Dielectric Strength of Plastics | Electrical Properties of Plastics | The Definitive Guide

Hello people; I hope you’re all doing fantastic. Today, I will share a very engaging piece on plastics’ dielectric strength and dielectric properties. So without further ado, let’s get started.

Dielectric Strength of Plastics 

The dielectric strength of most plastics typically falls between 100 and 300 kV/cm, averaging at about 200 kV/cm. In contrast, specific chlorinated and additive-enriched polymers showcase dielectric strengths as high as 500 kV/cm. Teflon, renowned for its outstanding chemical and impact resistance, can achieve a remarkable 700 kV/cm.

Most plastics are poor conductors of electricity and resist a current flow, thus called dielectrics or insulators. That is one of the most valuable properties of plastic material and makes them applicable in making products utilized in our day-to-day lives, such as switches & switchboards, wire coatings, light fittings, and other electrical goods & Appliances.

As plastics are insulators when voltage is applied and steadily increased on them, It will eventually reach a point when the electrical properties break down—the breakdown increases an electrical arc across the electrodes, which causes a catastrophic reduction in resistance.

What is Dielectric Strength? 

The dielectric strength of plastics or any insulating material can be understood as the ratio of the charge deposited in an insulating material between two metallic plates to the charge stored when a vacuum or air replaces the insulating material. The phenomenon is called electrical permittivity. The dielectric strength of a material showcases its ability to store electrical energy.

The dielectric strength of plastic depends on its type and shape, the field increase rate, and the medium surrounding the insulator. Dielectric strength is derived by a unit kV by mm of thickness.

How to Calculate Dielectric Strength?

The most common standard tests to calculate the dielectric strength of plastic materials are ASTM D149 or IEC 60243-1. Below are the methods used for measuring dielectric strength:

  1. Short time method
  2. Slow rate of rise method
  3. Step by step method 

Short Time Method

Here, the voltage is applied across the two electrodes and bumped up constantly at a uniform rate (500 V/sec) until the breakdown occurs. The meaning of breakdown is when the voltage punctures the sample or creates decomposition.

Slow Rate of Rise Method

The voltage is applied to the test electrodes at only 50% of the breakdown voltage until breakdown or decomposition happens.

Step By Step Method

The voltage is applied to the electrodes at a predetermined starting voltage in various steps and spans until the breakdown.

Interesting Read – 7 Best UV Resistant Plastics For Outdoor Applications 

Applications

  • Dielectric material for capacitors used in radio and other electrical equipment.
  • Development of material for energy storage solutions.
  • Used by circuit designers to evaluate different printed-circuit-board (PCB) materials.
  • Thin films in the high-speed digital microprocessor.

Factors Affecting Dielectric Strength 

  • Hold on tight because things are about to get heated! The dielectric strength of plastics tends to drop as temperatures rise, roughly moving in an inverse relationship to absolute temperature. Yet, it’s fascinating that dielectric strength remains remarkably unaffected by temperature fluctuations.
  • But wait, there’s more! Mechanical stress can significantly impact dielectric strength, as it introduces internal flaws in insulators, creating leakage pathways and weakening their dielectric fortitude.
  • And here’s the twist: manufacturing quirks can significantly affect a plastic’s dielectric strength. Even the tiniest defects can pack a punch from weld lines in injection molding to flow lines in compression molding. These seemingly insignificant imperfections can slash an insulator’s dielectric strength by 30-40%!

Polar Vs Non-Polar Plastics 

A plastic material’s dielectric strength and electrical properties heavily depend on its structure. The structure of a polymer decides whether it is polar or non-polar, thereby determining its electrical properties.

Polar polymers (PMMA, PC, Nylon, PVC, etc.) are comprised of dipoles created due to the imbalance in the distribution of electrons. These dipoles align themselves in the presence of the electric field. Thus dipole polarization is designed for the polymer, making them average-performing insulators.

On the other hand, Non-polar polymers (PS, PTFE, PP, PE) have symmetrical molecules and are entirely covalent. There is no presence of polar dipoles in them, and thus the attendance of the electric field doesn’t align with the dipoles. However, the movement of electrons in the direction of the electric field will erupt in a slight electron polarization. These polymers have elevated resistivities and low dielectric constant.

