Preparation Of Phthalic Anhydride Polyester Polyol Based Waterborne Polyurethane Membrane And Performance Of Pervaporation Separation Towards Benzene/Cyclohexane Mixture

In this work, waterborne polyurethane emulsion was synthesized by using Phthalic anhydride polyester, aliphatic polyester and aliphatic polyether polyols as soft segment, toluene diisocyanate/isophorone isocyanate(TDI/IPDI) as hard segment and small molecule glycol or diamine as chain extender through the method of pre-polymer process. Salivate method was used for membrane coating, the membranes were characterized using FT-IR, TGA, degree of swelling(DS) determination and pervaporation performance for benzene/cyclohexane (50/50 in wt.%).(1) The series membrane synthesized using phthalic anhydride polyester polyol mixture CP-2056 and polyester polyols and polyether polyols as soft segment, TDI as hard segment. The result indicated the degree of swelling and permeation flux of the series membrane using polyester polyols and CP-2056 compound as soft segment were higher than the membrane using polyether polyols and CP-2056 compound as soft segment, separation factor was contrary trend, because ether bond increased the flexibility of chain segment. In the same polyether polyols or polyester polyol content conditions, the membrane contains side chain methyl which can increase the intramolecular rotational barrier has higher degree of swelling and permeation flux.(2) The series membrane synthesized using polyphthalic acid-1,6-glycol polyester diol(PH-56) as soft segment, IPDI as hard segment, compared with the membrane synthesized using polyhexamethylene adipate glycol(PHA-2000) as soft segment, the result indicated that thermal stability and selectivity of PH-based membrane were better than PHA-based membrane. When the content of PH-56 increased from 55.0% to 73.6%,the degree of swelling increased gradually, the permeation flux rapidly increased from 6.91kg·?m/(m2·h) to 23.8 kg ?m/(m2·h), separation factor slowly decreased from 6.90 to 4.91.(3) The series membrane synthesized using PH-56 as soft segments, IPDI as hard segment, different amine as chain extender, the result indicated, under the condition of the same chain extender proportion, para-phenylene diamine and biphenyl diamine series membrane had better swelling resistance and selectivity towards benzene than the ethylenediamine series membrane. With the increasement of diamine in the series membrane, permeation flux decreased gradually and separation factor increased.