Wednesday, 23 April 2025

The Path to Polymer Selection Mastery: A Jedi's Journey

Hello and welcome to this new post, today in the theme of Star Wars, together with polymer material selection

FindOutAboutPlastics.com presents: The Path to Polymer Selection Mastery - A Jedi's Journey.

The path to becoming a master of polymer material selection is a challenging one, requiring dedication, perseverance, and a deep understanding of the Force, or in this case, the properties of plastics. Just as a Padawan must undergo rigorous training and face numerous trials to become a Jedi Knight, so too must an aspiring polymer engineer navigate a series of challenges to master the art of material selection.

This journey begins with a thorough understanding of the fundamental principles of polymer science, including the various types of polymers, their structures, and their unique properties. It is akin to a Padawan learning the basics of lightsaber combat and the Force. From there, the aspiring engineer must delve into the intricate details of polymer behavior, exploring how different polymers react under various conditions, such as heat, stress, and chemical exposure. This is similar to a Padawan mastering the subtle nuances of the Force, understanding its power and limitations.

The next step involves applying this knowledge to real-world applications, selecting the most suitable polymer for a specific purpose. This is where the true test of skill lies, as the engineer must weigh various factors, such as cost, performance, and environmental impact, to make the optimal choice. This is analogous to a Jedi Knight facing a dangerous mission, where they must use their knowledge and skills to overcome obstacles and achieve their goal.

Finally, the journey culminates in mastery, where the engineer can seamlessly integrate their knowledge of polymer science with their understanding of engineering principles to create innovative and sustainable solutions. This is akin to a Jedi Master, who has achieved enlightenment and can use the Force for the greater good.

In essence, becoming a master of polymer material selection is a continuous learning process, requiring a combination of theoretical knowledge, practical experience, and a deep understanding of the challenges and opportunities that lie ahead. It is a journey that demands dedication, perseverance, and a willingness to embrace the unknown, just as it does for a Padawan seeking to become a Jedi Master.

The path to polymer mastery may be arduous, but the rewards are great. Those who persevere will gain the ability to shape the future, creating products that are not only functional but also sustainable and beneficial to society. So, embrace the challenge, hone your skills, and embark on your journey to polymer mastery.

Ready to begin your journey to Polymer Mastery? Take the Polymer Material Selection scorecard today and discover your POMS score!

Polymer Material Selection scorecard

Also, you can get familiar with the 6 essential polymer material selection skills here

Thanks for reading and #findoutaboutplastics

Greetings

Herwig Juster

🔥 There is a problem keeping you awake - My personal website for Polymer Consulting

📊 Discover your Polymer Material Selection score by taking quick test here

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Literature: 


Saturday, 19 April 2025

More Than Just Profiles: Unlocking the Diverse Potential of Technoform's Flexible Pultrusion #insightsfromindustry

Hello and welcome to a new post in which we explore the new flexible pultrusion technology introduced by Technoform. I met with Dirk Moses, Head Of Market Development, at the KPA fair Ulm, Germany, discussing their new pultrusion technology. Watch the whole video here and check out our previous interview series here

Dirk Moses from Technoform (right in picture), together with Herwig Juster, discussing the new thermoplastic pultrusion technology at KPA Ulm, Germany.

Thermoplastic pultrusion: combining extreme strength with maximum cost-efficiency

Dirk explained to me their company's new thermoplastic pultrusion technology which was developed by Sindy Richter, Head of the Development Department at Technoform, and her team.

It is flexible in terms of material selection, allowing for the use of standard plastics such as polypropylene - PP, engineering plastics such as polyamides (PA6, PA66), and high-performance polymers. This positively impacts the properties of the pultruded profiles as well as their ability to connect to other plastic components. Furthermore, the fiber content can be varied depending on the specific application. The resulting products are characterized by a lower weight combined with high impact resistance and bending strength.

Thermoplastic pultrusion is an advancement of the classic pultrusion process, in which thermoplastics serve as the matrix material instead of thermosetting resins. In both processes, continuous fibers are impregnated with plastic to ensure optimal force transmission through the connection of adjacent fiber elements. A key challenge in thermoplastic pultrusion is the high viscosity of thermoplastics compared to the lower-viscosity thermosets, which makes fiber impregnation more difficult. To address this challenge, Technoform has developed a special process for thermoplastic melt pultrusion.

