Factors affecting the tensile stress and tensile strength of rubber

The elongation stress and tensile strength of rubber are two important indicators to measure the performance of rubber materials. They are not only related to the reliability of rubber in various engineering applications, but also directly affect the service life and safety of the product. This article will discuss the main factors that affect the elastic stress and tensile strength of rubber, including raw material selection, processing technology, vulcanization conditions and environmental factors, in order to provide reference for the optimized design and application of rubber materials.

1. Raw material selection

The raw materials of rubber mainly include raw rubber, compounding agents (such as vulcanizing agents, accelerators, antioxidants, etc.) and fillers. The types and proportions of these raw materials have a significant impact on the modulus stress and tensile strength of rubber.

Selection of raw rubber: Different raw rubbers have different molecular structures and physical properties. For example, natural rubber (NR) has good elasticity but relatively low strength; styrene-butadiene rubber (SBR) has high wear resistance and strength. Choosing the right type of raw rubber is fundamental.

The role of compounding agents: vulcanizing agents and accelerators determine the degree of cross-linking of rubber and directly affect its mechanical properties. An appropriate amount of vulcanizing agent can increase the elongation stress and tensile strength of rubber, but excessive amounts will cause the rubber to harden, which in turn reduces the toughness.

Effect of fillers: Fillers such as carbon black, white carbon black, etc. can enhance the strength and wear resistance of rubber. The type, particle size and amount of filler will affect the modulus stress and tensile strength of rubber. Generally speaking, an appropriate amount of nanoscale fillers can significantly improve the mechanical properties of rubber.

2. Processing technology

Rubber processing technology, including mixing, calendering, extrusion and molding, has a crucial impact on the performance of the material.

Mixing process: During the mixing process, various raw materials need to be fully mixed to ensure the uniformity inside the rubber. Uneven mixing will lead to inconsistency in rubber properties, affecting the elongation stress and tensile strength.

Pressure and temperature control: During processing, pressure and temperature control are crucial. Too high a temperature will accelerate the aging of rubber and reduce its mechanical properties; while too low a temperature may lead to insufficient mixing and affect the uniformity of the material.

3. Vulcanization conditions

Vulcanization is a key step in rubber processing. It forms a three-dimensional network structure through a cross-linking reaction, thereby giving rubber its unique properties.

Vulcanization time: The length of vulcanization time directly affects the degree of cross-linking of rubber. Appropriate vulcanization time can achieve the best modulus stress and tensile strength, while too short or too long time will lead to performance degradation.

Vulcanization temperature: Vulcanization temperature affects reaction rate and cross-linking density. Higher temperatures can speed up vulcanization, but too high temperatures may cause the rubber to be over-crosslinked, which in turn reduces toughness.

Vulcanization pressure: Vulcanization pressure ensures good contact between the mold and rubber, helping to form a uniform cross-linked structure, thereby improving the mechanical properties of the material.

4. Environmental factors

Rubber will be affected by environmental factors during use, such as temperature, humidity, and light. These factors will also affect its modulus stress and tensile strength.

Effect of temperature: High temperature will accelerate the aging process of rubber and reduce its mechanical properties; low temperature may cause rubber to become brittle and easy to break.

The role of humidity: Moisture can penetrate into rubber and react with certain ingredients, causing the material to degrade.

The role of light: Light such as ultraviolet rays can trigger the photooxidation reaction of rubber, accelerate its aging process, and affect its mechanical properties.

in conclusion

The elongation stress and tensile strength of rubber are determined by a variety of factors, including the selection of raw materials, control of processing techniques, optimization of vulcanization conditions, and the impact of the use environment. By rationally selecting raw materials, strictly controlling processing techniques, optimizing vulcanization parameters, and considering the impact of environmental factors, the elongation stress and tensile strength of rubber can be effectively improved to meet the needs of different application fields.

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