PVC is a polymer produced by the polymerization of the vinyl chloride monomer to get polyvinyl chloride. It has around a 56% of chlorine coming from the common salt (NaC1) and a 44% of carbon and hydrogen coming from petrol and natural gas, which makes it less dependent to non-renewable resources than other plastics.
2. PVC CHARACTERISTICS
PVC is an odorless, insipid and harmless material which is also characterized by being resistant to most of the inorganic chemical agents such as acids, alkalis, oils and alcohols. It has a high resistance to abrasion and impact. It is also a good thermal and electric insulator.
Moreover, it is characterized by having a high resistance to corrosion, what makes it highly advantageous for underground facilities, since they are liable to be outwardly eroded by the surrounding fields.
This advantage is also important in sanitary fittings, since they can be internally attacked by sulfur mainly in the shape of sulfuric acid. PVC-U elements remain unalterable when facing these attacks, even in lands with high gypsum content or in dangerous infiltrations.
This table shows PVC chemical resistance at 20º and 60º when contacting chemical products.
Chemical resistance table
PVC chemical resistance at 20º and 60º when contacting chemical products
|Oils and greases||√||√|
|Acetic acid -60%||√||√|
|Nitrous acid -45%||√||√|
|Perchloric acid -10%||√||√|
|Sulfuric acid -90%||√||√|
|Hydrogen peroxide -90%||√||√|
|Chlorine, gas, dry||√||X|
|√ Satisfactory Res. √ Limited Res. X NOT satisfactory Res.|
PVC is a thermoplastic, and for that reason when the temperature increases it starts to soften and when it gets cold it hardens. At 40º C it starts to lose its stiffness, so it is not recommended to use it at a continuous working temperature out of the 0-60ºC interval.
The rigid PVC used is called PVC-U (Unplasticized) due to the lack of plasticizers during its formation, what gives PVC-U the accurate stiffness to be used in the water channeling industry.
Other important characteristics of this material that should be taken into account are its longevity thanks to its exceptional resistance, which enables PVC products to last more than 50 years, as well as its no toxicity, since PVC accessories, thanks to its chemical inertia, do not alter water flavor nor smell and they keep their organoleptic properties.
Thanks to its chemical structure, containers and packaging manufactured with this polymer are chemically inert and it can be used in the health industry, by applying it in bags and tube for transferring blood, plasma, intravenous, etc. The use of PVC for health purposes is authorized by health authorities all over the world.
We must also highlight its 100% recyclability, since the material recovered is used to manufacture new products, to obtain other chemical products or to produce energy, with the consequent environmental advantage that it implies.
All these technical characteristics turn it into the most used plastic in the fluid channeling facilities as well as in another broad variety of applications in other industries, apart from construction, such as packing, motor industry, shoes, medicine and electronics.
PVC properties table
PVC properties table
|Density (kg/dm3)||1,35 a 1,46|
|Elasticity modulus by flexotraction (N/mm2)||3600|
|Traction modulus (MPa)||3000|
|Short-term transverse bending elasticity modulus (N/mm2)||3600|
|Long- term transverse bending elasticity modulus (N/mm2)||1750|
|Modulus of elasticity (50 years) (Mpa)||1500|
|Elastic limit (Mpa)||42|
|Ultimate tensile stress (Mpa)||≈ 50|
|Ultimate elongation (%)||80|
|Shore D hardness (20º)||70 a 85|
|Poisson’s ratio (transverse strain)||0,35|
|Vicat softening temperature (ºC) at a 49N load||74-80|
|Linear coefficient of expansion (ºC-1)||0,8·10-4|
|Thermal conductivity (kcal/mhºC)||0,14|
|Specific heat to 20 ºC (cal/gºC)||0,20-0,28|
|Dielectric strength Kv/mm||20-40|
|Dielectric constant 60 Hz||3,2 a 3,6|
|Volume resistivity 20 ºC (Ω/cm)||>1016|