The molecular structure of PET plastic is very symmetrical and has a certain ability to orient crystals, therefore it has high film-forming and shaping properties. PET plastics have good optical properties and weather resistance, and amorphous PET plastics have good optical clarity.
In addition, PET plastic has excellent abrasion resistance, dimensional stability and electrical insulation. PET bottles are widely used because of their high strength, good transparency, non-toxicity, impermeability, light weight and high production efficiency. PBT and PET have similar molecular chain structures, and most of properties are same, except that main chain of molecule has changed from two methylene groups to four, so molecule is more flexible and processing performance is higher.
PET is a milky white or light yellow highly crystalline polymer with a smooth and shiny surface. Creep resistance, fatigue resistance, good friction resistance, low wear and high hardness, with highest toughness among thermoplastics; good electrical insulating characteristics, little temperature dependent, but poor corona resistance. Non-toxic, weather resistant, good chemical resistance, high hygroscopicity, drying before molding is a must. Resistant to weak acids and organic solvents, but not resistant to hot water immersion, not resistant to alkalis.
PET resin has high glass transition temperature, slow crystallization rate, long molding cycle, long molding cycle, large molding shrinkage, poor dimensional stability,crystallized molding is brittle, heat resistant Low floor.
Due to improvement of nucleating agent, crystallizing agent and glass fiber reinforcement, PET has following characteristics in addition to those of PBT:
1. Thermal distortion temperature and long term operating temperature are highest among general purpose thermoplastics;
2. Due to its high temperature resistance, reinforced PET is immersed in a solder bath at 250°C for 10 seconds, with virtually no deformation or color change. It is especially suitable for preparing electronic and electrical parts for soldering. ;
3. The bending strength is 200MPa, modulus is 4000MPa, creep and fatigue resistance are also very good, surface hardness is high, and mechanical properties are similar to thermosetting plastics;
4. Since price of ethylene glycol used in PET production is almost half that of butanediol used in PBT production, PET resin and reinforced PET have lowest prices among engineering plastics at high cost efficiency.
5. PET resin bonding: One-component sili-1706 room temperature vulcanizing adhesive, after curing, it is an elastomer with excellent water resistance, impact resistance, high and low temperature resistance due to strength The technology is based on study of molecular structure of resin , so it is specially used for bonding engineering plastics.Target
Fiberglass reinforced PET is suitable for electrical, electronic and automotive industries, used in various coil coils, transformers, televisions, tape recorder parts and housings, automotive lamp holders, lampshades, incandescent lamp holders, relays, selenium rectifiers, etc. .
The current ratio of consumption of PET engineering plastics in several applications is: 26% for electrical appliances, 22% for cars, 19% for cars, 10% for household appliances, 10% for consumer goods. and 13% for rest. At present, total consumption of PET engineering plastics is low, accounting for only 1.6% of total PET volume.
1.Film sheets: all kinds of food, medicine, non-toxic and sterile packaging materials; high quality packaging materials for textiles, precision instruments, electrical components; audio cassettes, video cassettes, films Film substrates, computer diskettes, metal coatings and photosensitive films, electrical insulating materials, capacitor films, flexible printed circuit boards and membrane switches and other electronic and mechanical fields.
2.Packaging bottle application: Its application has been developed from original carbonated drink to modern beer bottle, edible oil bottle, condiment bottle, medicine bottle, cosmetic bottle, etc.< /p>
3.Electronic Appliances: manufacture of connectors, coils, coils, integrated circuits, capacitors, transformers, television accessories, tuners, switches, timers, circuit breakers, motor and relay brackets, etc. . e. .
4.Auto parts: such as switchboard covers, ignition coils, various valves, exhaust system parts, distributor caps, instrument caps, small engine caps, etc., PET can also be used . Excellent coloration. , surface gloss and hardness for manufacture of automotive exterior parts.
5. Mechanical Equipment: production of gears, cams, pump housings, pulleys, motor housings and watch parts, also used as microwave oven trays, various ceilings, outdoor billboards and models. .
6.PET plastic injection molding processing may include injection molding, extrusion, blow molding, coating, bonding, machining, electroplating, vacuum plating, printing.Authentication method
1. Smell first, smell of PET is different from ordinary plastic, burn it with a lighter, and then you will smell very fragrant and pleasant smell (burn bottle to smell it), if PET contains other ingredients, taste will be very spicy. If a bottle of SEBS ingredients is available, it must not be used.
2. Look at burnt part. If it is too black or oil drips quickly, most of melting points are abnormal, which is often found in PET film sheets.
3. Wire drawing, when it burns, pull lighter wire to see if it is long, and then break taut wire to see if wire is twisted into a small circle at break point in middle. The larger volumes, higher melting point.
But in general, if it's bottle flakes, it shouldn't be much of a problem. The most important point is to determine if it contains PVC, which is deadly to PET. Take more samples first and then lay them out in a sunny place, PVC in sun is light blue. If there are white folds in middle of fold. The above identification by naked eye, accuracy is limited, mainly depends on experience.
There is a more practical and better way. Buy an oven and set temperature to 250 degrees and bake in it for half an hour. If product contains PVC, there will be many yellow spots on surface; if melting temperature is not enough, it will melt quickly.
Actually, there are many varieties of PET, such as crushed PET film from foreign factories, pulp block, and roll film less than 30cm long. They have different customer groups.
Oven testing is strictly required to identify these items. In particular, PET rolls are a very scarce source of supply throughout market. In general, price of a film with a length of 80 to 120 cm and a thickness of 3-5 threads (white and transparent) is very high.