Designers & Engineers: Tired of Warped Polyamide Parts? Meet PolyArylAmide (PA MXD6)!

Hallo and welcome to a new blog post on one of my favorite high performance Polyamides: PA-MXD6 (also known as Nylon MXD6, or simple PARA). 

When designing with glass fiber-reinforced polymers, warpage is a common challenge—especially as fiber content increases. But what if you could achieve both high strength and dimensional stability?

Warpage Comparison: PA 6.6-GF30 vs PA MXD6-GF50

Figure 1 compares the warpage behaviour of a plate moulded in PA 6.6-GF30 and PA-MXD6-GF50. The graps shows that: 

🔹 PA-MXD6-GF50 (50 wt% glass fiber) shows dramatically lower warpage and anisotropy than standard PA 6.6 GF30 (30 wt% GF)—even with a 20 wt% higher glass content!

🔹 Lower anisotropy means your parts stay true to design, reducing costly rejects and post-processing.

🔹PARA’s unique structure minimizes the difference between parallel and transverse shrinkage, delivering precision and reliability for your most demanding applications.

Figure 1: Warpage comparison of PA 6.6-GF30 vs PA MXD6-GF50 [3]. 

Why compromise? Choose PARA for your next polymer selection project to achieve:

• Tighter tolerances
• Superior aesthetics
• Consistent, high-quality parts

More on PA-MXD6 / PARA here: 

Polyarylamide vs Polyamide (PARA vs PA): What are the Major Differences Between PARA and PA (Polymer Material Selection Tip)?

Design Properties for Engineers: The ABCs of Polyarylamide (PARA; MXD6)

Design Data for PolyArylAmide (PARA; PA MXD6) Selection: Mechanical Properties as Function of Temperature and Humidity

Mastering Injection Molding Tools for High Performance PolyArylAmide (PARA; PA MXD6): 6 Key Steps to Success

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster

🎥Join my YouTube channel community 

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature:

[1] https://www.carbonele.com/news/pa-mxd6-material-properties-and-applications/

[2] https://onlinelibrary.wiley.com/doi/10.1002/app.56089

[3] https://www.syensqo.com/en/chemical-categories/specialty-polymers/technical-literature

[4] www.polyarylamide.com

Mastering Injection Molding Tools for High Performance PolyArylAmide (PARA; PA MXD6): 6 Key Steps to Success

Hello and welcome to a new blog post. Today we dive into the optimal tool making for Polyarylamide parts. 

Designing and producing injection molding tools for Polyarylamide (PARA; PA-MXD6) is both an art and a science. This high-performance polymer offers outstanding mechanical properties and surface aesthetics—but only if your tooling is up to the challenge! 

Here’s a deep dive into the six essential steps for success (Figure 1):

Figure 1: Overview of the six steps of tool making for molding Polyarylamide (PARA; MXD6). 

1️⃣ Part Design: Build on Solid Foundations

• Use generous radii (≥0.6 mm) to reduce stress and ease ejection.
• Apply draft angles: at least 1° for polished, up to 3° for textured surfaces.
• Optimize gate placement and size—locate at the thickest section, with land lengths of 0.8–1.6 mm.
• Take advantage of PARA’s low shrinkage (0.20–0.25%) for tight tolerances and minimal sink marks.
• Simulate your design (Moldflow®, Flow-3D®) to predict flow, weld lines, and optimize geometry.

2️⃣ Mold Definition: Specify for Performance

• Select abrasion-resistant steel (≥54 HRc) like Stavax ESR or Orvar Supreme to withstand glass fiber wear.
• Design for “steel safe” dimensions—easier to remove than add steel!
• Ensure robust venting (max 0.01 mm) and cooling (10 mm channels, 15–20 mm spacing).
• Use hot runners for efficiency and consistent quality.
• Calculate clamping force: 1 ton/cm² of projected area.
• Add cavity pressure sensors for processing optimization, especially with multi-cavity tools.

3️⃣ Detailed Drawings & Production: Precision Matters

• Prepare comprehensive technical drawings with all tolerances and features.
• Plan for heat treatment and machining—every detail counts for tool longevity and part quality.

4️⃣ Cutting Steel: Prepare for the Long Haul

• Mill, heat treat, and quench your steel to achieve optimal hardness.
• Allow for deformation during heat treatment (“steel safe” approach).
• After treatment, remove any brittle, oxidized layers by sandblasting to prevent future tool issues.

5️⃣ Assembly & Testing: Fine-Tune for Perfection

• Assemble and adjust all tool components, ensuring smooth operation.
• “Blueprint” the tool at low clamping force to check split lines and prevent flash (PARA has good flow properties, similar to PPS).
• Design for easy maintenance: include features like mold centering adjusters, ejector return pins, and replaceable components.

6️⃣ Polishing & Surface Treatments: Finish Strong

• Polish all surfaces to ensure easy part ejection and premium aesthetics.
• Apply specialized surface treatments to extend tool life—especially important with glass-filled PARA.

Pro Tip:
PARA’s high flow and low shrinkage enable thin, complex parts with exceptional surface quality. But to fully leverage these benefits, every step of your tooling process must be meticulously planned and executed.

Are you working with PARA or considering it for your next project? Let’s connect and share best practices for robust, reliable, and beautiful injection-molded parts!

