Plastic Materials Questions & Answers

What's the difference between Nylon 6 and Nylon 66?

Nylon 6 and Nylon 66 are polyamides which are manufactured using different polymerisation methods and raw materials. The resulting polymers are very similar in many ways, but do differ, slightly, in some properties.

The main difference between the two materials is the melt temperature, with Nylon 66 melting at 260 deg C and Nylon 6 at 222 deg C. This means Nylon 66 needs to be processed at a higher temperature than Nylon 6 and as a consequence has a narrower processing window, but also means it has a slightly higher “in service” temperature.

Nylon 66 also absorbs a little less moisture than Nylon 6, which means, in its conditioned state. This means Nylon 66 is a little stiffer, but also a little less impact resistant

What is the best scratch-resistant plastic material?

Some plastic materials have harder surfaces than others and are therefore more scratch resistant. Acrylic (PMMA) is considered to be the highest scratch resistant material.

How do I choose the correct plastic material for an application?

Different plastic materials have varying properties which need to be considered when selecting the best plastic material for an application. When deciding on which material should be used the things which need to be considered are:

Transparent or Opaque?

The temperature at which the final component will be used – this should take into account the lowest temperature as well as the highest.  The in-use temperature requirement may well reduce the potential materials.

After temperature the environment the plastic part is to be used needs to be considered. Which substances will it come in contact with (chemical resistance required), will it be used indoors or out, and for how long (UV and weathering requirements)?

Following environmental considerations, the mechanical properties of the part need to be looked at. How strong, how stiff and impact resistance.

Finally does the material need to meet any recognised standards, eg food/water contact or need any special properties eg flame retardance.

Once a profile of what is required from the finished product is determined a shortlist of possible materials which can achieve all of the requirements will emerge. From this a selection can be made.

Which materials are flexible?

Different plastic materials have different stiffnesses, with some being more flexible than others.

The most flexible ones are commonly known as Thermoplastic Elastomers (TPE) or Thermoplastic Rubbers (TPR). The 2 terms are interchangeable as they refer to the same group of materials.

Within the TPE range there are a range of flexibilities and surface hardness. Materials are also based on many different polymers which give different properties such as chemical resistance, wear resistance etc.


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