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Kinetics of vulcanization of natural rubber coagulated by microorganisms (NR-m) was studied with the use of a vulcameter. In the induction period of vulcanization, the time t0 of NR-m is shorter than that of natural rubber coagulated by acid (NR-a), and the rate constant k1/a of NR-m are greater than that of NR-a. Both the curing periods of NR-m and NR-a consist of two stages. The first stage follows first-order reaction. The rate constants k2 of NR-m in the first stage are greater than that of NR-a at the same temperature, and so are the activation energy E2. The second stage (end stage of the curing period) does not follow first-order reaction, and the calculated reaction order n of NR-m is in the range of 0.82-0.85, and that of NR-a is in the range of 0.64-0.72. The rate constants k3 of the second stage for NR -m are greater than that of NR-a at the same temperature, and so is the activation energy E3.

The starch xanthate/natural rubber (SX/NR) composite was prepared by directly mixing and co-coagulating NR latex and the modified starch paste with carbon bisulfide. The vulcanization kinetics of NR and SX/NR composite were investigated by using a rubber process analysis (RPA). The mechanism of SX/NR composite vulcanization was similar to that of pure NR. The values t0and tdisof XS/NR composite were shorter than that of NR, and the activation energy E1for the induction period was smaller. The activation energies E2and E3for the curing period were smaller than that of NR.

The porous starch was modified by xanthates, and the starch/natural rubber composite was prepared by blending the modified starch with natural rubber latex. The morphology, thermal stability, swelling behavior and mechanical properties of the composite were investigated. Morphology studies by SEM showed that the modified porous starch were homogeneously dispersed in NR matrix. The composite has higher solvent resistance and lower water resistance after adding modified porous starch. The mechanical properties of composite are improved significanly with the increase of modified porous starch.