More on PA-MXD6 / PARA here: 

Polyarylamide vs Polyamide (PARA vs PA): What are the Major Differences Between PARA and PA (Polymer Material Selection Tip)?

Design Properties for Engineers: The ABCs of Polyarylamide (PARA; MXD6)

Design Data for PolyArylAmide (PARA; PA MXD6) Selection: Mechanical Properties as Function of Temperature and Humidity

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster

🎥Join my YouTube channel community 

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature:

[1] Syensqo - Ixef PARA Design Guide

Turning Product Requirements into Plastic & Plastic Part Specifications: The Key to Successful Material Selection!

Hello and welcome to a new blog post where we discuss an important material selection topic. 

When developing a plastic part, clear and meaningful specifications are essential—they help control variations in function, appearance, and cost. By translating product requirements into detailed plastic specifications, you set the foundation for selecting the optimal material and ensuring consistent quality. Also, the specifications will help for sourcing plastic parts with the correct material. 

What should a robust plastic specification and plastic part specification include? 

✔️ Material brand, grade, and generic name (e.g., Ryton® R-4-200BL, PPS)

✔️ Surface finish

✔️ Desired parting line location

✔️ Flash limitations

✔️ Permissible gating and weld line areas

✔️ Void intolerance zones

✔️ Allowable warpage

✔️ Tolerances

✔️ Color

✔️ Decorating needs

✔️ Performance criteria

Example of turning a product requirement into a plastic specification:

If your product requirement is “the part must withstand high temperatures, needs to have low tolerance, and have a glossy black finish,” this translates into a plastic specification such as:

• Material: Ryton® R-4-200BL (PPS) for heat resistance
• Color: Black, high-gloss surface finish
• Tolerance: ±0.05 mm
• No voids allowed in load-bearing areas
• Gating away from visible surfaces

Figure 1 demonstrates how plastic specifications act as a bridge between product requirements, material selection, and support for sourcing. First we turn product requirements into proper plastic specifications, which we can use for polymer selection. After identifying the plastic grade we can add it with commercial name to our specification list and use it for sourcing or to find alternativ materials, as well as sourcing the plastic parts themselfs. 

Figure 1: Plastic specifications as bridge between product requirements, material selection, and support for sourcing. 

Conclusions

Having proper specifications not only streamlines the material selection phase, but also greatly supports sourcing—especially when you need to identify or qualify alternative materials. Clear specifications ensure you can compare options confidently and maintain quality, even when supply chains change.

Getting these details right means your part will meet all functional, aesthetic, and economic goals. Start with clear specs—finish with a successful product!

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster

🎥Join my YouTube channel community 

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature:

[1] Herwig Juster - Polymer Material Selection, 2023

How Additives Make or Break Plastics - Examples PC and ABS (Rule of thumb)

Hello and welcome back, fellow explorers of the material world! Today, I invite you to join me on a journey behind the scenes of everyday plastics—a place where tiny additives can play the role of either hero or villain in the fate of your favorite products.

Chapter 1: The Perilous Partnership—Polycarbonate & Titanium Dioxide

Once upon a time, in the bustling world of manufacturing, Polycarbonate (PC) was the go-to plastic for making everything from monitor frames to sleek gadgets. It was strong, clear, and reliable. But every hero has a weakness, and for PC, it was its quest for the perfect color.

Enter Titanium Dioxide (TiO₂), the pigment famed for its ability to turn plastics dazzling white or vibrant in color. At first, the partnership seemed perfect. Products gleamed on store shelves, catching every eye. But beneath the surface, trouble was brewing.

As more TiO₂ was added, the very structure of PC began to change. Its molecular weight dropped, and with it, the material’s strength and fracture energy. What once was tough and resilient became brittle and prone to failure. The culprit? The very pigment that made it beautiful.

The lesson from this tale: Sometimes, the pursuit of perfection comes at a cost. If you want your PC products to last, consider alternative pigments that offer the same brilliance—without the heartbreak.

---

Chapter 2: The Unsung Guardians—ABS & Antioxidants

Now, let’s shift to a story of hope and protection. Meet Acrylonitrile Butadiene Styrene (ABS), a versatile plastic born from the union of acrylonitrile, styrene, and a dash of polybutadiene. ABS is everywhere—from car parts to LEGO bricks—thanks to its toughness and adaptability.

But ABS has a secret vulnerability: the polybutadiene phase, filled with unsaturated double bonds, is a magnet for environmental attackers like oxygen. When these bonds are struck, free radicals form, and the once-mighty ABS starts to crumble, losing its impact strength and behaving more like fragile styrene.

Enter the heroes: antioxidants! With just 0.5% of powerful defenders like benzophenone, benzotriazole UV stabilizers, or phenolic antioxidants (think Irganox 1010, 1076, 245), ABS gains a shield against the forces of degradation. These additives slow down the photo-oxidative process, especially when ABS faces the harsh outdoors.

For manufacturers, the moral is clear: choose ABS formulations fortified with antioxidants, and your products will stand strong against the test of time.

---

Chapter 3: The Detective’s Toolkit—FT-IR Spectroscopy

But how do we know our heroes are doing their job? Enter the detective: Fourier-Transform Infrared Spectroscopy (FT-IR). This tool lets us peer into the very soul of plastics, revealing the fingerprints of both the base polymer and its additives.

