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What is the difference between PC and PET?

Dec 24,2021

Polycarbonate (PC) is a colorless, transparent, bright and beautiful plastic. Because PC is non-toxic and odorless, it has good ultraviolet penetration resistance, moisture-proof and fragrance-preserving performance, wide temperature resistance range, no brittleness at -180°C, and long-term use at 130°C, so it is an ideal food Packaging material.

Taking advantage of PC's excellent impact resistance and easy forming characteristics, it can be manufactured into bottles, cans and various forms of containers for packaging beverages, alcohol, milk and other fluid substances.

The biggest disadvantage is stress cracking. In addition to the selection of high-purity raw materials and strict control of various processing conditions in the production, the modification of resins with low internal stress, such as a small amount of polyolefin, nylon, polyester, etc. melt blending, can significantly improve the resistance to stress cracking and resistance. Water-based.

It is a material with good crystallinity, colorless and transparent, and extremely tough. It has the appearance of glass, is odorless, tasteless, non-toxic, flammable, has a yellow flame with a blue edge when it burns, and has good air tightness.

PET has a small expansion coefficient and low molding shrinkage rate of only 0.2%, which is one-tenth that of polyolefins, which is smaller than PVC and nylon, so the size of the product is stable. The mechanical strength is the best, and its expansion degree is similar to that of aluminum. The film strength is 9 times that of polyethylene, 3 times that of polycarbonate and nylon, and the impact strength is 3 to 5 times that of ordinary films. The film also has moisture-proof and fragrance-preserving properties.

Although PET film has the above advantages, its film price is more expensive, heat sealing is difficult, and it is easy to be charged with static electricity. Therefore, it is rarely used alone. Most of them are coated with a resin with better heat sealability to make a composite film.

The PET bottle using the two-axis stretch blow molding method can give full play to the characteristics of PET, that is, it has good transparency, high surface gloss, and a glass-like appearance. It is the most suitable plastic bottle to replace glass bottles.

In recent years, the production of PET bottles has developed rapidly, and heat-resistant PET bottles are widely used in beverages that require hot cans such as tea beverages and fruit juice beverages.
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