Today's KNOWLEDGE Share : The annoying saddle twist warpage of low MFI polyolefin grades.

Today's KNOWLEDGE Share

The annoying saddle twist warpage of low MFI polyolefin grades.

If you ever molded extrusion or blow-molding grades of PP or PE, you have certainly experienced a big warpage problem, stemming from the surprisingly higher than usual IN-FLOW shrinkage.

The graph on the right (similar to my previous post nr. 146) shows that moving to a lower Melt Index increases the chance of freezing more molecular orientation in the part, as a result of the longer relaxation time of low MFI grades.

The graph in the center, from the cited article of 2006, shows the trend of increasing parallel to flow shrinkage with increasing molecular weight of a simple unfilled PP homopolymer.

Note that the three grades are all more viscous than typical in Injection Molding, and they all show a strong anisotropic shrinkage (this is measured on a dog-bone classical tensile bar sample) with larger shrinkage in the flow direction, due to strong molecular orientation. 

It is the exact contrary of classical higher flow PP grades where perpendicular shrinkage is higher than parallel !

Finally, as seen on the left drawing (by Covestro), a centrally gated part will warp in a “saddle twist” fashion when the In-FLOW shrinkage is larger than the CROSS-FLOW shrinkage (perimeter wants to be larger than the corresponding radius).

When dealing with these viscous “twisty-warpy” grades one could in theory add just a few % GF that create the opposite effect of lower IN-FLOW shrinkage. Magically, you could suddenly mold a perfectly flat disc, by adding just a pinch of GF to the mix !

A higher packing (qualifying probably as OVERPACKING of the part center) would also flatten these part by creating the opposite warp trend, something illustrated in classical MOLDFLOW® literature more than 40 years ago.

What is your own experience with low MFI grades ? 

Please comment and share so that we all learn more about this issue.

source :Vito leo

Today's KNOWLEDGE Share : Analysis of POM with other Plastics

Today's KNOWLEDGE Share

Comparative Analysis of POM with Other Plastics:

Some of the key advantages and limitations of POM compared to other plastics are highlighted below:

POM vs Nylon

• POM has lower moisture absorption and better dimensional stability than nylon
• It has higher tensile strength, hardness and modulus than nylon
• Nylon offers higher toughness, ductility and impact strength compared to POM
• Nylon has better chemical resistance than POM, especially to bases, oils and greases
• POM provides lower coefficient of friction than nylon

POM vs Polycarbonate

• POM has much higher strength, hardness and stiffness than polycarbonate
• PC offers very high impact resistance compared to brittle
• POMPolycarbonate has superior temperature resistance up to 140°C vs 90°C for POM
• POM has lower moisture absorption and better dimensional stability
• PC has higher ductility and fracture toughness compared to POM

POM vs Polyimide

• Polyimide can withstand much higher temperatures than POM
• It has excellent strength retention at high temperatures vs POM
• POM offers better impact strength and machinability
• Polyimide has superior wear resistance and chemical resistance
• POM has lower density and moisture absorption compared to polyimide

source:beeplastic.com

Today's KNOWLEDGE Share : THE REAL SCENARIO IN EUROPE CHEMICAL INDUSTRY

Today's KNOWLEDGE Share

Europe is….

losing chemical capacity….

at high pace……

Imports from China are up 27%, deliveries from the US have increased by 17%, while more than 20% of European chemical production has been lost since 2021, much of it permanently. This is not a temporary cycle but a structural change in global competitiveness.

Producers in China and the US benefit from lower energy costs, significant overcapacity, and supportive trade frameworks. European producers, by contrast, face persistently high costs, lengthy approval processes, and regulatory uncertainty. Under these conditions, competing on price alone becomes increasingly difficult.

The impact is visible across the value chain. Plants are being shut down, integrated sites are weakened, and interconnected chemical clusters are at risk. Calls for protective measures are therefore understandable, but protection alone will not secure Europe’s industrial base.