For example, when antioxidants like benzotriazole UV stabilizers are present, FT-IR shows unique peaks—C-H stretching at ~3053 cm⁻¹, N-H stretching at ~2848 cm⁻¹, and more. If you’re looking for Irganox 1076 in polyethylene, a clear peak at 1741 cm⁻¹ gives it away.

With FT-IR, we can confirm our heroes are present and ready for battle, and spot signs of degradation before disaster strikes.

FT-IR Example Irganox 1076 Quantitative Analysis in Polyethylene

Figure 1 shows the FT-IR spectra of a Polyethylene containing the anti-oxidant Irganox 1076. Clearly visible is the additive peak at 1741 cm-1.

Update - community feedback received: 

Chris DeArmitt, PhD gave the following feedback (many thanks!): The carbonyl peak at 1741 could also be Irganox 1135, 259, 245, 3125 or 1010 (1746 cm⁻¹). The peak at 1746 does not tell us whether the stabilizer is still active or consumed. GC-MS will tell you and so can OIT of you prepare a calibration curve with samples of known concentrations. An alternative proper extraction followed by HPLC will give u all insights of consumed and remaining AO and specifically 1076 content more precisely.

Figure 1: FT-IR Example Irganox 1076 Quantitative Analysis in Polyethylene [2].

---

Epilogue: Lessons from the Plastic Frontier

In the end, the story of plastics is one of balance—between beauty and strength, innovation and caution. By understanding how additives interact with polymers, we can craft materials that not only look good but last long.

So next time you hold a plastic part in your hand, remember: there’s a whole world of chemistry working behind the scenes, with heroes and villains shaping its destiny.

Thanks for reading & #findoutaboutplastics

Greetings,

Herwig Juster

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature:

[1] https://www.mdpi.com/2073-4360/11/1/25

[2] https://tools.thermofisher.com/content/sfs/brochures/Fundamentals-Polymer-Analysis.pdf

[3] https://www.azom.com/article.aspx?ArticleID=12386

[4] https://www.linkedin.com/posts/herwigjuster_findoutaboutplastics-polymerengineering-polymermaterialselection-activity-7373264573338058753-48IH?utm_source=share&utm_medium=member_desktop&rcm=ACoAABCkmMcBev71cuhh4-jzEaiPHFO5VFb4aO0

[5] https://www.researchgate.net/publication/360735659_Infrared_Spectroscopy_Method_for_Detecting_the_Content_of_Antioxidant_Irganox_1076_in_Polypropylene

Design-to-Cost (DTC) in Plastic Part Design - Example housing for electronic device

Hello and welcome to a new post. In today's post we discuss the Design-to-Cost (DTC) approach in plastic part design.

Example housing for electronic device

A company is developing a new plastic housing for an electronic device. The target cost for the housing is €1.00 per unit, including material, manufacturing, and finishing.

Figure 1: 5 steps of a Design-to-cost approach for a plastic part design

Step 1: Set Cost Target

The project team establishes that the plastic housing must not exceed €1.00 per unit to remain competitive in the market.

Step 2: Analyze Cost Drivers

Material selection: Polycarbonate (PC) is initially considered, but its cost is relatively high.

Wall thickness: Thicker walls increase material usage and cycle time.

Part complexity: Complex geometries require more expensive tooling and longer molding cycles.

Surface finish: High-gloss or textured finishes may require additional processing.

Step 3: Generate Design Alternatives

Material: Evaluate switching from PC to a less expensive material, such as polypropylene (PP) or ABS, if performance requirements allow.

Wall thickness: Reduce wall thickness from 2.5 mm to 2.0 mm, maintaining structural integrity through ribbing and optimized geometry.

Geometry: Simplify the design by minimizing undercuts and eliminating unnecessary features, allowing the use of a simpler mold.

Surface finish: Specify a standard mold finish instead of a high-gloss or textured finish to reduce costs.

Step 4: Cost Estimation and Iteration

The team estimates the cost of each design alternative using supplier quotes and manufacturing simulations.

For example, switching to ABS and reducing wall thickness lowers material and cycle time costs, bringing the estimated cost to €0.95 per unit.

Step 5: Finalize Design

The design that meets both functional requirements and the cost target is selected.

The team documents the design choices and cost rationale for future reference.

Conclusions 

By applying the Design-to-Cost method, the team systematically reviewed material, geometry, and process options to ensure the plastic part meets its cost target without compromising essential performance.

Thanks for reading & #findoutaboutplastics!

Greetings, 

Herwig Juster

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature: 

[1] https://www.megatron.de/en/category/plastic-housing.html

How many cavities should you choose for your injection molding tool? I Rule of Thumb Polymer Processing

Hello and welcome to a new post. In today's post we discuss a community question I received:

How many cavities should you choose for your injection molding tool?

It’s a question that can make or break your project’s budget. Go too low, and you’re missing out on efficiency. Go too high, and tooling costs skyrocket.

Figure 1 [1] compares the cost of the injection mold, material, and injection molding as function of the mold cavities.  The sweet spot is at eight cavities as the optimal cavity number before costs start to climb. It is a classic "bathtub" cost curve and allows one to balance between tooling investment and production savings. 

Figure 1: Choosing the optimal umbers of mold cavities [1].

