PVC or Polyvinyl chloride is a synthetic polymer and one of the most widely used plastics for pipes, medical tubing, and electronics. It is also commonly referred to as vinyl. PVC is a thermoplastic, which means it can be heated and cooled to transform into different shapes, which is why it finds so many uses across various industries.
There are many other properties of PVC that make it a useful plastic material, such as its chemical resistance, cost-effectiveness, and resistive properties.
What Is PVC Plastics?
Poly vinylchloride or PVC is a synthetic thermoplastic. The plastic is derived from the polymerization of vinyl chloride monomer. The process of producing PVC involves combining ethylene and chlorine to produce vinyl chloride. This vinyl chloride is polymerized to produce PVC resin.
Manufacturing Process of PVC
PVC is made using the synthesis of vinyl chloride monomer and a suspension or emulsion polymerization to create the PVC resin. The PVC resin is compounded by additives like processing aids and stabilizers to alter the properties to the specific application and type of PVC.
For example, rigid PVC that has no plasticizers has better structural integrity, while flexible PVC incorporates plasticizers to enhance its pliability. PVC is a common everyday plastic because of its durability and low cost in consumer products.
Properties of PVC Material
PVC has a composition of plastic and is a chemically stable plastic with minimal environmental degradation. It is often confused with a rubber because of its flexible form, but it is in fact a plastic. You can easily understand this from its thermoplastic properties.
PVC material is made from 57% chlorine from salts and 43% Carbon from oils, making it widely available almost anywhere and adding to its cost-effectiveness.
PVC properties make it well-suited compared to other plastics, and it often substitutes metals in several industries.
Mechanical Properties of PVC
| Property | Metric | English Range (Lbs - inches) |
| Hardness, Shore A | 28.0 - 99.0 | 28.0 - 99.0 |
| Hardness, Shore C | 75.0 - 95.0 | 75.0 - 95.0 |
| Tensile Strength, Ultimate | 1.47 - 59.0 MPa | 213 - 8560 psi |
| Tensile Strength, Yield | 29.6 - 52.0 MPa | 4290 - 7540 psi |
| Elongation at Break | 0.00163 - 3.24 GPa | 0.237 - 470 ksi |
| Flexural Yield Strength | 2.83 - 103 MPa | 410 - 15000 psi |
| Flexural Modulus | 1.65 - 3.31 GPa | 239 - 480 ksi |
| Izod Impact, Notched | 0.300 - 28.4 J/cm | 0.562 - 53.2 ft-lb/in |
Table of mechanical properties of PVC Rigid
The mechanical properties of PVC mainly include its tensile strength, which is 40 to 60 MPa for rigid PVC grades, and its hardness value, which is 75.0 – 95.0 Shore C.
Compressive strength: Up to 70 MPa, making it suitable for load-bearing plastic parts.
Impact resistance: Moderate, but can be enhanced with modifiers (as in PVC-M).
Creep resistance: Superior to many other plastics, ensuring long-term performance under stress.
Dimensional stability: Maintains shape under mechanical load and thermal cycling.
Abrasion resistance: High, making it ideal for outdoor applications and sports equipment.
Thermal Properties of PVC
The thermal properties of PVC mainly include a glass transition temperature of 85°C. PVC does not have a melting point; it transitions from a solid, rigid state to a softer, pliable state, which can be considered its “melting point” or glass transition temperature.
Flexible variants of PVC have a lower glass transition temperature. PVC shows thermal stability up to 140°C in processing, and its fire resistance can be improved using additives during manufacturing. It has a low thermal conductivity of around 0.14 to 0.28 W/(m·K), making it a good insulator.
Glass transition temperature: 85°C.
Heat deflection temperature: 70–80°C at 1.8 MPa.
Vicat softening point: 82–85°C.
Thermal conductivity: 0.16 W/m·K, suitable for insulation.
Coefficient of thermal expansion: 6.5×10⁻⁵ /°C.
