Synthesis and characterization of ethyl acrylate/allyl chloride grafting natural rubber latex in supercritical carbon dioxide
In this paper,the grafting modification of natural rubber latex with ethyl acrylate(EA)/ allyl chloride(AC) as monomer was performed by supercritical carbon dioxide (scCO2) swelling polymerization,and the graft copolymer NR-g-(EA/AC) was synthesized.The effects of reaction pressure and dosage of initiator on the monomer graft level and monomer conversion in the grafting copolymerization reaction were studied.The FT-IR spectra,mechanical properties,hardness,solvent resistance and fire resistance of NR-g-(EA/AC) were tested,and the graft level and conversion level of monomer were calculated,which were all compared with the values obtained from solution polymerization.It was found that the structure of grafted rubber changed significantly (the functional groups of C=O and —Cl were introduced) and the tensile strength,modulus of elasticity,hardness,solvent resistance and fire resistance of graft copolymers were improved greatly.The graft level and conversion level obtained from solution polymerization and supercritical carbon dioxide swelling polymerization were both high and the prepared products had similar mechanical properties,but the solvent resistance of the product obtained from solution polymerization was better than that obtained from supercritical carbon dioxide swelling polymerization.Due to the green solvent nature of supercritical carbon dioxide,supercritical carbon dioxide swelling polymerization would hopefully become a new green method for the grafting modification of natural rubber.