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Why do some rubber products require secondary vulcanization?

Update:14-11-2020
Summary:

First of all, it should be noted that not all rubber pr […]

First of all, it should be noted that not all rubber products need secondary vulcanization, but according to the different raw material formulations, some can be directly molded at one time, but some special materials such as fluorine rubber products and some EPDM rubber products are The need for secondary vulcanization is because firstly, when these materials are vulcanized, the peroxide in them will decompose and react with high polymers, producing some low-molecular compounds (such as benzene, benzoic acid, etc.), these low-molecular compounds Mixing in rubber will reduce the mechanical properties of the rubber and reduce its service life. Therefore, secondary vulcanization is often used to decompose and volatilize low molecular compounds.

Second, when the primary vulcanization is completed, the rubber molecules may not be fully crosslinked (insufficient vulcanization), and the secondary vulcanization can make the vulcanization more fully and uniformly, thereby improving the mechanical properties and durability of the rubber.

The third is to carry out secondary vulcanization. For example, after the secondary vulcanization of a large number of EPD rubber products used in automobiles, it can remove peculiar smell and improve the comfort of car occupants.

In order to reduce costs and increase production capacity, the Fourth Rubber Products Company often shortens the primary vulcanization time, and then extends the time during the secondary vulcanization, so as to ensure the full vulcanization of the product while also improving its own competitiveness.

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