Polypropylene plastic structure and properties

The structural formula of polypropylene is: [—CH2—CH—] n , which is a linear macromolecule, but the methyl side chain of polypropylene has three different arrangements, which makes it have a high degree of crystallinity. Due to the influence of the methyl side chain, the properties of polypropylene and polyethylene plastics are different, mainly in the following aspects:

1. Better chemical stability than polyethylene

In addition to fuming nitric acid and fuming sulfuric acid, it has good resistance to other chemical corrosion. In the laboratory, 80% sulfuric acid and concentrated hydrochloric acid can reach 100 °C without destroying polypropylene.

2. Outstanding heat resistance

It can be used for a long time at 100-120℃; but the impact strength decreases sharply at low temperature, and the impact strength at 0℃ is half of that at 20℃.

3. Air and water permeability are lower than polyethylene.

4. Rigidity and tensile strength are better than polyethylene.

5. Directional stretching

The strength in the tensile direction is improved, the bending resistance is good, the flexibility is increased, and the bent part will not turn white after 1 million times of bending.

6. Aging resistance is poorer than polyethylene

The long chain of polypropylene has methyl tertiary carbon atoms, which is unstable. During use, it is strictly necessary to prevent "copper damage" from long-term contact with copper.