It is an isomer of xylene. Other isomers include o-xylene and m-xylene. p-Xylene is used on a large scale for the manufacture of terephthalic acid for polyester. Its polymer is known as parylene.
p-Xylene is produced by catalytic reforming of petroleum naphtha as part of the BTX aromatics (benzene, toluene and the xylene isomers) extracted from the catalytic reformate. The p-xylene is then separated out in a series of distillation, adsorption or crystallization and reaction processes from the m-xylene, o-xylene and ethylbenzene. Its melting point is the highest among this series of isomers, but simple crystallization does not allow easy purification due to the formation of eutectic mixtures.It is also highly flammable.
Effect on health
It is harmful to people's health. It can be breathed in, ingested and absorbed through skin. It has a stimulating effect on the respiratory tract and eyes, while high concentrations have a narcotic effect on the central nervous system.What It's Used For
Paraxylene is primarily used as a basic raw material in the manufacture of terephthalic acid (TPA), purified terephthalic acid (PTA) and dimethyl-terephthalate (DMT). TPA, PTA and DMT are used to manufacture polyethylene terephthalate (PET) saturated polyester polymers. Polyesters are used to produce fibers and films. PET bottles are widely used for water because of its non-breakage properties as well as carbonated beverages because of good carbon dioxide barrier properties. In addition, they are light-weight, shatter-resistant and possess high tensile strength. Polyester uses include:- Carbonated and non-carbonated beverage containers
- Containers for household chemicals, toiletries, cosmetics, etc.
- Fabrics for curtains, upholstery, clothing, etc.
- Microwave oven packaging material
- Films for x-rays, magnetic tapes, photographic film and electrical insulation
- Packaging for boil-in bags, processed meats, shrink films and blister packs
Posts
