因LDPE、HDPE的流动性好，加工温度低，粘度大小适中，分解温度低，在惰性气体中高温度300℃不分解，所以是一种加工性能很好的塑料。但LLDPE的粘度稍高，需要增加电机功率20%～30%；易发生熔体破裂，需增加口模间隙和加入加工助剂；加工温度稍高，可达200～215℃。聚乙烯的吸水率低，加工前不需要干燥处理。

聚乙烯熔体属于非牛顿流体，粘度随温度的变化波动较小，而剪切速率的增加下降快，并呈线性关系，其中以LLDPE的下降最慢。

聚乙烯制品在冷却过程中容易结晶，因此，在加工过程中应注意模温。以控制制品的结晶度，使之具有不同的性能。聚乙烯的成型收缩率大，在设计模具时一定要考虑。

Due to the good fluidity of LDPE and HDPE, low processing temperature, moderate viscosity, low decomposition temperature, and high temperature of 300 °C in inert gas do not decompose, it is a plastic with good processing performance.However, the viscosity of LLDPE is slightly higher, and the motor power needs to be increased by 20%~30%; It is easy to melt rupture, and it is necessary to increase the gap between the mouth die and add processing aids,Its processing temperature is slightly higher, up to 200~215 °C.Polyethylene has low water absorption and does not need to be dried before processing.

Polyethylene melt belongs to a non-Newtonian fluid, the viscosity fluctuates less with the change of temperature, while the increase of shear rate decreases quickly and linearly, among which LLDPE decreases the slowest.

Polyethylene products are easy to crystallize during the cooling process, so pay attention to the mold temperature during processing. In order to control the crystallinity of the product, so that it has different properties.The molding shrinkage rate of polyethylene is large, which must be considered when designing the mold.

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