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 structed 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

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 – good wear resistance

  • 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,

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/

[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
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Tuesday, 3 February 2026

Blending Virgin Plastic Resins with Regrind/Recycled Materials - Checklist for Plastic Processors

Hello and welcome to a new blog post in which I provide you with a checklist on blending virgin plastic resins with regrind or recycled materials. 

Introduction

In today’s plastics industry, blending virgin resins with regrind or recycled materials is a powerful way to enhance sustainability and reduce costs. However, achieving consistent quality and performance requires careful attention to every step of the process.

To support your operations, we’ve developed a practical checklist (Figure 1) highlighting the 10 most important points to consider when blending virgin plastics with regrind or recycled content. Whether you’re optimizing for efficiency, compliance, or product quality, this checklist will help you avoid common pitfalls and ensure reliable results.

Use this tool as a guide to streamline your workflow, maintain high standards, and drive continuous improvement in your plastics processing. Remember: customizing these checks to your specific materials and processes will yield the best outcomes.

Figure 1: Checklist - Blending virgin plastic with regrind/recyled plastics.

Check out also this post: How to Mark Plastic Parts with Recycled Content: A Quick Guide to ISO 1043 & ISO 11469

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster

Literature:

[1] https://www.findoutaboutplastics.com/2023/07/plastic-part-design-for-recycling.html

[2] https://www.findoutaboutplastics.com/2023/04/guest-interview-bianca-gubi-product.html



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Tuesday, 27 January 2026

Personal Update: I have officially obtained my ISO/IEC 17024 Expert Witness certification specializing in plastics and plastic products

Hello and welcome to this personal update post. I am pleased to announce that I have officially obtained my ISO/IEC 17024 Expert Witness certification specializing in plastics and plastic products. 

Smiling for the camera with my freshly obtained ISO/IEC Expert Witness Certificate, together with the "Brick Moulding Machine" (© Herwig Juster)

Why does ISO/IEC 17024 matter in 2026?

The complexity of polymer science and engineering is increasingly at the heart of high-stakes litigation—from IP disputes and product liability to the emerging legal challenges of the circular economy.

The ISO/IEC 17024 represents an international gold standard for technical competence and—most importantly—procedural objectivity. In an era where expert testimony is under microscopic scrutiny, I provide a defensible, audited methodology to every case.

My Core Focus Areas:
  •  Plastics Failure Analysis & Root Cause (ESCR, Fatigue, Degradation)
  •  Intellectual Property & Patent Disputes
  •  Product Liability & Personal Injury 
  • Specialized Niche: Liability and failures in Recycled Plastics (PCR/PIR) including processing analysis (extrusion and injection molding).
Whether you are in the discovery phase or need an early-stage technical viability assessment, my goal is to bridge the gap between complex material science and the requirements of the court.

What's next?

Step by step I will roll out my dedicated Plastics Expert Witness landing page, and I am developing a "Case Viability Scorecard" which helps you to determine if your case is a fit for me - stay tuned. 

My certification is valid for five years and can be online checked at the EUCert via this link.

If you want to get in contact with me to discuss your case you can reach me here too 

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster



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Monday, 19 January 2026

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

Hello and welcome to a new blog post. Today we cover mental models and why the are not only important for us in polymer engineering, but also for private and other professional areas of life too.

In 2026, mental models—conceptual, often simplified frameworks for understanding the world—are critical for navigating a landscape defined by rapid AI advancement, geopolitical instability, and extreme information saturation. They serve as "cognitive toolkits" that allow individuals and leaders to parse complex, ambiguous data into actionable decisions. 

Mental models are important in 2026 for the following key reasons:

1. Navigating Complexity and AI-Augmented Environments

  • Example - Cutting Through "Noise": With AI generating massive amounts of data, mental models help filter information and focus on high-impact factors (e.g., using the Pareto 80/20 Rule to identify crucial data points).
  • Example - Contextualizing AI Outputs: As AI becomes ubiquitous in 2026, human judgment remains essential for interpreting AI insights; mental models provide the necessary framework for this contextualization.
  • Example - Systems Thinking: Understanding how different components (remote work, global supply chains, AI tools) interact is crucial. Systems thinking helps identify patterns and leverage points for change rather than reacting to symptoms. 

2. Professional Adaptability and Decision Speed

  • Example - Rapid Decision Making: In 2026, business leaders must make decisions 2.5 times faster than competitors. Mental models (like the OODA Loop—Observe, Orient, Decide, Act) enable swift, effective, and reasoned actions under pressure.
  • Example - Mitigating Cognitive Bias: The fast-paced environment increases the risk of emotional or faulty decision-making. Mental models like Inversion (considering how to avoid failure) or Second-Order Thinking (evaluating long-term consequences) allow for more objective, strategic choices.
  • Example - Increased "Model Literacy": Success in 2026 requires understanding multiple mental models across disciplines—a "latticework" that allows for more versatile, creative problem-solving rather than relying on a single, outdated framework. 

3. Personal Resilience and Growth

  • Example - Managing Cognitive Load: The sheer volume of information can cause "cognitive fatigue." Mental models help organize information and reduce the mental effort required to make sense of new, complex situations.
  • Example - Developing Emotional Stamina: As global instability creates stress, mental models assist in building emotional resilience and maintaining a "growth-oriented" perspective, allowing individuals to adapt to change rather than being overwhelmed by it.
  • Example - Lifelong Learning: In 2026, continuous learning is essential for career longevity. Mental models facilitate the learning of new concepts by connecting them to existing knowledge, accelerating the transition from novice to expert. 

4. Improved Collaboration 

  • Example - Shared Mental Models: In hybrid and remote work environments (which are standard by 2026), shared mental models enable teams to align on goals and expectations, leading to more cohesive and efficient collaboration. 

My 20 Mental Models for Effective Thinking

Over the past decade of my career in polymer engineering, I have systematically collected and applied a range of mental models to enhance my professional effectiveness. In the accompanying sketchnote (Figure 1), I have outlined the 20 mental models I utilize most frequently. 

These models are categorized into four key areas: Core Frameworks, Decision Making and Bias, Change and Adaptation, and System and Interaction.

Figure 1: 20 Mental Models for effective thinking in- and outside plastics industry

In summary, as we move through 2026, mental models are no longer optional, abstract concepts; they are the essential, daily tools for maintaining clarity, speed, and sanity in a rapidly evolving (plastics) world. 

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster

Literature:

[1] https://tetr.com/blog/mental-models-for-business-success-secrets-for-aspiring-founders#:~:text=Mental%20models%20are%20cognitive%20frameworks,identify%20patterns%20others%20might%20miss.

[2] https://taproot.com/mental-models/#:~:text=Simplifying%20Complexity:%20In%20today's%20fast,productive%20discussions%20and%20innovative%20solutions.

[3] https://medium.com/@chamiduweerasinghe/the-future-of-personal-development-trends-to-monitor-in-2026-and-beyond-0537609878f8#:~:text=Companies%20that%20invest%20in%20building,Technology%20as%20the%20Growth%20Engine

[4] https://academic.oup.com/ct/article/35/4/250/8166013#:~:text=These%20models%20map%20onto%20elements,.%2C%202004%2C%202007).

[5] https://modelthinkers.com/mental-model/mungers-latticework

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