Study On Preparation And Properties Of Epoxidized Natural Rubber

Natural rubber is a rubber made from natural rubber-producing plants.It is a natural polymer compound with polyisoprene as its main component.Its molecular formula is(C₅H₈)_n,which is a non-polar rubber and is not easily used in polar solvents.It is easily swelled in non-polar solvent and has poor organic solvent resistance and oil resistance.Therefore,it is necessary to modify natural rubber to overcome its limitations and broaden its special application fields.The epoxidation modification of natural rubber not only retains the basic structure and performance characteristics of natural rubber,but also enhances the air tightness,oil resistance,compatibility and wet skid resistance of natural rubber due to the introduction of epoxy groups on the molecular structure.The rolling resistance will greatly reduce the adhesion performance with other materials and obviously improve,at the same time,it also has some special properties.Therefore,it is of great significance to study the synthesis of epoxy natural rubber by a reasonable process.Epoxy natural rubber(ENR)was prepared by using mild potassium peroxybisulphate compound salt as oxidant,acetone as catalyst,and sodium bicarbonate as catalyst to adjust the p H of the control system.The formulation and process of the system are determined as follows:with isomeric tridecarbon alcohol polyoxyethylene ether as the emulsifier,the solid content of natural rubber in the emulsion is 25-28%(w/w),the temperature is 4-8?,the molar ratio of NR,acetone and potassium peroxide compound salt is 1:0.435:0.190,the epoxy degree is 28%and the reaction efficiency is 73.68%ENR.The structure of epoxy rubber is characterized by FTIR and ¹H NMR,Or the conditions of the process are mild,the properties of ENR are stable and the byproducts are few.ENR is synthesized by epoxidation of NR with H₂O₂/NaHCO₃ system,and the better experimental formula and process are optimized.The results show that the solid content of NR is 25-28%(w/w).When the concentration of hydrogen peroxide is 20%,the reaction time is about 4 h,the reaction temperature is below 10?,and the molar ratio of NR/H₂O₂/NaHCO₃/SDS/Mn SO₄ is 1/1.5/1.7/0.04/0.02,the ideal ENR of epoxy degree can be obtained.The structure of epoxidized NR is characterized by FTIR.The trans-polyisoprene(TPI)is epoxidized to synthesize epoxy trans-polyisoprene(ETPI)using H₂O₂/NaHCO₃ system.The preferred experimental formula and process were determined to be below 5?.Using toluene as an organic solvent,the molar ratio of TPI/H₂O₂/NaHCO₃/Mn SO₄/SDS is 1/1/1/0.01/0.025.The structure and heat resistance of the epoxidized trans-polyisoprene were analyzed by infrared spectroscopy(FTIR),TGA,DSC,and the like.The performance analysis of ENR and NR shows that during the processing,due to the lower Mooney viscosity of ENR,the feeding speed is slower than that ordinary natural rubber,and the ENR raw rubber is sticky,and the phenomenon of sticky rotor appears which is not conducive to Continuous processing.In the vulcanization process of rubber,the vulcanization speed of ENR is faster,the safe operation time is shorter,the tensile strength of ENR is better than NR,but the hardness is low,and the hardness can be increased and the cost can be reduced by increasing the amount of carbon black.