Study Of The Effect Of Cerium Compounds On Reinforcing Natural Rubber And Its Mechanism

Norganic rare earth auxiliaries can be used to strengthen the performance of rubber, but because of the bad compatibility between inorganic rare earth compounds and rubber, and high interface energy of inorganic rare earth compounds,inorganic rare earth compounds can not disperse into rubber matrix uniformly, the effect of rare earth auxiliaries on modifying rubber is not good and it is hard to add large amount of rare earth auxiliaries into rubber.Cerium oxide was modified by sodium lauryl sulfate(SLS) or stearic acid. In condition of keeping the original processing technology the effect of modified cerium oxide on tank track shoe rubber was investigated. Best additive quantity and influence rule was determined by analyzing the mechanical property, aging characteristic, and wear-resisting property of the natural rubber sample. Cerium oxide which was modified by SLS could improve all the performance of rubber except tear resistance, the rubber sample performed best when there was0.2phr cerium oxide which was modified by SLS added in, the tensile strength of rubber could reach to25.4MPa, and tear resistance could reach to16MPa, ageing coefficient was0.82, abrasion value was0.1666g. Cerium oxide which was modified by SA could improve all the performance of rubber, the rubber sample performed best when there was1phr cerium oxide which was modified by SA added in, the tensile strength of rubber could reach to26.4MPa, and tear resistance could reach to18MPa, ageing coefficient was0.94, abrasion value was0.1954g.Mechanism of cerium oxide effect on nature rubber was discussed by EDS, XRD and vulcanization curve. It was found that cerium oxide remained+4valent cerium oxide after vulcanization processing and presented in the rubber matrix. Cerium oxide took part in the vulcanization reaction, and prolonged the scorch time, shortened the optimum cure time, but didn’t change the crosslinking density. Cerium oxide improving tensile strength and aging characteristic of rubber is attributed to the special4f electronic shell of cerium: it could form “instant clathrate” during stretching process, so the degree of crystallinity of rubber, which was also instant crosslinking density was improved, the tensile strength of rubber was enhanced; During the thermo-oxidative aging process, rare earth additives could combine with some free radical, so free oxygen radical chain reaction was slowed down, the cross-linked structure was protected from been destroyed, and the aging characteristic of material was improved. At the same time, in order to replace traditional inorganic rare earth additive. We used a unsaturated carboxylic acid as organic ligand to prepare cerium methacrylic acid. The molecular formula of cerium methacrylic acid was determined as Ce(MAA)3by infrared spectroscopy, elemental analysis, thermogravimetry and so on. The size of aggregation was about20μm. After vulcanization Ce(MAA)3was polymerize in situ, it can dispersed well into the matrix of rubber, and the size of particle can decreased to about1μm. In the system of peroxide Ce(MAA)3had good reinforcing effect on natural rubber, and the effect was enhanced with the increasing additive dosage. When the added amount of Ce(MAA)3was50phr and there was no any other fortifier, the tensile strength of rubber could reach to11.8MPa, and tear resistance could reach to26.5MPa, hardness was57.