Study On Heat Resistance And Decomposition Kinetics Of Nitrile Rubber

In this paper,it is mainly focused on the logic rules for the functions in NBR vulcanization characteristics,mechanical properties,thermal aging resistance,high-temperature resistance,and oil resistance by using magnesium methacrylate(MDMA)and MDMA cooperated with traditional fillers(like carbon black,silica)to reinforce NBR.Furthermore,the thermal weight loss of NBR in air atmosphere was analyzed by TG-DTG.The thermal decomposition characteristics of NBR in air were systematically studied by Kissinger equation and Flynn-Wall-Ozawa method,while the thermal stability of NBR was quantitatively analyzed.The results show that magnesium methacrylate(MDMA)has outstanding performances in NBR’s reinforcement,and vulcanized rubber has a high elongation at break while maintaining high tensile strength.Increasing the amount of MDMA can promote the vulcanization rate and cross-linking degree of NBR,as well as improving the mechanical properties of NBR.The mechanical performances of NBR at high temperature are much worse than its performances at normal temperature.By the increase of MDMA dosage,the mechanical properties of NBR at high temperature are gradually enhanced.Meanwhile,after the MDMA dosage exceeding 30 parts,increasing the dose of MDMA is no longer playing an important role in improving the mechanical properties of NBR at high-temperature.The MDMA can improve the heat-resistant oxygen aging performance and high temperature oil resistance of NBR.By increasing the dosage of MDMA,NBR heat aging resistance and heat resistant oil properties become stronger.In general,NBR has the best performances overheat oxidative aging resistance and oil resistance when MDMA dosage is 30 parts.However,MDMA has an adverse effect on the NBR compression set.With increasing the amount of magnesium methacrylate,the NBR resilience performance deteriorates and the compression set increases.When MDMA is cooperated with carbon black or silica to reinforce NBR,the hardness,tensile strength,tear strength,and modulus of the vulcanized rubber increases by adding the amount of carbon black or silica under the circumstance of constant dosage of the MDMA.While the elongation at break increases first and then decreases with the increase of carbon black,and its elongation at break decreases with the increase of the amount of silica.Increasing the amount of carbon black or silica can improve the heat-resistant oxygen aging and oil resistance of NBR.And NBR oil resistance and aging resistance performances are the best when the amount of carbon black or silica is 20-30 parts.Carbon black or silica cooperated with MDMA to reinforce NBR can further improve the high-temperature resistance of NBR.When the amount of carbon black or silica is 30 parts,the tensile strength of NBR can reach about 15 MPa at 100 ℃,and the tensile strength retention rate can be maintained above 50% at high temperature.When MDMA is used to reinforce NBR with a certain amount of carbon black or silica,it can well reduce the compression set of NBR.However,the excessive use of carbon black or silica can lead to an increase in compression set.There are two decomposition processes when NBR is thermally decomposed in the air atmosphere.The heating rate plays an important role in the decomposition process of NBR.If the heating rates change rapidly,the measured decomposition temperature moves toward the high-temperature direction.By applying Kissinger maximum weight loss rate method,the activation energy in the first decomposition stage is 177.466 KJ/mol,and the activation energy in the second decomposition stage is 158.550 KJ/mol in the air atmosphere of NBR vulcanizate;using the Flynn-Wall-Ozawa method obtains the activation corresponding Ea to different weight loss rates,it found that the activation energy of NBR in the first decomposition stage of the air atmosphere increases first and then decreases with the increase of the weight loss rate,and the activation energy of the second decomposition stage decreases with the increase of the weight loss rate with the increase of weight loss rate;applying Coats-The Redfern method determined that the reaction order of the first decomposition stage and the seconddecomposition stage of the NBR vulcanizate air atmosphere was n=1,which indicated the type of NBR thermal decomposition reaction was independent of the heating rate.