GUOMAT rubber vulcanization process analysis
The rubber we are exposed to is always accompanied by a strong rubber smell, so most people think that rubber is "black, stinky". In fact, natural rubber itself is not black, and there is no smell. The "black" we saw was due to the addition of carbon black, and the smell of the rubber was produced after the rubber was vulcanized.
Before vulcanization, natural rubber is mainly based on linear structure. The interaction between molecules is mainly van der Waals force, and its stability is low. It is mainly in the aspects of low hardness, solubility, etc., and cannot fully adapt to complex use environments. In order to improve the performance of all aspects of rubber and adapt to the complex and ever-changing environment, the last step of rubber products is vulcanization. The vulcanized rubber will exhibit different hardness and toughness depending on the degree of vulcanization. A truly good rubber product can choose the most suitable balance point between hardness and toughness to maximize the performance of the rubber product.
The physical and chemical properties of rubber have changed during the rubber vulcanization process.
The improved physical properties of the high Matt air spring airbag during vulcanization, including strength (tensile strength, tensile strength, tear strength, etc.), elongation at break, hardness, density, breathability, elasticity, permanent Deformation, degree of swelling, etc.
1. Solubility: The vulcanization process gradually reduces the ability of the rubber to dissolve in the solvent, but only swells; after a certain period of time, the swelling has a minimum value, and the vulcanization continues to have a tendency to gradually increase the swelling property.
2, thermal stability: vulcanization improves the thermal stability of the rubber, reducing the impact of the external temperature difference on the performance of the air spring. For example, when the unvulcanized natural rubber is lower than 10 °C, the long-term storage will produce crystal hardening; the temperature exceeds At 70 ° C, the plasticity increases remarkably; when it exceeds 100 ° C, it is in a viscous flow state; at 200 ° C, decomposition begins to occur. However, after vulcanization, the high elastic temperature range is expanded, and the brittleness temperature can be lowered to below -20 to -40 ° C, and the plastic flow state of the raw rubber does not occur. Therefore, vulcanization greatly increases the temperature of use of natural rubber. In fact, the actual use environment of the air spring factory is far more complicated than the laboratory environment. High Matt constantly accumulates customer feedback data, actively cooperates with customers' needs, and customizes the air spring to win the praise of users.
3. Density and gas permeability: Within a certain range of vulcanization time, as the crosslink density increases, the rubber density increases, while the gas permeability decreases with the increase of crosslink density. This is very important for the use of air springs. The lower the gas permeability, the less gas is spilled during use. The higher the stability of the air spring, the lower the frequency of pumping.
At the level of chemical change, during the entire vulcanization process, the reactive functional groups or unsaturated chemical bonds of the rubber macromolecules of the balloon cross-link with the vulcanizing agent, becoming more and more saturated, thereby increasing stability and at the same time, crosslinking. At the same time, breaking the previous micro-light chain structure, one chain is cross-linked by vulcanizing agent, and gradually forms a network structure. Due to the change of rubber microstructure, the performance of rubber has also undergone a series of changes, and the plasticity is obviously reduced. The strength and hardness are greatly increased, while the elongation and swelling degree are reduced.