Temperature is an indispensable element in the rotational molding process, particularly, appropriate temperature control during the heating phase is a primary means to enhance product quality. Taking polyethylene as an example, a unique phenomenon occurs in the rotational molding process: during the melting of powder, trapped air between the particles forms bubbles, which then dissipate as the heating process continues. Further research indicates that these bubbles do not disappear due to their buoyancy moving towards the free surface of the melt, but rather because the air within them gradually blends into the molten plastic mass. Therefore, for polyethylene rotational molding, scientifically controlling the heating process is of great significance in eliminating bubbles in polyethylene products and improving product quality.

Due to the longer heating times associated with rotational molding, especially when the product walls are thick, it can take up to 30 minutes or more. Measures must be taken to prevent thermal oxidation of the material and a decrease in material properties during heating. Typically, adding antioxidants to polyethylene plastics can achieve this preventive goal. However, when polyethylene materials are heated to excessively high temperatures or for too long, antioxidants are unable to prevent oxidation. When thicker products require extended heating times, the heating temperature must be reduced. Increasing the temperature to shorten the heating time can result in trapped air bubbles if the air does not have enough time to dissipate. As polyethylene plastics are heated to the melting state, the material undergoes a transformation from crystalline to molten form, which is when the polyethylene granules begin to melt and soften. This process starts with a layer of material in contact with the mold's inner wall, forming a uniform layer of molten material. It then gradually extends inward until the entire cross-section is plastic melt. The next step is to continue heating to allow the bubbles to dissipate gradually. The temperature and time control of this process require adjustment.