What Is Heat Shrink Tubing Made Of?

Heat shrink tubing is tubing that shrinks when you heat it.

It’s pre-stretched to a certain size before you buy it and, when you heat it, it shrinks back to its original size.

But what is this tubing made of?

It can be different types of plastic material. Plastic in this sense is not the everyday use (eg a plastic toy) but the scientific meaning of a type of polymer – a malleable material that can be moulded into solid objects.

So it’s a polymer, moulded into a tube then pre-stretched.

But what is this polymer? And is it just the polymer or are there other ingredients?

Different polymers, processes and additives are used to suit the heat shrink’s purpose. For example, the intended use might need flexibility, mechanical strength, electrical insulation or resistance to heat, fluids, chemicals, abrasion etc.

Polymers:

• Polyolefin – this is a widely used material and is often found in general purpose heat shrink. It has properties that include good insulation and is ideal in strain relief, colour coding (see colorants below) and identification applications
• Modified fluoroelastomers – ideal for high-temperature applications
• Fluid resistant elastomers – used to protect against fuels and other fluids
• Fluoropolymers – extreme resistance to fluids and highly flame retardant and/or resistant to high temperatures which also makes them ideal for electrical insulation
• KynarTM (polyvinyl fluoride) – for high temperature resistance to most fuels, solvents and chemicals
• VitonTM (polyvinylidene fluoride / fluoroelastomeric material) – also for high temperature, abrasion and fluid resistance
• Silicon rubber which provides resistance to high and low temperatures as well as good physical strength and flexibility

Additional Process

• Cross linking can be used to increase tensile and mechanical strength, abrasion and chemical resistance

Other ingredients:

• Colorants – these are added to provide single colours (eg blue or red heat shrink) or multiple colours (eg yellow and green stripes). Without colorants we’d have to rely on some other method to colour code the heat shrink.
• Adhesives – these are added to the interior of the tube to line it, are heat activated and will help seal the tubing and the substrate against moisture or some other harmful environmental factor. (The substrate is the item onto which the heat shrink tubing has been shrunk – wire or components or connectors etc).
• Stabilisers – for example – items that spend their life outdoors will suffer UV exposure which causes the item to perish or breakdown. A relevant stabiliser will help prevent this.

Hopefully we have answered your question “What is Heat Shrink Made of?” You can read answers to other questions like this in our Help Hub Articles.

If you need help in selecting heat shrink tubing to meet your needs, please contact us.