Rubber blowing agent is a kind of substance that can decompose and produce gas under specific conditions, so that rubber produces fine pores or honeycomb structure, mainly used in the manufacture of sponge products, which can be divided into inorganic blowing agent and organic blowing agent. When EPDM reclaimed rubber or EPDM rubber/reclaimed rubber is used to produce EPDM sponge glue with continuous extrusion vulcanization, different varieties of blowing agents have different effects on its vulcanization behavior.
In actual production, the EPDM sponge glue with continuous extrusion vulcanization foaming mostly adopts sulfur vulcanization system, and the foaming agent H, foaming agent AC, foaming agent OBSH, etc. are commonly used in the foaming system, and the type of foaming agent E4LYY628 will affect the vulcanization rate and cross-linking degree of EPDM reclaimed rubber. When EPDM reclaimed rubber sponge foaming compound is used in combination with foaming agent H, foaming agent AC, foaming agent OBSH and foaming agent BK, the vulcanization behavior is different from that without foaming agent.
1. The by-product of the decomposition of foaming agent H is hexamethylenetetramine, which has the function of accelerator, so the vulcanization of EPDM reclaimed rubber compound with foaming agent H and foaming agent H/urea is fast.
2. The decomposition by-product of blowing agent AC is acidic substance, which may reduce the effect of the compounding agent in the vulcanization system, thereby affecting the vulcanization rate, and has a tendency to delay the vulcanization rate of EPDM reclaimed rubber; When the blowing agent AC is used in conjunction with the blowing agent BK, BK will accelerate the decomposition of the blowing agent AC, resulting in a slower vulcanization start.
3. The by-product of the decomposition of the blowing agent OBSH is an acidic substance, which will react with the sulfur and accelerator in the vulcanization system, thereby reducing the role of the compounding agent in the vulcanization system and significantly reducing the vulcanization rate and vulcanization density of EPDM reclaimed rubber sponge foaming compound.
When EPDM reclaimed rubber is produced by continuous extrusion vulcanization, the accelerator will reduce the decomposition temperature of the blowing agent, thereby affecting the vulcanization behavior of the reclaimed rubber. For example, when accelerators H and AC are mixed with different accelerators, their decomposition temperature will be greatly reduced; The decomposition temperature of the blowing agent H was reduced the most by the highly acidic accelerator M.
Therefore, the design of the experimental formula and the analysis of vulcanization characteristics are the key steps to optimize the formula of EPDM reclaimed rubber sponge, and the accelerator selected when adjusting the vulcanization rate of the sponge rubber formula must be discussed with the final rubber compound with foaming agent.
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