation of EPH/PEBA gel membranes. The results showed that PEBA2533has the bestcompatibility with EPH in four types of PEBA. The crystalline phase increased with theincreasing PA-12content in PEBA, and then decreased with the adding of EPH. The tensilestrength, Young’s modulus and maximum deformation of EP/PEBA gel membranes werereduced due to the plasticizing effect of EPH on the polymer. The diffusion, solubility andpermeability of CO2and N2enhanced with the increase of EPH in PEBA, exhibiting theexcellent permeability of CO2in PEBA2533and the high CO2/N2selectivity in PEBA4033.The use of EPH strongly increased the CO2diffusivity and solubility in all polymers. ForEPH/PEBA2533-60gel membrane, the CO2was up to1080Barrer and EPH/PEBA4033-60separation factor was47.8respectively.2. A series of EPH/PEBA4033gel membranes were prepared. The impact of differentEPH contents on thermal performances, mechanical properties and gas permeations ofEPH/PEBA4033gel membranes were reaserched. The results showed that both mechanicalproperties and the crystalline phases decreased with the increase of EPH, but CO2absorptionswere increased. When the content of EPH was up to80wt%, the permeability and separationfactor of the EPH/PEBA4033gel membrane were up to960Barrer and51.6respectively,expressing a brilliant performance.3. EPH was modified with IPDI and EPH-IPDI/PEBA4033gel membranes wereprepared via thermally induced phase separation (TIPS). The impact of different EPH-IPDIcontents on thermal performances, mechanical properties and gas permeations of EPH- IPDI/PEBA4033gel membranes were reaserched. The results showed that modified EPH-IPDI significantly improved the thermal stabilities of EPH-IPDI/PEBA4033gel membranescompared with EPH/PEBA4033gel membranes. With the modified EPH-IPDI, the CO2adsorptiones of gel membranes were improved significantly, and reprented excellent CO2/N2selectivities. When the content of EPH-IPDI was up to60wt%, the permeability andseparation factor of the EPH-IPDI/PEBA4033gel membrane were496Barrer and55.7respectively.