Conclusions

This curve serves as a first orientation. Important is that you collect all your costs and create such a total cost curve on your own. It depends if you are molding a packaging part, where more than eight cavities are beneficial, or if you are molding an engineering part such as a connector with pin overmolding, where fewer cavities may lead to an optimum already. 

Update - I received an interesting feedback: Prof. Jozsef Kovacs from University of Budapest highlights that László Sors developed a comprehensive analytical method for cavity number optimization as early as 1966, including equations, practical examples, and a nomogram. Sors’s work also addressed prototype molds, tool cost-efficiency, and the integration of thermal, rheological, and electrical calculations into mold design—well before these became industry standards. Sors is recognized as a pioneering figure in polymer tooling and design, leaving a significant legacy in the field. He published his know-how in the 1966 book: Műanyag-alakító szerszámok.

More "Rules of Thumb" posts can be found under "start here".

Thanks for reading & #findoutaboutplastics!

Greetings, 

Herwig Juster

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature: 

[1] A. Pouzada: Design and Manufacturing of Plastics Products: Integrating Traditional Methods With Additive Manufacturing

[2] H. Juster: Optimizing your injection moulding production – my 5+ How’s I Plastics processing tips

Discover the Future of Polyketone Selection: Introducing the Aliphatic Polyketone (PK) Grade Screening App

Hello and welcome to a new blog post in which I introduce to you my new created Polyketone selection app. 

Polymer Material Selection and Plastic Part Design with Polyketone

In the fast-paced world of polymer material selection and plastic part design, finding the right material can be a daunting task. With the growing demand for high-performance, sustainable materials, aliphatic Polyketone (PK) is gaining renewed attention among engineers and designers—especially in Europe. That’s why I’m excited to introduce my newly developed app, designed to revolutionize the way you scout and screen commercial aliphatic Polyketone grades!

A Brief Journey Through Polyketone’s History

Polyketone’s story is as unique as its properties. Originally launched in the 1990s by Shell under the brand name Carilon, aliphatic Polyketone quickly attracted interest for its remarkable balance of mechanical and chemical properties. However, the material was discontinued in 2000, leaving a gap in the market. Fast forward to 2013, and Hyosung Corporation breathed new life into PK with the launch of Poketone, making this versatile polymer available once again.

What makes Polyketone so special? 

Its semi-crystalline molecular structure, alternating between carbon monoxide (CO) and olefin, imparts a unique set of properties. PK is available as both a copolymer (ethylene and CO) and a terpolymer (ethylene, propylene, and CO). The terpolymer variant, in particular, offers enhanced processing for extrusion and injection molding applications. Thanks to its excellent mechanical strength, chemical resistance, and low permeability, PK is a strong candidate to replace traditional engineering polymers like Polyamides, POM, and PBT.

Your New Go-To Tool for PK Grade Selection

Selecting the right Polyketone grade just got easier! My new app (try out here) is tailored to help engineers, designers, and material specialists efficiently navigate the landscape of commercially available aliphatic PK grades—focusing on European providers.

Two Powerful Ways to Search

1. Direct Grade Selection:

Choose from a comprehensive list of commercial Polyketone grades. Instantly access key properties such as:

• Tensile strength
• Tensile modulus
• Elongation at break
• Heat Deflection Temperature (HDT) at 1.8 MPa
• UL rating
• Charpy notched impact

2. Property-Based Search:

Have specific requirements in mind? Simply enter your desired property values, and the app will recommend matching commercial PK grades that fit your needs.

This dual approach streamlines the material selection process, saving you valuable time and ensuring you find the best fit for your application.

Figure 1: Overview of the Polyketone Selector "PK Selector" V1.

Built for the Community—And Growing!

This is just the beginning. As the first version, the app currently covers the most critical properties and a robust selection of grades. Over time, I plan to expand the database with more properties and additional grades, making the tool even more powerful and versatile.

Get Involved!

I invite you to try out the new Polyketone selection tool here and experience a smarter way to choose your next engineering polymer. Your feedback is invaluable—please share your thoughts, suggestions, or feature requests to help shape future updates.

Are you a supplier or manufacturer with a Polyketone grade you’d like to see listed? Reach out to me directly—I’m eager to collaborate and make this resource as comprehensive as possible for the entire community.

Ready to streamline your Polyketone selection process? Try the app today and join the conversation!

Thanks for reading and trying out the app!

Greetings and #findoutaboutplastics

Herwig 

Literature: 

[1] https://www.poketone.com/en/index.do

[2] https://www.polyketon.de/

Choosing the Right Polymer: Why the Cheapest Isn’t Always the Best (Example Rib Plate)

Hello and welcome to a new blog post. When it comes to creating a successful product, the material you choose can make or break your design—literally! Imagine you’re building a plate that needs to be stiff enough to withstand bending (Figure 1). You have a few plastics in mind: unreinforced Polyamide 6.6 (PA 6.6), Polypropylene (PP), and High-Density Polyethylene (HDPE). Which one should you pick? If you’re thinking, “Easy! Just go for the cheapest per kilogram,” think again.

Let’s dive into the fascinating world of material selection, where things aren’t always as simple as they seem.