Polar plastics have the propensity to absorb moisture from the atmosphere. Moisture has the ability to raise the dielectric constant and lower the resistivity. As the temperature rises, polymer chains move faster, and the dipoles are aligned more quickly.

Non-polar plastics do not affect the rising atmosphere and moisture.

Dielectric Strength Values of Polymers 

Polymer Name
Minimum Value (kV/mm)
Maximum Value (kV/mm)
ABS – Acrylonitrile Butadiene Styrene 15.7 34
ABS Flame Retardant 24 35.4
ABS High Heat 12 20
ABS High Impact 12 20
ABS/PC Blend – Acrylonitrile Butadiene Styrene/Polycarbonate Blend 15 70
ABS/PC Blend 20% Glass Fiber 29.9 30
Amorphous TPI Blend, Ultra-high heat, Chemical Resistant (Standard Flow) 54 54
Amorphous TPI, Moderate Heat, Transparent 17 17
Amorphous TPI, Moderate Heat, Transparent (Food Contact Approved) 17 17
Amorphous TPI, Moderate Heat, Transparent (Mold Release grade) 14 14
Amorphous TPI, Moderate Heat, Transparent (Powder form) 17 17
ASA – Acrylonitrile Styrene Acrylate 40 105
ASA/PC Blend – Acrylonitrile Styrene Acrylate/Polycarbonate Blend 80 95
ASA/PC Flame Retardant 90 90
CA – Cellulose Acetate 8 15
CAB – Cellulose Acetate Butyrate 10 16
CP – Cellulose Proprionate 12 18
CPVC – Chlorinated Polyvinyl Chloride 50 60
ECTFE – Ethylene ChloroTriFluoroEthylene 14 14
ETFE – Ethylene Tetrafluoroethylene 7.87 7.87
EVA – Ethylene Vinyl Acetate 27 28
FEP – Fluorinated Ethylene Propylene 22 79
HDPE – High Density Polyethylene 17 24
HIPS – High Impact Polystyrene 12 24
HIPS Flame Retardant V0 33 35
Ionomer (Ethylene-Methyl Acrylate Copolymer) 40 40
LCP – Liquid Crystal Polymer 32 39
LCP Glass Fiber-reinforced 22 30
LCP Mineral-filled 26 35
LDPE – Low Density Polyethylene 16 28
MABS – Transparent Acrylonitrile Butadiene Styrene 34 37
PA 11 – (Polyamide 11) 30% Glass fiber reinforced 40 40
PA 11, Conductive 24 55
PA 11, Flexible 24 55
PA 11, Rigid 24 55
PA 12 (Polyamide 12), Conductive 24 55
PA 12, Fiber-reinforced 24 55
PA 12, Flexible 24 55
PA 12, Glass Filled 24 55
PA 12, Rigid 24 55
PA 46 – Polyamide 46 15 25
PA 46, 30% Glass Fiber 25 35
PA 6 – Polyamide 6 10 20
PA 6-10 – Polyamide 6-10 16 26
PA 66 – Polyamide 6-6 20 30
PA 66, 30% Glass Fiber 25 25
PA 66, 30% Mineral filled 25 30
PA 66, Impact Modified, 15-30% Glass Fiber 11.8 21
PA 66, Impact Modified 18 90
PA 66, Carbon Fiber, Long, 30% Filler by Weight 1.3 1.3
PAI – Polyamide-Imide 23.6 24
PAI, 30% Glass Fiber 27.6 34
PAR – Polyarylate 17 17
PARA (Polyarylamide), 30-60% glass fiber 23.7 30
