The best temperature for vulcanization of raw rubber?

Three elements of vulcanization of rubberproducts: temperature, time and pressure. When the pressure is constant, the vulcanization time at high temperature will be shortened, while the vulcanization time at low temperature will be prolonged. The rubber polymer will destroy the molecular chain at high temperature, resulting in the rupture of the cross-linking bond, that is, the phenomenon of "reversion" occurs. After the vulcanization temperature is determined, since the equipment and abrasive tools are existing in the enterprise, the pressure and time are determined accordingly.

The selection of vulcanization temperature generally considers the variety of raw rubber and the choice of vulcanization system:

The vulcanization temperature selection range of ordinary sulfur vulcanization system is 130~158℃;

Effective and semi-effective vulcanization system vulcanization temperature selection range is 160~165℃;

The temperature of the resin or peroxide curing system is preferably between 170 and 180 °C.

Thick products or wire-added products should be vulcanized at low temperature for a long time, and thin products should be vulcanized quickly at high temperature.

Low temperature vulcanization is selected for hard products, which slows down the rate of reaction heat generation, helps to dissipate heat, and reduces the internal temperature of the product to meet the vulcanization that is not easy to burst.

Refer to other literature for the most suitable vulcanization temperature selection for various rubber materials:

Compound type

Optimum vulcanization temperature/℃

Natural rubber 143

SBR 150

Isoprene rubber 151

Butadiene rubber 154

Neoprene 151

Nitrile rubber 180

EPDM 160-180

Butyl rubber 170

Silicone rubber (a vulcanization temperature) 170

Fluorine rubber (a vulcanization temperature) 170

Silica gel and fluorine rubber generally require two-stage vulcanization. The vulcanization temperature is preferably 180-200 °C, and the time is 4-12 hours according to the thickness of the product.

Due to the current market competitiveness, the vulcanization temperature is generally higher than the ideal vulcanization temperature to achieve the purpose of shortening the vulcanization time, so it is necessary to consider the matching application of accelerators in the formulation design. At the same time, it can improve productivity and meet the consistency of production process and product properties.