Today's KNOWLEDGE Share:Plastic fork

Today's KNOWLEDGE Share:

Plastic fork

I was travelling a few weeks ago and between flights grabbed some dinner at the Atlanta airport. I got my food and along with it came a plastic fork – nothing unusual there. As I looked around from my table, I noticed that there were signs indicating that the utensils were made from compostable material and that they were environmentally friendly. Cool, I thought. As I was eating, I noticed molded-in writing on my fork. On the top surface the fork was labelled as “Compostable Commercially*”. I thought it was funny that there was an asterisk. What could that be about I wondered, until I noticed even smaller molded-in printing on the reverse side. The reverse side markings indicated “*Facilities may not exist in your area.” Ahh – the asterisk is explained.

My curiosity was peaked - what is this *compostable* fork made from? I took the fork and when I returned to the office, I analyzed it. The first test I ran was Fourier transform infrared spectroscopy (FTIR). This identified the fork material as polylactic acid (PLA). This made sense because I found that PLA is compostable under controlled conditions.

Next, the material was analyzed using differential scanning calorimetry (DSC). This thermal analysis technique identified a glass transition temperature (Tg) of 65 °C and a melting point (Tm) of 177 °C. Both of these were consistent with a PLA resin.

Finally, thermogravimetric analysis was utilized, and this indicated that the base polymer underwent thermal degradation at 349 °C. Further, the composition was characterized with a nominal filler content of 15%.

On the non-technical side, I noticed that there were no special receptacles at the airport to collect these compostable utensils, and that people were throwing them into the garbage. From the little I know; I do not think that these PLA forks will compost in a landfill.

Source:The Madison Group

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#plastics #polymerengineering #polymerscience #materialsscience #forks #pla #compostable #ftir #dsc #tga #analysis #biobased #molded #food #printing #utensils

Today's KNOWLEDGE Share: Unbalanced Force

Today's KNOWLEDGE Share:

Unbalanced Force:

Based on consulting requests, I realize that a lot of people forget that huge forces are developed during the molding process, as a result of pressure levels exceeding often 1000 bar/100MPa.

That amounts to 1 metric Ton of equivalent force applied to each square cm of tool surface.That is why clamp tonnage numbers are what they are of course.

But, no matter how good your steel or tool design is, metal will bend significantly when subjected to huge unbalanced forces.

And, even more surprisingly, for balanced forces, the cavity will expand by "compressing" the steel by quite a few microns !

You can run a quick FEA to check that, by applying 1000-2000 bar on a piece of steel.

Of course tubular shaped parts will readily see significant core shift problems as soon as flow is slightly unbalanced, since a differential of a few Tons-force can quickly appear if flow is not perfectly balanced. The problem here is, of course, that the more the core deflects, the more the unbalance grows. So it is a bad case of positive feedback leading to catastrophic results (unexpected weldlines in the thinned side towards which the core has been bent/pushed).

Don't underestimate the importance of these effects in molding.

While coupling Flow Analysis with stress analysis on the steel structure can supposedly model this, it is very challenging to describe the complex tool assembly. And such coupled approaches can be very challenging numerically. So, while core-shifting predictions are now quite standard, full tool deflections are usually neglected in simulations. And the clear tendency of steel compressibility to lead to overpack is never accounted for.

Source:Vito Leo

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#plastics #polymerscience #plasticsengineering #tooling #steel  #polymerprocessing #injectionmoulding

Covestro & Partner Recover Raw Materials by Chemical Recycling of PU Foam

Covestro and Recticel demonstrate the two main raw materials originally used in flexible polyurethane (PU) foam from mattresses can be recovered by chemical means to a high level of quality and purity from the outcome of Europe-wide research project "PUReSmart".

For the first time, a flexible foam sample has now been produced from fully recycled polyol and toluene diisocyanate (TDI), respectively. Both raw materials were obtained in Covestro’s pilot plant in Leverkusen.

Polyol & TDA Recovery by Chemolysis:

Unlike other chemical processes for recycling PU flexible foam, the process does not use fossil-based polyol. It requires only the pre-sorted foam from mattress waste, a glycol and an additive. During chemolysis, the polyol and toluene diamine (TDA), the precursor to TDI, are recovered in high purity and yield.

After reprocessing, they can be used again as often as required for the production of new PU flexible foams. This ensures a sustainable circular economy for PU flexible foam with a reduced CO2 footprint.

"With this we have fully achieved the goal of developing a technology to chemically recycle these products and convert polyurethane into a high-quality recycled material," says Bart Haelterman, R&D director at Recticel. "For the first time in history polyurethane is truly fitting into a circular economy." The European Union funded the PUReSmart project with six million euros over a four-year period under its Horizon 2020 research and innovation program (agreement No. 814543).

Development of Flexible Foam Recycling:

Building on the PUReSmart project, Covestro is working with partners from the waste management industry to drive the further development of flexible foam recycling through to industrial use.

"Our goal is to turn waste into valuable raw materials and to anchor the principle of the circular economy in our company and along the value chain with our partners to achieve this," says Christine Mendoza-Frohn, head of Performance Materials Sales EMEA & LATAM of Covestro.

