2. Chemical and physical properties of PP PP is a semi-crystalline material. It is harder and has a higher melting point than PE. Because homopolymer PP is very brittle when the temperature is higher than 0C, many commercial PP materials are random polymers with ethylene content of 1~4% or pincer polymers with higher ethylene content. * * * Polymer-based PP material has low thermal deformation temperature (100C), low transparency, low gloss and low rigidity, but strong impact strength. The strength of polypropylene increases with the increase of ethylene content. The Vicat softening temperature of PP is150 C. Because of its high crystallinity, this material has good surface hardness and scratch resistance.
3.PP has no problem of environmental stress cracking. Usually, PP is modified by adding glass fiber, metal additives or thermoplastic rubber. The range of MFR of PP is 1~40. PP with low MFR has better impact resistance, but lower tensile strength. For materials with the same MFR, the strength of polymer type is higher than that of homopolymer type. Due to crystallization, the shrinkage of PP is quite high, generally 1.8~2.5%. And the directional uniformity of shrinkage is much better than that of PE-HD and other materials. Adding 30% glass additive can reduce the shrinkage to 0.7%. Both homopolymer and polymer PP materials have excellent moisture absorption resistance, acid and alkali corrosion resistance and solubility resistance. But it is not resistant to aromatic hydrocarbon (such as benzene) solvents and chlorinated hydrocarbon (carbon tetrachloride) solvents.
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1. Polypropylene is a thermoplastic polymer (thermoplastic: refers to a material that can be melted after heating and hardened after cooling, and can be reused; Polymer: refers to natural or synthetic compounds, the molecules of which are macromolecules formed by repeatedly connecting a series of simple monomers), which are widely used. Even Australian banknotes are made of PP, which has unusual chemical solvent resistance, acid resistance and alkali resistance. ?
2. It can produce high-purity polypropylene for semiconductor industry. It can also resist the generation of bacteria and is suitable for disposable syringes and medical equipment. Can be used for injection molding or machining and welding. It can be used for plastic products with higher quality requirements than polyethylene products, such as pipes, filter materials and loudspeakers. Banknotes are made of biaxially stretched polypropylene (BOPP), so their durability is improved. ?
3. Polypropylene was discovered at the beginning of 1950 by Italian chemist Leo Nata. In modern science, an invention may be invented by people in different places at the same time. Polypropylene is such an extreme example, which has been invented independently for about 9 times. This is a wonderful script that patent agents dream of, and the lawsuit didn't end until 1989. ?
Polypropylene has been trying to continue this legal series. Two American chemists, J paul hogan and Robert Banks, who work in Philip Oil Company, are now considered as the "official" inventors of this material. Polypropylene, like its close relative polyethylene, is very cheap and abundant. Products ranging from plastic bottles to carpets and plastic furniture are also used in the automobile industry.