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Three elements of rubber vulcanization

2019-05-27

Vulcanized rubber refers to vulcanized rubber, which has the characteristics of constant viscosity and is not easy to be broken. Most of the high temperature resistant silicone strip products are made of this rubber. After vulcanization, a solid three-dimensional structure is formed in the raw rubber, which has high elasticity, heat resistance, tensile strength and insolubility in an organic solvent.


The main factors of rubber vulcanization are as follows. The vulcanization temperature of the rubber vulcanization temperature is the most basic condition for the vulcanization reaction of the rubber, and has a direct influence on the vulcanization speed of the rubber and the quality of the product. The vulcanization reaction of the rubber increases with increasing temperature. If the temperature is 10 ° C higher, the vulcanization time of the vulcanizing press is reduced by about half. Since rubber is a poor thermal conductor, the vulcanization process of the product differs due to the difference in temperature of its various parts. In order to ensure a relatively uniform degree of vulcanization, thick rubber products are generally gradually heated, low temperature and long time vulcanization. With the increase in room temperature vulcanizates and the appearance of high temperature vulcanization, the vulcanization temperature tends to two extremes. From the viewpoint of improving the vulcanization efficiency, it is considered that the higher the vulcanization temperature, the better, but in practice, the vulcanization temperature cannot be increased wirelessly. The rubber is a high molecular polymer, and the high temperature causes the rubber molecular chain to undergo a cracking reaction, which causes the crosslink bond to be broken, that is, the phenomenon of "reversion to the original" occurs, thereby degrading the physical and mechanical properties of the vulcanized rubber. Rubber vulcanization time rubber vulcanization time is an important part of the vulcanization process. The time is too short and the degree of vulcanization is insufficient. The time is too long and the degree of vulcanization is too high. The vulcanizing press has only a suitable degree of vulcanization to ensure the best overall performance. Under a certain temperature and molding, in order to make the rubber from plastic to elastic and achieve the maximum crosslinking density, the time taken for optimizing the physical and mechanical properties is called the vulcanization time of the rubber product. The vulcanization time of the rubber is closely related to the vulcanization temperature of the rubber. In the vulcanization process, when the physical and mechanical properties of the vulcanized rubber reach or approach the optimum point, the degree of vulcanization is called positive vulcanization or optimum vulcanization. The vulcanization time required to achieve normal vulcanization is called the vulcanization time, and a certain vulcanization temperature corresponds to a certain vulcanization time. Rubber vulcanized pressure rubber vulcanization pressure refers to the pressure per unit area of the rubber compound during the vulcanization process. Rubber vulcanization pressure is an important factor to ensure the structural density, geometric size and physical and mechanical parts of rubber parts. At the same time, it can ensure the smooth and defect-free surface of the parts and achieve the sealing effect of rubber products.


The following five points are the principles for the selection of rubber vulcanization pressure: 1 the hardness of the rubber is low, the pressure should be small, the hardness should be large; 2 the structure is simple and the selection is small, the product structure is complicated and the choice is large; 3 the thin product selection is small, the thick product selection Large; 4 when the vulcanization temperature is higher, the pressure can be smaller, when the temperature is lower, the pressure should be higher; 5 mechanical properties require low selection, high requirements and high selection.



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