因LDPE、HDPE的流動性好，加工溫（wēn）度低，粘度大小適（shì）中，分解溫度低，在惰性氣體中高溫度300℃不分解，所（suǒ）以（yǐ）是一種加（jiā）工性能很好的塑料。但LLDPE的粘度稍高，需要增加電機功率20%～30%；易發生熔體破裂（liè），需增加口模間隙和加入加工助劑；加工溫度稍高，可達200～215℃。聚乙烯的吸水率（lǜ）低，加工前（qián）不需要幹燥處理。

聚乙烯熔體屬於非牛頓流體，粘度隨溫度的變化波動較小（xiǎo），而剪切速率（lǜ）的增加下降快，並呈線性關係，其中以LLDPE的下降（jiàng）最慢（màn）。

聚乙烯製品在冷卻過程（chéng）中（zhōng）容易（yì）結晶，因此，在加工過（guò）程中應注意模溫。以控製（zhì）製品的結晶度，使之具有不同的性能。聚乙烯的成型收縮率大，在設（shè）計模具時一定要考慮。

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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