Monday, 8 August 2022

Plastic Part Design Data - Thermal Conductivity of Polymers as a Function of Temperature

 Hello and welcome to a new blog post. Today we discuss the thermal conductivity of amorphous and semi-crystalline polymers (unfilled; only the polymer resin) as a function of temperature.

The importance of multi-point data

Multipoint data of different polymer and polymer compound properties prevail information which would otherwise may be overlooked during material selection and product design. 

In other posts we discussed multi-point data such as the DMA results of engineering and high performance polymers. Multi-point data are important for material selection since it has a lot to do with thinking in relationships of time-dependency and temperature-dependency behaviors. Graphically such behaviors can be better accessed. Single point data can lead to misjudgment and negatively impact the material selection process.

Thermal conductivity of polymers was already several times topic on this blog: 

-Thermal conductivity of filled and unfilled high performance polymers

-Thermal conductivity of 96 plastics for EV application design support

-Guest Interview: Max Funck from PlastFormance – “Our patented technology for innovative plastic compounds allows for high filler contents - up to 80% vol.”

-Polymer Chemistry meets A.I. – Finding and Developing New Polymers with Target Properties in the 21st Century

However, in those posts thermal conductivity mostly was discussed as a value estimated at one single temperature. Now we look how the thermal conductivity changes in a temperature range of -150°C and up to 150°C. There is no linear behavior of the different polymers in this temperature range. 

Amorphous polymers: thermal conductivity as function of temperature

Amorphous polymers: thermal conductivity as function of temperature

Semi-crystalline polymers: thermal conductivity as function of temperature

Semi-crystalline polymers: thermal conductivity as function of temperature

Here you can find further design property data of various polymers for your part design and material selection. 

Thanks for reading and #findoutaboutplastics

Herwig 

Interested to talk with me about your polymer material selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.

New to my Find Out About Plastics Blog – check out the start here section

Literature: 

[1] VDI Wärmeatlas

[2] Griesinger: Wärmemanagement in der Elektronik

[3] Hanser Kunststofftaschenbuch


Wednesday, 3 August 2022

Polymer Material Selection: Defining the Part Requirements as Common Starting Point

Hello and welcome to a new post. Today we discuss the starting point in polymer material selection. 

In general there are several procedures for material selection such as the Ashby methodology or my own developed funnel approach

However, all the selection processes and procedures should have the definition of the part requirements as their common starting point. 

How to do it the best? 

Polymer Material Selection - Estimation of product requirements as common starting point

First we have to ask some questions on the functionality of the part. Following questions can help us with this assessment:

-What are the performance requirements (structural, etc.)?

-Do you want to combine multiple parts or functions?

-What will be the structural load of the part (static, dynamic, cycling, impact, etc.)?

-What will be the environmental impact on the part (chemical, temperature, time)?

-What is the expected lifetime of the product?

With the collected answers we can define the part requirements as accurately as possible. Together with the understanding of the differences of thermoplastics (amorphous and semi-crystalline) and thermosets we have an understanding of the performance, thermal and mechanical properties, as well as chemical resistance and processing differences of thermoplastics and thermosets. 

Selection factors - checklist for your material selection 

There are more detailed lists , however in this post we cover the six essential questions on material selection factors. 

1. What is the service environment of your part?

-what is the operating temperature: high, low, duration, thermal expansion

-exposure to chemicals, solvents, lubricants, salt

-exposure to water and humidity

-UV stability for use in outdoor / indoor environment

2. What are the regulatory requirements?

-flammability rating needed such as UL 94 at different wall thickness

-food contact

-fulfillment of medical standards

-any other regulation such as IP 44 for electrical devices

3. What types of load at which service temperature need to be fulfilled?

-continuous load represented by Young modulus and creep resistance

-intermittent load represented by tensile strength

-impact load represented by impact strength

-fatigue represented by cycles to failure for example over a Wöhler curve

4. Other considerations such as: 

-dimensions and tolerances which need to be met

-electrical properties such as CTI, electrical breakdown strength

-wear and friction 

-thermally conductive materials with or without electrical isolation

-aesthetics and colour (relevant for application with food contact, and toys)

-painting and printing 

-life time needs 

5. What is the processing and fabrication method?

-injection moulding, extrusion, thermoforming

-assembling by using screws, laser welding, or adhesives

-secondary operations

6. What are the economic and commercial considerations

-useful to make when material short-list is available

The combination of questions on part functionality and selection factors will help to facilitate your polymer material selection, together with fundamental data in a systematic way. 

Thank you for reading and #findoutaboutplastics

Greetings,

Herwig 

Interested to talk with me about your polymer material selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.

New to my Find Out About Plastics Blog – check out the start here section

Literature:

[1] GE Plastics - Product Guide

[2] https://www.grantadesign.com/education/students/charts/

[3] https://www.findoutaboutplastics.com/2020/11/plastic-part-failure-part-2-antidote.html