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Plastics & Elastomers

Comprehensive Guide on Polyvinyl Chloride (PVC)

Polyvinyl Chloride (PVC or Vinyl) is a high-strength thermoplastic material. It is widely used in applications such as pipes, medical devices, and wire & cable insulation...the list is endless. It is the world's third-most widely produced synthetic plastic polymer. So, what is PVC? What is it made up of? How to process it? Get detailed technical information on Polyvinyl Chloride and its features.

Overview

What is PVC (PolyVinyl Chloride)?

What is PVC (PolyVinyl Chloride)?

Polyvinyl Chloride (PVC or Vinyl) is an economical and versatile thermoplastic polymer. It is widely used in the building and construction industry to produce door and window profiles. It also finds use in:

  • drinking and wastewater pipes, 
  • wire and cable insulation, 
  • medical devices, etc.

It is the world’s third-largest thermoplastic by volume after polyethylene and polypropylene.

It is a white, brittle solid material available in powder form or granules. PVC is now replacing traditional building materials in several applications. These materials include wood, metal, concrete, rubber, ceramics, etc. in several applications. This is due to its versatile properties such as:

  • lightweight,
  • durable, 
  • low cost, and 
  • easy processability.

DID YOU KNOW?

PVC was first made 'unintentionally' in 1872 by German chemist Eugen Baumann. He exposed vinyl chloride gas sealed in a tube to sunlight and produced a white solid called PVC. In 1913, German chemist Friedrich Klatte received the first patent for polymerizing PVC using sunlight. By World War I, Germany was producing several flexible and rigid PVC products. They were used as a replacement for corrosion-resistant metals.

What are the basic forms of PVC?

What are the basic forms of PVC?

Polyvinyl Chloride is widely available in two broad categories: Flexible and Rigid. But there are more types like CPVC, PVC-O and PVC-M.

  • Plasticized or Flexible PVC (Density: 1.1-1.35 g/cm3): Flexible PVC is formed by the addition of compatible plasticizers to PVC which lower the crystallinity. These plasticizers act like lubricants resulting in a much clearer and flexible plastic. This type of PVC is sometimes called as PVC-P.

  • Unplasticized or Rigid PVC (Density: 1.3-1.45 g/cm3): Rigid PVC is a stiff and cost-effective plastic. It shows high resistance to impact, water, weather, chemicals and corrosive environments. This type of PVC is also known as UPVC, PVC-U or uPVC.

  • Chlorinated Polyvinyl Chloride or perchlorovinyl: It is prepared by chlorination of PVC resin. High chlorine content imparts high durability, chemical stability and flame retardancy. CPVC can withstand a wider range of temperatures.

  • Molecular Oriented PVC or PVC-O: It is formed by reorganizing the amorphous structure of PVC-U into a layered structured. Bi-axially oriented PVC has enhanced physical characteristics (stiffness, fatigue resistance, lightweight, etc.).

  • Modified PVC or PVC-M: It is an alloy of PVC formed by addition of modifying agents, resulting in enhanced toughness and impact properties.


What are the pros and cons of rigid & flexible PVC?

What are the pros and cons of rigid & flexible PVC?

Strengths Limitations
Rigid PVC
  • Low cost & high stiffness
  • Intrinsic flame retardant
  • FDA compliant & also suitable for transparent applications
  • Better chemical resistance than plasticized PVC
  • Good electrical insulation & vapor barrier properties
  • Good dimensional stability at room temperature
  • Difficult to melt process
  • Limited solvent stress cracking resistance
  • Becomes brittle at 5°C (when not modified with impact modifiers and/or processing aids)
  • Low continuous service temperature of 50°C
Flexible PVC
  • Low cost, flexible & high impact strength
  • Good resistance to UV, acids, alkalis, oils and many corrosive inorganic chemicals
  • Good electrical insulation properties
  • Non-flammable & versatile performance profile
  • Easier to process than rigid PVC
  • Properties can change with time, due to plasticizer migration
  • Attacked by ketones; some grades swollen or attacked by chlorinated and aromatic hydrocarbons, esters, some aromatic ethers and amines, and nitro- compounds
  • Tends to degrade at high temperatures
  • Non-suitable for food contact with some plasticizers
  • Lower chemical resistance than rigid PVC

What is Chlorinated PVC (CPVC)?

What is Chlorinated PVC (CPVC)?

CPVC is manufactured by chlorination of PVC polymer thereby raising the chlorine content from 56% to around 66%.

