Thursday, 5 March 2026

First-Principal Thinking in Polymer Engineering I A Powerful Tool covering innovation till problem solving I Rule of Thumb

Hello and welcome to this new blog post! 

First-principles thinking is a powerful problem-solving approach where you break down complex problems into their most basic, fundamental elements and then reassemble solutions from the ground up. 

Mr. Michael Sepe, with his extraordinary contributions to the plastics industry as a teacher, expert, and consultant, was a strong believer in first principles thinking (Quote reported by Jeff J. :“the fundamentals don’t change” [1]).  By reading Michaels articles and books, I have learned a lot about polymer engineering and also the first-principles approach, which I would like to share with you in this post to keep the spirit of Michael among us!

How to apply First-principles thinking for your plastics challenges?

Instead of relying on analogies or established methods, you ask: “What do we know for sure?” and “What is truly essential?”

Here are some examples of first-principles thinking in polymer engineering and the plastics industry:

1. First principles approach on Understanding Material Performance

The performance of plastic materials is fundamentally determined by their structure. The polymer structure is defined by its molecular architecture, which directly affects key properties such as polarity, crystallinity, and viscoelasticity.

Molecular architecture can be divided into:

  • Molecular construction (including functional groups, branching, and tacticity)
    • Functional groups influence the polarity of the polymer.
    • Tacticity affects the crystallinity of the polymer.

  • Molecular weight (including molecular weight distribution)
    • Molecular weight distribution impacts the viscoelastic behavior of the material.

A plastic compound is composed of a base polymer and various additives. The characteristics of the base polymer are primarily determined by its molecular structure.

The final plastic compound defines the material’s mechanical, thermal, chemical, and environmental properties.  As a practical implication for polymer selection and design, you can pick the functional group for your target property: e.g., if you need high-temperature structural parts, aim for imide/sulfone/aryl ketone chemistries.

Figure 1 summarizes the first-principles approach on understanding plastic material performance. 

Figure 1: first-principles approach for understanding plastic material performance. 

2. Designing a New Polymer for a Specific Application

Traditional approach: Use existing polymers and modify them to fit the application. 

First-principles approach:

  • Start by asking: What are the fundamental properties required (e.g., thermal stability, flexibility, chemical resistance)?
  • Analyze the molecular structure-property relationships.
  • Design a polymer backbone and side groups from scratch to achieve the desired properties, rather than tweaking existing materials.
3. Reducing Plastic Waste

Traditional approach: Improve recycling rates using current technologies. 

First-principles approach:

  • Ask: What makes plastics hard to recycle? (e.g., immiscibility, additives, contamination)
  • Break down the recycling problem to its chemical and physical fundamentals.
  • Develop new polymers that are inherently easier to depolymerize or upcycle, or invent additives that enable closed-loop recycling.
4. Improving Barrier Properties in Packaging

Traditional approach: Add more layers or coatings to existing films. 

First-principles approach:

  • Ask: What fundamentally limits gas or moisture permeability?
  • Investigate the molecular interactions and free volume in the polymer matrix.
  • Engineer the polymer structure or blend with nanomaterials to minimize permeability at the molecular level, rather than just adding layers.
5. Coloring Polymers

Traditional approach: Use standard masterbatches and pigments. 

First-principles approach:

  • Ask: What causes color fading or poor dispersion?
  • Analyze the interaction between pigment molecules and polymer chains.
  • Design new pigment chemistries or surface treatments that bond better with the polymer, ensuring long-lasting and uniform color.
6. Lightweighting Automotive Parts

Traditional approach: Use existing glass-fiber reinforced polymers. 

First-principles approach:

  • Ask: What is the minimum material and structure needed for required strength and safety?
  • Use computational modeling to design new composite architectures or hybrid materials from the molecular level up, achieving strength with less material.
7. Developing Biodegradable Plastics

Traditional approach: Use known biodegradable polymers like PLA or PHA. 

First-principles approach:

  • Ask: What chemical bonds are most susceptible to environmental degradation?
  • Design new polymer structures with targeted weak links that break down under specific conditions, ensuring both performance and biodegradability.

In summary:

First-principles thinking in polymer engineering means questioning every assumption, understanding the science at the most basic level, and building innovative solutions from the ground up. It’s a mindset that can lead to breakthroughs in materials design, sustainability, and manufacturing.

