Fiber skeleton can limit the deformation of rubber products, and significantly improve the strength and performance of rubber products. Therefore, fiber skeleton material is generally used as the main stress layer to bear the internal and external effects of rubber products. Short fiber is the most commonly used rubber skeleton material. When using natural rubber / reclaimed rubber to produce rubber products, reasonable use of short fiber can further improve the mechanical strength of finished products.
1. The role of short fiber in NR / RR blends
Carbon black is the most commonly used reinforcing agent to improve the mechanical strength of NR / RR blends. However, excessive amount of carbon black will lead to some physical properties decline and processing difficulties. The use of short fiber reinforced natural rubber / reclaimed rubber can not only endow the compound with high modulus, high hardness, low compression deformation and low heat generation, but also improve the cutting resistance, puncture resistance, fatigue resistance, swelling resistance and creep resistance of rubber products.
In practical application, the natural rubber / reclaimed rubber compound reinforced by short fiber can be used to prepare various rubber products such as tire tread, rubber pipe, rubber V-belt, conveyor belt, seal, etc., with high mechanical strength and long service life.
2. The relationship the amount of short fiber and the mechanical strength of the blend
(1) Tensile strength: the reinforcing effect of a small amount of short fiber on NR / R is weak. Generally, the tensile strength of NR / R compound increases significantly when the amount of fiber is added to 10 phr. After that, the amount of fiber continues to increase and the change of tensile strength tends to be stable(7LYY222Y).
(2) Elongation at break: the addition of short fiber will hinder the directional arrangement of rubber molecular chain, resulting in the rapid decrease of elongation at break of NR / NR blends; With the increase of staple fiber content, the decreasing range becomes smaller.
(3) Tear strength: the tear strength of NR / RR blends will increase with the increase of short fiber content; When the amount of fiber is enough, the crack propagation can be effectively prevented. It should be noted that the arrangement of fibers with transverse orientation is parallel to the crack, which will reduce the resistance to crack diffusion. Therefore, the tear resistance of compound with transverse orientation is lower than that of compound with longitudinal orientation.
(4) Processing heat generation: the higher the amount of short fiber, the higher the heat generation performance of NR / RR blends.
(5) Springback and compression deformation: with the increase of short fiber content, the springback of NR / RR blends decreased, and the compression deformation increased.
(6) Wear resistance: with the increasing amount of short fiber, the wear resistance of natural rubber / reclaimed rubber blends is improved. Generally, the wear resistance in the longitudinal direction is greater than that in the transverse direction.
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