The Price Tag Trap

At first glance, HDPE looks like a winner. It’s often the least expensive plastic by weight. But here’s the twist: not all plastics are created equal when it comes to stiffness. To achieve the same bending stiffness as PA 6.6 or PP, you’d need to make your HDPE plate much thicker. Why? Because HDPE has a lower modulus of elasticity—it’s just not as stiff.

Figure 1: Example material selection of rib plate - HDPE vs PP vs PA 6.6 [1]. 

The Domino Effect of Thickness

Making the plate thicker doesn’t just mean using more material (and thus, more cost). In injection molding, thicker parts take longer to cool. In fact, the cooling time increases with the square of the wall thickness! That means your production slows down, your output drops, and your costs go up. Suddenly, that “cheap” HDPE isn’t looking so cheap after all.

The Surprising Winner

In our example, the most expensive material per kilogram—Polyamide 6.6—turned out to be the most cost-effective overall. Its higher stiffness meant we could use less material and keep production fast and efficient. Sometimes, paying more upfront saves you money in the long run. Also, you can decrease the wall thickness even more, by using a PolyArylAmide (PARA; MXD6) instead a PA 6.6. 

Beyond the Numbers

Of course, cost isn’t the only factor. When choosing a material, you also need to consider physical, chemical, and thermal properties, as well as how easy it is to process. The “right” material is the one that balances all these needs for your specific application.

The Takeaway

Next time you’re selecting a material, remember: the cheapest option per kilogram might not be the cheapest solution for your product. Think about requirements such as stiffness, processing time, and all the other requirements (chemical resistance) your product needs to meet. A little extra thought at the beginning can save a lot of headaches—and money—down the line.

Let’s Talk About Your Design!

Do you have a plastic part design or a material selection challenge? I’d love to hear about it! Share your project or questions with me here, and I’ll be happy to provide feedback and help you find the best solution for your needs. Let’s make your next product a success—together!

Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig Juster

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature:

[1] Konstruieren mit Kunststoffen - IKKV, University Leoben

[2] https://www.findoutaboutplastics.com/2025/04/nature-is-built-on-5-polymers-modern.html

[3] www.polymermaterialselection.com

Plastic Part Failure Analysis - Using Thermal Analysis (DSC) to Estimate the Anti-Oxidant Level in Polymers

Hello and welcome to a new blog post. Let me start today with the following question: How do you ensure the long-term performance of polyolefin materials in demanding applications?

Understanding and measuring oxidative stability is key. The following post explores why oxidative stability matters for polyolefins like polypropylene, and how Differential Scanning Calorimetry (DSC) provides valuable insights into material durability, processing effects, antioxidant performance, and ultimately prevent plastic part failure. Dive in to learn how this classic yet often overlooked test method can help you make informed decisions about material selection and process optimization.

DSC Testing for Oxidative Stability

DSC measures the heat absorbed or released by a material as temperature or time changes. While commonly used for phase transitions (melting, recrystallization, glass transition), it is also effective for detecting exothermic events like oxidation.

How does a typical test procedure for oxidative stability look like?

• A sample (raw material or molded part) is placed in the DSC.
• The sample is heated in a nitrogen atmosphere to a set temperature (commonly 200°C/392°F, which melts PE or PP).
• After reaching the target temperature, air or oxygen is introduced.
• The antioxidant in the polymer protects it until it is depleted; then, oxidation occurs, shown by a sharp increase in the DSC baseline.
• The time from oxygen introduction to oxidation onset is called the Oxidation Induction Time (OIT).
• Also, the test can be used to access the oxidation onset temperature (OOT).

Example PP raw material with standard antioxidant package vs. PP raw material with improved antioxidant package

Figure 1 shows the result for a tested polypropylene (PP) raw material and the OIT was measured at 2.29 minutes. A second PP raw material, which contains an improved antioxidant package, showed a higher OIT (6.42 minutes), indicating better resistance to oxidation under the same test conditions [1].

Figure 1: Using DSC to estimate the anti-oxidant level in Polyolefins - Example PP [1].

Interpreting OIT Results

The OIT value alone is not meaningful, but comparing OITs of materials with similar antioxidant chemistries provides a relative measure of oxidative stability. AS a rule of thumb, higher OIT indicates better oxidative stability and, typically, higher antioxidant content.

DSC offers a quick and practical way to assess oxidative stability compared to more complex antioxidant quantification methods.

Applications of OIT measurements

Raw Material vs. Molded Part:

• Processing (molding) consumes some antioxidants, so molded parts usually have a lower OIT than raw materials. 
• Changes in processing conditions (temperature, screw speed, backpressure) affect OIT and thus the remaining antioxidant content.

Post-Processing and Environmental Effects:

• Sterilization (gamma or E-beam) can significantly reduce OIT, leading to loss of material toughness.
• Long-term heat aging also reduces OIT over time.

Conclusion

DSC-based OIT testing, despite its limitations in perfectly simulating real-world conditions, remains a valuable and practical method for comparing the oxidative stability of polyolefins. It is particularly useful for evaluating the impact of processing and post-processing on antioxidant depletion and for comparing materials with similar stabilizer chemistries.

Thanks for reading & #findoutaboutplastics

Greetings, 

Herwig Juster

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature:

[1] https://www.ptonline.com/articles/the-importance-of-oxidative-stability-in-polyolefins-part-2

The Melting Point Mystery: Identifying Polyamide 6.6 & 6 with DSC (thermal analysis)

Hello and welcome to a new blog post. Today we are diving into a powerful technique for polymer identification: Differential Scanning Calorimetry (DSC). Specifically, we will explore how DSC can help you distinguish between two common polyamides, Polyamide 6.6 (PA 6.6) and Polyamide 6 (PA 6).