For further reading, I recommend my mental models post which can be found here:

20 Mental Models for effective thinking in- and outside the plastics industry

Thanks for reading & #findoutaboutplastics

Greetings, 

Herwig



Literature:

[1] https://www.linkedin.com/posts/jeffrey-jansen_plastics-education-scholarship-activity-7224029479042482176-0wcT

[2] https://give.4spe.org/campaign/michael-p-sepe-memorial-scholarship/c604608

[3] https://www.findoutaboutplastics.com/2026/01/20-mental-models-for-effective-thinking.html

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Sunday, 22 February 2026

Don Polimero & The Plastics Pellets Band - "Plastics are the solution and not the problem"

Hello and welcome to a new blog post.


🎶 Today I tried out the new Gemini Music feature, using the fast modus and created a 30s song.

1️⃣ First I created the artist Don Polimero as a picture. He is singing about plastics and that they are part of the solution and not the problem.

2️⃣ Then uploaded the picture to Gemini, create music and selected "Folklore" style and voilà the song is ready.

👇 Check it out below & give it a try for yourself.


And here is the 2nd verse with recycling and sustainability as main topic:

Thanks for listening and reading & #findoutaboutplastics

Greetings,

Herwig Juster



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Monday, 16 February 2026

📚 My new book, "Pumping Plastics 2025," is out now! Available as Paperback Worldwide on Amazon!

Dear coomunity, welcome to “Pumping Plastics 2025”—Your Essential Guide to the World of Modern Polymers!

Are you ready to dive into the dynamic world of plastics and polymers? 

This book brings together all the insightful posts from my 2025 FindOutAboutPlastics.com blog, curated to help you stay ahead in the fast-evolving plastics industry.

  • Inside, you’ll discover a rich collection of topics, including:
  • The latest in injection molding and processing techniques
  • Practical strategies for polymer selection and comparison
  • Fresh perspectives on materials science and industry trends
  • Inspiring stories of sustainability and innovation
  • Career tips and real-world advice for plastics professionals
  • Engineering insights, design best practices, and failure analysis
  • Special features and thought-provoking inspiration

Whether you prefer to read month by month or jump straight to the topics that spark your curiosity, this book is designed for flexible, practical learning. And as a special bonus, you’ll find the first chapter of my acclaimed book, “Polymer Material Selection,” included to kickstart your journey.

Let “Pumping Plastics” be your trusted companion—whether you’re a student, engineer, or industry veteran—on the path to mastering the science, art, and business of plastics.

Grab your copy here and stay ahead of the curve!

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster


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Tuesday, 10 February 2026

Plastics and Polymers Selection for Humanoid Robot Applications: From Structural Skeletons to Artificial Muscles



Hello and welcome to a new material selection post in which we discuss suitable plastics for humanoid robotic applications. It is a longer post and I have structured it into five chapters: 

  • Chapter 1: The Humanoid Market – From Industrial Tools to Bio-mimicry
  • Chapter 2: The Structural Skeleton – PEEK and Reinforced Composites
  • Chapter 3: The “Artificial Muscle” – Electroactive Polymers (EAPs)
  • Chapter 4: Actuation and Tribology – Gears, Wear, and Sealing
  • Chapter 5: The PFAS Challenge – Engineering Without “Forever Chemicals”

Introduction

Humanoid robots represent one of the most demanding convergence points of mechanical engineering, electronics, materials science, and biology-inspired design. Unlike traditional industrial robots, humanoids must be lightweight, energy-efficient, safe for human interaction, and capable of complex, biomimetic motion.

In this context, optimal polymer selection is a key engineering decision. The correct choice of plastic materials is essential to:

  • Ensure reliable function of all robot subsystems

  • Balance stiffness, weight, wear resistance, and durability

  • Prevent premature part failure due to fatigue, creep, wear, or environmental exposure

Poor material selection can lead to unexpected breakdowns, excessive wear, thermal deformation, or regulatory non-compliance, often only discovered late in development or during field operation.

Polymers and polymer-based composites are no longer auxiliary materials in this space — they are enablers. This article explores how advanced plastics underpin modern humanoid robot design, from structural frames to artificial muscles, while addressing emerging regulatory and sustainability challenges.

Chapter 1: The Humanoid Market – From Industrial Tools to Bio-mimicry

Market Context: From Cobots to Autonomous Humanoids

Early collaborative robots (“cobots”) were essentially industrial manipulators made safer through sensors and control algorithms. Their material choices reflected this heritage: steel, aluminum, and classical engineering plastics.

Today’s humanoid robots represent a paradigm shift:

  • Designed for unstructured environments

  • Expected to interact safely with humans

  • Required to move with human-like kinematics

  • Increasingly autonomous, powered by onboard batteries

This shift has forced engineers to rethink mass distribution, inertia, and energy efficiency — areas where polymers outperform metals.

