Physical and chemical properties of polypropylene

1. Odorless, odorless, and non-toxic. It is the lightest type of commonly used resin;
2. Excellent mechanical properties, including tensile strength, compressive strength, and hardness, outstanding rigidity and bending fatigue resistance. The movable hinge made of PP can withstand 7 × Folding and bending more than 107 times without damage, resulting in poor impact strength at low temperatures. The tensile strength of PP is generally 21-39 MPa; Bending strength 42-56 MPa, compressive strength 39-56 MPa, elongation at break 200%~400%, notch impact strength 2.2-5 kJ/m2, low-temperature notch impact strength 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 chemicals; At room temperature, the solvent cannot dissolve PP by 20%, only some halogenated compounds, aromatic hydrocarbons, and high boiling point fatty hydrocarbons can make it swell, and its water resistance is particularly good;
5. Excellent electrical performance, good resistance to high-frequency electrical insulation, and good electrical insulation even in humid environments;
6. Due to the presence of many methyl tertiary carbon atoms on the main chain of PP, the hydrogen on the tertiary carbon atoms is susceptible to oxygen attack, resulting in poor weather aging resistance of PP. Therefore, antioxidants or ultraviolet absorbers must be added [16];
7. Mice were gavaged with a dose of 8g/kg for 1-5 times and did not show any obvious poisoning symptoms. Rats inhaled the decomposition products of polypropylene heated to 210~220 ℃ 30 times, each time for 2 hours, and developed symptoms of irritation to the ocular mucosa and upper respiratory tract. Similar to polyethylene, it is prohibited to use its recycled products to hold food.