中层原料主要采用LLDPE，该原料黏度大，结晶度较LDPE高，且黏度随温度升高降低幅度很小，一般不采用提高加工温度的方法来提高挤出量，而采用添加LDPE或加工助剂的方法解决这一问题。
LLDPE is the main medium material. The viscosity of the material is high and the crystallinity is higher than that of LDPE, and the viscosity decreases slightly with the increase of temperature. Generally, the method of increasing the processing temperature is not used to increase the extrusion volume, but the method of adding LDPE or processing aids is used to solve this problem.
因此挤出机温度设定一般采用渐进式加温方法，即进料段加工温度较低，塑化段和混炼段加工温度较高，在保证原料充分塑化的情况下，为防止原料热氧化降解，温度越低越好。
Therefore, the gradual heating method is generally used to set the extruder temperature, that is, the lower the processing temperature of the feed section, the higher the processing temperature of the plasticizing section and the mixing section. In order to prevent the thermal oxidation degradation of the raw materials, the lower the temperature, the better.