Potential applications 

Furthermore, Dirk highlighted significant potential in sectors prioritizing lightweight construction and recyclability, particularly the automotive industry for components like battery casings and structural reinforcements. Other promising applications include façade elements using recyclable thermoplastics and opportunities within the sports and furniture sectors where lightweight and flexible materials are advantageous.

Figure 1: Herwig and Dirk discussing profiles, façade elements, and automotive battery casings.

What about recycling of pultruded profiles? 

Dirk emphasizes the technology's benefits over thermosets or aluminum, citing recyclability, material adaptability, and the ability to reshape or weld thermoplastic products. Their approach enables customized material combinations to meet specific requirements more effectively than aluminum. Regarding recycling, he explains that their pultruded profiles can be shredded and reused as high-quality components, with the retention of long fibers enhancing the mechanical properties of the recycled material. 

Metal replacement

In terms of economic viability, Dirk asserts that their technology presents an attractive alternative, especially when replacing steel or aluminum parts with intelligent system solutions that incorporate integrated functions, lightweight design, and recyclability, leading to both sustainable and economic advantages.

Thanks to Dirk and the team for the exchange on the new thermoplastic pultrusion technology! 

Literature: 

[1] https://plasticker.de/news/shownews.php?nr=46346&nlid=64581.d.h.2025-04-14

[2] https://www.technoform.com/en/reference/new-pultrusion-process-thermoplastic-profiles

[3] https://www.findoutaboutplastics.com/2024/06/plastics-sustainability-contradiction.html


Thursday, 10 April 2025

Mastering the Melt: Your Guide to Shear Rate Limits in Injection Moulding (Rule of Thumb)

Hello and welcome to a new Rule of Thumb post on plastics processing. In my previous post we discussed how to locate the maximum shear rates by using injection moulding fill simulations. Now we explore what shear rate limits we need to consider to not harm the processed polymer.

Rheology of polymers

Plastics exhibit non-Newtonian fluid behavior, where viscosity is dependent on the applied shear rate. In certain polymers, shear rate exerts a more significant influence on viscosity than temperature.

Under high stress conditions, such as during processing, polymer molecules align, leading to a substantial reduction and stabilization of the resin's viscosity. This phenomenon is known as shear thinning.

Injection moulding and shear rate / stress limit of polymer melts

In injection moulding, the injection rate or fill time directly correlates with the shear rate experienced by the plastic material. Fill time is a critical process parameter that affects shear heating and shear thinning.

Variations in fill time can alter the viscosity, pressure, and temperature of the polymer within the mould cavity, ultimately impacting the quality of the final part. Maintaining a consistent, optimized fill time is therefore crucial for process stability across different machines.

Excessive shear rates can induce polymer degradation, resulting in a decline in both the aesthetic and mechanical properties of the moulded component.

The shear rate within specific mould geometries, such as sprues, runners, and gates with a round cross-section, can be calculated using the formula: 

γ˙​=4Q​/Ï€r^3, where γ˙​ represents the shear rate (1/s), Q (mm^3/s) is the volumetric flow rate, and r (mm) is the radius of the channel.

Shear stress and shear limit control table

Calculated shear rate values can be compared against established material-specific shear rate limitations to identify potential processing issues related to excessive shear. This data facilitates the mathematical determination of optimal flow rates and mould design considerations. Your calculated shear rate should not exceed the shear rate limit  for the material. Figure 1 shows the shear stress and shear rates limits of different plastics, based on empirical experiments and literature. 

Figure 1: Shear stress and shear rate control table. 

Conclusion

In plastics processing, maximum shear rates can reach over 10,000 s⁻¹ in injection moulding and 1000 s⁻¹ in extrusion, with even higher rates (exceeding 1,000,000 s⁻¹) occurring in specific applications like wire coating. Calculating the shear rates of the material during processing and checking if they are below the shear rate limit of the material will lower the risk of polymer damage. Furthermore risk of plastic part failure is reduced since the part will have the desired properties. 

