Abstract:

Five series of waterborne polyurethane emulsions,respectively with different relative molecular masses ofsoft segments,different kinds of hard segment,different hard segment contents,different hydrophilic chain extendersas well as with blending modification by liquid paraffin were synthesized via the actone method with poly-1,4-butylene adipate glycol,1,4-butanediol,hexamethylene diisocyanate,isophorone diisocyanate,N-( 2-aminoethyl) -amino ethane sulphonated sodium,dimethylol propionic acid and ethylenediamine as the main raw materials.Then,the structure and hydrogen bonding of WPU were characterized by means of FT-IＲ,and the crystallinity and thermostabilityof WPU films were determined respectively through DSC and TG.The results indicate that ( 1) highercontents and more-defined structure of hard segment as well as the addition of liquid paraffin can increase hydrogenbonding degree of WPU; ( 2) with polyester polyol of higher relative molecular mass as the soft segment,diisocyanateof regular structure as the hard segment,sulphamate as the hydrophilic chain extender and liquid paraffin asthe modifier,WPU films show higher crystallinity; and ( 3) higher crystallinity of WPU films helps improve theirthermostability.

Key words: waterborne polyurethane, crystallinity, thermostability, microphase separation