Study On Preparation, Structure And Properties Of Polyurethane Elastomer With Long Alkyl-branched Chain

In this paper, four kinds of novel diols with long alkyl-branched chain, i.e. N-tetradecyl diethanolamine, N-octadecyl diethanolamine, N-docosyl diethanolamine,N-hexacosyl diethanolamine were synthesized and a series of PU elastomers withdifferent length of alkyl-branched chain were prepared by using these novel diols,PTMG and TDI as raw materials, MOCA as a curing agent.The effects of length and content of alkyl-branched chain on mechanicalproperties of PU elastomer were studied. The results showed that the mechanicalproperties of PU elastomer decreased dramaticlly after introducing short alkyl-branched chain in the structure of polyurethane; however, the mechanical propertiesof PU elastomer increased with increasing the length of alkyl-branched chain, due tothe alkyl-branched chain could separate with the PU main chain to form a microphase,and made the cross-linking density of PU elastomer increase. When the length of theintroduced alkyl-branched chain was in the range of tetradecyl to octadecyl, themechanical properties of obtained PU elstomer were even better than the PUelastomer without branched struture; Finally, when the length of alkyl-branched chainexceeded octadecyl, the mechanical properties of the obtained PU elastomer presenteda decreased trend again.The effects of length and content of long alkyl branched chain on dynamicmechanical property and microstructure of PU elastomer were investigated. Theresults showed that the dynamic mechanical property and microphase separationdegree of PU elastomer decreased significantly after introducing short alkyl-branchedchain in the structure of polyurethane; however, the dynamic mechanical property anddegree of microphase separation of PU elastomer increased with increasing thelength of alkyl-branched chain. When the length of the introduced alkyl-branchedchain was in the range of tetradecyl to octadecyl, the dynamic mechanical propertyand microphase separation degree of obtained PU elstomer reached a maximum valuewhich was much better than the PU elastomer without branched struture; Finally,when the length of alkyl-branched chain futher increased, the dynamic mechanical property and microphase separation degree of obtained PU elastomer presented adecreased trend again.