Why do some rubber products need secondary vulcanization

I believe everyone is familiar with rubber products. Common production processes include hot pressing, injection molding, extrusion, etc. After production, some rubber products require secondary vulcanization, which is also called secondary vulcanization. It seems that we are already good products, and it can be used normally. Why do we need to re-vulcanize it?

First of all, it should be noted that not all rubber products require secondary vulcanization, but according to different raw material formulations, some can be directly molded at one time, but some special materials such as fluororubber products and some EPDM rubber products are Secondary vulcanization is required because the peroxides in these materials will decompose and undergo a high-polymer reaction during primary vulcanization, producing some low-molecular-weight compounds (such as benzene, benzoic acid, etc.). These low-molecular-weight compounds Mixing in the rubber will reduce the mechanical properties of the rubber and reduce the service life, so 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 sufficiently cross-linked (insufficient vulcanization), and the secondary vulcanization can make the vulcanization more sufficient and uniform, thereby improving the mechanical properties and durability of the rubber.

The third is to perform secondary vulcanization. For example, after secondary vulcanization of EPD rubber products used in automobiles, the odor can be removed and the comfort of car occupants can be improved. 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 to ensure that the products are fully vulcanized and at the same time improve their own competitiveness.

After the above introduction, do you have a further understanding of the secondary vulcanization process of our rubber products?

Founded in 1993, Hangzhou Biaozheng Rubber Plastic Fittings Factory is a professional enterprise engaged in the research, design and manufacture of rubber diaphragms.
As China Molded Diaphragm Manufacturers and OEM Fabric Reinforced Diaphragms Factory , The company not only has a complete set of rubber molding products such as kneading machine, open mill, filter machine, flat vulcanizing machine, etc., but also set up a mold processing and production center, which can customize various rubbers Diaphragm for customers.