In the rubber industry, vulcanization refers to the cross-linking process of rubber. Rubber molecules are composed of many long-chain polymers, and the chemical bonds between these long-chain molecules are relatively weak. The vulcanization process is to add vulcanizing agents (such as sulfur, sulfur-containing compounds, etc.) under certain temperature, pressure and time conditions to form cross-linked bonds between rubber molecular chains, thereby transforming the linear rubber molecular structure into a three-dimensional network. Shape structure. For example, natural rubber has good elasticity and plasticity when it is not vulcanized, but its strength and wear resistance are poor. After vulcanization, the physical properties of rubber are significantly improved, including tensile strength, hardness, wear resistance, and aging resistance.
Sulfurization reaction process
Taking sulfur as a vulcanizing agent as an example, sulfur will react with the double bonds in the rubber molecular chain at high temperatures. First, the sulfur molecules break down into active sulfur atoms, which combine with the double bonds in the rubber molecular chains to form sulfur bridges (cross-links). Some intermediate products may be produced during the reaction, such as thiol groups and polysulfide bonds on the rubber molecular chain. As the reaction proceeds, more and more cross-linking bonds are formed and the network structure of the rubber is gradually improved. Generally speaking, the vulcanization process requires precise control of parameters such as temperature, pressure and time. The temperature is usually around 140 - 180 ° C, the pressure depends on the type of rubber product and process requirements, and the time ranges from a few minutes to dozens of minutes.
The role and significance of vulcanization
Vulcanized rubber products have better elastic recovery ability and can quickly return to their original shape after being deformed by force. At the same time, its strength and wear resistance are greatly enhanced, allowing rubber products to withstand greater friction and pressure. For example, automobile tires are vulcanized rubber products. During the driving process of the vehicle, the tires have to bear the weight of the vehicle body, the friction of the road surface and various complex stresses. The vulcanized tires can meet these performance requirements and ensure the vehicle's Drive safely. In addition, vulcanization can improve the chemical corrosion resistance and aging resistance of rubber products and extend their service life.
