4.7: Chlorinated PVC (PVC-C or CPVC)
4.7 Chlorinated PVC (PVC-C or CPVC)
Chlorinated polyvinyl chloride is produced by chlorination of polyvinyl chloride. The chlorine content can be as high as 65 70% versus 57% for PVCs. This leads to:
a higher service temperature
a better chemical resistance
a better retention of mechanical performances when the temperature rises.
Some properties vary significantly with the chlorine content and the molecular weights.
4.7.1 General Properties
PVC-C is appreciated, in comparison with PVC, for its chemical resistance except to certain solvents, its maximum operating temperature, its higher rigidity particularly when the temperature rises, dimensional stability, and fireproofing.
PVC-C is currently handicapped by the ecological problems concerned with chlorine, the limited number of producers, the cost, the attack by aromatic or chlorinated hydrocarbons as well as by esters and ketones, the impact sensitivity which increases as the temperature decreases, a high density, the fume toxicity and corrosivity in the event of fire.
PVC-C is a speciality polymer produced in a limited range of grades with different chlorine contents and additives for:
extrusion, injection, calendering, co-extrusion, thermoforming
stabilized against heat, UV, light and weathering; low combustibility
for pipes and fittings, window profiles, films and sheets, tubes
The cost is higher than that of PVC.
All the molten-state methods are usable but extrusion, injection, calendering, thermoforming, welding and co-extrusion are the most used.
(See Chapter 2 for further information.)
Applications are far less widespread than for PVC, for example:
Building & construction
pipes and fittings for...