P V C (POLY(VINYL CHLORIDE))
TEMPRITE® GEON® EXCELON®
With its ability to be compounded producing a broad variety of physical, chemical and electrical properties, PVC has the largest commercial application of any polymeric material. Well known as a grey, rigid, hard plastic (often referred to as UPVC meaning Unplasticized PVC) it is used in vast quantities in municipal and plant piping systems; rigid PVC is also produced in coloured sheet and rod; cellular, rigid PVC is available in decorative coloured sheet; rigid, clear PVC sheets, pipes and fittings are available for use in food contact applications; rigid, light grey PVC in high impact resistant grade sheets and rods overcomes the poor impact resistance of standard rigid PVC; and flexible PVC, plasticized to make it almost rubbery, is available in sheeting for door curtains and tube and hose for fluid handling. All properties vary widely depending on the amount of stabilizers, fillers, plasticizers, processing aids, impact modifiers, etc. added to the particular grade. The properties chart on the following page should be consulted for physical and electrical properties. Chemically, rigid PVC is very corrosion resistant to a wide range of pH and has many industrial uses such as plating tank lining, fume hoods, scrubbers, water treatment and solution tanks. As well, rigid PVC possesses good thermal and electrical insulation characteristics with rigid, cellular PVC enhancing the thermal insulating ability of PVC and providing improved impact resistance. PVC has poor abrasion resistance and should not be used for parts subjected to rubbing against rough or gritty surfaces. Rigid PVC is resistant to aliphatic hydrocarbons and alcohols; is swelled or dissolved by aromatic hydrocarbons, ketones and esters; and is soluble in halginated hydrocarbons which are commonly used in solvent cements for joining pipe and fittings. Polar adhesives such as epoxies and urethanes can be used when bonding PVC to dissimilar materials. Also, rigid PVC is weather and UV resistant. Flexible PVC has the same good resistance to inorganic compounds but the presence of a plasticizer may reduce its resistance toward some aliphatic hydrocarbons and alcohols. In some applications, the plasticizer may be leached out by organic materials contacting flexible PVC or volatilized by heat resulting in stiffening and embrittling. With its rather low resistance toward heat, PVC can easily be vacuum formed and heat bent. This means machinists must provide substantial coolant to minimize softening during normal machining operations. In addition, due to the susceptibility of PVC to organic chemical attack, water-soluble emulsions must be used in cooling. High speeds, feed rates and sharp tooling provide good results. Flexible PVC cannot be satisfactorily machined. PVC can be hot gas welded with good results by using air as the heating medium.
Chlorinated PVC (known as CPVC) extends the useful characteristics of PVC to a higher range of temperatures finding applications in hot water piping, hot exhaust ducts, heated tank linings, etc. Also, the flame retardancy of PVC is improved with CPVC and smoke evolution is greatly reduced. With higher heat resistance, machinability is improved. Chemical resistance is quite similar to PVC while electrical insulation is substantially improved. Physical properties of both PVC and CPVC are quite similar. CPVC can also be solvent cemented and hot gas welded using heated air as the medium.
Values shown in the above table are averages and there will be variances from lot to lot. After selecting a material based upon these values, you must conduct tests specific to your application to be assured the material suits your needs.
In the above table, Clear PVC refers to sheet material, not pipe. Clear PVC Pipe is actually a transparent Vinyl Chloride/Propylene Copolymer and does not possess the optical clarity of the sheet material.