What is DSC?

Differential Scanning Calorimetry (DSC) is a thermal analysis technique used to observe thermal transitions in polymers. This includes identifying key characteristics such as:

• Glass Transition Temperature (Tg): The temperature at which an amorphous polymer transitions from a rigid, glassy state to a more flexible, rubbery state.
• Melting Points (Tm): The temperature at which crystalline regions of a semi-crystalline polymer melt.
• Crystallization and Crystallization Rate: For semi-crystalline polymers, DSC can also reveal information about how they crystallize upon cooling.

The Polyamide Puzzle: PA 6.6 vs. PA 6

Imagine you have a failed injection molded part made of polyamide, but you are unsure if it is PA 6.6 or PA 6. As part of your failure analysis you need to identify the polyamide type. This is where DSC becomes incredibly handy. You can take a small piece of the part, perform a DSC analysis, and the results will provide a clear answer.

Looking at a typical DSC diagram, which plots heat flow over temperature, we can observe distinct differences between PA 6.6 and PA 6 (Figure 1):

Polyamide 6.6 (PA 6.6): This polymer typically exhibits a melting point around 268°C (approximately 270 °C). On the DSC curve, this appears as a clear, sharp peak in the higher temperature range.

Polyamide 6 (PA 6): In contrast, Polyamide 6 has a lower melting point, typically around 220 °C. Its peak will appear distinctly at this lower temperature on the DSC curve.

While both PA 6.6 and PA 6 have similar glass transition temperatures (around 50°C to 70 °C), making them less ideal for differentiation, their melting points provide a robust and clear identification.

Figure 1: Material identification using DSC - Example PA 6.6 vs PA6.

Conclusion

Using DSC to identify PA 6.6 and PA 6 by their distinct melting points is a very practical and effective method. While it requires a laboratory equipped with a DSC instrument, the clarity it provides in material identification can be invaluable for quality control, material verification, and troubleshooting in the plastics industry.

Thanks for reading & #findoutaboutplastics

Greetings, 

Herwig Juster

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature:

[1] Schadensanalyse an Kunststoff-Formteilen, VDI Verlag

Polymers and the Lindy Effect (Rule of Thumb Plastic Selection and Part Design)

Hello and welcome to a new Rule of Thumb post with focus on the Lindy Effect.

What is the Lindy Effect?

The Lindy Effect, when applied to polymers, suggests that the longer a polymer material or its application has been in use, the longer it is likely to continue to be used in the future. This effect highlights the idea that longevity in the face of time and competition implies robustness and adaptability, making older technologies or materials potentially more durable and relevant than newer, less tested alternatives. 

Examples - Polymers and the Lindy Effect

1. Established Polymer Applications: Consider the long-standing use of polyethylene (PE) in packaging or polyvinyl chloride (PVC) in construction as flame retardant flooring material as well as window frame polymer. The Lindy Effect would imply that these established uses are likely to continue for many years to come, as they have already demonstrated their longevity and reliability (Figure 1). 

Figure 1: Polymers and the Lindy Effect - Examples PVC and PE.

2. Mature Polymer Materials: Similarly, materials like natural rubber or certain types of thermosetting plastics, which have been used for a considerable time, are likely to remain relevant due to their proven track record. 

In essence, the Lindy Effect in the context of polymers suggests that the longer a polymer or its application has been around, the more likely it is to persist into the future. This is because its longevity indicates a degree of robustness and adaptability that makes it a reliable choice in the face of new innovations and changing needs. This brings me to one of my top 10 rules for plastic part design and selection (Rule Nr. 10): Past performance can be guarantee of future results. It can pay of to revisit past application designs to understand what worked in the past (materials selection and design).

Check out more Rules of Thumb in the "Start Here" section.

Thanks for reading & #findoutaboutplastics

Greetings, 

Herwig Juster

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature:

[1]  Nassim Nicholas Taleb (2012). Antifragile: Things That Gain from Disorder

High Performance Thermoplastic Selection - Polyether (PPE, PAEK, PEEK, PEKK) [Part 2C]

Hello and welcome to the Part 2C of our High Performance Thermoplastics selection blog series. Today we discuss Polyphenylene Ether (PPE) and PPE blends, their chemistry and production processes, their main properties, processing methods, and applications.

