Effect of synthetic process on properties of PCL waterborne polyurethane
Isophorone diisocyanate and polycaprolactone glycol were used as main raw materials,dimethylol propionic acid as hydrophilic agent,1,4-butanediol and trimethylolpropane as chain extender/cross-linker to prepare waterborne polyurethane emulsion under the conditions as the isocyanate index of polymer is 1.10,the mass fraction of hydrophilic chain extender and the chain extender/crosslinking agent in polymer are 5%and 3%,respectively.The effects of different synthetic processes on properties of emulsion and membrane were investigated.The results show that the properties of waterborne polyurethane prepared by prepolymerization→introduction of hydrophilic group→chain extension/crosslinking→neutralization→emulsific ation are the best,the particle size distribution is narrow,the average particle size is small,and the Zeta potential is the highest absolute value,the stability of the emulsion is better.The degree of microphase separation in the hard and soft segments of the membrane is increased,its tensile strength is increased and its water absorption is decreased obviously.
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