Design Step: Lightweighting as a System-Level Strategy

In humanoid robots, weight is not neutral:

  • Every gram saved in the frame can be reassigned to:

    • Battery capacity (longer runtime)

    • Sensors and AI hardware

    • Payload capability

Polymers enable functional integration (snap-fits, ribs, channels, cable guides) that would require multiple machined metal parts, thereby reducing both part count and mass.

Chapter 2: The Structural Skeleton – PEEK and Reinforced Composites

Material Focus: High-Performance Structural Polymers

The “skeleton” of a humanoid robot must provide high stiffness, fatigue resistance, and dimensional stability under cyclic loads.

Key materials include:

  • PEEK (Polyetheretherketone)

    • Carbon- or glass-fiber reinforced

    • Exceptional stiffness-to-weight ratio (interesting for metal replacement)

    • High thermal stability and chemical resistance

    • Structural frames, gears, joints, bushings, insulation

  • PA 6.6 (Polyamide 6.6)

    • Tough, cost-effective

    • Suitable for secondary load-bearing structures, housings, covers

    • 3D printing possible (SLS)

    • PolyArylAmide (PARA, PA-MXD6): for appliactions in robotics where low moisture, high dimensional stability (enabling complex parts), excellent surface appearance (“best-in-class” among the Polyamides), and outstanding stiffened and strength is needed.

  • Polycarbonate (PC)
    • Impact-resistant, transparent, stable
    • Sensor/camera covers, shields, panels

  • PPS (Polyphenylene Sulfide)

    • Glass-fiber reinforced

    • Excellent dimensional stability

    • High thermal and creep resistance

    • Connectors, housings, parts near heat sources

  • PEI (Polyetherimide)
    • High strength, flame retardant, heat resistant, good electrical properties
    • Connector housings, structural frames
    • Strong, safe, reliable in harsh environments

  • LFT (Long Fiber Thermoplastics)

    • Continuous or long glass/carbon fibers

    • Ideal for large, injection-molded structural parts

    • High load capacity, reduces robot weight

  • High density plastics: 
    • can be used as counter weights / balancing weights
    • locally integrated in plastic part where it is needed via 2-component injection molding

Design Example: Replacing Aluminum with CNC-machined or 3D-printed PEEK

CNC-machined or 3D-printed carbon-filled PEEK can achieve:

  • Elastic modulus approaching aluminum

  • Up to 50% weight reduction

  • Significantly lower rotational inertia

Lower inertia directly translates into:

  • Faster acceleration and deceleration

  • Reduced motor size

  • Lower energy consumption

Additive manufacturing further enables topology-optimized structures, closely mimicking biological bones with hollow cores and load-aligned fiber orientations.

Chapter 3: The “Artificial Muscle” – Electroactive Polymers (EAPs)

Defining EAPs

Electroactive Polymers (EAPs) are materials that change shape, size, or mechanical properties when subjected to an electrical stimulus. They are often described as “muscle-like” materials because their actuation principles resemble biological muscle contraction.

Electronic vs. Ionic EAPs

Electronic EAPs

Examples:

  • Dielectric Elastomers (DEAs)

  • Electrostrictive Graft Elastomers

  • Ferroelectric Polymers

Characteristics:

  • Fast response times

  • High energy density

  • Require high operating voltages

  • Suitable for dry environments

Ionic EAPs

Examples:

  • Ionic Polymer-Metal Composites (IPMCs)

  • Conducting Polymers

  • Carbon Nanotube (CNT) networks

Characteristics:

  • Operate at low voltages

  • Slower response

  • Often require moisture or electrolytes

  • Ideal for fine, low-force movements


Design Example: Eliminating Gears and Motors

EAPs enable soft robotics, where motion is achieved without:

  • Gearboxes

  • Bearings

  • Lubricants

Applications include:

  • Facial expression systems

  • Dexterous fingers

  • Artificial skin and haptics

The result is silent, compliant, and lifelike motion, impossible to achieve with rigid electromechanical systems alone.

Chapter 4: Actuation and Tribology – Gears, Wear, and Sealing

Motion Control: Tribological Plastics

Despite advances in soft actuation, many humanoid joints still rely on conventional rotary actuation. Here, tribological performance is critical.

Key materials:

  • POM (Acetal) – low friction, dimensional stability

  • PA 4.6 – high melting point, excellent fatigue resistance

  • PA 6.10 – outstanding wear resistance

  • Polyketone & PEEK – good wear resistance: Polyketone, as an example,  has a 14 times higher anti-abrasion property compared to POM, allowing for almost permanent use without change.