Overview - 6 major high performance thermoplastics families (“the magnificent six”) 

In this blog post series we discuss six major high performance thermoplastics families (“the magnificent six”) which are outlined in the following enumeration

1. Introduction to High Performance Polymers

2. Short profile of the "magnificent six" families:

-Part 2A: Polysulfides (Polyphenylene sulfide - PPS), Polysulfones (PSU, PESU, PPSU), and Polyarylates (PAR)

-Part 2B: Imide-Based Polymers (PEI, PAI, PESI, TPI, PI) and Polybenzimidazoles (PBI, PBI+PEEK, PBI+PEKK)

-Part 2C: Polyether (PPE, PAEK, PEEK, PEKK)

-Part 2D: Liquid Crystal Polymers (LCP) and High-performance Polyesters (Polycyclohexylene terephthalate - PCT)

-Part 2E: Semi- and Fully Aromatic Polyamides (PARA, PPA, Aramid)

-Part 2F: Polyhalogenolefins (PTFE, PCTFE, FEP, PVDF, ECTFE)

Polyphenylene Ether (PPE) and its Blends with Polystyrene (PS) and Polyamide (PA)

Polyphenylene ether (PPE), also known as polyphenylene oxide (PPO), is a high-performance thermoplastic polymer renowned for its excellent thermal, mechanical, and electrical properties. While pure PPE exhibits some processing challenges due to its high melt viscosity, blending it with polystyrene (PS) significantly improves its processability while retaining many of its desirable characteristics. These PPE/PS blends have become commercially significant engineering thermoplastics.   

Jack Welch's team at General Electric faced a challenge with Polyphenylene Oxide (PPO): its extremely high glass transition temperature (208°C) made it difficult to process without degrading the material (the methyl groups of PPE are expected to undergo autoxidation). An important key to future success was the research team around Dan Fox, Allan S. Hay, and E. M. Boldebuck, who found out the miscibility of PPO with PS first. To overcome this, they decided to blend PPO with polystyrene (PS). This clever solution allowed them to maintain many of PPO's desirable properties, lower the glass transition temperature,  while also making the material easier to process at lower temperatures and more cost-effective.

Chemistry and Production Process

1. Chemistry of Polyphenylene Ether (PPE)

The base polymer, PPE, is typically synthesized through an oxidative coupling polymerization of substituted phenols, most commonly 2,6-dimethylphenol (also known as 2,6-xylenol). This reaction is catalyzed by a copper-amine complex in the presence of oxygen. The general chemical structure of PPE can be represented as (Figure 1):

Figure 1: Chemical structure of the polymer Polyphenylene Ether (PPE) [1].

The ether linkages (-O-) in the polymer backbone, along with the aromatic rings and the methyl substituents, contribute to PPE's stiffness, thermal stability, and chemical resistance.

2. Production of PPE/PS Blends

The production of PPE/PS blends primarily involves melt blending the two polymers. This process is typically carried out in extruders or other intensive mixing equipment. The key steps include:

• Raw Material Preparation: PPE and PS resins are typically received in pellet form. They may be dried to remove any moisture before blending.
• Melt Blending: The PPE and PS pellets are fed into an extruder, where they are heated and mechanically mixed. The screw design and processing conditions (temperature, screw speed) are crucial for achieving a homogeneous blend. Compatibilizers, such as styrene-butadiene-styrene (SBS) or styrene-ethylene/butylene-styrene (SEBS) block copolymers, are often added to improve the compatibility between the relatively non-polar PS and the more polar PPE. These compatibilizers help to reduce interfacial tension and prevent phase separation, leading to enhanced mechanical properties.
• Pelletizing: The molten blend exiting the extruder is then cooled and cut into pellets, which are the final product form for subsequent processing by manufacturers.

The ratio of PPE to PS in the blend can be varied to tailor the properties of the final material to specific application requirements. Higher PPE content generally leads to better thermal and mechanical performance, while higher PS content improves processability and reduces cost (Figure 2).   

Figure 2: Changing the glass transition temperature of PPE by changing the ratio of PPE and PS [1].

Main Properties of PPE/PS Blends

PPE/PS blends exhibit a combination of properties derived from both constituent polymers, often enhanced by the presence of compatibilizers. 

Key properties include:

• Excellent Thermal Stability: PPE inherently possesses high glass transition temperatures (Tg ) and heat deflection temperatures (HDT). Blending with PS can reduce these values compared to pure PPE, however the blends still offer good high-temperature performance compared to many other engineering thermoplastics.   
• Figure 3 shows the DMA of PPE+PS blend in comparison to High Impact Polystyrene (HIPS) and Polycarbonate (PC). PS has a glass transition temperature of about 100°C and up to this temperature PPE+PS can match PC in thermal performance (PC drops sharply at Tg of 147°C). There is no sharp drop in modulus observed with PPE+PS. 

Figure 3: Dynamic Mechanical Analysis (DMA) of PPE+PS vs HIPS vs PC. 

• Good Mechanical Strength and Stiffness: PPE contributes to the blend's rigidity and strength. The impact strength can be tailored depending on the blend ratio and the use of impact modifiers.  
• Excellent Electrical Insulation Properties: PPE is an excellent electrical insulator with a low dielectric constant and high dielectric strength, which are largely retained in the blends.   
• Good Chemical Resistance: PPE offers good resistance to many chemicals, including acids, bases, and detergents. The chemical resistance of the blend is generally good but can be influenced by the PS content, which is more susceptible to certain solvents.   
• High Stability towards Hydrolysis: hydrolysis resistance of PPE is superior when compared to other engineering plastics such as PBT and PA.
• Improved Processability: The addition of PS significantly lowers the melt viscosity of PPE, making the blends easier to process using conventional methods like injection molding and extrusion.   
• Dimensional Stability: PPE contributes to low water absorption and excellent dimensional stability, which is important for applications requiring tight tolerances.   
• Flame Retardancy: PPE is inherently flame retardant. Blends often exhibit good flame retardant properties, especially when combined with flame retardant additives.   

