HOME

TheInfoList



OR:

Chlorinated polyvinyl chloride (CPVC) is a
thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...
produced by chlorination of polyvinyl chloride (PVC)
resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on nat ...
. CPVC is significantly more flexible than PVC, and can also withstand higher temperatures. Uses include hot and cold water delivery pipes and industrial liquid handling. CPVC, like PVC, is deemed safe for the transport and use of
potable water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ...
.


History

Genova Products located in Michigan initially created the first CPVC tubing and fittings for hot- and cold-water distribution systems in the early 1960s. The original
tetrahydrofuran Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...
(THF) /
methyl ethyl ketone Butanone, also known as methyl ethyl ketone (MEK), is an organic compound with the formula CH3C(O)CH2CH3. This colourless liquid ketone has a sharp, sweet odor reminiscent of acetone. It is produced industrially on a large scale, but occurs in n ...
(MEK) formulas for CPVC cements were developed by Genova in conjunction with the
B.F. Goodrich Company The Goodrich Corporation, formerly the B.F. Goodrich Company, was an American manufacturing company based in Charlotte, North Carolina. Founded in Akron, Ohio in 1870 as Goodrich, Tew & Co. by Benjamin Goodrich, the company name was ch ...
, the original developer of the CPVC resin.


Production process

Chlorinated polyvinyl chloride (CPVC) is PVC that has been chlorinated via a free radical chlorination reaction. This reaction is typically initiated by application of thermal or UV energy utilizing various approaches. In the process,
chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
gas is decomposed into
free radical A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Ailments of unknown cause Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabo ...
chlorine which is then reacted with PVC in a post-production step, essentially replacing a portion of the hydrogen in the PVC with chlorine. Depending on the method, a varying amount of chlorine is introduced into the polymer allowing for a measured way to fine-tune the final properties. The chlorine content may vary from manufacturer to manufacturer; the base can be as low as PVC 56.7% to as high as 74% by mass, although most commercial resins have chlorine content from 63% to 69%. As the chlorine content in CPVC is increased, its
glass transition temperature The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or ru ...
(''T''g) increases significantly. Under normal operating conditions, CPVC becomes unstable at 70% mass of chlorine. Various additives are also introduced into the resin in order to make the material more receptive to processing. These additives may consist of stabilizers, impact modifiers, pigments and lubricants.


Physical properties

CPVC shares most of the features and properties of PVC, but also has some key differences. CPVC is readily workable, including machining, welding, and forming. Because of its excellent corrosion resistance at elevated temperatures, CPVC is ideally suited for self-supporting constructions where temperatures up to 200 °F (93 °C) are present. The ability to bend, shape, and weld CPVC enables its use in a wide variety of processes and applications. It exhibits fire-retardant properties.


Comparison to polyvinyl chloride (PVC)


Heat resistance

CPVC can withstand corrosive water at temperatures greater than PVC, typically greater by 40–50 °C (greater by 72–90 °F), contributing to its popularity as a material for water-piping systems in residential and commercial construction. CPVC maximal operating temperature peaks at 200 °F (93 °C).


Mechanical properties

The principal mechanical difference between CPVC and PVC is that CPVC is significantly more ductile, allowing greater flexure and crush resistance. Additionally, the mechanical strength of CPVC makes it a viable candidate to replace many types of metal pipe in conditions where metal's susceptibility to
corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...
limits its use. : Additionally, CPVC is a thermoplastic and as such has greater insulation than that of copper pipes. Due to this increased insulation, CPVC experiences less condensation formation and better maintains water temperature for both hot and cold applications.


Bonding

Due to its specific composition, bonding CPVC requires a specialized solvent cement different from PVC, with high-strength formulas being first introduced in 1965 by Genova Products, followed by alternatives such as IPS's Weld-On line. Primers, solvent cements, and bonding agents for CPVC reportedly must meet ASTM F493 specifications, differing from PVC solvent cements that must adhere to ASTM D2564 standards.


Fire properties

CPVC is similar to PVC in resistance to fire. It is typically very difficult to ignite and tends to self-extinguish when not in a directly applied flame. Due to its chlorine content, the incineration of CPVC, either in a fire or in an industrial disposal process, can result in the creation of chlorinated dioxins and the similarly dangerous polychlorinated dibenzofurans, both which
bioaccumulate Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
.


References


External links


PVC4Pipes (Global PVC Pipe trade association)
{{DEFAULTSORT:Chlorinated Polyvinyl Chloride Vinyl polymers Plastics