  • Self-lubricating materials using fillers such as Graphite, Molybdenum Disulfide (MoS2), Carbon fiber, and PTFE/UHMWPE – maintenance-free bearings and joints

These materials allow:

  • Dry-running systems

  • Reduced maintenance

  • Long service life under oscillating motion

Sealing: Protecting Sensitive Electronics

Humanoid robots operate in dusty, humid, and unpredictable environments. Advanced sealing systems are essential.

  • IPSR (Ingress Protection Seals) / PSS (Precision sealing systems)

  • Advanced EPDM, NBR and FKM elastomers

  • High-temperature thermoplastics such as Quantix® ULTRA (1.200 °C)

These seals protect:

  • Motors

  • Sensors

  • Control electronics
    …without adding excessive friction or bulk.

Chapter 5: The PFAS Challenge – Engineering Without “Forever Chemicals”

The Regulatory Hurdle

Historically, many high-performance plastics relied on PTFE additives to reduce friction and wear. However:

  • PTFE belongs to the PFAS ( Per- and polyfluoroalkyl substances) containing family

  • Increasingly restricted under REACH / ECHA and EU 2019/1021

  • Long-term environmental persistence (“forever chemicals”)

This has forced a fundamental rethink of tribological design.

The Innovation Step: Molecular Engineering

Instead of relying on fluorinated additives, modern polymers achieve performance through intrinsic molecular structure.

A prime example:

  • PA4.6

    • Higher melting point than PA 6 or PA 6.6

    • Superior crystallinity (80%)

    • Excellent fatigue and wear resistance

    • Performs under high speed and load without PTFE

This enables PFAS-free gears and bearings suitable for humanoid robot actuators.

Apart from PA 4.6, there are polymers which are inherently wear-resistant too: 

-Polyketone (PK)

-Polyoxymethylene (POM): crystallinity level above 90% possible

-Ultra-high molecular weight polyethylene (UHMWPE)

-Polyamide-Imide (PAI)

-Polybenzimidazole (PBI)

-Polyetheretherketone (PEEK)

As alternative, Hexagonal boron nitride (hBN) which can offer a fluorine- and micro plastic-free replacement. The very good lubricating properties of hBN come from its crystal structure. We discussed this in detail with Michaela Schopp - Product Manager at Henze BNP AG in this guest interview here.

Conclusion

The selection of high-performance plastics in humanoid robotics is driven by the need for lightweight, durable, and reliable components that can withstand mechanical stress, environmental exposure, and regulatory requirements. Materials like PEEK, PA, PC, POM, PPS, PEI, PU, and LFT each offer unique advantages for specific robot parts, from structural frames to gears and sensor housings (Figure 1). As the robotics industry evolves, the role of advanced, sustainable polymers will only increase, enabling the next generation of agile, efficient, and compliant humanoid robots.

Figure 1: Summary of materials used for Humanoid Robotic applications.

If you need selection support, or a deeper dive into a specific material or application, please let me know!

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster

Literature: 

[1] https://www.fst.com/de/news-stories/pressemitteilungen/2024/thermoplaste-fuer-bis-zu-1200-grad-celsius/

[2] https://www.fst.com/markets/robotics/6-axis-robot/

[3] https://toolbox.igus.com/motion-plastics-blog/understanding-the-humanoid-robot-market/?pk_vid=1727719344ad05051727719347ad0505
[4] https://toolbox.igus.com/motion-plastics-blog/maximizing-humanoid-robot-longevity/?pk_vid=1727719906ad0505
[5] https://www.peekchina.com/blog/plastics-for-humanoid-robots.html
[6] https://www.lft-g.com/blog/peek-the-ultimate-lightweight-material-for-humanoid-robots_b210
[7] https://www.fst.com/news-stories/robotics/humanoid-robots/
[8] https://www.honyplastic.com/news/eight-major-polymer-materials-used-in-humanoid-robots-309468.html
[9] https://www.therobotreport.com/envalior-offers-pfas-free-materials-wear-friction-applications/
[10] https://www.protolabs.com/en-gb/resources/blog/materials-that-command-the-robotics-industry/
[11] https://www.zhongyanpeek.com/peek-composite-materials-reshape-the-future-of-industry-and-humanoid-robots.html
[12] https://schunk.com/de/de/news/schunk-gruendet-tech-spin-off-fuer-humanoide-roboterhaende/36224
[13] https://www.linkedin.com/pulse/syensqos-ketaspire-peek-enables-durability-flexible-joints-baleno-5oj9c/?trackingId=DBuQvo0eWn86WUTpTpAECQ%3D%3D
[14] https://www.dreyplas.com/en/polyketone/
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