Views:0 Author:Site Editor Publish Time: 2020-10-10 Origin:Site
Crude oil is processed to the later part and then extracted, which is the original plastic turnover box raw material. The most familiar part of PC material is extracted from petroleum. When the PC material is burned, it has a rotten smell of flowers and fruits, and there is charcoal. The first molecule, ABS is extracted from coal, ABS will be soot-like when it is burned out, without foaming; POM is extracted from natural gas.
HDPE: A non-polar thermoplastic resin with high crystallinity, the scientific name is polyethylene, pure polyethylene is tasteless, odorless and non-toxic white crystalline particles with a melting point of about 130°C and a relative density of 0.941~0.960. It has good heat resistance and cold resistance, good chemical stability, high rigidity and toughness, and good mechanical strength. Dielectric properties and environmental stress cracking resistance are also good. The melting temperature is 220~260℃. For materials with larger molecules, the melting temperature range is recommended to be between 200 and 250°C. High-density polyethylene is a white powder granular product, non-toxic and odorless, with a density in the range of 0.940～0.976 g/cm3; crystallinity is 80%～90%, softening point is 125～135℃, and the use temperature can reach 100 ℃; hardness, tensile strength and creep are better than low-density polyethylene; abrasion resistance, electrical insulation, toughness and cold resistance are all better, but slightly worse than low-density insulation; good chemical stability, At room temperature, it is insoluble in any organic solvents, resistant to corrosion by acids, alkalis and various salts; the film has low permeability to water vapor and air, and has low water absorption; poor aging resistance, and environmental cracking resistance is not as good as low-density polymer Ethylene, especially thermal oxidation will reduce its performance, so the resin needs to be added with antioxidants and ultraviolet absorbers to improve and improve this deficiency. The high-density polyethylene film has a lower thermal deformation temperature under stress. Attention should be paid to this point in application. If HDPE material is used to make plastic turnover boxes, it has the following characteristics.
[Main advantages] The plastic turnover box is resistant to acid and alkali, organic solvents, excellent electrical insulation, and can still maintain a certain degree of toughness at low temperatures. Surface hardness, tensile strength, rigidity and other mechanical strength are higher than LDPE, close to PP, tougher than PP, but the surface finish is not as good as PP.
[Main Disadvantages] The plastic turnover box has poor mechanical properties, poor ventilation, easy deformation, easy aging, easy to be brittle, less brittle than PP, easy to stress cracking, low surface hardness, easy to scratch. It is difficult to print. When printing, surface discharge treatment is required, no electroplating, and the surface is dull.
[Basic Features] Plastic Turnover Box HDPE is an opaque white wax-like material. Its specific gravity is lighter than water, with a specific gravity of 0.941~0.960. It is soft and tough, but slightly harder than LDPE, and slightly stretchable, non-toxic. Tasteless.
[Combustion characteristics] The plastic turnover box is flammable and can continue to burn after leaving the fire. The upper end of the flame is yellow and the lower end is blue. It will melt when burning, dripping liquid, and no black smoke. At the same time, it emits paraffin when burning. Smell.
PP plastic (polypropylene) English name: Polypropylene
Specific gravity: 0.9-0.91 g/cm3 Molding shrinkage rate: 1.0-2.5% Molding temperature: 160-220℃
Drying conditions: --- Material properties: low density, strength and rigidity, hardness and heat resistance are better than low-pressure polyethylene, can be used at about 100 degrees. It has good electrical properties and high-frequency insulation. Not affected by humidity, but low temperature It becomes brittle with time, is not resistant to molds and is easy to age. Suitable for making general mechanical parts, corrosion-resistant parts and insulating parts
PP is a semi-crystalline material. It is harder than PE and has a higher melting point. Since homopolymer PP is very brittle when the temperature is lower than 0℃, the PP materials of many commercial plastic turnover boxes are random copolymers with 1~4% ethylene or clamp copolymers with higher ethylene content. . Copolymer PP material has a lower thermal distortion temperature (100°C), low transparency, low gloss, and low rigidity, but the plastic container has 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 crystallinity, the surface stiffness and scratch resistance of this material are very good. PP does not have the problem of environmental stress cracking. Usually, the PP is modified by adding glass fiber, metal additives or thermoplastic rubber.
The flow rate MFR of PP ranges from 1 to 40. PP materials with low MFR have better impact resistance but lower elongation strength. For the same MFR material, the strength of the copolymer type is higher than that of the homopolymer type. Due to crystallization, the shrinkage rate of PP is quite high, generally 1.8~2.5%. And the direction uniformity of shrinkage is much better than that of PE-HD and other materials. Adding 30% of glass additives can reduce the shrinkage to 0.7%.
Both homopolymer and copolymer PP materials have excellent moisture absorption, acid and alkali corrosion resistance, and solubility resistance. However, it has no resistance to aromatic hydrocarbon (such as benzene) solvents, chlorinated hydrocarbon (carbon tetrachloride) solvents, etc. PP does not have oxidation resistance at high temperatures like PE.