Plasticizing properties of several glues:
When natural rubber is plasticized with an open mill, the roller temperature is 30-40 ° C, and the time is about 15-20min. When using an internal mixer to plasticize, the time is about 3-5min.
The Mooney viscosity of styrene-butadiene rubber is mostly between 35-60. Therefore, styrene-butadiene rubber can be used without plasticizing, but the dispersion of the compounding machine can be improved after plasticizing.
Butadiene rubber has cold flow and lacks plasticizing effect. The Mooney viscosity of butadiene rubber is relatively low, so it does not need to be plasticized.
Neoprene has a large plasticity, and can be thinned 3-5 times before plasticizing, and the thinning temperature is 30-40 ° C.
The molecular main chain of ethylene-propylene rubber is a saturated structure, and it is difficult for plasticization to cause molecular cracking. Therefore, it is necessary to choose a variety with low Mooney viscosity instead of plasticization.
Nitrile rubber has low plasticity, high toughness, and high heat generation during plasticization. It should be used at low temperature below 40 ℃, small roll distance, low capacity, and segmented plasticization, which can get better results.
2.2 Mixing process
Mixing refers to the process of uniformly mixing various compounding agents to raw rubber on a rubber extruder. The quality of the compounding has a decisive influence on the further processing of the compound and the quality of the finished product. Even if the compound is well formulated, if the compounding is not good, there will be uneven dispersion of the compounding agent and the plasticity of the compound is too high. If it is too low, it is easy to scorch, bloom, etc., making the processes such as calendaring, extrusion, gluing and vulcanization normal, and it will also cause the performance of the product to decline.
Kneading methods are generally divided into two types: open kneader mixing and internal mixer kneading. Both methods are batch-type mixing, which is by far the most widely used method.