Fire resistance: Naturally flame-retardant due to chlorine content. Has a UL 94 V-0 rating.
Maximum service temperature: around 60°C for standard rigid PVC, up to 95°C for PVC-C.
Thermal degradation: Begins above 140°C, releasing vinyl chloride and hydrogen chloride gases.
Electrical Properties of PVC Plastic
PVC plastic is an electrical insulator. It does not conduct electricity and exhibits excellent electrical insulation properties.
Although PVC is not a conductor, its insulation properties can be altered using additives. For example, the use of antistatic agents in manufacturing PVC can change its insulation effectiveness. For most electrical insulation properties, it is a reliable plastic in almost all environments.
Dielectric strength: Typically around 40–60 kV/mm.
Volume resistivity: Greater than 10¹⁴ ohm·cm, a typical high value for materials resistant to electrical current.
Surface resistivity: High
Arc resistance: Good, minimizing surface tracking under high voltage.
Insulation resistance: Maintains performance even in humid conditions.
Low dielectric constant: Around 3.0–3.4, suitable for signal transmission.
Low dissipation factor: Ensures minimal energy loss in AC applications.
Chemical Properties of PVC
Chemical properties of PVC show an excellent corrosion resistance to acids, alkalis, salts, and marine environments. PVC does not absorb chemicals and even shows resistance to oils and grease, but can be damaged by some hydrocarbons and ketones.
Resistant to acids, alkalis, salts, and many industrial solvents.
Excellent resistance to oxidizing agents and moisture.
Low water absorption: <0.06%
Corrosion resistance: Ideal for drinking water systems and chemical tanks.
Photochemical stability: Enhanced with UV stabilizers to reduce environmental degradation.
Additives improve long-term chemical durability.
Vinyl chloride monomer residues are tightly controlled to ensure human health safety.
Physical Properties
In physical properties, PVC shows a high density of 1.3 – 1.45 Kg/m³ and lower for flexible PVC grades. It is a lightweight plastic for its strength and density, waterproof with an absorption of below 0.5%, and good abrasion resistance.
The physical properties of PVC make it a transitional material between rigid and flexible structures.
Density: 1.38 g/cm³, contributing to its high density and strength.
Transparency: Naturally opaque, but can be modified for clarity.
Surface hardness: High, suitable for plastic parts and vinyl products.
Abrasion resistance: Excellent, ideal for outdoor applications and high-wear environments.
Moisture resistance: Critical for shower curtains, inflatable products, and medical tubing.
Dimensional stability: Maintains form under mechanical and thermal stress.
Processing aids: Improve flow and finish during injection molding and extrusion.
Types of PVC Plastics
PVC has many grades and forms. Since PVC plastic can be made through different processes like molding, extrusion, and machining, all types of PVC materials show a variation in properties.
Below are the chemically different grades of PVC that offer a better differentiation of PVC plastic types.
UPVC (Unplasticized)
Unplasticized PVC or rigid PVC does not have plasticizers and offers a high tensile strength and chemical resistance. This makes UPVC useful for pipes and window frames. It is commonly referred to as a durable, low-cost alternative to metal in the construction industry.
UPVC grades of PVC show excellent resistance to environmental degradation and are well-suited for structural elements requiring impact resistance and a long product life.
PVC (Plasticized)
Plasticized PVC has another name: flexible PVC. It uses phthalates or other plasticizers to achieve flexibility or pliability. Plasticized PVC is often used in blood bags and IV bags.
Flexible PVC is produced by adding plasticizers to the base resin.
PVC-M
PVC-M or modified PVC enhances impact resistance through copolymerization, and this type of PVC is suitable for pressure applications like pipes and fittings. PVC-M has better toughness compared to rigid PVC, and in the PVC industry, it is reserved for applications that require mechanical load.
