What is Kynar® Plastic? — PVDF Plastics for Flow Control Parts

Last updated on December 27th, 2018

Learn why Kynar® and PVDF plastic might be the best material choice

What is Kynar® Plastic?

Kynar® is Arkema's trade name for their PVDF plastic. PVDF or polyvinylidene difluoride plastic is a tough, stable, very non-reactive thermoplastic.

PVDF is a useful engineered plastic because it has important advantages over other plastics: strength, durability, abrasion resistance, low permeability, recyclable and more.
 

What is PVDF plastic?

Technically, PVDF is a semi-crystalline high-performance thermoplastic.



Semi-crystalline plastics

Semi-crystalline plastic materials have a very organized molecular structure and sharp melting points. This means that they do not gradually soften as their temperature increases. Instead, they stay solid until their melting point is reached. When they are hot enough, semi-crystalline plastics quickly change from solids into low viscosity or thin liquids that flow easily.

Drawing of amorphous versus semi crystalline thermoplastics.
Amorphous vs semi-crystalline
thermoplastics

Amorphous vs. Semi-Crystalline Thermoplastics at Redwood Plastics and Rubber.

Typically, semi-crystalline thermoplastics melt and flow at temperatures ranging from about 275º to 335º F (135º to 335º C). The specific melting point depends on the type of plastic.
 

Thermoplastics

Thermoplastics are useful for making products because they can be heated until they melt and flow. After cooling, thermoplastics become hard again.

This cycle of melting, reforming and cooling can be repeated again and again. Injection molding is a production process that takes advantage of this. It can be used to quickly and economically produce large numbers of consistently high-quality thermoplastic parts.


Thermoplastics - An Introduction at AZO Materials.

Fluoropolymers

PVDF is also a fluoropolymer. Fluoropolymers are polymers or plastics that have multiple carbon-to-fluorine bonded sections inside each molecule. Fluoropolymer plastics are very resistant to solvents, acids, and bases.

PVDF is also FDA compliant and completely non-toxic. This means it can be used in repeated contact with food.

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Modular Check Valves

We've taken spring-loaded check valves to a whole new level. Mix and match imperial and metric connections. Watch the video.

A play button for a video about ISM's modular check valves. Click here to go to a landing page where you can watch the video.

What chemicals are PVDF plastics resistant to?
  • Bases
  • Ozone
  • Alcohols
  • Mineral acids
  • Organic acids
  • Halogenated solvents
  • Aromatic hydrocarbons
  • Aliphatic hydrocarbons
  • Oxidizing environments

Check out the Chemicals and chemistry resources section at the end of this article. It includes more information about these chemical groups including links to in-depth descriptions by highly reputable reference resources.

Learn more about chemical compatibility and get a copy of the ISM PVDF (Kynar®) Chemical Compatibility Chart

These are the key useful characteristics of PVDF plastics:
  • Low weight
  • Recyclable
  • High Strength
  • Good toughness
  • Weather resistant
  • High heat resistance
  • Good electrical insulator
  • Good chemical resistance
  • Slippery or low coefficient of friction
  • Low permeability to most gases and liquids

 

What does is really mean to describe Kynar® or PVDF as a tough plastic?
  • Good endurance
  • Radiation resistant
  • Mechanically strong
  • High abrasion resistance
  • Good resistance to stress cracking
What is stress cracking?

Environmental stress cracking is when a thermoplastic fails after it has been exposed to certain chemicals. This failure is not the direct effect of being exposed to a particular chemical. Instead, stress cracking is caused by a combination of

  • A plastic’s susceptibility to stress cracking
  • Its exposure to a chemical that causes stress cracking
  • The mechanical stresses caused by pulling or tugging on the material

Chemicals that can cause stress cracking include detergents, surfactants, lubricants, oils, ultra-pure water and plating additives such as brighteners and wetting agents. Learn more about stress cracking.

Evaluating Environmental Stress Cracking of Medical Plastics from MDDI, Medical Device and Diagnostic Industry.

 
So, why use Kynar® and other PVDF plastics?

PVDF is a strong, tough, durable plastic. Its abrasion resistance is greater than other plastics and even some metals. It does not leach any chemicals and is highly resistant to a broad range of chemicals.

Using Kynar and PVDF plastic components is the right choice when it is important to prevent system failures due to weathering, stress cracking, abrasion and chemical corrosion.

For a much more in-depth technical description of PVDF plastic, check out Polyvinylidene Fluoride (PVDF): Complete Guide and PVDF Properties and Their Values from SpecialChem.

Get a copy of our PVDF (Kynar®) Chemical Compatibility Chart.

Get the Chart >> 

This reference chart provides guidelines for evaluating PVDF compatibility with a wide range of chemicals used in industrial, commercial and laboratory applications.
 

« Back to “What chemicals…”
 

Chemicals and chemistry resources

 

Alcohols

Alcohols are organic compounds with a hydroxyl group attached to one end of the molecule. Hydroxyl groups are one hydrogen atom bonded or attached to an oxygen atom.
Get more information at the Alcohol page from Encyclopædia Britannica

 

Bases

Bases are the opposite of acids. Like acids, bases also tend to be very corrosive depending on the specific chemical and how concentrated it is. Lye is a strong base that most people are familiar with.
Get more information at the Base page from Encyclopædia Britannica.

 

Mineral acids

Sulfuric acid, hydrochloric acid and nitric acid for example. Mineral acids are acids made from an inorganic compound. These acids easily dissolve in water and are highly acidic.
Get more information at the What is a Mineral Acid page from ThoughtCo.

 

Organic acids

Carboxylic acids and sulfonic acids are organic acids. These acids are organic compounds that have acidic properties: liquids, corrosive and so on. Organic acids tend to be weak acids and do not dissolve completely in water.
Get more information at the Organic Acid page from Wikipedia.

 

Halogenated solvents

Chloroform, carbon tetrachloride, and methylene chloride are examples of halogenated solvents. These solvents are compounds that contain halogen atoms (see below).
Get more information at the Halogenated Solvents page of the LibreTexts™ Chemistry library.

 

A rendered two-color 3D model of the benzene ring molecule.Aromatic hydrocarbons

Benzene is an aromatic hydrocarbon. These chemicals are organic compounds that contain one or more benzene rings. A benzene ring is a hexagonal ring of six carbon atoms.
Get more information at the Aromatic Hydrocarbon page from Wikipedia.

 

Aliphatic hydrocarbons

Methane, acetylene, and ethylene for example. Aliphatic hydrocarbons are organic compounds whose atoms do not link together to form a ring.
Get more information at the Aliphatic Hydrocarbon Definition page from ThoughtCo.

 

Oxidizing environments

Oxygen, hydrogen peroxide and the halogens are examples of oxidizers. In the Earth's atmosphere, iron is converted to iron oxide or rust because there is plenty of oxygen available.
Get more information at the Oxidizing Agent page from Wikipedia.

 

Halogens

Halogens are the group non-metallic elements that includes fluorine, chlorine, bromine and iodine. These elements are poisonous and are highly chemically reactive.
Get more information at the Halogen page from Wikipedia.

« Back to “What chemicals…”

 

Steven C. Williams headshot March, 2018.

About the author
Steven C. Williams my LinkedIn profile link button.
Steven C. Williams, BS, is the technical writer and an inbound marketing specialist at Industrial Specialties Manufacturing (ISM), an ISO 9001-2015 supplier of miniature pneumatic, vacuum and fluid circuitry components to OEM's and distributors all over the world. He writes on technical topics related to miniature pneumatic and fluidic components as well as topics of general interest at ISM.       


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