Tag: Polypropylene PP Material

Polypropylene, abbreviated as PP, is a polymer formed by the polymerization of propylene. It is a white waxy material with a transparent and lightweight appearance. Its chemical formula is (C3H6)n, and its density is 0.89-0.91g/cm3. It is flammable and has a melting point of 164-170℃. It softens around 155℃ and can be used in the temperature range of -30 to 140℃. It can resist corrosion from acids, alkalis, salt solutions, and various organic solvents below 80℃, but it can decompose under high temperature and oxidation. Polypropylene is a high-performance thermoplastic synthetic resin. It is a colorless and semi-transparent lightweight general-purpose plastic with excellent chemical resistance, heat resistance, electrical insulation, high-strength mechanical properties, and good high-wear processing performance. It is widely used in the production of fiber products such as clothing and blankets, medical instruments, automobiles, bicycles, parts, conveyance pipes, chemical containers, and also in food and pharmaceutical packaging.

Physical and Chemical Properties

1. Odorless, tasteless, and non-toxic. It is the lightest among commonly used resins;
2. Excellent mechanical properties, including tensile strength, compressive strength, and hardness, outstanding rigidity and fatigue resistance. The active hinge made of PP can withstand more than 7×107 folding and bending without damage, and the impact strength at low temperature is poor. The tensile strength of PP is generally 21-39 MPa; bending strength is 42-56 MPa, compressive strength is 39-56 MPa, elongation at break is 200%~400%, and notch impact strength is 2.2-5 kJ/m2. The low-temperature notch impact strength is 1-2 kJ/m2. Rockwell hardness R95~105
3. Good heat resistance, continuous use temperature can reach 110-120℃
4. Good chemical stability, except for strong oxidants, it does not react with most chemical drugs. Solvents cannot dissolve PP at room temperature, only some halogenated compounds, aromatic hydrocarbons, and high-boiling-point fatty hydrocarbons can cause swelling. It has particularly good water resistance;
5. Excellent electrical properties, good high-frequency electrical insulation parts, and good electrical insulation properties in humid environments;
6. Due to the presence of many methylated tertiary carbon atoms on the main chain of PP, the hydrogen on the tertiary carbon atoms is easily attacked by oxygen, so the weather resistance and aging resistance of PP are poor, and antioxidants or ultraviolet absorbers must be added;
7. Mice were orally administered with 8g/kg dose for 1-5 times, and no obvious toxic symptoms were observed. Rats inhaled the decomposition products of polypropylene heated to 210-220℃ for 30 times, 2 hours each time, and showed symptoms of eye mucosa and upper respiratory tract irritation. It is forbidden to use recycled products of polypropylene to package food, the same as polyethylene.