How do you tell PP from PE?
Polyethylene (PE) is a thermoplastic resin obtained by polymerizing ethylene.
It belongs to the alkane inert polymer, has good chemical stability, and is resistant to corrosion of acid, alkali, and salt aqueous solutions at normal temperatures. Because polyethylene is non-polar, it can be used as an insulating material or as a high-voltage insulating material. Under the action of the atmosphere, sunlight, and oxygen, polyethylene will age, discolor, and crack, it can become brittle or chalk, and lose its mechanical properties. Because polyethylene possesses these qualities and is easy to process, the degradable and recyclable research on polyethylene has far-reaching value.
Polyethylene materials are widely used for processing into films, wire, and cable sheaths, pipes, various hollow products, injection molded products, fibers, and the like. For example, a representative low-density polyethylene (LDPE), which is odorless, odorless, non-toxic, matte, milky white waxy particles, has a density of about 0.920 g/cm3, and a use temperature of -100 to 110 °C. It is insoluble in water, can withstand most of the acid and alkali erosion, has low water absorption, and can maintain softness and electrical insulation at low temperatures. Low-density polyethylene can be processed into various industrial products by processing methods such as injection molding, extrusion molding, and blow molding. It is widely used as packaging materials for various foods, clothing, medicines, fertilizers, industrial products, and agricultural films. It plays a pivotal role in the plastics industry.
We can see the presence of polyethylene in many scenarios. For example, in the industry, plastic end caps for industrial pipes, or protective plugs, flange protection caps, etc.
Definition of PP: First of all, what is polypropylene? Polypropylene is abbreviated as “PP”, which is a highly crystalline (crystallinity up to 95%) thermoplastic resin which is polymerized from propylene. It can be divided into PP injection molding, PP drawing, PP fiber, and PP film according to the application. PP pipe. Among the plastics commonly used in life, polypropylene is one of the lightest varieties.
Here are the properties of PP: Physical properties: non-toxic, odorless, tasteless, milky white, a high crystalline density of only 0.9-0.91g/cm3, good stability to water; Thermal properties: It has good heat resistance, and its products can be sterilized and sterilized at temperatures above 100 °C. Under the condition of no external force, it is not deformed at 150 °C. The embrittlement temperature is -35 ° C, embrittlement occurs below -35 ° C, and the cold resistance is not as good as polyethylene; Chemical stability: chemical stability is very good, in addition to being able to be attacked by concentrated sulfuric acid, concentrated nitric acid, is stable to other various chemical agents, but low molecular weight aliphatic hydrocarbons, aromatic hydrocarbons, and chlorinated hydrocarbons can be polymerized Propylene softens and swells, and its chemical stability increases with the increase of crystallinity. Therefore, polypropylene is suitable for making various chemical pipes and fittings with a good anti-corrosion effect; Electrical properties: a higher dielectric coefficient, and with the rise of temperature, can be used to make heated electrical insulation products. It also has a high breakdown voltage and is suitable for use as an electrical accessory. It has good resistance to voltage and arc resistance, but it has high static electricity and is easy to age with copper.
PP is widely used in household appliances and plastic packaging. Household appliances have developed rapidly in recent years, with many varieties and large output. Therefore, in the next few years, efforts will be made to develop PP special materials for household appliances to meet the changing needs of the market. In addition, with the improvement of people’s living standards, PP plastic packaging is a good development trend, in order to design and process PP products that people love. PP material packaging products, durable, and corrosion-resistant, can be made into food-grade packaging products, with more features, more advantages, and development prospects. In addition, polypropylene is also used in stretching PP films and the like.
(The description of the PE and PP application in this article only represents the author’s point of view. You are welcome to ask and exchange. The email address is packaging@qimingpackaging.com, thank you for reading. )