PVC-C
PVC – C or chlorinated PVC improves thermal stability for high temperatures. PVC-C applications include hot water systems with enhanced fire resistance. It withstands high temperatures without deformation, offering excellent resistance to chemicals and corrosion. If you require parts that can sustain high thermal conditions, PVC-C is a great choice.
PVC-O
PVC-O stands for oriented PVC and features molecular alignment for superior strength and reduced weight. It is suitable for outdoor applications. PVC-O is manufactured through a process that produces aligned polymer chains in the plastic, resulting in superior tensile strength and fatigue resistance.
Vinyl vs. PVC: What’s the Difference in Plastics?
Vinyl refers to a broad class of ethylene polymers, and PVC is a subclass of those ethylene polymers, specifically Polyvinyl chloride. A special polymer product from vinyl chloride. Vinyl includes other materials like polyethylene vinyl acetate, whereas PVC is distinguished by its chlorine content.
In most cases, vinyl products refer to flexible applications like flooring that uses vinyl resin. PVC, in contrast, can be rigid and flexible. PVC’s vinyl chloride base monomer offers durability and fire resistance compared to other vinyl grades.
PVC vs. Polypropylene vs. Polycarbonate
| Property | PVC | Polypropylene | Polycarbonate |
| Tensile Strength | Moderate to High | Moderate | High |
| Chemical Resistance | Excellent | Excellent | Moderate |
| Temperature Resistance | Up to 95°C (PVC-C) | Up to 100°C | Up to 135°C |
| Impact Resistance | Moderate to High | Moderate | Very High |
| Cost Effectiveness | High | High | Moderate |
| Applications | Pipes, medical tubing | Packaging, textiles | Optical lenses, electronics |
Table comparing PVC, Polypropylene, and Polycarbonate
PVC, Polypropylene (PP), and PC differ in key physical properties, and this affects their applications. PVC has excellent chemical resistance and a low cost, but a limited transparency and a small heat resistance. PP offers better thermal resistance up to 100 °C compared to 80°C of PVC and has better fatigue resistance.
PC excels in impact resistance and optical clarity, making it an alternative to PVC in electronics and sports equipment, but it is more costly and has worse chemical resistance compared to PVC.
Processing of PVC Plastic
There are many ways of producing PVC plastic products, and the resin can be modified using additives to change mechanical and physical properties. Depending on how you produce your PVC or the type of PVC, you can produce parts using any of these methods.
Extrusion
Extrusion melts PVC resin with additives and forces the melted PVC through a die to form continuous profiles, such as PVC pipes and PVC sheets. Extruding PVC is suitable for high-volume, continuous, and uniform-shaped PVC production.
Extrusion of PVC requires a controlled temperature of 160 – 200 °C to prevent any degradation. It can be used in cable insulation and in construction.
CNC Machining
CNC machining is suitable for rigid PVC, where it can cut material using sharp cutting tools controlled by computer numerical control programs. It is ideal for quick prototypes and custom machining of PVC parts.
CNC machining is capable of handling flexible PVC, but some accuracy and precision are lost due to material deformation as chips are cut away from it.
Injection Molding
Injection molding is suitable for most plastics, including PVC, as it uses melted PVC and a strong pressure shot that injects molten PVC into the mold, where it takes the shape of the part. For flexible PVC, precise control of additives is required. Injection molding PVC is a cost-effective solution for smooth, finished parts of high volume.
3D Printing
3D printing extrudes PVC filament through a hot nozzle and prints layer by layer to create a 3D model or part. It is similar to extrusion, but there is no die, and the shape is made using a nozzle moving in 3 axes.
3D printing PVC is ideal for low-volume and complex designs that require some design validation.
Applications of PVC Plastic
PVC in Construction: Pipes, Sheets, and Window Frames
In construction, PVC pipes are used to transport water and wastewater because of their chemical and impact resistance. PVC sheets are also used as roofing and cladding, and window frames use rigid PVC as they are low maintenance and weatherproof.
