Key Difference – UPVC vs CPVC
PVC or polyvinylchloride is a synthetic thermoplastic often made by the suspension or emulsion polymerization of acetylene and anhydrous hydrochloride acid. It is one of the oldest and most common plastics. During its production process, various chemicals such as impact modifiers, plasticizers, fillers, reinforcing agents, lubricants, and stabilizers can be added in order to widen the uses of PVC. PVC may be available in the forms of flexible thin films, rigid plastics, foams or elastomers. Depending on the addition of certain ingredients, different types of PVCs are formed; namely, PPVC (plasticized PVC), PVCA (polyvinyl chloride acetate), UPVC and CPVC. In this article, the difference between UPVC and CPVC is highlighted. UPVC stands for unplasticized PVC, whereas CPVC stands for post-chlorinated PVC. The key difference between UPVC and CPVC is that UPVC is produced without the addition of plasticizers, whereas CPVC is produced by post-chlorination of PVC to enhance the chlorine content in the polymer.
CONTENTS
1. Overview and Key Difference
2. What is UPVC
3. What is CPVC
4. Side by Side Comparison – UPVC vs CPVC in Tabular Form
5. Summary
What is UPVC?
UPVC is the PVC type contains no plasticizers. UPVC can be manufactured by calendaring, extrusion, and injection moulding. UPVC is well known for its low water absorption. In addition, it offers good resistance to alkalis, oils, acids and inorganic chemicals. However, it is not compatible with ketones, chlorinated and aromatic hydrocarbons, aromatic ethers, esters, amines. UPVC is widely used in many applications including electrical insulation applications, pipes, sheets and films, window frames, translucent glazing, gaskets, seal frames, packaging, flexible toys, books, bottles, office equipment, etc. UPVC possess high tensils strength and high impact strength.
Figure 01: A UPVC Pipe
Moreover, it can withstand high pressures for long periods of time even in high temperatures. However, its low-temperature stability is limited. UPVC is lightweight and much easy to handle during installation. The plasticizers of UPVC can be leached out by certain hydrocarbons resulting in the degradation of properties.
What is CPVC?
CPVC is produced by raining the chlorine content from 56% to around 66% though the post-chlorination process. Chlorination takes place at –CH2 groups that ultimately converts the PVC into a copolymer of vinyl chloride with 1,2-dichloroethylene. Chlorination process reduces the attraction forces between polymer chains and makes PVC more amorphous. These factors will lead CPVC to increase its glass transition temperature approximately by 50% than PVC and also to enhance the melt viscosity during processing.
Figure 02: CPVC Pipes
The upper service temperature of CPVC is about 100 °C, whereas that of PVC is about 60 °C. When compared to PVC, CPVC is non-toxic and possess excellent heat resistant properties. In addition, CPVC offers greater flexibility and strength over PVC. CPVC is also known for its fire-resistant properties and will not burn without a flame source. This lightweight material is easy to install. The pipes of CPVC are used for hot-water lines, metal treating, food and beverage industry, and wastewater treatment. CPVC is also resistant to polar organic solvents such as chlorinated hydrocarbons, esters, ketones, etc. However, CPVC may not be reliable to use with certain oils and grease under stress conditions.
What is the Difference Between UPVC and CPVC?
UPVC vs CPVC |
|
| UPVC contains no plasticizers. | CPVC is produced by post-chlorination, so the chlorine content is greater than UPVC. |
| High Temperature Stability | |
| High temperature stability in UPVC is low. | High temperature stability in CPVC is high. |
| Compatibility with Chlorinated and Aromatic Hydrocarbons | |
| UPVC is incompatible with chlorinated and aromatic hydrocarbons | CPVC is compatible with chlorinated and aromatic hydrocarbons |
| Toxicity | |
| UPVC can be toxic especially when plasticizers leached out | CPVC is non-toxic |
| Density | |
| The density of CPVC is higher than that of UPVC. | The density of UPVC is lower than that of CPVC. |
| Melt Viscosity in Processing | |
| UPVC has a low melt viscosity during processing. | CPVC has a higher melt viscosity in processing. |
| Maximum Service Temperature | |
| Around 65 °C | Around 100 °C |
| Glass Transition Temperature | |
| 80-84 °C | 99-123 °C |
| Flammability | |
| Lesser compared to CPVC | Higher compared to UPVC |
Summary – UPVC vs CPVC
UPVC and CPVC are two types of PVC that are used in wide range of applications owing to their different set of properties. UPVC contains no plasticizers, thus resulting in more strength and impact resistant. CPVC is made by post-chlorination to increase the chlorine content. Thus it is more strong and resistant to wide range of chemicals. In addition, the service temperature is high in CPVC than UPVC due to higher glass transition and melting viscosity of CPVC.
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Reference:
1.Titow, W. V. “PVC plastics: properties, processing, and applications”. Springer Science & Business Media, 2012
2.Ahmed, A., & Sturges, J. “Materials Science in Construction: An Introduction”. Routledge,2014
3.Patrick, S.” A practical guide to polyvinyl chloride”. iSmithers Rapra Publishing,2005
4.Bashford, D. P. “Thermoplastics: directory and databook”. Springer Science & Business Media, 1996
5. Dickenson, T. C. “Valves, Piping, and Pipelines Handbook”. Elsevier,1996
Image Courtesy:
1.’UPVC Rainwater goods 2080′ By Photograph by Clem Rutter, Rochester, Kent. (CC BY-SA 4.0) via Commons Wikimedia
2.’CPVC tees’ By Asadabbas – Own work, (CC BY-SA 4.0) via Commons Wikimedia