More Rule of Thumb posts can be found in the "Start here" section. 

Literature: 

[1] https://s3.amazonaws.com/entecpolymers.com/v3/uploads/pdfs/Rheology-vs-Shear-Rate-RGB.pdf

[2] https://www.findoutaboutplastics.com/2015/04/injection-molding-filling-simulation-my.html

[3] https://www.findoutaboutplastics.com/2022/05/6-benefits-of-injection-moulding.html

Tuesday, 1 April 2025

Nature is built on 5 Polymers. Modern life is built on over 200 different Polymers - How to select the right one?

Hello and welcome to a new post. Today I would like to start with a quote of mine: 

"Nature is built on 5 polymers. Modern life is built on over 200 different polymers. Therefore, optimal polymer selection is key for successful applications and to prevent plastic art failure in the long run." 

"Nature works with 5 polymers," is a statement from Mrs. Janine Benyus and reflects a key concept in her advocacy for biomimicry. It highlights the efficiency and elegance of natural systems compared to human industrial processes. Here's a breakdown of what she means:

Polymers in Nature:

Polymers are large molecules made up of repeating smaller units. They are the building blocks of many materials. Nature primarily uses a limited set of these polymers to create a vast array of structures and functions.

These "five polymers" generally refer to:

  • Cellulose: Found in plant cell walls, providing structural support. Cellulose was used in the past to create one of the first human made plastics: Celluloid. It is made by mixing nitrocellulose and camphor.
  • Chitin: Forms the exoskeletons of insects and crustaceans, as well as fungal cell walls.
  • Lignin: A complex polymer that provides rigidity to plant cell walls, particularly in wood.
  • Proteins: Versatile polymers that perform a wide range of functions, from structural support to enzymatic activity.
  • Nucleic acids (DNA and RNA): Carry genetic information.
5 Natural Polymers: Cellulose, Chitin, Lignin, Proteins and Nucleic Acids [1].

Biomimicry Application:

Benyus's statement encourages us to look to nature for inspiration in materials science.

By mimicking the way nature uses these polymers, we can create materials that are:

  • Stronger
  • More durable
  • More sustainable
  • Easier to recycle.

In essence, "Nature works with five polymers" is a powerful reminder of nature's ingenuity and a call to action for us to learn from its wisdom.

Modern life is built on over 200 different polymers - How to select the right one? 

An important step in the selection journey are the mastering of the what i refer to as the 6 Polymer Material Selection skills (6 POMS skills; Figure 1): 
P- Properties: Understanding key polymer properties
P - Part Design: Defining Application Requirements for Plastic Part Design
P - Polymer material values: Translating application requirements to qualitative and quantitative material values
P - Process: Polymer material selection process
P - Performance: Evaluation of material and part performance
P - Plastic supplier: Selection of material and supplier

Figure 1: Overview of the 6 Polymer Material Selection skills. 

Check out the detailed description of the 6 POMS here

In order for you to assess where you are currently ranking at the 6 POMS skills, I created a simple scorecard consisting out of 26 Yes / No questions and after completing the questionnaire, you receive an overall POMS score and detailed scores for each of the six critical elements of polymer material selection.

Also, you get a customised report with actionable steps to immediately start improving your POMS score and your impact in the field of polymer material selection.

A quick 5-step selection guide
Selecting the optimal thermoplastic material can be challenging and my aim is to provide you with a practical guide which leads you fast through the selection journey. 
Improper selection of plastics for the application is the leading cause for plastic part failure and since most parts fail along weld lines or knit lines, optimal mould design including filling and processing of the part are crucial too. 

Apart from the 200 polymers,  there are almost 100 generic “families” of plastics and additionally blending, alloying, and modifying with additives results in 1,000 sub-generic plastic types. Also, selecting the wrong polymer for your product may result in additional financial resources, since the selection process needs to be repeated (including making new tools) or even worse, product failure leads to claims and recalls. The following guide will help you to prevent the major mistakes and if you want to be sure, you can always reach out to a plastic expert to review your selection or help you to select the optimal grade.

