Wednesday, 25 August 2021

Polymer Material Selection: Pre-Selection of Thermoplastics

Hello and welcome to this post. Today I will discuss with you a practical approach on how to pre-select thermoplastics for your application.

In a past post I touched on some rules of thumb for making an educated guess on plastics material selection and in this post we will add another approach into our plastic selection toolbox.

Thermoplastics can be divided into amorphous and semi-crystalline morphology. Amorphous polymers are transparent or translucent, whereas semi-crystalline polymers are opaque. If you need a transparent part, then selecting an amorphous polymer is the path forward. Flexible polymers with a Young’s Modulus of < 1500 MPa are always semi-crystalline. Amorphous polymers can only be used below their glass transition temperature (Tg) and therefore have always a stiff behavior up to their Tg. If you need flexible and transparent polymers, amorphous Polyamide can be an option when working with additives (clarifiers) helping to make a semi-crystalline transparent. 

Maximum use temperature and Young’s modulus

In the table below are amorphous and semi-crystalline resins shown, together with the Young’s modulus and maximum use temperature as selection criteria. All the values are for orientation and further investigation for proper material selection needs to be done (for example, mechanical properties over different temperatures). Detailed data can be found in the Technical Data Sheets (TDS) of material suppliers or in material databases. Also on my blog, I have several engineering data in particular for high performance polymers listed.


Polymer material selection: pre-selection of thermoplastics by using maximum use temperature and Young's modulus


Thanks for reading and #findoutaboutplastics,

Herwig

#polymerMaterialSelection #herwigjuster

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Literature:

[1] M. Bonnet: Kunststofftechnik: Grundlagen, Verarbeitung, Werkstoffauswahl und Fallbeispiele


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