When the factory is making the electroplating tank, in order to prevent the corrosion of acid and alkali and other requirements, the PP material is generally selected, and the thickness ranges from 10-15mm. PP can be simply understood as plastic, but do you understand its chemical composition and physical properties? PP is a semi-crystalline material. It is stronger and has a higher melting point than PE. Since homopolymer PP is very brittle at temperatures above 0°C, many commercial PP materials are random copolymers with 1 to 4% ethylene or pincer copolymers with higher ethylene content.
The copolymer-type pp square tube has a lower heat distortion temperature (100 ° C), low transparency, low gloss, low rigidity, but has a stronger impact strength. The strength of PP increases with the increase of ethylene content. The Vicat softening temperature of PP is 150°C. Due to the high degree of crystallinity, this material has good external stiffness and scratch resistance. PP does not have environmental stress cracking problems. Generally, PP is modified by methods involving glass fibers, metal additives or thermoplastic rubber. The flow rate MFR of PP ranges from 1 to 40. The low MFR pp square tube has better impact resistance but lower ductility. For the same MFR material, the strength of the copolymer type is higher than that of the homopolymer type.
Due to crystallization, the shortening rate of PP is appropriately high, generally 1.8~2.5%. And the directional uniformity of the shortening rate is much better than that of PE-HD and other materials. Adding 30% of glass additives can reduce the shortening rate to 0.7%. Both homopolymer and copolymer pp square pipes have excellent moisture absorption resistance, acid and alkali corrosion resistance, and dissolution resistance. However, it is not resistant to aromatic hydrocarbon (eg ) solvents, chlorinated hydrocarbon (carbon tetrachloride) solvents, etc. PP is also not as resistant to oxidation at high temperatures as PE.
PP square tube is the lighter one of the common plastics. It has excellent electrical performance and can be used as a high-frequency insulation material that is resistant to humidity and heat. The pp square tube is a crystalline polymer. When the melt is condensed, a large shortening rate (1.0%-1.5%) occurs due to the large specific volume change and the high degree of molecular orientation. In the molten state of PP, the effect of reducing its viscosity by heating is not effective. Therefore, in the molding process, the injection pressure and shear rate should be improved to improve the molding quality of the product.