Medical-Grade PVC: IV Bags, Tubing, and Devices
Medical-grade PVC, mainly flexible PVC, is used in IV bags, blood bags, and medical tubing because it is biocompatible and non-reactive to most chemicals. It provides excellent resistance to sterilization chemicals, which is important in health care. Flexible PVC can also be clear enough for fluid level checks in medical applications.
PVC in Upholstery and Textiles
Flexible PVC coats for fabric upholstery, shower curtains, and any inflatable products offer a degree of abrasion-proofing and waterproofing. Its vinyl nature ensures easy cleaning and UV resistance for outdoor products.
Packaging PVC Material
Packaging utilizes PVC in blister packs, plastic bottles, and some shrink wraps, which use chemical resistive properties of PVC.
Electronics Insulation Using PVC
PVC also makes a good electrical insulator and, as a result, is used as a cable insulator. Flexible PVC sheathing protects against abrasion and water in wiring harnesses.
PVC Signage
Signage uses foamed sheets for durable, lightweight displays that are resistant to weather and most impacts for outdoor advertising. Printing on PVC and its rigidity make it ideal for billboards and some signs.
Rigid PVC vs. Flexible PVC: Which One Works Best for CNC
For CNC machining parts, rigid PVC is a better option because it offers better dimensional stability and is easier to cut. It also reduces the chance of deformation. Flexible PVC requires special tooling and parameter setting with slower feed rates, which complicates the CNC process for PVC.
Using CNC to Cut and Shape PVC: Best Practices and Tooling Tips
CNC machining PVC requires optimized parameters depending on the main elongation or modulus of elasticity of the material (whether PVC is rigid or flexible). For clean cuts, use sharp carbide tools with adequate helix angles for chip removal.
You can start your PVC machining at 800 RPM and 0.005 inch per tooth feed rate. Most CNC machinists use air instead of coolant for PVC, but the choice depends on heat generation and buildup.
Carefully set up the PVC in the machining jig or fixture, as it can cut into or leave impression marks on the PVC blank. For shaping, use climb milling to reduce burrs on rigid PVC and use single-flute bits.
Injection Molding vs. CNC Machining: When to Choose Each for PVC Production
Injection molding is preferable for high-volume production of identical PVC parts, such as fittings, enclosures, consumer products, and casings, because injection molding offers rapid cycle times and uniform parts with smooth surface finish.
It has a high initial setup cost but has many advantages, like producing complex geometries with undercuts or making thin-walled structures. CNC machining suits low-volume or custom PVC parts, offering flexibility without tooling investments and superior precision (±0.001 inch tolerances).
Conclusion
PVC material comes from the synthesis of vinyl chloride monomer, and depending on the manufacturing process, it can be rigid and flexible, suiting different types of applications. There are many forms, grades, and types of PVC, each with different tensile strength, durability, and thermal properties.
While PVC alternatives like Polypropylene or polycarbonate offer some niche industrial advantages, PVC still remains a top choice for most parts because of its low cost and high chemical resistance.
FAQs
Q: Is PVC Toxic?
A: PVC itself is a non-toxic material, but its production involves vinyl chloride, a potential carcinogen. Finished PVC products are safe to use, and there are no leaching effects.
Q: Can PVC Conduct Electricity?
A: No, PVC cannot conduct electricity; it is an excellent insulator.
Q: Is PVC Rubber or Plastic?
A: PVC is a thermoplastic polymer and not a rubber.
Q: Is PVC Material Strong?
A: Yes, PVC material is strong, with tensile strength up to 60 MPa in rigid form. Although it is not as strong as most metals, it can support mild structures with no direct loads.
Q: Is PVC Material Waterproof?
A: PVC material is waterproof. It has a low water absorption rate, less than 0.5%.
Q: What is PVC Material Made Of?
A: PVC is made from polymerized vinyl chloride monomer, derived from ethylene and chlorine with additives and stabilizers.