Polyvinyl chloride (PVC) is a very popular plastic material. In the present situation, it is one of the most valuable products of the petrochemical industry. Generally, more than 50% of PVC is used in building construction, because PVC is cheap and easily bonded. In recent years, PVC has replaced traditional building materials such as wood, cement and pottery in many areas. Despite the advent of an ideal material in construction, there is still concern about the cost of PVC for the natural environment and human health.
Frequent uses for PVC include: Vinyl Siding, magnetic sign of cards, vertical cutting of windows, phonograph pages, tubes, plumbing, ducts and fittings, cheap handbags, dark windows (without sight) and in its soft form for There are clothes, upholstery, such as blinds, flooring and roofing, electrical cables, lightweight balls.
It is also often used for plumbing water and sewage because of its natural cost and flexibility.
PVC shaping techniques
Powder mixers: mixing different materials is done by these mixers. Of course, it should be noted that there may be practical problems in mixing stabilizers, lubricants, pigments, etc., which should be relatively small.
Gelling machines: Typically, they are machine-made.
Forming machines: Includes one or more winding screws.
Cylinders: To make long sheets of rubber and thermoplastics, the resin is passed between two or more cylinders.
Shaping at low pressure: Mouldings are used very quickly and very quickly to produce small and medium sized molded objects.
Injection molding, extrusion and thermal forming are also other methods.
Polyvinyl chloride is formed by polymerization of vinyl chloride monomer. Commercial production The majority of PVC is mainly made through suspension plaster, and less mass and emulsion polymerization is used, and solution soluble is rarely used. Polyvinyl chloride has a slight crystallinity, but its strength and hardness are due to the bulk of polymer chains (the result of a large chlorine dissolution). The TG is high for 81 degrees Celsius, but the TG is not high enough to make the process more difficult in a variety of ways. In contrast, heat and light are relatively unstable and hydrogen chloride is released. This material has deleterious effects on the properties of the hand (electric components), in addition to its physiological effects. Plastic Pvc is hard to add by soft and flexible lubricants. The most commonly used is phthalate.
Before the twentieth century, Russian chemist Ivan Strela Milesensky and Fritz Kallet of Grisham, Germany’s electron chemistry, both tried to use PVC in commercial products, but the problems in the process, the hardness and sometimes the fragility of the polymer did not work. In 1926, Waldo Simon of Beef Goodrich developed a way to soften the PVC by mixing it with various additives. The result was a flexible element that simply participated in processes, and became prevalent in commercial use.
Vinyl chloride monomer
It is believed that most of the vinyl products are normally harmless when properly consumed, although some additives and plasticizers can leak from the vinyl product, even though PVC soft toys have been made for babies for years, this concern There are these additives that leak from soft toys to the mouths of the children who take it into their mouths.
Despite the fact that PVC products are produced, they release one of the most toxic chemical substances called dioxin. PVC products can be harmful when burned or buried. The burning of the production and release of a large amount of dioxin and the components of chlorine that emit the environment.
In January 2006, the European Union imposed a ban on six types of softener fatalities in toys. In 2003, the US Consumer Product Safety Commission denied a similar boycott in the United States. In the United States, however, most companies have optionally stopped making PVC toys for babies.
U-PVC (Hard Polyvinyl Chloride Unplasticized PolyVinyl Chloride)
There are also sub-products that have extruded profiles based on hard polyvinyl chloride (UVV) with high impact resistance, which have a white outer surface and are used in the construction of doors and windows used in the outer wall of the building.
The profiles can be made entirely of raw material or have a core of waste or recycled materials, which can be coated by coil-hardened PVC.