Chlorination of PVC reduces the forces of attraction between the molecular chains. CPVC is also essentially amorphous. Both of these factors allow CPVC to be stretched more easily and to a greater extent than PVC above its glass transition temperature, Tg. Pipes (436), moldings (376), and sheets are formulated for high-temperature use based on CPVC or blends of CPVC and PVC.


How is PVC Manufactured?

How is PVC Manufactured?

Vinyl chloride monomer (VCM) is produced from the chlorination of ethylene and pyrolysis of the resulting ethylene dichloride (EDC) in a cracking unit. PVC (glass transition temperature: 70-80°C) is produced by polymerization of vinyl chloride monomer (VCM).

PVC Manufacture

The popular methods used to manufacture PVC commercially are:

  • Suspension PVC (S-PVC)
  • Bulk or Emulsion (E-PVC)


Suspension PVC (S-PVC) Process


In the pressure-tight reactor, the monomer is introduced with a polymerization initiator and other additives. The content of the reaction vessel is mixed continuously to:

  • maintain suspension and
  • ensure uniform particle size of PVC resin.

Typical suspension polymerized PVC has a mean particle size of 100-150 µm with a range of 50-250 µm.

S-PVC grades are formulated to meet an extensive range of requirements such as:

  • high plasticizer absorption for flexible products, 
  • high bulk density and good powder flow are required for rigid extrusion

Suspension Polymerization accounts for 80% of PVC production worldwide


Bulk or Emulsion (E-PVC) Process


In this process, surfactants (soaps) are used to disperse the vinyl chloride monomer in water. The monomer is trapped inside soap micelles that are protected by the soap. The polymerization takes place using water-soluble initiators.

The primary particles are solid, smooth-surfaced spheres which are clustered into irregularly shaped aggregates. These aggregates have a mean particle size of 40-50 µm with a range of 0.1-100 µm.

E-PVC resins are used in a wide range of specialty applications such as coating, dipping, or spreading.


Difference between S-PVC and E-PVC


Suspension PVC (S-PVC) Process Bulk or Emulsion (E-PVC) Process
  • Lower flexible PVC formula costs 
  • PVC particles obtained are mixed with plasticizers & can be extruded in pellets which are further used for processing via extrusion, calendering, injection molding... 
  • Processing equipment is typically very expensive
  • Higher flexible PVC formula costs 
  • PVC powder obtained is mixed with plasticizers to produce a paste which is further used for coatings, dipping, spraying... 
  • Processing Equipment may or may not be very expensive