PBT – Polybutylene Terephthalate 15 30
PBT, 30% Glass Fiber 50 50
PC (Polycarbonate) 20-40% Glass Fiber 20 20
PC (Polycarbonate) 20-40% Glass Fiber Flame Retardant 17 38
PC – Polycarbonate, high heat 16 35
PCTFE – Polymonochlorotrifluoroethylene 21 24
PE – Polyethylene 30% Glass Fiber 19.7 19.7
PEEK – Polyetheretherketone 20 20
PEEK 30% Carbon Fiber-reinforced 18.5 19
PEEK 30% Glass Fiber-reinforced 15 24
PEI – Polyetherimide 28 33
PEI, 30% Glass Fiber-reinforced 25 30
PEI, Mineral Filled 20 25
PEKK (Polyetherketoneketone), Low Cristallinity Grade 23.6 23.6
PESU – Polyethersulfone 16 80
PESU 10-30% glass fiber 14.6 40
PET – Polyethylene Terephthalate 60 60
PET, 30% Glass Fiber-reinforced 16.8 22.5
PETG – Polyethylene Terephthalate Glycol 45 45
PFA – Perfluoroalkoxy 2.1 2.2
PGA – Polyglycolides 34 80
PI – Polyimide 22 27.6
PMMA – Polymethylmethacrylate/Acrylic 15 22
PMMA (Acrylic) High Heat 18.7 20
PMMA (Acrylic) Impact Modified 15 60
PMP – Polymethylpentene 28 30
PMP 30% Glass Fiber-reinforced 23.6 23.6
PMP Mineral Filled 23.6 23.6
POM – Polyoxymethylene (Acetal) 13.8 20
POM (Acetal) Impact Modified 19 19
POM (Acetal) Low Friction 16 16
PP – Polypropylene 10-20% Glass Fiber 30 45
PP, 10-40% Mineral Filled 30 70
PP, 10-40% Talc Filled 30 70
PP, 30-40% Glass Fiber-reinforced 30 45
PP (Polypropylene) Copolymer 20 28
PP (Polypropylene) Homopolymer 20 28
PP, Impact Modified 20 28
PPA – Polyphthalamide 20.8 20.9
PPA, 30% Mineral-filled 20 22
PPA, 33% Glass Fiber-reinforced 20 22
PPA, 33% Glass Fiber-reinforced – High Flow 18 20
PPA, 45% Glass Fiber-reinforced 22 24
PPE – Polyphenylene Ether 20 22
PPE, 30% Glass Fiber-reinforced 22 22
PPE, Flame Retardant 16 25
PPE, Impact Modified 1 1.1
PPS – Polyphenylene Sulfide 11 24
PPS, 20-30% Glass Fiber-reinforced 13.8 17
PPS, 40% Glass Fiber-reinforced 17 17
PPS, Glass fiber & Mineral-filled 13 13
PPSU – Polyphenylene Sulfone 14.2 20
PS (Polystyrene) 30% glass fiber 15 19.7
PS (Polystyrene) Crystal 16 28
PSU – Polysulfone 15 10
PSU, 30% Glass finer-reinforced 16.9 40
PTFE – Polytetrafluoroethylene 17 24
PTFE, 25% Glass Fiber-reinforced 20 20
PVC, Plasticized 10 30
PVC, Plasticized Filled 10 30
PVC Rigid 10 40
PVDF – Polyvinylidene Fluoride 10 27
SAN – Styrene Acrylonitrile 12 24
SAN, 20% Glass Fiber-reinforced 19.7 20
SMA – Styrene Maleic Anhydride 16 16
SMA, 20% Glass Fiber-reinforced 21 21
SMMA – Styrene Methyl Methacrylate 19.7 19.7
UHMWPE – Ultra High Molecular Weight Polyethylene 28 28

