Understanding of hydraulic O type ring should understand the curing process

   Rubber vulcanization temperature is one of the three major factors of vulcanization, rubber hydraulic O ring for curing reaction (crosslinking reaction) of the basic conditions, the direct impact of rubber vulcanization speed and the quality of products.The same with all the chemical reaction, reaction temperature and curing followed up, which produced more sulfur crosslinks;Low curing temperature, the speed is slow, low power generation, the formation of more sulfur cross - linked bonds.Curing temperature and generally applicable van't Hoff rule that temperature increase of 8 to 10 DEG C (equivalent to about in a gauge pressure of vapor pressure), the response speed about adding a times; perhaps, response time about cut in half.

   Follow the room temperature vulcanized rubber and the high temperature vulcanization of the present, the curing temperature tends to two poles.From the progress of curing power, should think of curing temperature as high as possible, but not actually infinite progress of curing temperature.Rubber is a polymer, high temperature will cause the rubber molecule chain to produce cracking reaction, resulting in the cross link breaking, that is, the phenomenon of "curing back to the original" appearance, so that the physical and mechanical properties of vulcanized rubber reduced.When the high temperature vulcanization of natural rubber, dissolved oxygen in the rubber with the increase in the activity of the temperature, leading to intense oxidation, the destruction of the rubber arrangement, reducing the physical mechanical properties of vulcanized rubber.

   The heat resistance of the rubber and the idea of "curing back to the original" were summarized, and the curing temperature of various rubber was as follows:

   NR rubber hydraulic O type circle is best at 140-150 degrees, the maximum not exceeding 160;The ring type hydraulic polybutadiene rubber, isoprene rubber and chloroprene rubber best at 150-160 degrees, highest do not exceed 170 DEG C styrene butadiene rubber, acrylonitrile butadiene rubber (NBR) can be selected more than 150 DEG C, but highest do not exceed 190 DEG CButyl rubber, EPDM rubber is generally used in 160-180 Deg. C, highest do not exceed 200 DEG C; silicone rubber, fluorine rubber generally used in two sections and sulfur, a temperature optional 170-180 DEG C, cure chooses to 20-23 degrees, according to the needs of technology can be selected in the range of 4-24h.

   According to the end of the hydraulic O type of the ring is not the same functional requirements, the use of rubber formula is not the same as the curing system.According to the end of the hydraulic O type of the ring is not the same functional requirements, the use of rubber formula is not the same as the curing system.And according to the practical vulcanization system to select the corresponding curing temperature. General sulfur curing system, the curing temperature selection range 130-160 DEG C, according to the specific requirements by the use of promoter activity temperature and the product of physical machinery function to judge.

   Promoter activity of temperature low or hydraulic O-ring needs high strength, low stretch should force and hardness, curing temperature can be selected was lower, so generated more polysulfide crosslinks; promoter active temperature higher or product demand high modulus should force and hardness, low elongation, curing temperature should choose higher so generated more sulfur crosslinks.