Rubber powder is processed from waste rubber products mainly made of waste tires by means of normal temperature crushing, freezing and normal temperature chemical methods. It is the product of waste rubber recycling and can be added to rubber products again. For example, adding 5-15 parts of rubber powder to automobile tires can not only reduce costs, but also improve the dynamic fatigue resistance of the blended rubber and reduce the heat generated during tire driving. In actual production, the addition of rubber powder will affect the rheological properties of rubber compound.
With the addition of rubber powder in raw rubber, the Mooney viscosity of rubber compound will increase to a certain extent. Generally, the rubber powder with rough surface and large specific surface area can have better interaction with the rubber matrix. Therefore, the Mooney viscosity of rubber compound added with normal temperature crushed rubber powder will increase more than that added with the same amount of frozen crushed rubber powder.
At high shear rate, the rubber compound added with rubber powder may exhibit lower viscosity, which is directly related to the composition of rubber powder. For example, adding fluororubber powder 2SLYY227 to fluororubber can increase the Mooney viscosity of rubber and Mooney viscosity at high shear rate; When EPDM rubber powder is added to EPDM raw rubber, the Mooney viscosity of the rubber will increase and the viscosity at high shear rate will decrease.
The EPDM rubber powder containing a large amount of oil and carbon black is filled into the EPDM compound. The migration of plasticizer will lead to interface slip, and the viscosity of EPDM compound will be reduced under high shear rate.
The influence of rubber powder on the rheological properties of rubber compound can improve the extrusion performance of rubber and reduce the demoulding expansion.
The results showed that the extrusion properties of raw rubber without reinforcement were poor, and the addition of fillers, especially reinforcing fillers, could significantly improve its extrusion properties; The addition of rubber powder can reduce the distortion of rubber extrusion. The rubber strip extruded from the unreinforced rubber compound is highly twisted and deformed. The rubber compound added with waste rubber powder can obtain the extruded rubber strip with smooth surface in a wider range of shear rate.
The addition of rubber powder will reduce the proportion of un-crosslinked chain rubber macromolecules in the compound. These un-crosslinked rubber macromolecular chains can be untwisted under the action of the shear force field, and then curl again after the shear force field is removed, resulting in demoulding expansion; The rubber components in the rubber powder have a cross-linked network structure, which can effectively limit the curling of macromolecular chains, thus reducing the mold release expansion. The strong interaction among vulcanized rubber powder, especially the ultra-fine rubber powder with high specific surface area and rough surface, and the rubber matrix will also reduce the demoulding expansion.
Therefore, many rubber product manufacturers will choose the method of adding vulcanized rubber powder into the rubber compound to reduce the demoulding expansion of the rubber compound. In actual production, the addition of rubber powder in raw rubber will also affect the vulcanization characteristics of the rubber blend. Later, Xiaobian will continue to discuss relevant issues with you.
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