Rubber resilience is a key indicator for measuring the dynamic performance of rubber materials, which directly affects the service life and performance of automotive tires, shock absorbers, rubber pads, and other products. Insufficient resilience can lead to energy loss and performance degradation, therefore optimizing rubber resilience is an important goal in formulation design and process improvement. This article will deeply analyze the factors that affect rubber resilience and propose five optimization strategies to help rubber practitioners improve product quality.

1、 Regulating crosslinking density

（1） The relationship between crosslink density and resilience

Crosslinking density refers to the degree of connection between rubber molecular chains, which directly affects the elasticity, strength, and resilience of rubber. Appropriate cross-linking density can enable rubber to quickly recover its original state and maintain good elasticity after being subjected to stress. Research has shown that a low crosslinking density can lead to loose connections between molecular chains and poor resilience; If the cross-linking density is too high, it will increase the hardness and weaken the elasticity of the rubber. For example, when the crosslinking density of natural rubber is 2.0 × 10 ^ -3 mol/cm ³, the resilience is about 60%, but when the crosslinking density increases to 4.0 × 10 ^ -3 mol/cm ³, the resilience may decrease to 45%.

（2） Methods for regulating crosslinking density

Optimizing crosslinking density requires precise control of the dosage of vulcanizing agent, vulcanization temperature, and time. The vulcanization temperature is generally suitable between 150 ° C and 180 ° C. The type and amount of vulcanizing agent are crucial, commonly used vulcanizing agents such as peroxides, disulfides, etc., with concentrations typically controlled between 1.5% and 3%. If it is necessary to improve resilience, the crosslinking density can be appropriately reduced, but excessive softening should be avoided.

2、 Optimize the dispersibility of fillers

（1） The relationship between filler dispersibility and resilience

The dispersibility of fillers is an important factor affecting the resilience of rubber. Poor dispersion of fillers can lead to micro unevenness inside the rubber, increase energy dissipation and internal friction, and reduce resilience. For example, carbon black particles are small in size and have a large surface area, making them prone to agglomeration. Agglomerated carbon black can cause uneven intermolecular interactions, reducing rubber elasticity and resilience. Experimental data shows that when the dispersibility of carbon black is poor, the rebound may decrease by 10% to 15%.

（2） Methods to improve the dispersion of fillers

The use of dispersants such as silane coupling agents and functional surfactants can improve the surface properties of fillers and promote their uniform dispersion. Research has shown that the use of dispersants improves the dispersibility of fillers by about 20% and increases their resilience by 5% to 10%.

Optimize mixing process: By increasing mixing temperature, extending mixing time, or using high shear equipment, enhance the affinity between fillers and rubber matrix, and improve dispersibility.

Using nano fillers: Nano fillers have a large specific surface area and can enhance rubber resilience at the micro level. For example, when the amount of nano carbon black added is 2%, the rebound performance can be improved by about 12%.

3、 Choose the appropriate rubber substrate

（1） Comparison of resilience of different rubbers

There is a significant difference in the resilience of different types of rubber substrates. Natural rubber has a regular arrangement of molecular chains, a low glass transition temperature (about -70 ° C), and excellent resilience at room temperature, reaching over 60%. However, synthetic rubbers such as styrene butadiene rubber and chloroprene rubber have poor resilience due to their non-linear molecular chains or strong rigidity, typically below 50%.

（2） How to choose a suitable rubber substrate

To enhance resilience, it is recommended to prioritize natural rubber as the substrate, or add an appropriate amount of natural rubber or soft synthetic rubber (such as polyvinyl chloride rubber) to synthetic rubber. In addition, high resilience monomers can be added to synthetic rubber through copolymerization. When the ratio of natural rubber to synthetic rubber is 70:30, the resilience can be significantly improved.

4、 Reduce the use of plasticizers and softeners

（1） The effect of plasticizers on resilience

Plasticizers lower the glass transition temperature of rubber to maintain its elasticity at low temperatures, but excessive addition can reduce the elastic modulus of rubber and weaken its resilience. Experiments have shown that for every 5% increase in the addition of certain plasticizers (such as styrene and diphenyl phosphate), the rebound will decrease by 2% to 4%.

（2） Reasonable use of plasticizers

When optimizing the formula, the amount of softener added can be reduced, or appropriate softeners (such as light mineral oil and plasticizers) can be selected to balance rubber softness and resilience. According to the requirements of the usage environment, accurately calculate the amount of softener, usually controlled between 5% and 15%, to avoid a significant decrease in resilience.

5、 The influence of temperature and humidity control on rubber

（1） The influence of temperature on resilience

The resilience of rubber varies with temperature. Rubber becomes brittle and has poor resilience at low temperatures; Rubber excessively softens and loses elasticity at high temperatures. Reasonable control of temperature during production and use can effectively enhance rubber resilience. For example, natural rubber can have a resilience of over 60% at room temperature (25 ° C), but may drop to below 30% at low temperatures (-30 ° C).

（2） The influence of humidity on resilience

A high humidity environment may cause rubber to absorb water and expand, changing its internal structure and reducing its resilience. Controlling humidity during production and storage processes is an important measure to enhance resilience. Generally speaking, humidity control within the range of 40% to 60% can effectively ensure stable rubber performance.

summary

The five optimization strategies for improving rubber resilience include: regulating crosslinking density, optimizing filler dispersion, selecting suitable rubber substrates, reducing the use of plasticizers and softeners, and controlling temperature and humidity. By comprehensively regulating these aspects, not only can rubber resilience be improved, but its overall performance can also be enhanced, improving product competitiveness.