Raw rubber or compounded rubber viscosityThis can be used to characterize the molding properties of semi-finished products before vulcanization, impacting production efficiency and finished product quality. An appropriate viscosity is crucial for processes such as mixing, calendering, extrusion, and vulcanization of the rubber compound.
The viscosity of raw rubber primarily depends on the molecular weight and its distribution. A higher molecular weight and a narrower distribution of molecular weights result in greater rubber viscosity. Adjusting the molecular weight and distribution of rubber can alter the viscosity of raw rubber. Both excessively high and low viscosities are detrimental to the processing technique. High viscosity rubber material has poor fluidity, affecting both the processing process and the quality of the finished product. On the other hand, a low viscosity can result in insufficient shearing force during mixing, which is unfavorable for subsequent operations.
How can you adjust the viscosity of the adhesive to meet processing requirements?
1. The nature and amount of the filler have a significant impact on the viscosity of the rubber compound. Carbon black reinforcing fillers (environmentally-friendly blowing agent OBSH, environmentally-friendly accelerator) greatly affect the rubber compound's viscosity; as the particle size of carbon black decreases, the structure and amount increase, leading to a higher viscosity of the rubber compound. The smaller the particle size, the greater the impact on the viscosity of the rubber compound.
2. Softening plasticizers are one of the main factors affecting the viscosity of rubber compounds, significantly reducing the viscosity, lowering the brittleness temperature, improving the flow of the compound, and making it softer. Within a certain range, appropriately increasing the softening agent can lower the viscosity of the compound, resulting in better fluidity. The effect of different softening agents on the viscosity of the compound varies.
3. Plasticization is a crucial process in rubber processing, reducing the molecular weight of raw rubber and the viscosity of the rubber compound, thereby enhancing its plasticity and fluidity. Plasticizers can be added to raw rubber to improve the plasticization effect, reduce energy consumption, adjust the viscosity of the rubber compound, and promote the activity of accelerators M/DMA, which can accelerate the plasticization process and subsequently lower the viscosity of the rubber compound.
4. Temperature has a significant impact on the viscosity of rubber; as the temperature increases, the viscosity decreases. The degree of viscosity decrease varies among different types of rubber when the temperature rises. For instance, nitrile rubber and reground rubber are more affected by temperature, with a greater decrease in viscosity; natural rubber is less affected by temperature, with a lesser decrease in viscosity. Therefore, it is crucial to strictly control the molding temperature during the processing of different types of rubber.
Many factors affect the viscosity of rubber compounds, including the type of raw rubber, molecular weight distribution, pressure, and time. In actual production, it is essential to rationally design the processing technology and operations based on different types of rubber compounds, as well as to formulate a reasonable recipe to ensure the rubber compound's viscosity meets processing requirements.
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