Polyethylene Resin

Injection molding. At a certain temperature, the plastic is completely melted by stirring with the screw. Then inject it into the mold cavity by high pressure, and after cooling and solidification to obtain molded product.

Mould pressing. Put the powdery, granular or fibrous PE material into the mold cavity at the molding temperature, and then close the mold and pressurize it to form and solidify.

Blow molding. With the help of gas pressure, the hot-melt parison closed in the mold is inflated to form hollow products.

Extrusion molding. Through the action between the extruder barrel and the screw, the material is heated and plasticized, pushed forward by the screw, and continuously passed through the machine head to make various cross-section products or semi-finished products.   

According to the polymerization pressure, the production methods of polyethylene can be divided into high pressure method, medium pressure method and low pressure method.

The high pressure method is used to produce low density polyethylene. In terms of its mplementation methods, the low pressure method includes slurry method, solution method and gas phase method. The slurry method can produce high-density polyethylene, while the solution method and gas-phase method can not only produce high-density polyethylene, but also produce medium and low-density polyethylene by adding comonomers, also known as linear low density polyethylene.

The polyethylene catalysts currently researched and developed mainly include chromium-based catalysts, Ziegler-Natta catalysts, metallocene catalysts, non-metallocene catalysts, bifunctional catalysts, and bimodal or broad-peak molecular weight distribution polyolefin composite catalysts.

Polyethylene resin should have a storage period, generally no more than 12 months from the dat of production.

The PE resin beyond the shelf life has reached the lower limit in terms of various values. But even so, as long as its various values are still within the standard range of the storage period, it can continue to be used. In order to prolong its shelf life, please store the resin away from heat sources. This can reduce the rate of free radical curing initiation and reduce the consumption of inhibitors.

As we all know, polyethylene is one of the four general-purpose thermoplastic materials. Polymer resin materials are widely used in daily life, various industries and high-tech fields because of their light weight, easy processing, beautiful and practical characteristics.

However, with the continuous expansion of the consumer market and the continuous diversification of consumer varieties, the amount of polyethylene waste is also increasing. The recycling of waste plastics has important social and economic significance for saving energy, reducing waste volume, reducing the harm of waste plastics to the environment.

At present, many At present, many effective methods for recycling and degrading or recycling polyethylene products have been developed.

Polyethylene resin is non-toxic and has good transparency. It is an ideal packaging material because it is relatively stable polymers resistant to acids, alkalis, solvents, as well as high and low temperature. But in the production process, it needs to use special technology to improve the quality to meet the food-grade safety requirements.

Polyethylene is the fastest-growing polyolefin resin.

Polyethylene granular has reduced solubility, high mechanical strength and hardness, and minimal water absorption.

PE material has outstanding electrical insulation properties and good radiation resistance.

It has excellent low temperature resistance and can withstand most acid and alkali corrosion.

PE resin is very sensitive to environmental stress, poor heat aging resistance.

The mechanical strength is not high and the thermal deformation temperature is very low.

High density polyethylene has strong macromolecular structure, high crystallinity and high strength. Generally, the tensile strength and other properties of high-density polyethylene are significantly higher than those of low-density polyethylene. Among them, the tensile strength can reach more than 2 times that of low-density polyethylene. However, the impact strength of high-density polyethylene is lower than that of low-density polyethylene.

Polyethylene PE is resistant to most dilute acids, and is usually not corroded by various salts and their solutions. But it will be damaged by oxidizing concentrated acid, and it will also be corroded by oxidizing substances at high temperatures.

PE is usually not corroded by alcohols, aldehydes, ketones and esters. However, at room temperature, it will cause a certain degree of swelling due to the action of aromatic hydrocarbons, aliphatic aromatic hydrocarbons, and halogenated hydrocarbons. The dissolution of LDPE above 60°C and HDPE above 80°C also increases. PE is less affected by halogen at room temperature, but the effect will be accelerated at high temperature.

PE also absorbs oil, such as mineral oil and essential oil, which will escape through PE material.

PE products may produce stress cracking under the action of stress cracking agents such as aliphatic and aromatic hydrocarbons, aldehydes, ketones, alcohols, concentrated sulfuric acid, detergents, soaps, oils and fats, and alkali metal hydroxides.

In most applications plastic containers for hollow goods, barrier properties are often very important. Among the barrier properties to various substances, the permeability to oxygen, carbon dioxide, nitrogen, organic solvents, and the permeability to water and water vapor are particularly important in practical applications. They can directly affect the protective effect of plastic containers on the packaged items.

For outdoor applications or PE hollow containers that are exposed to direct sunlight, weather-resistant formulas should be used. That is, an appropriate amount of UV absorbers, sunscreens and other additives should be added to the PE main material to prevent the harm of ultraviolet light.