Epoxidized Natural Rubber is prepared with latex processing technology. The relationships of the epoxidation with the reaction times and temperature were investigated. The structure of ENR was characterized by Fourier transform-infrared spectroscopy (FIIR). It is found that, the by products, ring-open components increases with the reaction temperatures and the reaction times. It is found that as the level of epoxidation increased, the number of tetrahydrofuran ring increased.
Deproteinization of natural rubber was achieved in the latex stage. The structure of deproteinized natural rubber (DPNR) was characterized by fourier transform infrared spectroscopy (FTIR). The thermo degradation of DPNR was studied by thermogravimetry analysis (TG) under air atmosphere and nitrogen atmosphere. The kinetic parameters apparent activation energies (Ea) of the thermal decomposition reaction been calculated from the TG curves using the method described by Broido. And the results were compared with the thermo degradation of natural rubber (NR) under the same conditions. The effect of proteins in natural rubber latex on thermal/ thermo-oxidative stability of NR was discussed. The results show that: the absorptions of the proteins in DPNR at 1546 ㎝-1, compared to NR, become significantly weaker, nearly disappear, which indicates most of proteins has been removed from NR. The thermo degradation of DPNR in nitrogen atmosphere is a one-step reaction. The initial degradation temperature (T0) 、the maximum degradation temperature(Tp) and the final degradation temperature(Tf)as well as the Ea of DPNR are higher than those of NR, which indicates that DPNR represents a better thermal stability than NR under nitrogen atmosphere. Thermo-oxidative degradation of DPNR and NR are two-step reaction. The characteristic temperatures (T0, Tp and Tf) of DPNR are lower than those of NR. The Ea during the First Step of Thermooxidative Degradation of DPNR are also lower than those of NR. These results prove that the thermo-oxidative stability of DPNR is worse than that of NR. Protein is the key role to the thermal stability of natural rubber.
NR/ENR/silica composites with different ENR amount were prepared in an open two-roll laboratory mixing mill at room temperature. Dynamic properties of ENR filled NR/silica were performed by dynamic mechanical thermal analyzer (DMA) and compression fatigue analyzer. DMA and compression fatigue test results showed that the effect of ENR on dynamic properties of NR/silica was significant. DMA displayed the tanδ of NR/ENR/silica composites at 0 °C was increased with increasing ENR amount. Compression fatigue test indicated the presence of ENR decreased the heat produced during compression test and the heat build-up is the least when NR to ENR ratio is 80 to 20. Scanning electron microscopy was used to investigate the morphology of NR/silica filled with ENR. It is found that silica self-aggregation was improved in the presence of ENR and sea-island structure was formed in NR/silica when 30phr ENR added, which maybe the reason of decrement of heat produced during compression.
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