What are the 5-steps (download here the guide): 

1. Define Application Requirements: In the first step we lay out all the application requirements and focus on Function, Loading Conditions, Environmental Factors, Regulatory Requirements, and Processing Considerations. A suitable acronym for this step is called FLERP:  F- Function; L- Loading conditions; E - Environmental Factors; R- Regulatory requirements; P- Processing requirements.

2. Identify Candidate Materials: Based on your application requirements, research potential engineering plastics that possess the necessary properties. Material selection charts and dashboards, supplier websites, and technical data sheets can be helpful resources. Consider factors like: Mechanical properties (short- and long-term; as a function of time and different temperature levels), thermal properties, chemical resistance, electrical properties, processing characteristics, and cost. 

3. Evaluate Material Performance: 
Carefully review technical data sheets from potential suppliers to understand the specific properties of different plastic grades within a material family. Most of the time only a single temperature is covered (room temperature). This is useful for comparing different material data sheets to each other, however for part design it has its limitations. Also, consider Multipoint Design Data which helps to think in time-dependency and temperature-dependency behaviors. Graphically such behaviors can be better accessed. Utilizing CAE software to simulate the filling of your part as well as the performance of your design using different material options.

4. Additional Considerations: Consider processing methods and cost. Evaluate environmental and regulatory factors.
Consider the material availability in order to ensure the chosen material is readily available from reliable suppliers. Additionally, evaluation of the environmental impact of the material, including its recyclability or biodegradability, if applicable can be done. Long-term performance check is needed to check the  material's resistance to degradation and expected lifespan in your application. 

5. Testing and validation. 
In the last step, prototyping is done. You can start by obtaining samples from material suppliers for simple analysis.
Next is to create prototypes using the previous identified candidate materials to test performance under real-world conditions. After concluding the final tests, final material selection can be done and a suitable supplier of the material chosen. 

6. Bonus Consult with Plastic Experts and Material Suppliers:
Discuss your application requirements with experienced polymer engineers and material suppliers. Seek recommendations based on their expertise and access to the latest materials.

My Polymer Selection Funnel Method

For a more detailed selection approach, as mentioned before,  I created the Polymer Selection Funnel methodology (POMS-Funnel).  Figure 2 presents the four different stages of the material selection funnel as well as the tools we can use to facilitate the selection. We can use this as a guideline throughout the selection journey.

Figure 2: Overview of the Polymer Selection Funnel method. 

Funnel stage 1: Material selection factors
In this first stage we map out the true part functions and material requirements. After this we translate the requirements into material selection factors.

Funnel stage 2: Decision on thermoplastic or thermoset
After translating the requirements into material selection factors, the first decision is made:
Which is the most suitable polymer chemistry to fulfill the listed requirements and selection factors? Thermoplastics or thermosets?

Funnel stage 3: Selection discussion with worksheet (qualitative matrix analysis)
The third funnel stage represents a core element in the whole material selection funnel. It is a detailed selection discussion with a worksheet. I call it the decision matrix analysis and it ranks all of the pre-selected polymers. The decision matrix analysis consists of five steps. The base calculation principle is a scoring of each of the pre-selected materials for each of the material selection factors. In the end we add up all weighted scores for each material. The material with the highest score is most suitable for selection and further investigation in the fourth stage.

Funnel stage 4: Testing, selection of material and vendor
In the last funnel stage, we would like to know in detail how the materials with the highest scores perform as a final part in a system of plastic parts or as a single plastic part alone. After all the tests are done and the material has passed all tests, commercial conditions with the material supplier can be finalized and first small serial production can start. 

I created a dedicated page for Polymer Material Selection which contains all you need for your material selection, from taking the scorecard test, online selection tools, and examples which have used the POMS funnel method. 

If you want to see the POMS funnel method in action, check out this example: Base plate of a filter coffee machine.

Conclusion

In material selection, there is no "one-size-fits-all" solution. The optimal material will depend on the unique needs of your specific application. A balance between performance, cost, and processing is often necessary. By following a five step guide or the POMS funnel method, leading to a thorough evaluation, you can make an informed decision and select the optimal engineering plastic for your project!

Literature: 
[1] https://www.amazon.de/-/en/Janine-M-Benyus/dp/1094025003
[3] https://www.polymermaterialselection.com/