Wednesday, 29 June 2022

Summary of Testing Standards for Polymer Material Selection

Hello and welcome to a new post.  Looking at a technical data sheet of an engineering polymer, we can find the values and also the standard how this value was estimated. 

It is helpful in the material screening phase during polymer selection for your application to have a feeling which tests can be done and what standards are linked to them. 

In general there are two standardization companies: the American Society for Testing and Materials (ASTM) and  the International Organization for Standardization (ISO). Both are well known organizations in the plastics industry. 

Apart from plastic tests, they also develop all kinds of standards for different industries.

ASTM vs ISO - Are they the same? 

Results of ASTM and ISO are similar and there are one-to-one correlations of some ASTM and ISO standards. 

ASTM and ISO differ in measurement procedures and conditions leading to slightly different results.

Example tensile modulus

The plastic's tensile modulus can be measured according to ASTM D638 or ISO 527-1. Looking at the results, they are similar however not the same. 

There are cases where they are the same, however they are rare cases.

Overview of plastics testing standards: mechanical, thermal, and electrical. 

Figure 1 shows the summary of the mechanical standards, Figure 2 of the thermal standards, and Figure 2 of the electrical standards. 

Figure 1: Overview Standards for Mechanical Tests

Figure 2: Overview Standards for Thermal Tests

Figure 3: Overview Standards for Electrical Tests

There are more standards which can be accessed over the ASTM and ISO homepages. 

Also I made a video where I compare the ASTM/ISO data with real world application requieremnts: 


Thanks for reading and #findoutaboutplastics

Greetings

Herwig 

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Tuesday, 21 June 2022

Ocean Plastics Episode 2 - What The Media, NGOs and Others Still Not Tell You

Ocean Plastics - Episode 2

Hello and welcome back to a new post. Today we continue with Episode 2 of  “Ocean Plastics”. 

Here is the link to Episode1.

Media and NGOs are pushing the topic of ocean plastic contamination in their publications up and down in turn for attention and more funding. It was already proven by Mr. DeArmitt and others that the science was ignored in most cases and even pictures of turtles were photo shopped to make it even more dramatic.

Due to the low density of plastics (0.9 -1 g/ccm) they are floating on and right beneath the water surface which allows them to be relatively easy to bee seen. 

Since plastics represent only 1% of the material and waste, following key question opens up to me: 

What else is in and on the ground of our seas? 

Turns out a lot! Let us examine in detail. 

Oil 

Oil represents a large share of sea pollutants. It was estimated that there are 6,300 wrecks, sunk in World War II, rusting at sea for more than 70 years. Researchers estimate the amount of oil left in them at up to 15 million tons. If the oil storage of the wrecks starts to burst, oil spills will destroy all the plant and animal life of a particular region. Additionally to the 6,300 potentially polluting wrecks around the world, there are 1,583 tank vessels which are a ticking bomb too. Apart from oil, a warship itself contains huge quantities of bronze, brass, copper, and other non-ferrous metals. Interesting is the low-background steel from wrecks sunk before 1945 since this type of steel is not emitting ionizing radiation.

Heavy metals

Metals with a density greater than 3.5 g/ccm can be classed as heavy metals. In this category fall copper, nickel, cadmium, iron, lead, mercury and zinc. Out of the aforementioned metals, lead, mercury and cadmium are the most concerning for sea life. Due to increased industrial activity, heavy metals get into the atmosphere and from there they end up in the oceans. 

Radioactive waste

Mr. Calmet investigated back in 1989 the radioactive waste disposal in oceans and found out that thirteen countries used ocean disposal to get rid of their radioactive waste. 200,000 tons in nuclear waste was approximated which derives mainly from the medical, research and nuclear industry.

Airplanes

Particularly in the WWII area, hundreds of airplanes found their last station on the bottom of the sea. Similar to ship wrecks, they have oil and ammunition which can impact sea life.

Ocean dumping in the United States prior to 1972

The US National Academy of Sciences estimated in 1968 the following annual volumes of ocean dumping by vessel or pipes: 

-100 million tons of petroleum products;

-two to four million tons of acid chemical wastes from pulp mills;

-more than one million tons of heavy metals in industrial wastes; and

-more than 100,000 tons of organic chemical wastes.

Conclusion

The "out of sight, out of mind” attitude for dumping waste into our ocean is wrong. Also, blaming plastics to be the number one littering source for our oceans is wrong too. The data speaks a clear language. There is more and more ideological thinking involved in such anti-plastics topics and too less decision making based on facts. Plastics are part of our solution and are not the problem. 

Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig 

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature:

[1] https://www.linkedin.com/pulse/plastic-fact-over-fiction-chris-dearmitt-phd-frsc-fimmm/

[2] https://www.newscientist.com/article/mg20727761-600-why-wartime-wrecks-are-slicking-time-bombs/

[3] https://www.youtube.com/watch?v=XgdE55ZAFvs&t=4s

[4] Michael F. Ashby: Materials and the Environment: Eco-informed Material Choice

[5] https://assembly.coe.int/nw/xml/XRef/Xref-XML2HTML-en.asp?fileid=18077&lang=en

[6] https://www.envirotech-online.com/news/water-wastewater/9/breaking-news/why-is-there-heavy-metal-in-our-oceans/32291

[7]https://www.todayifoundout.com/index.php/2020/12/the-bizarre-market-for-old-battleship-steel/

[8] https://inis.iaea.org/search/searchsinglerecord.aspx?recordsFor=SingleRecord&RN=21044010

[9] https://www.epa.gov/ocean-dumping/learn-about-ocean-dumping#Before

[10] https://www.findoutaboutplastics.com/2018/08/what-media-does-not-tell-you-about.html

[11] https://plasticsparadox.com/

Friday, 17 June 2022

Flame Retardants - Why Do We Need Them and What Are The Major Systems?

Hello and welcome to a new blog post. Today with the topic of flame retardants, starting with an overview and then discussing as an example effective flame retardants for Polyamides. 

Why do we need flame retardants in plastics?

In general, adding flame retardants to your polymer compound formulation helps to prevent the immediate start of fire or slowing the growth of fire of your material. This in turn helps to fulfill a certain burning classification such as the UL V0 at a certain material thickness. The material requirement list of your application should consider flame rating needs since it will be easier later during polymer material selection to not miss such an important detail. 

Do all polymers need them?

Aliphatic polymers need them to achieve a desired level of UL V0. Semi-aromatic polymers such as PPS do not need them since the benzene rings enable an intrinsic flame retardancy. As a rule of thumb the higher the aromatic amount (benzene) the better the flame retardancy level of your polymer compound. 

Overview of the 3 major systems

There are three major systems used in the plastics industry: nitrogen-phosphorus systems, halogenated systems, and metal-hydroxide systems.

Nitrogen-phosphorus systems are halogen free and show a lower smoke emission compared to halogenated flame retardants. Furthermore they do not decrease the mechanical properties of your base polymer too much. Usually, adding the flame retardants results in a lowering of properties. Downside of this system is the narrow production window, water solubility and poss surface aesthetics. 

Halogenated systems are very good flame retardants and can be used at low concentration levels, together with a wide production window. Major disadvantage is the use of halogens (pay attention to local regulations) and during combustion it develops a lot of smoke emissions, together with the release of free radicals. Also, stabilization against weathering is not possible. 

Metal-hydroxide systems are halogen free and stabilization towards weathering is possible. During combustion, this system only releases water. Downside is the high concentration of flame retardant needed, and lower mechanical properties as a result. 

Figure 1 summarizes the advantages and disadvantages of the different flame retardant systems. 

Figure 1: Comparison of the advantages and disadvantages of the different flame retardant systems

Example: Use of flame retardants in Polyamide PA 6

Alumina Trihydrate (ATH) is a widely used flame retardant and can be a starting point for Polyamide 6. The decomposition temperature of ATH is around 180°C and it releases water.  However, the compounding and processing temperature of PA 6 is between 230°C and 290°C which leads to an activation of the decomposition of ATH. Therefore we need an alternative to safely bring PA 6 onto a certain flame rating. The solution is in Magnesium Hydroxide (MDH) which has a decomposition temperature of 330°C. Apart of MDH, boron zinc oxide and organophosphorus salt can be used for high performance Polyamides such as PPA and PARA. 

Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig 

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature: 

[1] https://www.hubermaterials.com/products/flame-retardants-smoke-suppressants/flame-retardant-smoke-suppressant-applications.aspx

[2] https://www.findoutaboutplastics.com/2019/03/plastics-part-design-continuous-use.html


Wednesday, 8 June 2022

Plastic Part Design Properties for Engineers - HDT @ 1.82 MPa Filled and Unfilled Thermoplastics

Hello and welcome to a new blog post. Today we have a look at the HDT (1.82 MPa) of filled and unfilled amorphous and semi-crystalline polymers. 

