PlasticRanger

  • Injection molding
    • Injection Molding Defects
    • Injection Molding Materials
    • top 10 injection molding machine manufacturers in china
  • Plastic Material
    • Types of Plastics
    • Polypropylene Material
    • HDPE Material
    • Acrylic Plastic
    • PLA Plastic
    • PET Plastic
  • General Properties
    • Modulus of Elasticity Units
    • Tg of Plastics
    • Processing Temp. of Plastics
    • Plastic Density
    • Hardness In Plastics
    • Polystyrene Properties
  • Pipes
    • PVDF Pipe Sizes
    • PVC Pipe Sizes & Dimensions
    • PEX Pipe Sizes
    • HDPE Pipe Sizes
    • PVC Pipes: Schedule 40 VS 80
    • CPVC VS PVC
    • Schedule 80 PVC Pipe Dimensions
    • PVC Fittings | PVC Connection
  • Plastic Hacks
    • Best Plastic Glue
    • How to Remove Scratches from Plastic
    • Repair PVC Pipe Without Cutting
    • How to Cut Plexiglass
    • How to Cut PVC Pipe
    • How To Get Sticky Residue Off Plastic
    • How to Clean Plexiglass

Thermal Properties of Plastics | The Ultimate Guide

April 25, 2021 by Sagar Habib Leave a Comment

thermal properties of plastics

Quick Navigation

  • What are the Thermal Properties of Plastics?
  • Thermal Properties in Plastics Materials- 
  • 1. Glass Transition Temprature:
  • Crystalline Polymers:
  • Amorphous Polymers:
  • Semi-crystalline Polymers:
  • 2. Continues Service Temprature:
  • Amorphous Polymers:
  • Semi-crystalline Polymers:
  • 3. Heat Deflaction Temprature:
  • 4. Coefficient of Linear Thermal Expansion:
  • Final Words – 

What are the Thermal Properties of Plastics?

Thermal properties in plastics mean their response to changes in their temperatures and how they react when applied with heat. As a solid material absorbs heat, its temperature rises with a slight increase in dimensions.

There are generally 4 thermal properties in plastic materials – heat deflection temperature, glass transition temperature, Continuous Service Temperature, and Coefficient of Thermal Expansion.

Here is a table explaining the thermal properties of all mainstream plastic materials.

Materials Max Continus Servoce temprature in air Heat Deflection Temperature
Coefficient of Linear Thermal Expansion
°F, 264/psi
ASTM Test °F D648
in/in/°F x 10-5, D696
ABS (Acrylonitrile-Butadiene-Styrene) 160 177 5.6
Acetal 212 257 6.8
Acrylic 160 195 4
CAB – 181 –
ECTFE (Ethylene Chlorotrifluoroethylene) 302 160 5
ETFE (Ethylene Tetrafluoroethylene) 311 – 7.4
HDPE 170 – 9
High Impact Polystyrene – 169 4.5
LDPE – – –
Nylon 210 194 4.5
PAI (Polyamide-imide) 500` 532 1.7
PBT 245 130 –
PEEK 480 306 2.6
PET 230 175 3.9
PETG – 157 3.8
Polycarbonate 240 270 3.8
Polypropylene 180 – 5
PTFE 500 – 8.9
PVC 140 158 3.2
PVDF 302 235 7.1
TPE – – –
UHMW 180 – 11.1
Ultem® 338 392 3.1

Thermal Properties in Plastics Materials- 

thermal properties

  • Glass Transition Temprature 
  • Continues Service Temprature 
  • Heat Deflection Temperature
  • Coefficient of Linear Thermal Expansion 

1. Glass Transition Temprature:

When an amorphous material is heated, the temperature at which the material transforms into a viscous liquid is called the glass transition temperature.

Crystalline Polymers:

Crystalline materials don’t have a specific glass transition temperature. Instead, they have a melting point. Their melting point is a temperature where is ordered molecular structure becomes disordered liquid. Crystalline materials have a highly ordered and defined molecular structure.

It includes materials like PEEK, PPS, PFA, etc. These polymers have regular chain structures and are more likely to form crystalline regions. More crystallinity means more strength and less flexibility for the materials. High crystallinity also means that less light will pass through these materials.

Crystallinity will provide benefits like chemical resistance, strength, stability, and stiffness.

Amorphous Polymers:

Amorphous polymers are also known for not having a melting point but a glass transition temperature. These polymers soften upon heating over a wide range of temperatures. Their molecular structure comprises unsynchronized molecular chains not arranged in ordered crystals.; however, they have scattered around even though they are not solid-state.

Semi-crystalline Polymers:

There are polymers with a partially crystalline structure, with the crystalline regions spread within the amorphous material. The crystalline molecules have a melting point, and the amorphous molecules have a glass transition temperature.

Interesting Read – How is Plastic Made? A Simple and Detailed Explanation.

2. Continues Service Temprature:

The temperature at which a material can perform assuredly in a long-term application is called continuous service temperature. Over the temperature limit, the mechanical and electrical properties of the material will start degrading over a period of time.

The crucial factors affecting the continuous service temperature of many materials are – time and loading levels and additive and reinforcements used in the formations.

The most common method used for comparing different materials in terms of continuous service temperatures is called the Underwriter Laboratory (UL) Relative Thermal Index or RTI.

The process of RTI is utilized to figure out the loss of properties of plastic versus time. Generally speaking, when plastic exhibits maximum continuous temperature – strong, long-term performance is observed.

