Blow molding production and processing is a common operation in plastics processing. What key points should be noted for blow molded products? Temperature plays a decisive role in the processing of plastic bottles. When operating an extrusion blow molding machine for production, accurate temperature control is essential to produce qualified plastic bottles.

The maximum temperature at which plastic does not flow under a certain pressure. Place a fixed amount of plastic into the barrel at the upper die opening of a capillary rheometer, heat it to a set temperature and keep constant temperature for 20 minutes. Then apply a constant pressure of 60 MPa. If the material does not flow out of the die opening, release the pressure, raise the material temperature by 15°C, hold for another 15 minutes, and apply the same constant pressure again. Repeat the process until the melt flows out from the die opening. Subtract 15°C from this temperature, and the result is defined as the no-flow temperature of the material.

It refers to the temperature at which amorphous polymers transform from the high-elastic state to the viscous flow state. It is the lower limit of processing temperature for amorphous plastics.

For polymers in the viscous flow state, further temperature rise will aggravate the degradation of molecular chains. The temperature at which obvious molecular chain degradation occurs is defined as the decomposition temperature.

For crystalline polymers, it is the temperature at which the long-range three-dimensional ordered structure of macromolecular chains transforms into a disordered viscous flow state, also known as the melting point. It serves as the lower limit of molding processing temperature for crystalline polymers.

It refers to the transition temperature of amorphous polymers (including the amorphous part of crystalline polymers) between the glassy state and the high-elastic state. It is the minimum temperature at which macromolecular chain segments of amorphous polymers can move freely, and also the upper limit of service temperature for finished products.