Preparation and properties of self-healing polyurethanes with different alicyclic-type hard segment distributions
Two kinds of polycarbonate diol(PCDL)with different relative molecular masses were synthesized by controlling the ratio and feeding sequence of raw materials polycarbonate diol-2000(PCDL-2000)and hexamethylene diisocyanate(HDI)with linear structure.Three kinds of self-healing polyurethanes(PC-PU)and films with different alicyclic-type hard-segment distributions were then prepared from polymerization of PCDL-2000 and PCDL with isophorone diisocyanate(IPDI)and 1,4-butanediol(BDO),respectively.PC-PU and films were characterized by FTIR,XRD,TGA,AFM,3D ultra-depth-of-field microscope,and electronic universal testing machine for analysis on the crystal structure,crystalline morphology,thermal stability,tensile strength and self-healing properties,with the self-healing mechanism explored.The results showed that the crystallinity of PC-PU increased from 23.3%to 26.5%,the modulus of elasticity increased from(17.9±1.1)to(62.7±2.3)MPa,the elongation at break decreased from 1420%±40%to 1060%±50%,and the tensile strength ranged between(18.6±2.5)and(20.5±3.4)MPa as the distribution of the alicyclic-type hard segments was concentrated.Based on the hydrogen bonding and the thermal movement of the soft segments,the self-healing efficiency of PC-PU could reach as high as 81.9%±3.3%.
polyurethanealicyclic-type hard segment distributionhydrogen bonding actionthermal movement of polymer chainsself-healing
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