The comprehensive reasons that affect the plastic mixing process of plastic machinery can be mainly divided into: time, temperature, pressure, and rotor speed. Below, Lina will explain in detail the reasons why these factors dominate the internal mixer.
1: Time: The plasticity of raw rubber increases continuously with the increase of molding time in the internal mixer, which is different from that in the open mill. Therefore, the formulation of rubber mixing conditions is mainly based on the requirement of plasticity to determine the appropriate plasticizing time.

2: Temperature: With an increase in temperature, thermal oxidation cracking occurs quickly and the plasticizing effect is good. However, excessive temperature can lead to excessive cracking of rubber molecules, resulting in a decrease in physical and mechanical properties. The rubber extrusion temperature of natural rubber is generally controlled at 140 ℃ -160 ℃, while that of styrene butadiene rubber is controlled at 140 ℃, because excessive temperature can cause cross-linking or branching reactions, which can actually reduce plasticity. NBR is generally not plasticated in an internal mixer. At internal mixing temperature, instead of obtaining plasticizing effect, it will lead to the formation of gel.

3: Glue filling amount and top bolt pressure: If the glue filling amount is too small, the plasticizing effect will be low. Excessive amount of glue can cause uneven molding of raw rubber, and also result in excessively high glue discharge temperature. Additionally, it can overload the equipment and make it prone to damage. During the mixing process of the internal mixer, the top plug must apply pressure to the rubber material to ensure good mixing effect. Within a certain range, the mixing effect increases with the increase of the top plug pressure.

4: Rotor speed: The faster the sub speed, the greater the heat generation, the faster the oxidation cracking, the better the plasticizing effect, and the shorter the plasticizing time.