LDPE Resin

LDPE Resin, also known as high-pressure polyethylene (LDPE), is the lightest variety of polyethylene resin and is a milky-white, tasteless, odorless, non-toxic, waxy granule with a non-glossy surface. It has good flexibility, extensibility, electric insulation, transparency, easy processing and certain air permeability. Its chemical stability performance is good, alkali resistance, resistance to general organic solvents.

 

LDPE Resin (high pressure-low density polyethylene, HP-LDPE, abbreviated as LDPE) has been industrialized for more than 70 years. Although the varieties and outputs of polyethylene have progressed tremendously with the discovery and development of olefin polymerization catalysts, high-pressure polyethylene still occupies an important position. Ethylene is polymerized into high molecular weight polyethylene by free radical mechanism under high temperature and high pressure with the following characteristics:

(1) The polymerization reaction process of ethylene is a strong exothermic process. The heat of polymerization of ethylene is about 93.5kJ/mol (or 3.3kJ/g), and the specific heat capacity of ethylene is 2.51~2.85J/(g-°C) at 235MPa and 150~300°C. If the reaction heat is not removed in time, the polymerization of every 1% of ethylene will raise the temperature by 12~13°C. If the temperature is too high, it will also cause the polymerization of ethylene. If the temperature is too high, it will also lead to ethylene decomposition.

(2) under high pressure, ethylene has been compressed to the density of 0.5g/mL of the gas-tight phase state, similar to the liquid can no longer be compressed, at this time, the distance between the ethylene molecules is significantly shortened, thereby increasing the probability of collision of free radicals and molecules of ethylene, so it is easy to polymerization reaction.

(3) high temperature growth chain of free radical activity, easy to chain transfer reaction, the polymer obtained with more branched chain linear structure. Usually every 1000 carbon chain atoms contain 20~30 branched chains, crystallinity of 45%~65%, density of 0.910~0.925g/mL, lightweight, flexible, low temperature resistance, impact resistance is better.