What Europe needs is a clear focus on competitiveness, affordable and reliable energy, faster permitting, realistic transformation pathways, and an industrial policy that balances ambition with economic feasibility. Without a strong base chemical industry, downstream sectors such as pharmaceuticals, materials, and the energy transition itself are put at risk.

The key question is no longer whether capacity will leave Europe, but how much, and how quickly.

source : Markus Hartung

#ChemicalIndustry

🍽️ Rethinking Waste, Powering Travel 🚍

 In Sweden, yesterday’s food scraps are powering today’s buses, trucks, and garbage collection vehicles. What sounds futuristic is already a reality—and a blueprint for circular, low-carbon cities.

Here’s how it works:

👉 Households separate food waste from other trash.

👉 Waste is collected and sent to biogas plants.

👉 Through anaerobic digestion, organic leftovers are transformed into bio-CNG (compressed natural gas).

👉 This clean, renewable fuel powers public transport, closing the loop between consumption and energy.

🌱 Why it matters for climate and cities:

Each ton of food waste diverted prevents the release of methane, a greenhouse gas 25 times more potent than CO₂.

Cities reduce dependence on fossil fuels while lowering air pollution.

Public transport becomes greener, cheaper, and circular, demonstrating that everyday waste can be a valuable energy resource.

Sweden’s approach proves that solutions to climate challenges don’t always require high-tech innovation—sometimes, it’s about rethinking what is considered waste. Scaling this globally could drastically cut urban emissions, improve air quality, and accelerate the transition to Net Zero.

Food waste isn’t just trash—it’s an untapped energy goldmine. Circular thinking can turn yesterday’s leftovers into tomorrow’s clean energy, powering cities while protecting the climate.

Would you ride a bus fueled by last night’s dinner? The future of sustainable transport might be closer than it seems.

Image Credit: Wangechi Kuria

source : Waste Innovation Stories

Bosch manufactures one of its drills using only recycled technical plastics:

Reinforced plastics, or composite materials, are always more difficult to recycle than other materials such as metals. Nevertheless, Bosch decided to try to reduce the carbon footprint of its power tools, which are largely made from engineering plastics. In this context, the company launched a pilot project to produce a special edition of its UniversalImpact 800 hammer drill, whose casing – all visible external components of the main product, except for cables and accessories – would be made with the highest possible proportion of recycled engineering plastics from old appliances, without compromising appearance, feel and quality.

It was clear that products made from recycled materials had to retain the characteristics of those made from virgin materials, i.e. their ability to withstand both variable thermal stresses and impact loads during drop tests. In addition, Bosch wanted the recycled material to be able to be integrated into regular production lines without any adjustments. “The challenge was to achieve a series production quality for our special edition based on old devices – this was completely new territory, without established standards or years of practical experience,” explains Thomas Hampel, Sustainability Expert at Bosch Power Tools.

A pioneering project for the circularity of engineering plastics

Before producing the Closed-Loop edition of its UniversalImpact 800 hammer drill, Bosch conducted a feasibility study in which thousands of discarded power tools were collected, dismantled and analysed. Subsequently, only technically suitable and legally approved plastics were used to manufacture the recycled edition of the UniversalImpact 800. The Bosch team was able to use the recovered material directly, without adding any additives or additional glass fibres, and the final material met all the usual quality requirements.

The success of this pioneering project has become a model for other circular economy initiatives. Bosch’s closed loop has been certified by TÜV Süd. Bosch’s UniversalImpact 800 Closed-Loop Edition contains 78% recycled materials, but this does not mean that recycled engineering plastic cannot be used on its own. The remaining 22% consists of components such as switches, mandrels and soft handles, which are made from other types of plastic or different colours.

