Design And Synthesis Of Self-healing Elastomer Materials Based On Eucommic Ulmoides Gum And Natural Rubber

Self-healing elastomers based on Eucommia ulmoides gum(EUG)and nature rubber(NR)were prepared via epoxidation followed by in situ ring opening grafting and free radical initiated grafting copolymerization.Infrared spectroscopy(IR)and nuclear magnetic resonance(NMR)were adopted to investigate the effects of temperature,pH and the reactant dosage on the reactions.Differential scanning calorimeter(DSC)and polarizing optical microscope(POM)were used to study the effect of degree of modification on the aggregate structure of tproducts.Optical microscope(OM)was used to observe and record the self-healing behavior of the product,and tensile test was used to evaluate the effect of contact temperature,time and healing numbers on self-healing efficiency of the products with different degree of modification.The results showed that the optimum reaction conditions are 50℃ and pH=5 under which the moderate degree of modification products can be obtained and almost no side reactions occur.With the increase of degree of modification,the morphology of the products transformed from hard plastics to soft plastics and finally to soft elastomer.DSC and POM results showed that GEEUG12.5 isa crystalline,the GEEUG17.2 is amorphous but containing a small amount of scattered little spherocrystal and GEEUG21.8 is completely amorphous.The OM results show that EEUG cannot self-heal,while the cracks on GEEUG 21.8 surfaces can be fully repaired in 22min in the absence of any external force.The tensile stress-strain curve showed GEEUG possessed a fast and efficient self-healing ability under mild temperature conditions,and the self-healing efficiency was up to 83.9%after 50℃ for 2h.IR and the dynamic frequency spectrum confirmed the existence of hydrogen bond and hydrogen bond network in GEEUG.The self-repairing behavior of EUG-g-BMA gel was analyzed under microscope,and the self-repairing efficiency of the gel was studied by tensile test.The results show that the self-repairing efficiency of the gel is closely related to the repairing time and temperature,and the repair efficiency can reach 90.21%at 60℃,12 hours.It also can reach 67.86%at 90℃,1 hours.When the gel content is more than 36%,from 50℃,the repair time 12 hours,repair efficiency can reach 82.6%.The results of NR showed that the optimum reaction conditions are 50℃ and pH=5under which the moderate degree of modification products can be obtained and almost no side reactions occur.With the increase of degree of modification,the morphology of the products transformed from hard plastics to soft plastics and finally to soft elastomer.The OM results show that GENR 20.8 surfaces can be fully repaired in 21min in the absence of any external force.The tensile stress-strain curve showed GENR possessed a fast and efficient self-healing ability under mild temperature conditions,and the self-healing efficiency was up to 81.5%after 50℃ for 2h.IR and the dynamic frequency spectrum confirmed the existence of hydrogen bond and hydrogen bond network in GENR.