"That’s why we make innovative recycling a priority. We call this ongoing Evolution of Recycling: Evocycle® CQ. The first initiative of this kind is dedicated to the chemolysis of PU mattress foam and is called 'Evocycle® CQ Mattress'. This underlines our willingness to further invest in this technology," says Mendoza-Frohn.

Source:Covestro/specialchem

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#polyurethane #polyurethanefoam #recycling #circulareconomy

#mattresses #wastemanagement

Today's KNOWLEDGE Share: Translucent composite tiles

Today's KNOWLEDGE Share:

Translucent composite tiles for natural lighting and energy savings!

More than reducing the electricity bill, companies can improve their work environment by including these GFRP tiles, which have high thermal resistance, on their buildings!

In addition to opaque composite roof tiles, Planefibra is adding translucent versions to its product offerings, highlighting their advantage in providing natural lighting to reduce electricity use, while blocking direct solar radiation to prevent overheating in buildings. According to the company’s website, the translucent tiles are made from glass fiber-reinforced polyester and have UV protection film on both sides.

“Natural lighting strengthens the sustainable profile of companies because consuming less, under any circumstances, preserves the environment. It is also an important ally in improving workplace conditions,”

Depending on the dimensions of the building, the season of the year and the incidence of sunlight, that companies are able to reduce their energy bill by up to 95% with lighting during business hours when using its composite tiles. “To obtain this result, the ideal is to cover 10% of the shed area with translucent tiles.

With a minimum useful life of ten years, composite tiles have high thermal resistance. That is, even in places where the incidence of sunlight is high, there is said to be no risk of the roof deforming. Another advantage is the production of custom-made tiles, which adapt to the various existing roofing models. “Add to that the price, on average, 30% lower than polycarbonate tiles, the main competitor of those made of composites.

Source: CompositesWorld/ #managingcomposites #thenativelab
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#composites #polyester #gfrp #tiles #lighting #roofing

Today's KNOWLEDGE Share: Solar Panels burning:

Today's KNOWLEDGE Share:

Solar Panels burning:
Solar panels typically do not burn on their own. However, if a malfunction or failure occurs within the solar panel system, it can lead to overheating and potentially cause a fire. This can happen due to a variety of reasons, such as faulty wiring, damage to the panel itself, or an electrical surge.

It's worth noting that incidents of solar panel fires are relatively rare and usually occur due to improper installation or maintenance. To prevent fires, it's essential to have a professional installer properly set up and maintain the solar panel system, ensuring all components are functioning correctly and safely. Additionally, it's important to follow proper safety guidelines when handling and installing solar panels.

Source:Capstone/renewable Energy experts
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#solarenergy #solarpanels #maintenance #electrical #safety #burn
#solar #alternativeenergy #renewableenergy

Today's KNOWLEDGE Share:Lubricant:

Today's KNOWLEDGE Share:

Lubricant:

Some molding compounds contain a so-called "external lubricant". It is essentially a second immiscible polymeric material with a much lower viscosity.

What happens when you mold such materials ?

In extrusion things are quite obvious. The hydrodynamic forces push the dispersed lubricant to the surface of the die where they can act as expected and promote slip of the major phase polymer.

In Injection Molding the combination of the Fountain flow, moving inner flow layers to the very edge, and the presence of a frozen skin, create a more complex situation.

The high shear layer where lubricant will accumulate is INSIDE the frozen skin ! While this can still help to reduce the pressure to fill, this situation will also induce a serious risk of blistering/delamination.

This delamination was well known for instance in the Xenoy grade made of PC/PBT. But other compounds, containing for instance a silicon based lubricant, will produce the same result, as reported by some of my customers.

So, keep in mind that the lubricant (possibly necessary at the outer surface of the molded part if the intention is to control friction coefficient) doesn't quite go where you'd hope to see it.

Note that this delamination can also occasionally be observed in pure HDPE if the molecular weight is high enough. In this case the low molecular tail (waxes) will accumulate at the frozen skin interface, promoting delamination.

Source:Vito Leo

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#injectionmolding #lubrication #plastics #polymerscience #medicaldevices #delamination #extrusion

Today's KNOWLEDGE Share:Failure Analysis of PC hub

Today's KNOWLEDGE Share:

Failure Analysis of PC hub

I recently completed a failure analysis on a polycarbonate hub used to secure a steel tube. A number of parts had cracked while undergoing engineering use testing in the laboratory. The fractographic examination, which included scanning electron microscopy (SEM), revealed fracture surface features that indicated that the parts failed though the application of stress at a high strain rate. It was concluded that the engineering testing produced rapid mechanical overload, in which the stresses exceeded the short-term strength of the material. Plastic materials, including polycarbonate, can undergo a ductile-to-brittle transition associated with high strain rate events.

The high strain rate failure mechanism was specifically identified in the SEM images by the presence of features known as river markings. They extended out from and bounded the crack origin. The crack origin area also displayed a relatively smooth texture, which was indicative of a brittle fracture mode. The cracking initiated with a design corner (yellow circle), which likely acted as a point of stress concentration.

Source:The Madison Group

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#failureanalysis #plastics #fractography #SEM #polymerscience #materialsscience #polycarbonate #plasticengineering #crack #stress #fracture