Self-healing Of Transparent Polyurethane Elastomers Based On Phenolic Hydroxyl And Hindered Alcohol Hydroxyl Chain Extension

When the transparent polymer is damaged,its mechanical properties and transparency will decrease.The self-healing of the polymer can repair the damaged polymer material,restore its origin performance and extend its service life.Polyurethane is widely used in self-healing miaterials because of its unique micro-phase separated structure.However,most previous researches show that the problem of healing temperature higher than 120 °C still exist in the polyurethane based on dynamic urethane bond exchange,so the healing temperature needs to be lowered.In addition,the relationship between its transparency,self-healing and structure is still not clear.In order to solve the above problems,bisphenol A and 2,5-dimethyl-2,5-hexanediol based on the molecular design are selected as chain extenders to prepare polyurethanes.The aim is to obtain a polyurethane elastomer with good transparency and lower healing temperature.Polyurethanes containing aromatic carbamate bonds were prepared from polytetramethylene ether glycol(PTMG),hexamethylene diisocyanate(HDI)and bisphenol A.The effects of hard segment content,healing temperature,healing time and healing cycles on the healing efficiency were studied.The results showed that polyurethane had a higher healing efficiency,moreover,the healing temperature decreased significantly due to the incoropration of aromatic carbamate.The effect of bisphenol A on the transparency of polyurethane was proved by using bisphenol F and 1,4-butanediol(BDO)chain-extended polyurethane as control samples.The results showed that the incoropration of bisphenol A was beneficial to the improvement of transparency.Polyurethane was prepared with PTMG,diphenylmethane diisocyanate(MDI)and 2,5-dimethyl-2,5-hexanediol.The effects of hard segment content,healing temperature,healing time and healing cycles on the healing efficiency were investigated.The results showed that the healing efficiency of polyurethane at 80 ° C can reach 90%.The urethane bond with steric hindrance can reduce the healing temperature of polyurethane.Moreover,polyurethane had better transparency.