Study On Regeneration Process Of Waste Rubber

In this paper, reclaimed rubber was prepared by open mill regeneration, banburying regeneration and high-speed hybrid then heat preservation regeneration method. The effect of regeneration technology on structure and property of reclaimed rubber was investigated. The ratio of main-chain scission to crosslink scission is studied according to horikx theory and the regeneration mechanism analysed by SEM. The efficiency of the reclamation process is studied by measurement of the Mooney viscosity, sol analysis and swelling experiments. The cure characteristics and physical properties of the reclaimed rubber were also studied. In addition, the permeability of reclaim activator and devulcanization of NR vulcanizate under the environment of supercritical CO2fluid were discussed.The results of high-speed hybrid then heat preservation devulcanization showed that with the increase of reaction temperature and reaction time, the sol fraction of the reclaimed rubber increased and the crosslink density decreased, when the temperature reached180℃, the sol fraction reduced instead and the crosslink density tended to be banlanced. It is calculated according to horikx theory that reclamation has mainly occurred through crosslink scission and the reaction temperature and time had almost no influence on bond breaking type. With the increase of reaction temperature, the scorch time(ts1) and recurring time(t90) of reclaimed rubber showed a trend of gradually increase, and the tensile strength decreased, the hardness value changed little. With the increase of reaction time, the tensile strength of revulcanizates reduced slightly and the tensile elongation changed little. The results showed that the optimum conditions for the reaction is that the temperature was180℃and the reaction time was90min. Comparing the three different regeneration process, it is founded that the reclaimed rubber prepared by banburying regeneration has the most sol, a appropriate Mooney viscosity while the physical and mechanical properties is poor. The reclaimed rubber prepared by open mill regeneration had the highest tensile strength but a poor processability. And High-speed hybrid then heat preservation devulcanization balanced the performances of reclaimed rubber better.Vulcanized natural rubber was devulcanized by using supercritical CO2, the reaction pressure was10MPa and the reaction time was2h. When the reaction temperature was90℃, only the permeation of reclaim activator(420) happened and the rubber not devulcanized. When the temperature rised to180℃, the devulcanizatin occurred, the crosslink density decreased from1.06×10-4mol/cm3to1.86×10-5mol/cm3and the sol fraction increased from2.54%to15.71%. In addition, the degree of devulcanization was dependent on the type of crosslinks, and the reclamation has also mainly occurred through crosslink scission.