Preparation And Separation Performance Of A New Type Of Polyurethane Permeation Membrane

According to the characteristics of the molecular structure of dihydric alcohol polyoxyethylene ether(N120)and polyethylene glycol(PEG),the prepolymer reactions were occurred using N120 and PEG as the soft segment respectively,isophorone diisocyanate(IPDI)as material at first,then adding 1,4-butanediol(BDO)as chain extender,trimethylolpropane(TMP)as crosslinking agent,the N-PU membrane and PEG-PU membrane were prepared by changing the content of hard segment and crosslinking parameter.The structure and properties of the two membranes were characterized by FT-IR,DMA,TG,uniaxial tensile testing and static contact angle testing.Firstly,the effect of N-PU membrane with different hard segment content and crosslinking parameter on the pervaporation performance of a small amount of water in n-butanol and the effect of PEG-PU membrane with different hard segment content and crosslinking parameter on the pervaporation performance of a small amount of n-butanol in tributyl borate were studied respectively.Secondly,the experimental conditions of N-PU membrane and PEG-PU membrane were investigated.Finally,the N-PU membrane and PEG-PU membrane were modified by inorganic nanoparticles.The main research contents and results are as follows.(1)The N-PU membrane had two glass transition temperatures which was tested by DMA instrument,indicating that the structure of the soft segment and hard segment were incompatible,and the micro phase separation structure was formed.The N-PU membrane had good swelling property in water,but the swelling degree was lower in n-butanol,and the calculation results of permeability coefficient showed that the N-PU membrane had good selectivity for water and n-butanol system.In 1.0 wt%water/n-butanol system separation,with increasing hard segment content and crosslinking parameter of the N-PU membrane,the separation factor of the N-PU membrane was decreased,and when the hard segment content was 0.40,crosslinking parameter was 0.60,the operating temperature was 60℃ the separation factor of the N-PU membrane was 42.21,the permeation flux of the N-PU membrane was 1084 g/m ·h.The pervaporation performance of N-PU membrane was affected by the concentration of the solution,the thickness of the membrane,and the operating temperature.With the introduction of inorganic carbon nanotubes,the permeation flux of N-PU membrane was improved,and the greater the amount of carbon nanotubes,the greater the permeate flux of N-PU membrane,but the lower the separation factor.(2)The PEG-PU membrane had two glass transition temperatures which was tested by DMA instrument,indicating that the structure of the soft segment and hard segment were incompatible,and the micro phase separation structure was formed.The PEG-PU membrane had good swelling property in n-butanol,but the swelling degree was lower in tributyl borate,and the calculation results of permeability coefficient showed that the PEG-PU membrane had good selectivity for water and n-butanol system.In 1.0 wt%n-butanol/tributyl borate system separation,with increasing hard segment content and crosslinking parameter of the PEG-PU membrane,the separation factor of the PEG-PU membrane was increased,and when the hard segment content was 0.55,crosslinking parameter was 0.90,the operating temperature was 60℃,the separation factor of the N-PU membrane was 59.77,the permeation flux of the N-PU membrane was 255 g/m2·h.The pervaporation performance of PEG-PU membrane was affected by the concentration of the solution,the thickness of the membrane,and the operating temperature.With the introduction of inorganic carbon nanotubes,the permeation flux of PEG-PU membrane was improved,and the greater the amount of carbon nanotubes,the greater the permeate flux of PEG-PU membrane,but the lower the separation factor.