Apart from blending PPE with PS; blends out of PPE with PA are possible too. PPE/PA blends have the following advantages: 

• Combines Key Strengths: Blends the excellent dimensional stability, low water absorption, and heat resistance of PPE with the superior chemical resistance and flow of PA.
• Enhanced Performance: The resulting material is exceptionally chemically resistant and boasts the stiffness, impact resistance, and heat performance needed for demanding applications like on-line painting.
• Significant Weight Savings: Unfilled PPE/PA blends can offer part-weight reductions of up to 25% compared to glass or mineral-filled resins, thanks to their low density.

Outperforming properties of PPE/PS blends:  

• Low specific gravity: 1.1 g/cm3. Most engineering polymers such as PC, PBT, and POM have a specific density of 1.2 g/cm3 and more. 
• High self-extinguishing property: PPE has a high oxygen index (27-29) and it is easy to add flame resistancy. 
• Excellent dielectric properties: PPE has a dielectric constant of 2.8 and a dielectric tangent of 6x1E-3. The dielectric breakdown strength (110 MV/m @ 0.5 mm thickness) is the highest among engineering plastics. 
• High dimensional accuracy: PPE has one of the lowest coefficient of linear thermal expansion among engineering polymers (5.8 x 10E-5 1/°C).

Processing Methods

PPE/PS blends can be processed using various thermoplastic processing techniques, including:

• Injection Moulding: This is the most common method for producing complex shaped parts from PPE/PS blends, leveraging their improved flow properties compared to pure PPE.
• Extrusion: These blends can be extruded into profiles, sheets, and films for various applications.  
• Blow Moulding: Certain grades of PPE/PS blends can be blow molded to produce hollow parts.
• Thermoforming: Sheets extruded from PPE/PS blends can be thermoformed into various shapes. 

Applications of PPE/PS Blends

The unique combination of properties makes PPE/PS blends suitable for a wide range of applications across various industries:

• Construction and Plumbing: Applications include pump housings, impellers, and other components requiring good mechanical and chemical resistance.
• Automotive Industry: Interior and exterior components such as instrument panels, door panels, wheel covers, and electrical connectors benefit from the blends' thermal stability, dimensional stability, and impact resistance.   
• Electrical and Electronics: Housings for electrical connectors, circuit breakers, switchgear, and other electrical components utilize the excellent electrical insulation properties and flame retardancy of PPE/PS blends.   
• Household Appliances: Components for washing machines, dishwashers, microwave ovens, and other appliances benefit from the blends' heat resistance, chemical resistance, and good mechanical properties.
• Business Equipment: Housings and internal components for computers, printers, and other office equipment utilize the blends' dimensional stability, electrical properties, and aesthetic appeal.   
• Healthcare: Certain grades of PPE/PS blends can be used in medical devices and equipment due to their sterilizability and chemical resistance.   

Trade Names

Several companies market PPE/PS blends under various trade names. Some well-known examples include:

• Noryl™: Formerly a trademark of GE Plastics, now owned by SABIC Innovative Plastics. This is one of the most widely recognized families of PPE-based resins, including various PPE/PS blends and other modifications.
• XYRON™ from Japanese chemical company Asahi Kasei.
• Various manufacturers such as Global Acetal (Lemalloy PPE) produce generic PPE/PS blends with specific property profiles.   

Economic Aspects

The market for PPE/PS blends is significant within the broader engineering thermoplastics market. The demand is driven by the increasing need for high-performance materials in automotive, electronics, plumbing and appliance industries.   

• Cost Factors: The cost of PPE/PS blends is influenced by the price of the base polymers (PPE and PS), the concentration of PPE in the blend, the type and amount of compatibilizers and additives used, and the manufacturing process. Generally, higher PPE content leads to higher costs.
• Market Trends: The trend towards lightweighting in the automotive industry and miniaturization in electronics continues to drive the demand for materials like PPE/PS blends that offer a balance of performance and processability. Growing environmental concerns are also pushing for more sustainable material solutions, which may influence the development of new PPE-based blends with recycled content or improved recyclability.
• Regional Variations: The demand and market dynamics for PPE/PS blends can vary across different geographical regions based on industrial activity and specific application needs.

In conclusion, polyphenylene ether (PPE) and its blends with polystyrene and polyamide represent a versatile class of engineering thermoplastics offering a compelling combination of high-performance properties and improved processability. Their wide range of applications across various industries underscores their economic and technological significance in the world of polymer engineering. As a polymer engineering student, understanding the nuances of these materials will undoubtedly be valuable in your future endeavors.   

In the upcoming Part 2C we will continue to discuss the Polyether high performance polymers such as PAEK, PEEK, and PEKK.

Thanks for reading & #findoutaboutplastics

Greetings, 

Herwig Juster

🔎I review your polymer material selection and plastic part design - contact me here

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

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

Literature: 

[1] Allan S. Hay: Polymerization by Oxidative Coupling: Discovery and Commercialization of PPO and Noryl Resins

[2] https://www.sabic.com/en/products/specialties/noryl-resins

[3] https://www.gpac.co.jp/en/product/lemalloy/

[4] https://www.findoutaboutplastics.com/2016/09/jack-welch-and-his-uprise-in-ge.html

[5] https://www.findoutaboutplastics.com/2024/08/high-performance-thermoplastic.html