Study Of The New Mothods To Reclaime Wasted Rubber

As the biggest rubber used country, we also has the largest amount of wasted rubber, limited by natural resource, we imported the vast majority of rubber. So in consideration of resource and environment, it is important to reclaim wasted rubber. Traditional reclaiming methods had obviously chain scission of rubber main chain, and the low molecule mass of reclaimed rubber also limited the use of reclaimed rubber. To protect the environment and save resources, it is important to increase the molecule mass of the reclaimed rubber. In this paper different reclaiming methods were used to reclaim natural rubber (NR), butyl rubber (IIR), ethylene propylene rubber (EPDM), and silicon rubber (SIR).In order to make selective chain scission of crosslink bond, we chose high energy ultraviolet (UV) reclaiming method firstly. The results showed that after irradiated by UV, the vulcanized rubber got photo degradation in the surface, the degradation rate was NR>IIR> EPDM, with irradiating time increase, the molecule mass of NR, EPDM sol component decreased, molecule mass of IIR sol component was stable at50000.’HNMR showed oxygen-containing groups in NR and EPDM.The photo-degradation was characterized by FI-IR (Fourier Transform Infra-Red) test, Contact angle test, EDX test, the FI-IR results showed that NR, IIR got chain scission in=C-H bond, NR and EPDM had-OH,-C=O and-C-O in the rubber surface. SIR showed no reaction in UV condition. Contact angle test, EDX test results showed that oxygen reacted with vulcanized rubber after stimulated by UV and made the decreasing of molecule mass of reclaimed rubber.To avoid the oxygen, we chose supercritical CO2reactor to reclaim NR, it showed that with reacting time increasing the sol fraction of reclaimed NR increasing while the molecule mass of reclaimed NR was stable at about17000. When the sol fraction was30%, and the formula of vulcanizing agent was50%of virgin NR curing formula, the reclaimed NR rubber had the best tensile stress Mooney viscosity of radical mechanism reclaimed rubber would increase with time increasing, that main because the reclaiming rubber might crosslink again making the increasing of crosslinking density.To study the nucleophilic mechanism of NR reclaiming in low temperature and no oxygen condition, we chose DTT (DL-Dithiothreitol) to reclaim NR, it showed that the Crosslinking density decrease with the reacting time, DTT content; temperature increasing in the certain range, DTT could prevent the Crosslinking of NR rubber.