What factors cause late hardening of Neoprene Zipper Cable Sleeve?

Neoprene Zipper Cable Sleeve are composite materials prepared from a two-part mixture of addition-type silicone elastomers that provide high elasticity and thermally conductive fillers that provide thermal conductivity. Therefore, the main influencing factors are as follows:

① Too much cross-linking agent (this factor is the largest and the most prone to problems):

Generally speaking, when adding hydrogen-containing silicone oil, the molar ratio of hydrogen to vinyl should be controlled at (1.2-1.8): 1. The hydrogen-containing here includes side hydrogen and terminal hydrogen silicone oil. Many people mistakenly believe that adding a little more hydrogen-terminated silicone oil will increase the strength and decrease the hardness. Therefore, excessive hydrogen-terminated silicone oil will be added. As a result, the resilience of the colloid will decrease, the surface viscosity will decrease, and the hardness will increase rapidly after aging.
②The volatile content in hydrogen-containing silicone oil is generally relatively high, even reaching about 12%. Some of these volatile components are cyclosiloxane monomers (DMC), and some are hydrogen-containing small molecular monomers (linear Or cyclic), these hydrogen-containing small molecules are characterized by low activity at medium and low temperatures, and slow reaction at high temperatures, which causes the hardness to increase in the later stage or after aging.
③When the volatile content of vinyl silicone oil and hydrogen-containing silicone oil is high, these small molecules will escape during the aging process, which is equivalent to the reduction of the amount of system oil, which will not only cause the Neoprene Zipper Cable Sleeve to harden, but also will decrease the thermal conductivity. After volatilization, the contact interface of the Neoprene Zipper Cable Sleeve will also dry out, and the surface viscosity will decrease.
④Powder factor, the chemical additives added to the raw materials are different, the quality of each powder and the standard method of refining are different, so the factors that lead to the quality problems of Neoprene Zipper Cable Sleeve also occupy one of them.
Calculate the molar ratio of hydrogen to vinyl and control it at (1.2-1.8): 1. The amount of hydrogen-terminated silicone oil added should not be too high, generally lower than 0.9 relative to vinyl. This can not only ensure the stability of hardness, but also maintain the resilience of the product.