Zinc oxide (ZnO) has many uses of zinc oxide in the rubber industry, mainly because of its extraordinary properties which function as a catalyst in the rubber vulcanization process.
Vulcanization is a chemical transformation that increases the durability of natural rubber, and zinc oxide plays an important role in strengthening the rubber compound, strengthening its resistance to heat, abrasion, and protecting it from ultraviolet light degradation.
The widespread use of zinc oxide in the rubber sector can be attributed to its numerous optical, physical and chemical properties. For example, in the case of tires, the addition of large amounts of zinc oxide is essential to ensure durability and effective heat dissipation.
This is very important because the generation of heat in the tires at high speeds contributes significantly to vehicle safety.
1. To initiate the complete curing process
The combination of zinc oxide and stearic acid results in the formation of zinc soap. This, in turn, enhances the zinc oxide's solubility within the compound and facilitates the creation of a dynamic complex with the accelerator. This complex exhibits high reactivity, engaging with sulfur to generate an exceptionally potent vulcanizing agent.
2. Improve the cross-linking density
Enhancing the density of cross-linking is achieved by the interaction between zinc oxide and stearic acid, resulting in the formation of Zn2++ salt. This salt forms chelates with the sulfur-containing side-chaining groups of the rubber accelerator. Consequently, it alters the stability of the weak bonds in their stable state, causing a shift in the position of sulfur bond fractures during rubber vulcanization. This process leads to the creation of shorter cross-links and introduces new cross-linking sites, thereby increasing the overall cross-linking density.
3. Enhancing the resistance
Enhancing the resistance of vulcanized rubber to aging is achieved through a process where, during vulcanization and subsequent use, the polysulfide bonds break, yielding H2S, which accelerates rubber degradation.
Zinc oxide, when it reacts with H2S, forms fresh cross-linking bonds. This serves to stabilize the vulcanization network and ultimately enhances the rubber's resistance to aging.
In brief, zinc oxide serves primary functions within rubber formulation, which include:
• Functioning as an activator or accelerator.
• Serving as an acidic agent during rubber vulcanization, absorbing certain acidic byproducts produced in the process.
• Enhancing the thermal characteristics of the compound.
In conclusion, the use of zinc oxide in the rubber industry is undeniably pivotal. Its multifaceted role as an activator, acidic agent, and enhancer of thermal properties contributes significantly to the overall quality and performance of rubber products.
Whether it's reinforcing tire durability for road safety or bolstering the resilience of industrial rubber components, zinc oxide proves its worth. Its ability to create stronger cross-links, absorb acidic substances, and improve thermal resistance ensures the rubber industry can continue to innovate and meet the ever-growing demands of various sectors.
As technology advances and sustainability becomes paramount, the versatile role of zinc oxide in rubber formulations remains a cornerstone in shaping the future of this crucial industry.