HDPE and LDPE difference
LDPE is high-density polyethylene. Low-density polyethylene is usually produced by free radical polymerization under high temperature and high pressure. Due to the chain transfer reaction during the reaction, many branches are formed on the molecular chain. These branches hinder the neat arrangement of molecular chains, so the density is low. Its structure is shown in the figure below. It is very soft and sticky. At the same time, due to its low crystallinity, the transparency of LDPE is relatively high, so our daily life is mainly in cling film, plastic bags, etc. Oil resistance and water resistance are relatively low.
The Chinese name of HDPE is high-density polyethylene. It is usually manufactured by the Ziegler-Natta catalyst polymerization method. Its characteristic is that there are no branches on the molecular chain, so the molecular chain is arranged regularly and has a higher density. This process uses ethylene as a raw material in a tubular or kettle-type low-pressure reactor and uses oxygen or organic peroxide as an initiator to initiate the polymerization reaction.