Why does rubber need to be vulcanized? What are the benefits of vulcanizing rubber?
Although rubber raw rubber also has some useful application characteristics, it also has many drawbacks, such as low strength and low elasticity; Cold makes it hard, hot makes it sticky; Easy to age, etc. As early as the 1840s, it was discovered that rubber can undergo cross-linking by heating it together with sulfur. Therefore, until now, although rubber can be crosslinked not only with sulfur, but also with many other chemical crosslinking agents and physical and chemical methods, in the rubber industry, it has always been customary to refer to rubber crosslinking as “vulcanization”, while the plastic processing industry sometimes refers to crosslinking reaction as curing. Vulcanization greatly improves the performance of raw rubber, expands the application range of rubber, and lays the foundation for large-scale industrial production and application of rubber.
Rubber vulcanization is one of the main processes in rubber product processing, and it is also the last processing step in rubber product production. In this process, rubber undergoes a series of complex chemical changes, from a plastic blend to a highly elastic or hard cross-linked rubber, in order to obtain more complete physical, mechanical and chemical properties, and improve and expand the use value and application range of rubber materials. Therefore, vulcanization is of great significance for the manufacturing and application of rubber and its products.
The concept of vulcanization
Vulcanization refers to the semi-finished product made from rubber materials with a certain plasticity and viscosity (raw rubber, plastic compound, mixed rubber) through appropriate processing (such as rolling, extrusion, molding, etc.) under certain external conditions, through chemical factors (such as vulcanization system) or physical factors (such as γ The process of converting the effect of radiation back into soft elastic rubber products or hard rubber products to obtain performance in use. During the vulcanization process, external conditions (such as heating or radiation) cause a chemical reaction between the raw rubber in the rubber material components and the vulcanizing agent or between the raw rubber and the raw rubber, resulting in the cross-linking of linear rubber macromolecules into three-dimensional network structured macromolecules.
Through this reaction, various properties of rubber have been greatly improved, enabling rubber products to obtain physical, mechanical, and other properties that can meet the needs of product use. The essence of vulcanization is cross-linking, which is the process of transforming linear rubber molecular structures into spatial network structures.
Sulfurization process
After weighing the amount of mixed rubber and vulcanizing agent, the next step is to add vulcanizing agent. It is recommended to follow the following steps to complete.
1. Firstly, clean the opening mill to ensure its cleanliness to prevent the mixing of other impurities. Then adjust the roller pitch of the opening mill to the minimum and pour the mixed rubber into the opening mill for thin pass. After the thin pass is completed, the roll spacing of the mixer should be appropriately enlarged to ensure that the mixed rubber is evenly wrapped on the rolls. The surface temperature of the mixed rubber should be around 80oC.
2. By adjusting the roller pitch and appropriately cooling water, the temperature of the mixed rubber is controlled at around 60-80 ° C. At this point, the vulcanizing agent is started to be added to the mixed rubber.
Post time: Oct-25-2023