In a previous post we discussed the HDT values of high performance polymers such as PPS and PEEK. In general the Heat Deflection Temperature or Heat Distortion Temperature (HDT) describes the temperature at which a polymer test bar bends 0.25 mm under a given load and is estimated by the ASTM D 648 or ISO 75. Apart from the DMA, HDT can be used to predict the maximum service temperature of parts under mechanical loads. For this the HDT at 1.8 MPa is used. It can be measured at 0.46 MPa and 8 MPa too. 

HDT @ 1.82 MPa of filled and unfilled thermoplastics

Figure 1 shows the HDT values at 1.8 MPa loading for unfilled and filled (30% glass fiber) amorphous and semi-crystalline polymers. 

HDT @ 1.82 MPa of filled and unfilled thermoplastics

Are there differences in the HDT between amorphous and semi-crystalline polymers when they are filled with glass fibers?

Yes, there are differences. Amorphous polymers such as Polystyrene, ABS, Polycarbonate, and Polysulfones show a minimal effect in change of HDT with glass fiber incorporation. However, semicrystalline polymers show large effects and the HDT value can be increased. For unfilled semicrystalline polymers, the HDT is close to the glass transition temperature and the filled version have a HDT close to the melting temperature. 

How does the HDT with other fillers such as mineral?

Figure 2 compares the HDT of glass and of mineral filled PA 6.6 and PEI. Mineral filler increases the HDT of semi-crystalline polymers, however not as much as glass fibers. Amorphous polymers show again a lower impact in terms of HDT increase. 

Figure 2: Comparison of PA 6.6 and PEI filled with glass and mineral

This needs to be kept in mind during your part design phase and polymer material selection, especially for technical parts and temperature load, glass fiber reinforced materials can make the difference. 

Check also out my UL RTI vs. HDT post here

Thanks for reading!

Greetings and #findoutaboutplastics

Herwig 

Literature:

[1]  McKeen - the effect of temperature and other factors on plastics and elastomers

[2] https://www.findoutaboutplastics.com/2021/09/design-properties-for-engineers-ul-rti.html


Friday, 27 May 2022

Plastic Part Design Properties for Engineers - Water Uptake of Aliphatic Polyamides

Hello and welcome back to a new post. Today we discuss the water and moisture uptake of aliphatic short and long chain Polyamides. In a previous post I discussed the water uptake for high performance polymers - check it out here. Here you can find a collection of all my "Design Properties for Plastics Engineering" posts. 

Properties of Polyamides

In general, Polyamides are often used as engineering material due to their high thermal stability, very good strength and hardness, combined with high mechanical damping characteristics and good chemical resistance. However, all Polyamides are hygroscopic due to the polar amide groups which form hydrogen bonds with water. Water absorption (at a given temperature and relative humidity) is proportional to the amount of amorphous part of the Polyamide. As a consequence, the water acts as a plasticizer and lowers the mechanical properties. At higher temperatures, hydrolysis can take place too. 

How much is the water uptake of aliphatic Polyamides? 

Figure 1 shows the water uptake situation of the most used aliphatic Polyamides at equilibrium in 50% relative humidity and at equilibrium in complete saturation.

Figure 1: Water uptake data of most used aliphatic Polyamides

Long chain aliphatic Polyamides such as PA 6.10, PA 6.12, PA 11, and PA 12 show a lower water absorption compared to PA 6, PA 6.6, and PA 4.6.  Higher dimensional stability, together with low variation in the properties during ambient humidity changes are the result. Major reason for the lower water uptake is the relatively long hydrocarbon chain length (limiting the amide groups to form hydrogen bonds with water).

Important during material selection is the consideration of the  behavior of Polyamides when they are exposed to water (part immersion) or humid environment. The part dimensions need to be still kept within the specified tolerance. 

Thank you for reading and #findoutaboutplastics

Greetings, 

Herwig 

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature:

[1] https://www.findoutaboutplastics.com/2020/12/design-properties-for-engineers-water.html

[2] https://www.sciencedirect.com/science/article/pii/S2590048X20300911

[3] https://www.hanser-elibrary.com/doi/book/10.3139/9783446437296


Sunday, 22 May 2022

The Penguin Circle - A Symbol For Teamwork and Leadership

Hello and welcome to a new post. Today we have leadership and teamwork as the main topic, always in relation to the plastics industry. Read my leadership series here. 

