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Identification of high-quality PET plastic raw materials, do you know?
As plastic raw materials, PET mainly includes polyethylene terephthalate PET and polybutylene terephthalate PBT. Polyethylene terephthalate is also commonly known as polyester resin. It is a polycondensate of terephthalic acid and ethylene glycol, and together with PBT, it is collectively referred to as thermoplastic polyester, or saturated polyester. PET is heard a lot in daily life, but not many people know what is the high-quality PET plastic raw material.
PET is a milky white or light yellow highly crystalline polymer with a smooth and shiny surface. It has good creep resistance, fatigue resistance and friction resistance, small wear and high hardness, and has the largest toughness among thermoplastics; good electrical insulation performance, little influence by temperature, 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 immersed in hot water and alkalis.
The glass transition temperature of PET resin is high, the crystallization speed is slow, the molding cycle is long, the molding cycle is long, the molding shrinkage rate is large, the dimensional stability is poor, the crystallization molding is brittle, and the heat resistance is low.
Through the improvement of nucleating agent, crystallizing agent and glass fiber reinforcement, in addition to the properties of PBT, PET has the following identification methods for PET plastics:
1. Smell the smell first. The smell of PET is different from ordinary plastic. Burn it with a lighter, and then you will smell a very aromatic and comfortable smell (burn a bottle to smell it), if PET contains other ingredients, the smell will be very pungent. . There is a bottle that contains SEBS ingredients that can't be used.
2. Wire drawing, when burning, pull the wire on the lighter to see if the wire is long, then break the pulled wire, and check the breakpoint in the middle to see if the wire is rolled into a small circle, and the longer the roll is. More indicating a high melting point.
3. If the burning part is too dark or the oil drops very quickly, most of the melting points are abnormal, which is often found in PET film.
But generally if it is a bottle tablet, it should not be a big problem. The most critical point is to distinguish whether it contains PVC, which is the fatal injury of PET. First take more samples, and then lay flat in a sunny place, the PVC is light blue in the sun. If you fold in half, there will be white creases. The above is the naked eye identification, the accuracy is limited, mainly depends on experience.
There is also a more practical and better way. Buy an oven and adjust the temperature to 250 degrees and bake there for half an hour. If the goods contain PVC, there will be a lot of yellow spots on the surface; if the melting point is not enough, it will be very fast. melt.
In fact, there are many varieties of PET, such as PET shredded films from foreign factories, pulp blocks, and roll films with a length of less than 30 cm, all of which have different customer groups.
The identification of these goods is strongly required to be tested with an oven. In particular, PET rolls are a very scarce source of supply in the entire market. Generally, the length is more than 80 to 120 cm. The price of high-quality PET plastic films with a thickness of 3-5 filaments is also very high (white and transparent).