With this project, we are demonstrating that we can indeed circulate technical plastic. The project targets several key areas of our sustainability strategy: responsible material use, circularity and CO₂ reduction,” explains Anne Purper, Circular Economy Project Manager at Bosch Power Tools.

picture: Bosch

source: Jeccomposites

Today's KNOWLEDGE Share : Color control and Waste prevention

Today's KNOWLEDGE Share

The process appears to run correctly through all its stages: crystallization and pre-drying, extrusion, pelletizing and post-crystallization.

The pellets coming out of the centrifuge are white and glossy, have a homogeneous IV value and are ready for the final step of IV-boosting and decontamination (super-clean).

They are then reheated and fed into the Solid State Polycondensation (SSP) tower - under nitrogen atmosphere or under vacuum with nitrogen flow.

🟥 But here a problem arises: 𝘁𝗵𝗲 𝗽𝗲𝗹𝗹𝗲𝘁𝘀 𝗲𝘅𝗶𝘁𝗶𝗻𝗴 𝘁𝗵𝗲 𝗿𝗲𝗮𝗰𝘁𝗼𝗿 𝗮𝗿𝗲 𝘃𝗶𝘀𝗶𝗯𝗹𝘆 𝘆𝗲𝗹𝗹𝗼𝘄𝗲𝗱.

The heat required for the polycondensation reaction has triggered a 𝘁𝗵𝗲𝗿𝗺𝗮𝗹 𝗱𝗲𝗴𝗿𝗮𝗱𝗮𝘁𝗶𝗼𝗻 that did not appear in the previous stages.

Pellets that were formally suitable up to that point suddenly become 𝗻𝗼𝗻-𝗰𝗼𝗺𝗽𝗹𝗶𝗮𝗻𝘁 𝗳𝗼𝗿 𝗳𝗼𝗼𝗱-𝗰𝗼𝗻𝘁𝗮𝗰𝘁 𝗮𝗽𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻𝘀: they may be downgraded and sold for alternative uses (e.g., strapping) or reprocessed, but they can no longer be used in food-grade applications.

The result is the 𝗹𝗼𝘀𝘀 𝗼𝗳 𝘁𝗼𝗻𝘀 𝗼𝗳 𝗺𝗮𝘁𝗲𝗿𝗶𝗮𝗹, 𝘄𝗮𝘀𝘁𝗲𝗱 𝗸𝗪𝗵 𝗼𝗳 𝗲𝗻𝗲𝗿𝗴𝘆, 𝗻𝗶𝘁𝗿𝗼𝗴𝗲𝗻 𝗮𝗻𝗱 𝗼𝘁𝗵𝗲𝗿 𝗼𝗽𝗲𝗿𝗮𝘁𝗶𝗼𝗻𝗮𝗹 𝗰𝗼𝘀𝘁𝘀 - all inevitably thrown away.

💡 𝗧𝗵𝗶𝘀 𝘀𝗰𝗲𝗻𝗮𝗿𝗶𝗼 𝗰𝗮𝗻 𝗼𝗰𝗰𝘂𝗿 𝗶𝗻 𝗿𝗣𝗘𝗧 𝗯𝗼𝘁𝘁𝗹𝗲-𝘁𝗼-𝗯𝗼𝘁𝘁𝗹𝗲 𝗽𝗹𝗮𝗻𝘁𝘀 𝘄𝗵𝗲𝗿𝗲 𝘁𝗵𝗲 𝗦𝗦𝗣 𝗿𝗲𝗮𝗰𝘁𝗼𝗿 𝗶𝘀 𝗽𝗼𝘀𝗶𝘁𝗶𝗼𝗻𝗲𝗱 𝗮𝘁 𝘁𝗵𝗲 𝗲𝗻𝗱 𝗼𝗳 𝘁𝗵𝗲 𝗹𝗶𝗻𝗲 – 𝗮𝗳𝘁𝗲𝗿 𝗲𝘅𝘁𝗿𝘂𝘀𝗶𝗼𝗻 𝗮𝗻𝗱 𝗽𝗲𝗹𝗹𝗲𝘁𝗶𝘇𝗶𝗻𝗴.

