PVC is the second largest plastic variety after polyethylene. The glass transition temperature is 8 ~ 85℃, the density is 1.35 ~ 1.45g/cm, and the service temperature is-15 ~ 6℃. PVC has excellent acid and alkali resistance, wear resistance, fire resistance and insulation performance, and good miscibility with most plasticizers, so it can greatly change the mechanical properties of materials. Excellent processing performance and low price, but poor stability to light and heat, and the performance drops rapidly above 1℃ or under illumination.
polystyrene: polystyrene (PS) is a kind of thermoplastic resin, which is widely used because of its low price and easy processing and molding. Polystyrene is in the form of homopolymer (transparent granular material) or toughened grafted polymer or mixed with elastomer (impact polystyrene IPS). Polystyrene * * * polymer is better than homopolymer in physical and thermal properties. These kinds of polystyrene have many grades, such as standard IPS and standard transparent grade, environmental stress cracking resistance grade (ESCR) and ultraviolet resistance grade. Flame-retardant grade, wear-resistant grade, high flexibility grade for light products, foamable grade, super primary grade and low residual volatile grade, etc.
polystyrene resin is used to make disposable tableware, automobile parts, packaging materials, toys, building materials, electrical appliances and household items in daily life.
The molded products of expandable polystyrene include cups, refrigerators, traditional packaging and floating life-saving appliances. The biggest application field of flame retardant expandable polystyrene is as building materials and thermal insulation materials. The preform of expandable polystyrene can be used to make upholstered chairs filled with granules and loose fillers.
polyethylene: it can be divided into low molecular weight and high molecular weight. The low molecular weight is generally liquid, colorless, odorless and insoluble in water, with a density of .92g/cm3, which can be used as lubricating oil and coating. High molecular weight polymers are generally solid, milky white, thermoplastic, waxy to the touch, and the density is between .92 and .96 g/cm3. It is corrosion-resistant and has good insulation performance. High-density polyethylene has the characteristics of rigidity, hardness and high mechanical strength, and can be used as containers, pipelines and high-frequency electrical insulation materials for radar and television. It is insoluble in water and has little water absorption. Even for some chemical solvents, such as toluene and acetic acid, it is only slightly soluble at a temperature above 7℃. However, particulate polyethylene can melt or solidify with the change of temperature between 15℃ and 4℃, and melt when the temperature rises to absorb heat; When the temperature decreases, it solidifies and gives off heat. Because it absorbs little water, is not easy to get wet and has insulating properties, it is a good building material. Particles of polyethylene mixed with cement can be used as walls and floors. Using its characteristics of endothermic melting and exothermic solidification at normal temperature, when the room temperature rises, it melts and absorbs heat; When the temperature drops, it solidifies and gives off heat. This can keep the room temperature stable. Therefore, it is a good heat storage material. According to its other characteristics, this building material also has the functions of preventing electricity leakage, heat, moisture and corrosion.
It is often used to make: 1. Electrical insulating material
Because of its high specific stability, moisture resistance and high dielectric properties, polyethylene has become an insulating material in electrician and electrical engineering.
2. Materials used as corrosion resistant chemical reagents can be used as chemical structural materials, such as various parts, pipes, anticorrosive linings, etc.
3. For packaging
Polyethylene sheets and films have low density, softness without adding plasticizer, high tear strength, water absorption, water impermeability and chemical resistance, all of which are necessary for packaging materials, so polyethylene films have a very broad market in the packaging industry and gradually replace celluloid.
polypropylene: PP is a semi-crystalline material. It is harder than PE and has a higher melting point. Because homopolymer PP is very brittle when the temperature is higher than C, many commercial PP materials are random * * * polymers with 1~4% ethylene or clamp-type * * * polymers with higher ethylene content. * * * Polymer-based PP material has lower thermal distortion temperature (1C), low transparency, low gloss and low rigidity, but it has stronger impact strength. The strength of PP increases with the increase of ethylene content. The Vicat softening temperature of PP is 15C C. Because of its high crystallinity, this material has good surface stiffness and scratch resistance.
there is no environmental stress cracking problem in PP. Usually, PP is modified by adding glass fiber, metal additives or thermoplastic rubber. The MFR of PP is in the range of 1~4. 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 3% glass additive can reduce the shrinkage to .7%. Both homopolymer and * * polymer PP materials have excellent moisture absorption resistance, acid and alkali corrosion resistance and solubility resistance. However, it has no resistance to aromatic hydrocarbon (such as benzene) solvents and chlorinated hydrocarbon (carbon tetrachloride) solvents.
commonly used to make: 1, automobile industry (mainly using PP containing metal additives: fenders, ventilation pipes, fans, etc.).
2. Instruments (dishwasher door gasket, dryer ventilation pipe, washing machine frame and cover, refrigerator door gasket, etc.).
3. Consumer goods for daily use (lawn and gardening equipment such as lawnmowers and sprinklers).