Key Properties

Key Properties

Property PLASTICIZED (FLEXIBLE) PVC UNPLASTICIZED (RIGID) PVC
Chemical Resistance
Acetone @ 100%, 20°C Non Satisfactory Non Satisfactory
Ammonium hydroxide @ 30%, 20°C Satisfactory Satisfactory
Ammonium hydroxide @ diluted, 60°C Limited Limited
Ammonium hydroxide @ diluted, 20°C Satisfactory Satisfactory
Aromatic hydrocarbons @ hot conditions Non Satisfactory Non Satisfactory
Aromatic hydrocarbons, 20°C Non Satisfactory Non Satisfactory
Benzene @ 100%, 20°C Non Satisfactory Non Satisfactory
Butylacetate @ 100%, 60°C Non Satisfactory Non Satisfactory
Butylacetate @ 100%, 20°C Non Satisfactory Non Satisfactory
Chlorinated solvents, 20°C Non Satisfactory Non Satisfactory
Chloroform @ 20°C Non Satisfactory Non Satisfactory
Dioctylphtalate @ 100%, 100°C Non Satisfactory Non Satisfactory
Dioctylphtalate @ 100%, 60°C Non Satisfactory Non Satisfactory
Dioctylphtalate @ 100%, 20°C Non Satisfactory Non Satisfactory
Ethanol @ 96%, 20°C Non Satisfactory Satisfactory
Ethyleneglycol (Ethane diol) @ 100%, 100°C Non Satisfactory Non Satisfactory
Ethyleneglycol (Ethane diol) @ 100%, 20°C Satisfactory Satisfactory
Ethyleneglycol (Ethane diol) @ 100%, 50°C Satisfactory Satisfactory
Glycerol @ 100%, 20°C Satisfactory Satisfactory
Hydrogen peroxide @ 30%, 60°C Satisfactory Satisfactory
Kerosene @ 20°C Satisfactory Satisfactory
Methanol @ 100%, 20°C Satisfactory Satisfactory
Methylethyl ketone @ 100%, 20°C Non Satisfactory Non Satisfactory
Mineral oil @ 20°C Satisfactory Satisfactory
Phenol @ 20°C Limited Limited
Soap @ 60°C Satisfactory Satisfactory
Soap @ 20°C Limited Limited
Sodium hydroxide @ <40%, 20°C Satisfactory Satisfactory
Sodium hydroxide @ <40%, 60°C Limited Limited
Sodium hydroxide @ 10%, 20°C Satisfactory Satisfactory
Sodium hydroxide @ 10%, 90°C Non Satisfactory Non Satisfactory
Sodium hypochlorite @ 20%, 20°C Satisfactory Satisfactory
Strong acids @ concentrated, 20°C Satisfactory Satisfactory
Toluene @ 20°C Non Satisfactory Non Satisfactory
Toluene @ 60°C Non Satisfactory Non Satisfactory
Xylene @ 20°C Non Satisfactory Non Satisfactory
Electrical
Arc Resistance, sec - 60 - 80
Dielectric Constant 3 - 5 3 - 4
Dielectric Strength, kV/mm 10 - 30 10 - 40
Dissipation Factor x 10-4 400 - 1600 60 - 200
Volume Resistivity x 1015, Ohm.cm 10 - 16 15 - 16
Mechanical
Elongation at Break, % 100 - 400 25 - 80
Flexural Modulus (Stiffness), GPa 0.001 - 1.8  2.1 - 3.5
Hardness Rockwell M 1 - 70
Hardness Shore D 15 - 70 65 - 90
Tensile Strength at Break, MPa 7 - 25 35 - 60
Tensile Strength at Yield, MPa 4 - 7 35 - 50
Toughness, J/m - 20 - 110
Young's Modulus, GPa 0.001 - 1.8 2.4 - 4
Optical
Haze, % 3 - 5 -
Transparency (Visible Light Transmission), % 75 - 85 80
Physical
Density, g/cm3 1.3 - 1.7  1.35 - 1.5
Glass Transition Temperature, °C -50 - -5 60 - 100
Shrinkage, % 0.2 - 4 0.1 - 0.6
Sterilization Resistance (Repeated) Poor -
UV Light Resistance Fair Fair
Water Absorption 24 hours, % 0.2 - 1 0.04 - 0.4
Service Temperature
Ductile / Brittle Transition Temperature, °C -40 - -5 -10 - 1
HDT @0.46 Mpa (67 psi), °C 30 - 56 57 - 80
HDT @1.8 Mpa (264 psi), °C 30 - 53 54 - 75
Max Continuous Service Temperature, °C 50 - 80 50 - 80
Min Continuous Service Temperature, °C -40 - -5 -10 - 1
Thermal
Coefficient of Linear Thermal Expansion x 10-5, /°C 5 - 20 5 - 18
Flammability, UL94 HB V0
Limiting Oxygen Index (LOI), % 20 - 40 40 - 45
Thermal Insulation, W/m.K 0.16 0.16
What are the key properties of PVC?

What are the key properties of PVC?

PVC is a very versatile and cost-effective material. Its main properties and benefits include:

  1. Electrical Properties: PVC is a good insulation material. Thanks to its good dielectric strength.

  2. Durability: PVC is resistant to weathering, chemical rotting, corrosion, shock, and abrasion. It is the preferred choice for many long-life and outdoor products.

  3. Flame Retardancy: Because of its high chlorine content, PVC products are self-extinguishing. Its oxidation index is ≥45. Antimony trioxide has been extensively used in combination with phosphate ester plasticizers. This gives excellent fire performance and mechanical properties.

  4. Cost/Performance Ratio: PVC has good physical as well as mechanical properties. It also provides excellent cost-performance advantages. It has a long life span and needs low maintenance.

  5. Mechanical Properties: PVC is abrasion-resistant, lightweight, and tough.

  6. Chemical Resistance: PVC is resistant to all inorganic chemicals. It has very good resistance against diluted acids, diluted alkalis, and aliphatic hydrocarbons. Some grades are attacked by:
    • ketones and esters,
    • chlorinated and aromatic hydrocarbons,
    • aromatic ethers and amines, and
    • nitro-compounds


How additives affect PVC properties?

How additives affect PVC properties?

PVC resin obtained from polymerization is extremely unstable. This is due to its low thermal stability and high melt viscosity. It needs to be modified before processing into finished products. Its properties can be enhanced or modified by adding several additives. Selecting additives dependent on end application requirements.

