OK
The Universal Selection Source:
Plastics & Elastomers

Dielectric Strength


Dielectric Strength of PlasticsDielectric Strength reflects the electric strength of insulating materials at various power frequencies. Or it can be defined as the measure of dielectric breakdown resistance of a material under an applied voltage and is expressed as Volts per unit thickness. It is an indicator of how good an insulator a material is.

In other words, it is the voltage per unit thickness at which a material will conduct electricity. The higher the value, the more electrically insulating a material is.

It is an important property sought for materials used in applications where electrical field is present and is a vital parameter for electrical industry applications.

Applications include:
  » Development of materials for energy storage applications
  » Dielectric materials for capacitors
  » Thin films in high speed digital circuitry



The dielectric strength depends on:

  » The type of the plastic and electrodes
  » The shape of the plastic and electrodes
  » The rate with which the field is increased, and
  » The medium that surrounds the insulator

Unit for Dielectric Strength is kV by mm of thickness (customary units sometimes refer to in V/mil).

Check out more on Dielectric Strength:

  »  Dielectric Strength Values of Several Plastics
  »  How to Calculate the Dielectric Strength of Plastic
  »  Factors Affecting Dielectric Strength

How to Measure Dielectric Strength?


The most generally used standard tests to calculate dielectric strength are ASTM D149 or IEC 60243-1 (ofcourse there exist several other methods as well, but they are not discussed here).

The measurement of dielectric strength is usually carried out either by the:

  »  Short-time method
  »  Slow rate-of-rise method
  »  Step-by-Step method

Short-time method


In this method, the voltage is applied across the two electrodes and increased continuously at a uniform rate (500 V/sec) until the breakdown occurs. Breakdown is defined as when an electrical burn- through punctures the sample or decomposition occurs in the sample.

Slow rate-of-rise method


In this test method, the voltage is applied to the test electrodes from the starting voltage 50% of the breakdown voltage until breakdown occurs.

Step-by-Step method


The voltage is applied to the test electrodes at the preferred starting voltage in steps and duration until breakdown occurs.

Specimen Size - The recommended specimen type is a 4 inch plaque or larger. Any specimen thickness can be used.

Dielectric strength is calculated by dividing the breakdown voltage by the thickness of the sample.
Most plastics have good dielectric strengths (in the order of 100 to 300 kV/cm).


Factors Affecting Dielectric Strength


  • The dielectric strength of an insulation material usually decreases with increase in temperature 
    It is approximately inversely proportional to the absolute temperature. At the same time, it is equally important to note that below room temperature, dielectric strength is substantially independent of temperature change.

  • Mechanical loading has a pronounced effect on dielectric strength
    Since, a mechanical stress may introduce internal flaws which serve as leakage paths, mechanical loaded insulators may show substantially reduced values of dielectric strength.

  • Dielectric Strength of an insulating material is influenced by the fabrication details
    For example, flow lines in a compression molding or weld lines in an injection molding may serve as paths of least resistance of leakage currents, this reducing the dielectric strength. Even nearly invisible minute flaws in a plastics insulator may reduce the dielectric strength to one-third this normal value.

Find commercial grades matching your dielectric strength target using "Property Search - Dielectric Strength" filter in Omnexus Plastics Database:


Omnexus Plastics Database - Property Search


Dielectric Strength Values of Several Plastics


Click to find polymer you are looking for:
A-C     |      E-M     |      PA-PC     |      PE-PL     |      PM-PP     |      PS-X

