| Short fiber reinforced rubber(SFRR)combines the excellent physical and chemical properties of fibers with the unique elasticity of rubber materials to develop a series of high-performance rubber products,which can improve the service life of products in harsh service environments.As a reinforcement phase,fiber has a lot of advantages,such as large molecular weight,high orientation,small amount of addition and so on.However,as a rigid material,fiber has poor adhesion to rubber matrix and will lead to the problem of high heat generation of the composite when the fiber is added into the rubber matrix.At present,there are few reports about the heat generation behavior and mechanism of the fiber/rubber composites.In this paper,we chose hemp fiber,aramide fiber,natural rubber and styrene-butadiene rubber to study the thermal generation behavior of fibers/rubber composites.Through alkali treatment,thermal oxidation treatment,silane treatment and natural latex coating,we tried to investigate the influences of different modification methods on the thermal generation behavior of hemp fiber/natural rubber composites.Also,we explored the mechanism of natural latex to reduce the heat generation of rubber materials,on the basis of ensuring certain mechanical properties of rubber composites,and different contents of aramid pulp were used to replace carbon black for low heat generation experiments,so as to reduce the heat generation of rubber materials as far as possible.The main content includes the following aspects:(1)We treated the hemp fiber with alkali treatment,thermal oxidation treatment,silane treatment and natural latex coating.Subsequently,we carried out tests of vulcanization characteristics,rubber processing analysis,mechanical properties,scanning electron microscopy,rubber compression heat generation and fatigue performance.Through the analysis of vulcanization characteristics,it is concluded that the crosslinking density of hemp compound is increased after the modification of the hemp fiber.Among them,the hemp fiber's crosslinking density was the highest after alkali treatment and natural latex coating.The results of mechanical properties,rubber processing analyzer and scanning electron microscope showed that the hemp fiber treated with alkali did better in adhesion to natural rubber and had better strengthening effect on rubber composite material.Compression heat generation test and dynamic fatigue test results showed that natural latex treatment of hemp fiber can reduce the heat generation of hemp fiber/natural rubber composite significantly.(2)After treated with natural latex,the heat generation of aramid pulp/natural rubber composite was also reduced.The mechanism of reducing heat generation of rubber material by coating natural latex was analyzed through compression heat generation,fatigue hysteresis and DMA tests.The flexible interface layer between the natural latex and the rubber matrix produces the "deformation transfer" effect in the dynamic process of the rubber material,which reduces the overall heat generation of the rubber composite.(3)Different contents of aramid pulp coated with natural rubber latex were added into styrene butadiene rubber(SBR)to replace certain contents of carbon black,and the tests of compression heat generation,the mechanical properties,rheological characteristics and scanning electron microscopy(SEM)were carried out.Under the condition of ensure the strength of the composite materials,it was found that the heat generation of the rubber composite was the lowest when 0.5phr aramid pulp coated with natural rubber latex was added,when the content of fiber is low,the dispersion of fiber in rubber matrix is good,and the internal friction of fiber itself is small.Adding 0.5 the phr aramide-pulp can replace 4phr carbon black in CB-SBR system.The 100% and 300% constant elongation of the composites increase by 7.3% and3.3%,the heat generation decreases by 10.4% from 103.2? to 92.4?. |
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