Engaging Read – What is the Glass Transition Temperature of Plastics?

Dielectric Constant Values of Mainstream Polymers 

Polymer Name Min Value Max Value
ABS – Acrylonitrile Butadiene Styrene
2.7 3.2
ABS Flame Retardant
2.8 3
ABS High Heat 2.4 5
ABS High Impact 2.4 5
ABS/PC Blend – Acrylonitrile Butadiene Styrene/Polycarbonate Blend
2.9 3.2
ABS/PC Blend 20% Glass Fiber
3.1 3.2
Amorphous TPI Blend, Ultra-high heat, Chemical Resistant (Standard Flow)
3.5 3.5
ASA – Acrylonitrile Styrene Acrylate
3.3 3.8
ASA/PC Blend – Acrylonitrile Styrene Acrylate/Polycarbonate Blend
3 3.4
ASA/PC Flame Retardant
3.2 3.2
CA – Cellulose Acetate
3 8
CAB – Cellulose Acetate Butyrate
3 7
CP – Cellulose Proprionate
3 4
CPVC – Chlorinated Polyvinyl Chloride
3 6
ECTFE 2.57 2.59
ETFE – Ethylene Tetrafluoroethylene
2.6 2.6
EVA – Ethylene Vinyl Acetate
2.5 3
EVOH – Ethylene Vinyl Alcohol
4.8 5.6
FEP – Fluorinated Ethylene Propylene
2.1 2.1
HDPE – High Density Polyethylene
2.3 2.3
HIPS – High Impact Polystyrene
2.4 4.8
HIPS Flame Retardant V0
2 3
LCP – Liquid Crystal Polymer
3.3 3.3
LCP Glass Fiber-reinforced
3 4
LCP Mineral-filled
3 5.9
LDPE – Low Density Polyethylene
2.3 2.3
LLDPE – Linear Low Density Polyethylene
2.3 2.3
MABS – Transparent Acrylonitrile Butadiene Styrene
2.8 3
PA 11 – (Polyamide 11) 30% Glass fiber reinforced
4.8 4.8
PA 11, Conductive
3 9
PA 11, Flexible 3 9
PA 11, Rigid 3 9
PA 12 (Polyamide 12), Conductive
3 9
PA 12, Fiber-reinforced
3 9
PA 12, Flexible 3 9
PA 12, Glass Filled
3 9
PA 12, Rigid 3 9
PA 46 – Polyamide 46
3.4 3.8
PA 46, 30% Glass Fiber
4 4.6
PA 6 – Polyamide 6
4 5
PA 6-10 – Polyamide 6-10
3 4
PA 66 – Polyamide 6-6
4 5
PA 66, 30% Glass Fiber
3.5 5.6
PA 66, 30% Mineral filled
4 5
PA 66, Impact Modified, 15-30% Glass Fiber
3.4 4.2
PA 66, Impact Modified
2.9 5
PAI – Polyamide-Imide
3.9 7.3
PAI, 30% Glass Fiber
4.2 6.5
PAR – Polyarylate
3.3 3.3
PARA (Polyarylamide), 30-60% glass fiber
3.9 4.5
PBT – Polybutylene Terephthalate
2.9 4
PBT, 30% Glass Fiber
3 4
PC (Polycarbonate) 20-40% Glass Fiber
3 3.5
PC (Polycarbonate) 20-40% Glass Fiber Flame Retardant
3 3.8
PC – Polycarbonate, high heat
2.8 3.8
PC/PBT Blend – Polycarbonate/Polybutylene Terephthalate Blend
2.95 3.14
PC/PBT blend, Glass Filled
3.3 3.9
PCTFE – Polymonochlorotrifluoroethylene
2 3
PE – Polyethylene 30% Glass Fiber
2.7 2.8
PEEK – Polyetheretherketone
3.2 3.2
PEEK 30% Carbon Fiber-reinforced
3.2 3.4
PEEK 30% Glass Fiber-reinforced
3.3 4.2
PEI – Polyetherimide
3.1 3.2
PEI, 30% Glass Fiber-reinforced
3 4
PEI, Mineral Filled
3 4
PEKK (Polyetherketoneketone), Low Cristallinity Grade
3.3 3.3
PESU – Polyethersulfone
3.5 4.1
PESU 10-30% glass fiber
4.2 4.3
PET – Polyethylene Terephtalate
3 4
PET, 30% Glass Fiber-reinforced
3 4
PETG – Polyethylene Terephtalate Glycol
3 4
PFA – Perfluoroalkoxy
2.1 2.1
PI – Polyimide 3.1 3.55
PMMA – Polymethylmethacrylate/Acrylic
2 5
PMMA (Acrylic) High Heat
3.2 4
PMMA (Acrylic) Impact Modified
2.9 3.7
PMP – Polymethylpentene
2.1 3.6
PMP 30% Glass Fiber-reinforced
2.4 2.4
