PP: Polypropylene is a thermoplastic resin polymerized from propylene. According to the arrangement position of methyl groups, they can be divided into isotactic polypropylene, atactic polypropylene and syndiotactic polypropylene.
PC: Polycarbonate (PC for short) is a polymer with carbonate groups in its molecular chain, which can be divided into aliphatic, aromatic, aliphatic-aromatic and other types according to the structure of ester groups. Among them, aliphatic and aliphatic-aromatic polycarbonates have low mechanical properties, which limits their application in engineering plastics.
2. Different characteristics
PP: Non-toxic, tasteless, low density, better strength, rigidity, hardness and heat resistance than low-pressure polyethylene, and can be used at around 100℃. Good dielectric properties, high-frequency insulation, not affected by humidity, but brittle at low temperature, not wear-resistant, easy to age. Suitable for manufacturing general mechanical parts, corrosion-resistant parts and insulating parts. Common organic solvents such as acid and alkali have little effect on it and can be used for tableware.
PC: High strength and elastic coefficient, high impact strength and wide temperature range; High transparency, no dyeing; Low molding shrinkage and good dimensional stability; Good fatigue resistance; Good weather resistance; Excellent electrical characteristics; Odorless and odorless, harmless to human body, in line with health and safety.
3, the process is different
PP: It is formed by polymerization of vinyl acetate in the presence of acetic acid, and the degree of polymerization should be 250 ~ 600. After polymerization, the residual trace catalyst (usually peroxide), monomer and/or solvent in the resin are removed by vacuum drying, stripping, washing or combined treatment.
Bulk polymerization of vinyl acetate with benzoyl peroxide as initiator in the presence of acetic acid; Or using polyvinyl alcohol as dispersant, and carrying out solution polymerization in a solvent at 70-90 DEG C for 2-6 hours (the polymerization degree should be controlled at 250-600) to obtain the product.
PC: oven drying temperature 1 15- 120℃, 16-20 hours. The thickness of the material on the tray is below 30mm, so that the water content of the resin is below 0.03%.
The temperature of the third zone of the barrel is 200-220, 250-280 and 260-290℃, and the temperature of the nozzle is slightly lower than the barrel temperature, which is 5- 10℃. The injection pressure is 60- 100MPa, the molding cycle is 25 seconds, and the heat treatment temperature is 1 15- 120℃, 1 hour. The heat treatment should be carried out in an inverted manner.
Compared with wooden bobbin, the service life of bobbin is extended by three times, with stable size, good weather resistance, no shedding and good finish. It can provide bobbin with various colors, which is convenient for team economic accounting.
For the waste and recycled PC materials, toughening treatment can also be carried out to replace new materials. A small amount of nylon resin or high impact polystyrene resin can be mixed into the recycled PC material, which can improve the impact strength 1 times of the product, improve the bending strength and improve the processability and surface gloss of the resin.
In addition, because the viscosity of nylon is extremely low when it melts, it can produce excellent wetting and coating effects on the pigments in the blending system, destroy the aggregation structure of pigments and increase the dispersibility of pigments, so the dosage of pigments can be reduced by 20%.
Baidu encyclopedia -PC
Baidu encyclopedia -PP