Polymer Name Min Value (kV/mm) Max Value (kV/mm)
ABS - Acrylonitrile Butadiene Styrene 15.70 34.00
ABS Flame Retardant 24.00 35.40
ABS High Heat 12.00 20.00
ABS High Impact 12.00 20.00
ABS/PC Blend - Acrylonitrile Butadiene Styrene/Polycarbonate Blend 15.00 70.00
ABS/PC Blend 20% Glass Fiber 29.90 30.00
Amorphous TPI Blend, Ultra-high heat, Chemical Resistant (Standard Flow) 54.00 54.00
Amorphous TPI, Moderate Heat, Transparent 17.00 17.00
Amorphous TPI, Moderate Heat, Transparent (Food Contact Approved) 17.00 17.00
Amorphous TPI, Moderate Heat, Transparent (Mold Release grade) 14.00 14.00
Amorphous TPI, Moderate Heat, Transparent (Powder form) 17.00 17.00
ASA - Acrylonitrile Styrene Acrylate 40.00 105.00
ASA/PC Blend - Acrylonitrile Styrene Acrylate/Polycarbonate Blend 80.00 95.00
ASA/PC Flame Retardant 90.00 90.00
CA - Cellulose Acetate 8.00 15.00
CAB - Cellulose Acetate Butyrate 10.00 16.00
CP - Cellulose Proprionate 12.00 18.00
CPVC - Chlorinated Polyvinyl Chloride 50.00 60.00
ECTFE - Ethylene ChloroTriFluoroEthylene 14.00 14.00
ETFE - Ethylene Tetrafluoroethylene 7.870 7.870
EVA - Ethylene Vinyl Acetate 27.00 28.00
FEP - Fluorinated Ethylene Propylene 22.00 79.00
HDPE - High Density Polyethylene 17.00 24.00
HIPS - High Impact Polystyrene 12.00 24.00
HIPS Flame Retardant V0 33.00 35.00
Ionomer (Ethylene-Methyl Acrylate Copolymer) 40.00 40.00
LCP - Liquid Crystal Polymer 32.00 39.00
LCP Glass Fiber-reinforced 22.00 30.00
LCP Mineral-filled 26.00 35.00
LDPE - Low Density Polyethylene 16.00 28.00
MABS - Transparent Acrylonitrile Butadiene Styrene 34.00 37.00
PA 11 - (Polyamide 11) 30% Glass fiber reinforced 40.00 40.00
PA 11, Conductive 24.00 55.00
PA 11, Flexible 24.00 55.00
PA 11, Rigid 24.00 55.00
PA 12 (Polyamide 12), Conductive 24.00 55.00
PA 12, Fiber-reinforced 24.00 55.00
PA 12, Flexible 24.00 55.00
PA 12, Glass Filled 24.00 55.00
PA 12, Rigid 24.00 55.00
PA 46 - Polyamide 46 15.00 25.00
PA 46, 30% Glass Fiber 25.00 35.00
PA 6 - Polyamide 6 10.00 20.00
PA 6-10 - Polyamide 6-10 16.00 26.00
PA 66 - Polyamide 6-6 20.00 30.00
PA 66, 30% Glass Fiber 25.00 25.00
PA 66, 30% Mineral filled 25.00 30.00
PA 66, Impact Modified, 15-30% Glass Fiber 11.80 21.00
PA 66, Impact Modified 18.00 90.00
PA 66, Carbon Fiber, Long, 30% Filler by Weight 1.300 1.300
PAI - Polyamide-Imide 23.60 24.00
PAI, 30% Glass Fiber 27.60 34.00
PAR - Polyarylate 17.00 17.00
PARA (Polyarylamide), 30-60% glass fiber 23.70 30.00
PBT - Polybutylene Terephthalate 15.00 30.00
PBT, 30% Glass Fiber 50.00 50.00
PC (Polycarbonate) 20-40% Glass Fiber 20.00 20.00
PC (Polycarbonate) 20-40% Glass Fiber Flame Retardant 17.00 38.00
PC - Polycarbonate, high heat 16.00 35.00
PCTFE - Polymonochlorotrifluoroethylene 21.00 24.00
PE - Polyethylene 30% Glass Fiber 19.70 19.70
PEEK - Polyetheretherketone 20.00 20.00
PEEK 30% Carbon Fiber-reinforced 18.50 19.00
PEEK 30% Glass Fiber-reinforced 15.00 24.00
PEI - Polyetherimide 28.00 33.00
PEI, 30% Glass Fiber-reinforced 25.00 30.00
PEI, Mineral Filled 20.00 25.00
PEKK (Polyetherketoneketone), Low Cristallinity Grade 23.60 23.60
PESU - Polyethersulfone 16.00 80.00
PESU 10-30% glass fiber 14.60 40.00
PET - Polyethylene Terephtalate 60.00 60.00
PET, 30% Glass Fiber-reinforced 16.80 22.50
PETG - Polyethylene Terephtalate Glycol 45.00 45.00
