How is PVC Made?
A pvc raw material is a common plastic used in many products. It has good electrical and thermal insulation properties and can be molded into shapes.
It is made when chlorine (which comes from industrial salt), carbon, and ethylene (which comes from oil) are mixed. This gives it a unique structure that makes it highly versatile, durable, and flexible.
The raw materials used to make PVC are ethylene and pvc chlorine. These are derived from the basic petrochemical and chlor-alkali industries via the thermal cracking of naphtha and natural gas.
The first step in the process is to combine ethylene and chlorine to produce an intermediate product called ethylene dichloride (EDC). This chemical is then decomposed by heating in a high-temperature furnace or reactor.
Next, the ethylene is transformed into vinyl chloride, a base material that is the basis for PVC production. This is a white powder that can be mixed with plasticizers to produce formulations for a variety of products, including pipes and sheets.
The hard and flexible pipes you see in your bathroom or kitchen are made from PVC, as are some of the bottles you use to store medicines. However, PVC can be a toxic and flammable substance when it is heated or when certain additives are added to it. So, if you are concerned about the safety of your purchase, ask your brand or manufacturer about this before purchasing.
A polymerization process involves the blending of basic constituents (building blocks) to create a polymer. Typically, different temperatures and pressures are applied to allow the building blocks to react with each other. Sometimes a catalyst is used to speed up the reaction and make it more efficient.
The first step in the production of PVC is to combine ethylene with chlorine that has been produced by the electrolysis of salt water. This produces ethylene dichloride, which is then converted at high temperatures into vinyl chloride monomer, the basic building block of PVC.
The vinyl chloride monomer is then polymerized into polyvinyl chloride resin using a chain-growth polymerization process. PVC is manufactured in two different forms, rigid and flexible, and can be made in a wide variety of colors. Rigid PVC isn't softened, so it's stiff. Flexible PVC, on the other hand, is softened with chemicals like dioctyl phthalate or tritolyl phosphate. These plasticizers help to make PVC more soft, able to bend, and also more resistant to abrasion.
Additives and modifiers
PVC is a versatile material that can be used for a wide variety of products. It is usually made in two different types: rigid PVC (RPVC or uPVC) and flexible PVC (FPC).
In order to make PVC useful for many applications, it requires a range of additives and modifiers. These include stabilizers, lubricants, heat stabilizers, impact modifiers, processing aids, and fillers.
A key role of these additives is to enhance the mechanical, electrical, thermal, and light properties of PVC. The most important additives for this purpose are heat stabilizers, lubricants, and plasticizers.
Alternatively, these additives may be used to improve the mechanical properties of rigid PVC by modifying its chemical resistance and toughness. This can be achieved by using impact modifiers (toughening agents) that have rubber-like properties, such as acrylic rubber, chlorinated polyethylene, or butadiene styrene.
These impact modifiers and processing aids are used in many rigid PVC products, such as window profiles, pipes, pipe fittings, and sheets. They improve the mechanical properties of these products and also make them easier to fuse and melt.
PVC is highly recyclable and can be recycled up to eight times, depending on the application. This reduces the amount of virgin PVC produced and helps lower global warming potential by reducing the amount of carbon released into the atmosphere.
Through grinding, scrubbing, or other mechanical processes that break up the PVC into small pieces, waste can be turned into new materials. This can then be remelted into different products.
The pvc chemical recycling uses chemical processes to break down the waste into chemicals that can be used in new PVC products or as feedstock for other manufacturing processes. This is a common process for other types of plastics, but it has its limitations when it comes to PVC.
Thermal recycling, on the other hand, is a more advanced process that involves heating waste material to extract hydrogen chloride (HCI) or other substances from the waste. This is a good option for industrial waste, but it is limited by the presence of additives in the recycled material and by the low recovery rates.