PMP Mineral Filled
2.3 2.3
POM – Polyoxymethylene (Acetal)
3.3 4.7
POM (Acetal) Impact Modified
4 4.3
POM (Acetal) Low Friction
3 4
PP – Polypropylene 10-20% Glass Fiber
2.6 2.6
PP, 10-40% Mineral Filled
2.3 2.3
PP, 10-40% Talc Filled
2.3 2.3
PP, 30-40% Glass Fiber-reinforced
2.6 2.6
PP (Polypropylene) Copolymer
2.3 2.3
PP (Polypropylene) Homopolymer
2.3 2.3
PP, Impact Modified
2.3 2.3
PPA – Polyphthalamide
4.3 4.3
PPA, 30% Mineral-filled
4 4.2
PPA, 33% Glass Fiber-reinforced
4.4 4.6
PPA, 33% Glass Fiber-reinforced – High Flow
3.7 3.9
PPA, 45% Glass Fiber-reinforced
4.4 4.6
PPE – Polyphenylene Ether
2.7 2.7
PPE, 30% Glass Fiber-reinforced
2.9 2.9
PPE, Flame Retardant
2.7 2.7
PPS – Polyphenylene Sulfide
3 3.3
PPS, 20-30% Glass Fiber-reinforced
3.3 3.8
PPS, 40% Glass Fiber-reinforced
4 4
PPS, Glass fiber & Mineral-filled
5 5
PPSU – Polyphenylene Sulfone
3.4 3.5
PS (Polystyrene) 30% glass fiber
2.5 2.5
PS (Polystyrene) Crystal
2.4 2.7
PS, High Heat 2.4 2.7
PSU – Polysulfone
3 3.2
PSU, 30% Glass finer-reinforced
3.6 3.7
PTFE – Polytetrafluoroethylene
2.1 2.1
PTFE, 25% Glass Fiber-reinforced
3 3
PVC, Plasticized 3 5
PVC, Plasticized Filled
3 5
PVC Rigid 3 4
PVDC – Polyvinylidene Chloride
3 6
PVDF – Polyvinylidene Fluoride
6 9
SAN – Styrene Acrylonitrile
2.5 3.4
SAN, 20% Glass Fiber-reinforced
3.2 3.8
SMA – Styrene Maleic Anhydride
2.8 2.8
SMA, 20% Glass Fiber-reinforced
3.3 3.3
SMMA – Styrene Methyl Methacrylate
3.2 3.2
SRP – Self-reinforced Polyphenylene
3.1 3.1
UHMWPE – Ultra High Molecular Weight Polyethylene
2.3 2.3

Fascinating Read – What is the Density of Plastics? | The Complete Guide

FAQs 

 

Get ready to dive headfirst into the electrifying world of the dielectric strength of polymers! We’ve compiled a list of sizzling FAQs to quench your thirst for knowledge. Come on, let’s take a look!

What is the formula of dielectric strength?

M1L2T−2Q−1.

What is the dielectric strength of Bakelite?

300-550 Kv/inch

Why is plastic an electrical insulator?

In layman’s language, they don’t possess free electrons moving around, a phenomenon also called delocalized electrons. That makes them bad conductors of electricity and heat, which gives them the property of great insulators.

How can polymers be made electrically conductive?

The two main methods used to make insulators electrically conductive – Chemical synthesis and electro (co) polymerization. Chemical synthesis means connecting the carbon-carbon bond of monomers by placing the simple monomers under various conditions, such as heating, light exposure pressing, and catalyst.

Suggested Read 

Final Thoughts 

That is all I wanted to say about the electrical properties of plastics and the dielectric strength of plastics. Dielectric strength and dielectric const of any plastic material are essential properties that should not be neglected. The electrical properties of any plastic material make it applicable for making many types of products.

Have a wonderful day.

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