PFA - Perfluoroalkoxy 2.100 2.200
PGA - Polyglycolides 34.00 80.00
PI - Polyimide 22.00 27.60
PMMA - Polymethylmethacrylate/Acrylic 15.00 22.00
PMMA (Acrylic) High Heat 18.70 20.00
PMMA (Acrylic) Impact Modified 15.00 60.00
PMP - Polymethylpentene 28.00 30.00
PMP 30% Glass Fiber-reinforced 23.60 23.60
PMP Mineral Filled 23.60 23.60
POM - Polyoxymethylene (Acetal) 13.80 20.00
POM (Acetal) Impact Modified 19.00 19.00
POM (Acetal) Low Friction 16.00 16.00
PP - Polypropylene 10-20% Glass Fiber 30.00 45.00
PP, 10-40% Mineral Filled 30.00 70.00
PP, 10-40% Talc Filled 30.00 70.00
PP, 30-40% Glass Fiber-reinforced 30.00 45.00
PP (Polypropylene) Copolymer 20.00 28.00
PP (Polypropylene) Homopolymer 20.00 28.00
PP, Impact Modified 20.00 28.00
PPA - Polyphthalamide 20.80 20.90
PPA, 30% Mineral-filled 20.00 22.00
PPA, 33% Glass Fiber-reinforced 20.00 22.00
PPA, 33% Glass Fiber-reinforced – High Flow 18.00 20.00
PPA, 45% Glass Fiber-reinforced 22.00 24.00
PPE - Polyphenylene Ether 20.00 22.00
PPE, 30% Glass Fiber-reinforced 22.00 22.00
PPE, Flame Retardant 16.00 25.00
PPE, Impact Modified 1.000 1.100
PPS - Polyphenylene Sulfide 11.00 24.00
PPS, 20-30% Glass Fiber-reinforced 13.80 17.00
PPS, 40% Glass Fiber-reinforced 17.00 17.00
PPS, Glass fiber & Mineral-filled 13.00 13.00
PPSU - Polyphenylene Sulfone 14.20 20.00
PS (Polystyrene) 30% glass fiber 15.00 19.70
PS (Polystyrene) Crystal 16.00 28.00
PSU - Polysulfone 15.00 10.00
PSU, 30% Glass finer-reinforced 16.90 40.00
PTFE - Polytetrafluoroethylene 17.00 24.00
PTFE, 25% Glass Fiber-reinforced 20.00 20.00
PVC, Plasticized 10.00 30.00
PVC, Plasticized Filled 10.00 30.00
PVC Rigid 10.00 40.00
PVDF - Polyvinylidene Fluoride 10.00 27.00
SAN - Styrene Acrylonitrile 12.00 24.00
SAN, 20% Glass Fiber-reinforced 19.70 20.00
SMA - Styrene Maleic Anhydride 16.00 16.00
SMA, 20% Glass Fiber-reinforced 21.00 21.00
SMMA - Styrene Methyl Methacrylate 19.70 19.70
UHMWPE - Ultra High Molecular Weight Polyethylene 28.00 28.00

Find commercial grades matching your dielectric strength target using "Property Search - Dielectric Strength" filter in Omnexus Plastics Database:


Omnexus Plastics Database - Property Search

Disclaimer: all data and information obtained via the Polymer Selector including but not limited to material suitability, material properties, performances, characteristics and cost are given for information purpose only. Although the data and information contained in the Polymer Selector are believed to be accurate and correspond to the best of our knowledge, they are provided without implied warranty of any kind. Data and information contained in the Polymer Selector are intended for guidance in a polymer selection process and should not be considered as binding specifications. The determination of the suitability of this information for any particular use is solely the responsibility of the user. Before working with any material, users should contact material suppliers in order to receive specific, complete and detailed information about the material they are considering. Part of the data and information contained in the Polymer Selector are genericised based on commercial literature provided by polymer suppliers and other parts are coming from assessments of our experts.

Copyright SpecialChem SA
Back to Top