The Preparation of Polysiloxane Modified Polyurethane Sealant Prepolymer
One-component polysiloxane/polyether polyurethane sealant prepolymer were synthesized by the ad-dition reaction of dihydroxybutyl-terminated polydimethylsiloxane ( DHPDMS) with isocyanate-terminated polyether PU prepolymer, which was prepared by polymerization of 2,4-tolylene diisocyanate ( TDI) and polyether glycol (PPG). The effects of DHPDMS content on the properties(tensile strength, surface, low temperature durability, thermal stability etc.)of modified PU sealant prepolymer were studied. The results showed that, when the content of DHPDMS was 15%, the modified PU sealant prepolymer had a proper degree of microphase separation and the me-chanical properties was better. The glass transition temperature ( Tg ) decreased from -58.6℃ to -79.8℃, com-pared with polyether PU prepolymer. Meanwhile, the initial decomposition temperature was higher than polyether PU prepolymer.
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