Plasticizers


Plasticizers are used as softening agents. Some examples include Phthalates, Adipates, and Trimellitates, to name a few. These additives enhance the rheological properties of vinyl products by raising the temperature. They are also added to increase mechanical performance such as toughness and strength. Factors that affect the selection of plasticizers of vinyl polymer are:

  • Polymer Compatibility
  • Low Volatility
  • Cost
Flexible PVC Pipe 

Flexible PVC Pipe


Heat Stabilizers


PVC has very low thermal stability. Stabilizers help prevent the degradation of polymer during processing or exposure to light. When subjected to heat, vinyl compounds initiate a self-accelerating dehydrochlorination reaction. These stabilizers neutralize the HCl produced enhancing the life of the polymer. Factors to consider while selecting heat stabilizers are:

  • Technical requirements
  • Regulatory Approval
  • Cost

Take the course - PVC Stabilizers - Decoding the Black Box to Meet Processing & Quality Needs


Fillers


Fillers are added to PVC compounds for a variety of reasons. Today, a filler can be a true performance additive by delivering value in new and interesting ways at the lowest possible formulation cost. They help to:

  • Increase stiffness and strength
  • Improve impact performance
  • Add color, opacity, and conductivity
  • And more

Some types of fillers include calcium carbonate, titanium dioxide, calcined clay, glass, talc, etc.


Lubricants


Several types of lubricants improve the properties of PVC. They include:

  • External lubricants assist in the smooth passage of PVC melt through processing equipment.
  • Internal lubricants reduce melt viscosity, prevent overheating, and ensure good color of the product.

Other additives like processing aids and impact modifiers are added to enhance mechanical as well as surface properties of PVC.

Rigid PVC: How to Maximize Performance to Cost Ratio


What happens when PVC blends with thermoplastics?

What happens when PVC blends with thermoplastics?

PVC/Polyester Blends – Polyester has superior physical properties. While PVC has excellent processing characteristics. This combination provides benefits like:
  • abrasion resistance,
  • tensile properties, and
  • tear resistance.

PVC/PU Blends – These blends offer increased abrasion and chemical resistance. Some biocompatible TPUs blend with PVC. This results in valuable products for the PVC industry.

PVC/NBR Blends – Flexible PVC modified with NBR are melt processable. They possess good elasticity/recovery characteristics

PVC/Polyolefin Rubber Alloys – They have potential utility in many applications. Especially where conventional flexible vinyl compounds do not meet certain end-use performance requirements.


What are the processing conditions of vinyl plastic?

What are the processing conditions of vinyl plastic?

Some of the main processes include extrusion, calendering, injection molding, and stretch blow molding, to name a few. The intimate mixing of the PVC resin with its associated additives is necessary. Later they can convert it into a thermoplastic melt.

Thermal stabilization is required for processing rigid PVC. Otherwise, the material may decompose during processing. Also, spray, blush & peel are very common molding defects associated with rigid PVC. Learn systematic methods to solve routine molding issues!

PVC is sensitive to temperature. They have a small window of processing temperatures. Drying before processing is highly recommended for plasticized PVC. The moisture rate should be lower than 0.3%.

Plasticized PVC Rigid PVC
Injection Molding
  • Melt temperature: 170 and 210°C 
  • Mold temperatures: 20 to 60°C
  • Mold shrinkage: 1 and 2.5% 
  • Material Injection Pressure: Up to 150 MPa
  • Packing Pressure: Up to 100 MPa
  • Melt temperature: 170 and 210°C
  • Mold temperatures: 20 to 60°C
  • Mold shrinkage: 0.2 and 0.5%
  • Recommended Screw with an L/D ratio of 15 to 18
Extrusion
  • Extrusion temperatures are 10-20°C below injection molding temperatures in order to avoid premature thermal degradation. 

3D Printing of PVC


PVC has largely been overlooked as being suitable for 3D printing. The new developments are paving way for PVC into the world of additive manufacturing. For example, Chemson Pacific Pty Ltd, a Vinyl Council of Australia member, demonstrated a world-first for 3DVinyl™ PVC material by 3D printing a giant flower vase using a pellet-fed 3D-printer.


Bonding Methods for PVC


PVC material can be bonded using different joining techniques. The bonding fabricates PVC into the finished article. All welding techniques involve the application or generation of heat. The heat softens the material while pressure is applied side by side. Bonding techniques, involving adhesives, are also common.

Plasticized PVC: How to Troubleshoot Adhesive Failures


Is PVC recyclable?

Is PVC recyclable?

PVC Resin Identification CodeProducts made from PVC are 100% recyclable. They can be identified as recycling code #3.

