EPDM reclaimed rubber is processed from EPDM waste rubber (EPDM scrap from the machine head, unvulcanized EPDM rubber) or used EPDM rubber products (waste EPDM sealing strips). It has good resistance to high and low temperatures, ozone, and weathering. It can be used alone or combined with EPDM rubber, butyl rubber, or reclaimed butyl rubber to produce extruded rubber products, reducing raw material costs. When producing extruded rubber products with EPDM reclaimed rubber, the rubber formulation, processing conditions, and semi-finished product specifications all affect extrusion deformation.
1. The formulation of EPDM reclaimed rubber extruded products affects extrusion deformation.
When producing extruded rubber products using EPDM reclaimed rubber as the main raw material, the higher the rubber content in the compound, the greater the extrusion deformation. Choosing carbon black with a higher structure and appropriately increasing the amount of carbon black E5LYY530 can reduce the extrusion deformation of EPDM reclaimed rubber compounds. Among fillers, highly active white fillers can result in smaller extrusion deformation. Proper use of oils and lubricating softeners can increase the fluidity and relaxation rate of EPDM compounds, thereby reducing extrusion deformation.
Compared with pure EPDM rubber, uncured rubber compounded with recycled EPDM shows much less expansion and contraction during processing than uncured rubber made only of new rubber, making it easier to process and ensuring accurate shape and dimensions of the finished product.
2. The processing conditions of EPDM recycled rubber extrusion products affect extrusion deformation
When producing extruded rubber products using EPDM reclaimed rubber, the higher the plasticity of the compound, the lower the elasticity, the better the flow of the compound, and the smaller the extrusion deformation. Appropriately increasing the plasticity of the compound and improving the uniformity of the compound's pre-extrusion masticating are beneficial for reducing extrusion deformation.
(1) Properly increasing the die temperature can enhance the flowability and relaxation rate of EPDM reclaimed rubber compounds and can also reduce extrusion deformation.
(2) When process performance and costs allow, extruding EPDM reclaimed rubber products at a slower extrusion speed and appropriately increasing the die thickness can help reduce extrusion deformation.
(3) When producing different varieties of EPDM extruded products using EPDM reclaimed rubber, core-type extrusion has less extrusion deformation than coreless extrusion; at the same die aperture size, more complex shapes have smaller extrusion deformation.
(4) Allowing extruded EPDM reclaimed rubber semi-finished products to rest under applied force or appropriately increasing the resting temperature can reduce extrusion deformation.
3. Specifications of EPDM reclaimed rubber semi-finished products affect extrusion deformation.
Ternary EPDM recycled rubber compound with the same formula has different specifications and shapes for semi-finished products, resulting in different extrusion deformations; the larger the size of the extruded semi-finished product, the smaller the extrusion deformation.
When producing extruded rubber products using recycled EPDM rubber, there are many factors that affect extrusion deformation. Rubber product manufacturers can approach this from multiple angles, controlling the main factors while considering secondary factors, effectively reducing extrusion deformation and achieving accurate cross-sectional dimensions and stable semi-finished products of recycled EPDM rubber.
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