In a nutshell, continuous service temperature backs up the materials’ integrity for its intended application period.

Let’s see the use of continuous service temperature is commonly used polymers:

Amorphous Polymers:
Material Max. Value (°C) Min. Value (°C)
Glass transition temp. (°C)
PC 140 100 147
PEI 170 170 217
PMMA 90 70 105
PESU 185 175 230
PSU 180 150 190

The above table shows the maximum and minimum values of continuous temperatures along with their glass transition temperature.

For all the above-mentioned amorphous polymers, the glass transition temperature is directly proportional to the continuous use temperature. There can be seen a significant change in the mechanical and electrical properties of the polymer at Tg.

Semi-crystalline Polymers:
Material Max. Value (°C) Min. Value (°C)
Glass transition temp. (°C)
PEEK 260 154 143
PET 140 80 69
PPS 220 200 126
PBT 140 80 40
PA6 120 80 50

The above table shows that the continuous service temperatures for all the polymers are more than the Tg value.

3. Heat Deflaction Temprature:

Heat deflection temperature or heat distortion temperature is a way to measure the polymer’s resistance or withstanding capacity towards distortion in a given temperature.

In simple words, it can be any particular temperature at which the test bar will be warped of 0.35 mm under a given load (0.35 is a random value and doesn’t have any significance).

The factors making HDT significant are:

  1. Used in many characteristics products design and manufacturing of parts using thermoplastic components.
  2. Provides a value to be compared withing different materials
  3. The greater the heat deflection higher the chances of a faster molding process in the injection molding method.

Engaging Read – Mechanical Properties of Plastic Materials | The Definitive Guide

4. Coefficient of Linear Thermal Expansion:

The coefficient of linear thermal expansion is a polymer attribute that comprises the ability of a plastic to expand under temperature elevation. It shows us the dimensional stability of a developed part under temperature variation.

The linear coefficiency is measured using the following formula:

α = ΔL / (L0 * ΔT)

Thermal expansion and differences can be detrimental and develop internal stresses and unusual warping in the material, which can hurt the integrity of the final part, thus making CLTE crucial for the unit economies of the production as well as the functioning and aesthetics of the product. Below are some applications:

  1. It assists in determining the dimensional characteristics of parts subject to temperature changes.
  2. It helps in maintaining the aesthetic of a product by predicting shrinkage in injection molded components.
  3. It also comes in handy for predicting the thermal stresses that can occur while bonding plastic material with metals.

Below is the table with CLTE value for all mainstream plastics

Material Max. Value (10-5 /°C)
Min. value (10-5 /°C)
ABS 15 7
CA 18 8
CAB 17 10
ECTFE 9 6
EVA 20 16
HDPE 11 6
HIPS 20 5
LDPE 20 10
PA 6 12 5
PBT 10 6
PC 4 2
PE 5 5
PEEK 10.8 4.7
PEI 6 5
PET 8 6
PETG 8 8
PMMA 9 5
PP 17 7
PS – Crystal 8 5
PTFE 20 7
PVC 4 2
UHMWPE 20 13
XLPE 10 10

All the values shown in all the tables in the post are derived after extensive research, but they are for information purposes only. Do consult your manufacturer for accurate values.

Suggested Read – 

  • What is Compressive Strength of Plastics | The Complete Guide
  • Physical Properties of Plastic Materials | The Complete Guide
  • What is Hardness in Plastics? An In-Depth Guide
  • What is Shore Hardness Scale? | The Complete Guide
  • What is Processing and Drying Temperatures of Plastics
  • Mold Temperature in Plastics | A Complete Analysis
  • Top 10 Injection Molding Defects (And How To Prevent Them)
  • What is Injection Molding Wastage? | Remedies to Reduce Plastic Waste
Final Words – 

That was my take on the thermal properties of plastics. Ensuring accurate thermal properties for your plastic materials can do wonders as far a the production economics is concerned.

I hope you like my article. Kindly comment your reviews in the comment box

Have a wonderful day.

Filed Under: General Properties

About Sagar Habib

Sagar Habib, a certified Plastics Engineer, and a plastics aficionado having detailed knowledge about plastic engineering, processing, and manufacturing.

Through PlasticRanger I want to share my insights with maximum people. You can read more about him on his About Page.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Popular Posts

Recent Posts

  • Top 10 Injection Molding Machine Manufacturers in China
  • CPVC VS PVC | Difference Between PVC and CPVC
  • How to Clean Plexiglass | How to Clean Acrylic | A Complete Guide
  • How To Get Sticky Residue Off Plastic? The Complete Guide
  • How to Glue PVC Pipe | The Definitive Guide

The smarty pants behind PlasticRanger

Sagar Habib, a certified plastics engineer, and aficionado. Learns and shares consistently about plastics technologies.

He covers everything within Plastics manufacturing and processing.

Advertise

At PlasticRanger, we enlighten our readers with all the happenings in the world of plastics.

Get Traffic & Exposure. We help brands optimize their online presence & performance.

GET IN TOUCH

What People are Talking About

What is Shore Hardness Scale
What is TPU Material
What is Polypropylene Material
What is Bakelite
How to Cut Plexiglass

About Me | Meet Our Team | Privacy Policy | Contact Us | Sitemap
© Copyright 2020-2022 PlasticRanger | The Content May Not Be Reproduced On Other Websites