Adopting an appropriate recycling pathway for PVC is of economic value and has an environmental benefit. Key methods for PVC recycling include:

Mechanical Recycling


In mechanical recycling, the PVC waste is treated through shredding, sieving, and grinding. Depending on the composition, the quality of the recyclates can vary a lot. To discard impurities within these recyclates they are further:

  • mechanically separated,
  • ground,
  • washed, and 
  • treated

It is reprocessed using various granulated or powder techniques and reused in production. "High-quality" recyclates can be re-used in the same types of applications. "Low-quality" recyclates can only be used in products made from other materials.


Chemical Recycling


Chemical recycling breaks up polymer into monomers and other substances.

  • Monomers - Used to produce new polymers.
  • Other substances - Used as starting materials in processes of the basic chemical industry.

The Chlorine is set free in the form of HCl that can be re-used or neutralized to form various products. Stabilizers containing heavy metals mostly end up in solid residues that will most probably have to be landfilled.


Feedstock Recycling


It usually involves thermal treatment of the PVC waste stream with the recovery of hydrogen chloride. It can be then returned to the PVC production process or used in other processes.

Recycled PVC can be used to produce packaging, film and sheet, loose-leaf binders, pipes, carpet backing, electrical boxes, cables and more. The industry is working with the regulatory authorities to ensure that recycling activities remain sustainable while complying with the regulatory regime.


What are the PVC recycling initiatives across the globe?

What are the PVC recycling initiatives across the globe?

US


Vinyl (PVC) Institute (in the US) is one of the premier organizations representing the leading manufacturers of:

  • vinyl,
  • vinyl chloride monomer, and
  • vinyl additives and modifiers.

Recently, it launched a new initiative called +Vantage Vinyl. Its motto is to advance sustainability efforts throughout the vinyl industry. It engages companies across the entire vinyl value chain:

  • from raw material manufacturers and suppliers
  • to final product manufacturers.


Europe


Recycling now being a key to the circular economy. The European PVC industry is also contributing to the circular economy goals.

Recovinyl is an industry-wide recycling platform. It is an initiative by the European PVC value chain.

  • Aimed at facilitating PVC waste collection and recycling. 
  • It is gathering recyclers and converters from all over Europe.

The scheme is funded by VinylPlus, the voluntary commitment to sustainable development by the European PVC Industry (originally funded through the Vinyl 2010 initiative).

Related Read: Recycled Plastics & Circular Economy - Turning Challenges into Opportunities


Australia


The Vinyl Council of Australia represents the PVC/vinyl value chain in Australia. It closely follows Europe’s VinylPlus program. With its own PVC Stewardship Program, the Vinyl Council of Australia aims to enable raw material suppliers, products manufacturers and distributors to be joint stewards of the safe and beneficial production, use, and disposal of PVC products.

Canada


The Vinyl Institute of Canada and FEPAC, Quebec’s leading plastics association, offer Eco Responsible. It is a sustainability management certification program for:

  • Manufacturers in the vinyl industry, and
  • Any other organizations in the plastics industry across Canada.


Is polyvinyl chloride toxic?

Is polyvinyl chloride toxic?

For a number of years, PVC is under scrutiny due to the:

  • Presence of chlorine content
  • Use of additives such as plasticizers

Concerns about the negative impact of phthalates have been raised at regular intervals in several regions. These additives impact the environment and human health. However, on further investigations and studies, certain phthalates are now confirmed safe for use.

Similarly, Europe has phased out the use of lead-based stabilizers in vinyl compounds. They are classified as reprotoxic, harmful, and dangerous for the environment. Their presence (heavy metal) causes issues in waste management strategies.


What are the new innovations in bio-PVC?

What are the new innovations in bio-PVC?

Developing plastics from soy, wheat, or even sugarcane is not new. Now, like several other polymers, advancement in bio-based PVC formulations or even produce bio-based PVC resins is gaining momentum. Two industry players – Ineos and Vynova – have developed bio-PVCs based on renewable ethylene feedstock derived from non-food chain-based biomass. Read more!


What are the limitations of polyvinyl chloride?

What are the limitations of polyvinyl chloride?

  • Poor heat stability
  • Properties can change with time, due to plasticizer migration
  • Flexible PVC has lower chemical resistance than rigid PVC
  • Rigid PVC has low continuous service temperature of 50°C


Key Applications

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2 Comments on "Comprehensive Guide on Polyvinyl Chloride (PVC)"
Warren G Dec 19, 2022
Does anyone know where I can find mass polymerized PVC resin?
Nanda Kumar N Dec 23, 2021
Excellent review on rigid and plasticzed PVC.

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