At that stage, the only corrective action is to over-dose the melt with anti-yellow additives - even when, in reality, they would not be needed.

🟩 The 𝘀𝘁𝗿𝗮𝘁𝗲𝗴𝗶𝗰 𝗰𝗼𝗻𝗳𝗶𝗴𝘂𝗿𝗮𝘁𝗶𝗼𝗻 of the 𝗶𝗤𝗼𝗻𝗶𝗰𝗧𝘄𝗶𝗻 𝗛𝘆𝗽𝗲𝗿𝗣𝗘𝗧 stands in sharp contrast to competing mechanical-recycling systems, because 𝘁𝗵𝗲 𝗦𝗼𝗹𝗶𝗱 𝗦𝘁𝗮𝘁𝗲 𝗣𝗼𝗹𝘆𝗰𝗼𝗻𝗱𝗲𝗻𝘀𝗮𝘁𝗶𝗼𝗻 (𝗦𝗦𝗣) 𝘀𝘁𝗮𝗴𝗲 𝗶𝘀 𝗽𝗲𝗿𝗳𝗼𝗿𝗺𝗲𝗱 𝗯𝗲𝗳𝗼𝗿𝗲 𝗲𝘅𝘁𝗿𝘂𝘀𝗶𝗼𝗻.

This approach delivers at least three decisive advantages:

✅ Color correction can be applied to the pellets only when needed and in the exact required amount.

✅ Pellets with non-conforming color are identified 𝘣𝘦𝘧𝘰𝘳𝘦 entering the so-called “food” storage area and can therefore be immediately diverted to the “non-food” zone, preventing contamination.

✅ Production can be stopped instantly if the incoming material shows abnormal levels of non-conformity, avoiding tons of already-extruded waste.

📌𝗖𝗼𝗹𝗼𝗿 𝗰𝗼𝗻𝘁𝗿𝗼𝗹 𝗮𝗻𝗱 𝘄𝗮𝘀𝘁𝗲 𝗽𝗿𝗲𝘃𝗲𝗻𝘁𝗶𝗼𝗻 are only some of the benefits enabled by the strategic configuration of the 𝗶𝗤𝗼𝗻𝗶𝗰𝗧𝘄𝗶𝗻 𝗛𝘆𝗽𝗲𝗿𝗣𝗘𝗧 by MAS Austria.

source : Christian Schiavolin

#PETrecycling

𝗔𝗺𝗲𝗿𝗶𝗰𝗮’𝘀 𝗠𝗮𝗴𝗻𝗲𝘁 𝗠𝗼𝗺𝗲𝗻𝘁

 𝗔𝗺𝗲𝗿𝗶𝗰𝗮’𝘀 𝗠𝗮𝗴𝗻𝗲𝘁 𝗠𝗼𝗺𝗲𝗻𝘁

North America’s #magnet industry is quietly powering into a new era

Now worth $𝟱.𝟭𝗕 and growing faster than global averages at 𝟱.𝟱%

1️⃣ 𝗡𝗱𝗙𝗲𝗕 magnets dominate with 𝟱𝟭% market share, driven by EV and wind growth.

2️⃣ #Automotive accounts for nearly 40% of demand, making magnets the new oil wells of electrification.

3️⃣ U.S. policy and capital are fueling domestic production, #recycling, and feedstock recovery.

𝗕𝗨𝗧:

China still refines 90% of #NdFeB and controls most magnet patents and pricing.

At 𝗥𝗮𝗿𝗲 𝗘𝗮𝗿𝘁𝗵 𝗘𝘅𝗰𝗵𝗮𝗻𝗴𝗲𝘀, our latest Magnet Market Rankings show which North American projects are best positioned to close that gap

🔗https://lnkd.in/ei28BiRX

🔗https://lnkd.in/efqzt3bn

source : Rare Earth Exchanges