Everything about PVC
From manufacturing to recycling
PVC is an amorphous thermoplastic consisting of rock salt (57%) and petroleum (43%). Additives are used to process the white powder into semi-finished or finished products. PVC's broad-ranging properties make it suitable for numerous applications. PVC is used in piping, flooring, window profiles, roof sheeting, cable sheathing, in profile or film form.
PVC is essentially a hard and brittle material. Plasticisers and/or modifiers can be used to transform it into a flexible and readily workable material. Other additives such as stabilisers and pigments can be applied to obtain weather-resistant and durable products.
Examples of thermoplastics:
Polypropylene (PP): Partially crystalline thermoplastic belonging to the polyolefins group, produced entirely from petroleum.
Polyethylene terephthalate (PET): Thermoplastic belonging to the polyesters group. Best-known form of use is for drinks bottles and textile fibres. PET is produced entirely from petroleum.
Polyethylene (PE): Thermoplastic which is produced entirely from petroleum by polymerising ethene (ethylene). PE belongs to the polyolefins group.
Polystyrene (PS): PS is a transparent, partially crystalline thermoplastic which is well-known in its form as a white foamed material. PS is produced entirely from petroleum.
PVC is essentially a hard and brittle plastic. Plasticisers render PVC flexible and extensible, thus endowing it with special properties.
Plasticisers are polar organic molecules or polymers which are inserted between the PVC polymer chains, making them flexible. Soft PVC can be processed into a broad spectrum of products. The plasticiser type can be adapted to requirements, to produce materials which are flexible in the cold or flame-resistant, for example
The most commonly used group of plasticisers is the phthalates. This group is increasingly being replaced by so-called non-phthalates, such as Hexamoll® DINCH, terephthalates or adipates.
PVC is thermally unstable and thus requires stabilisers for processing purposes. These prevent degradation under thermal stress and extend the useful life of the end product. Stabilisers are also able to repair eroded plastic. These effects take place according to the chemical composition of the stabilisers, whose colouring is duly neutral, avoiding any yellowing. PVC stabilisers predominantly take the form of organic salts of calcium, barium and zinc. Organotin compounds are being phased out, while lead and cadmium compounds have already completely disappeared from film applications.
Special additives endow PVC film with individual properties:
Processing aids and lubricants ensure good processing of the film compound on the calender and production of a homogeneously formed film.
UV absorbers serve to absorb ultraviolet light, which is harmful to the chemical bonds, transforming it into harmless thermal energy.
Antioxidants render the reactive radicals produced by oxygen harmless before they can cause further damage in secondary reactions.
Pigments are the colouring additives which give the film both colour and opacity.
Fillers such as chalk or talcum reinforce the film matrix and influence the mechanical properties.
Flame-retardant additives provide the PVC film with flame-proof properties.