A small amount of organometallic compounds was added to an unvulcanized rubber sheet and the sheet was vulcanized in contact with a zinc plate. The organometallic compounds which included metals such as Co, Cu, and Pb, were found to transfer to the zinc plate during vulcanization. A certain amount of Co in Co-naphthenate diffused into the zinc plate. The free sulfur in rubber transferred to the surface of the zinc plate. The amounts of Co and S which transferred onto the surface increased proportionally to the concentration of Co-naphthenate. The adhesive force between rubber and the zinc plate increased with quantity of Co-naphthenate as far as 0.6% of Co content and it dropped remarkably at 0.8% of Co content. The free sulfur in the vulcanized rubber decreased with an increasing amount of Co-naphthenate, but the crosslink was kept at a constant density. The tensile strength and the elongation of vulcanized rubber were little affected by the addition of Co-naphthenate. The residual Co-naphthenate in the vulcanized rubber accelerated the thermal degradation of rubber at temperatures above 60°C. The dielectric behavior of rubber which did not include carbon black showed that Co-naphthenate affected the relaxation mode of chain segments in rubber molecule.

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Soft PVC compounds containing fillers have been crosslinked by 2-dibutylamino-4, 6-dithio-s-triazine, and their mechanical and thermal properties have been also studied in regard with fillers and crosslinking degree.
An optimum condition for the formation of the crosslinked products is that blending be carried out at 165°C for 5-10min, and crosslinking at 180°C for 30min.
Tensile strength and elongation for the crosslinked products were influenced by fillers, crosslinking degree, plasticizers and the polymerization degree of PVC. Though the reinforcing effect of fillers was hardly observed, the dependence of crosslinking degree on tensile strength and elongation was relaxed by addition of fillers and an additive effect of fillers was recognized.
Though compression set was improved by crosslinking, it was hardly improved by addition of fillers.
Thermal properties such as heat distortion and zero strength temperature were improved by crosslinking and addition of fillers.

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