The Penguin Circle - Teamwork and Leadership (Findoutaboutplastics.com / Herwig Juster)

Penguins - fighting the chilling freeze by huddling

Emperor penguins have their home in the Antarctic which is known to be a harsh environment with chilling temperatures. Penguins huddle together to heat up and stay warm. They also take turns to be in the center of the huddle. Researchers found it can get up to 37°C in the center of the huddle which can be too hot for the penguins. Also for breeding the circle formation is important since the male penguin takes care of the egg which is placed between the legs. 

Why is the Penguin circle so important?

What is valid for penguins is also valid for us: forming circles and huddling protects us from harsh cold conditions. It is better to be in the circle, otherwise you will freeze and face the danger of not surviving. The circle has several meanings. Most of us know the “Circle of Life” philosophy (life starts at the end and ends in the beginning), however the aforementioned penguin example shows the circle as a powerful symbol for teamwork and reaching goals together. 

Plastics industry - is the circle closed? 

In our plastics industry environment, tasks became complex and multi-leveled so that working together in teams is essential. It is in particular the interfaces between project stages, product development stages or production that bring challenges. It is well reported that other industries such as automotive, have to deal most of the time with interface challenges. Also, circular economy embraces to keep polymers in a loop.

Altogether, developing a feeling and empathy for the other working areas will help to close the circle and make the upcoming tasks more successful. 

Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig 

#findoutaboutplastics

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature:

[1] https://www.gizmodo.com.au/2015/12/the-social-dynamics-of-penguin-huddles-are-more-complex-than-we-thought/

[2] https://theconversation.com/curious-kids-how-can-penguins-stay-warm-in-the-freezing-cold-waters-of-antarctica-116831#:~:text=Male%20emperor%20penguins%20gather%20close,huddle%20is%20below%20%2D30%E2%84%83.


Thursday, 19 May 2022

6 Major Benefits of Injection Moulding Simulation in Polymer Part Design and Material Selection

Hello and welcome to a new blog post. Today we have a closer look at how injection molding simulations support us in part design, polymer material selection and processing.

1. Injection point and gate placement

Finding the optimal injection point and gating is key to fulfill certain aesthetics or warpage requirements. Also, it helps to prevent flow line situations and as a consequence lower mechanical performance of your part. Nowadays most polymer injection molding simulations have gate placement tools integrated which can recommend you the optimal injection point. 

2. Placement and balancing of runners

Bringing the molten polymers towards the cavity, runners (thin channels) are needed. Aim is to ensure an even filling of your cavity. Runner analysis is hand in hand with the gating analysis from the previous point and most simulation software have a runner balance tool too. 

3. Warpage and shrinkage situation 

Analyzing the shrinkage and warpage situation is in particular needed when you use fiber-reinforced polymers which have an effect on the shrinkage and warpage of your part. Filling simulation can use the information of the velocity vectors to predict fiber behavior in the final part. And over this route, calculate the effect on shrinkage and warpage. 

4. Packing situation 

Analyzing the packing situation allows you to set the packing pressure and time for your part. There are several factors such as the material and mould shape which are influencing the packing. Packing analysis covers the prediction of the gate freeze time, clamping force needed in this phase, and predict areas where high volumetric shrinkage may appear. 

5. Cooling - mold 

There are injection moulding simulation tools which allow a design and optimization of the cooling channel layout of your moving and fixed moulding half. However, most tools simulate a uniform mould cooling at a set temperature.

6. Processing - identify critical shear rates

In case you work with polymers which are sensitive to mechanical stresses like shear rates then it is worth to have a plan of action how to locate critical areas and solve them by using simulation or in a simple way with analytic methods.

In the video I made you can see the perforated plate in the version of side gating and central gating. This applied method of shear rate tracer release is possible in the virtual molding package Sigmasoft.

In the following are the four steps of my procedure I use in the post-processing after I have done a process simulation:

1) Watch the shear rate contour plot to get the "big picture"

2) Activate the shear rate tracer

3) Analyze the release places and where the sheared material will end up in the part (to predict if there will be a decrease in the mechanical properties of the part)

4) Make geometry changes or process changes (melt temperature; inlet velocity profile)

The shear rate tracer method helps you to locate the punctual critical areas. So far, those are the advantages of such an approach. Another aspect is that the allover simulation will take more time and more memory as well as more working space.

In detail you can read here about my shear rate analysis. 

What are some of the most used injection moulding simulations?

There are several suppliers and often used are Autodesk Moldflow, SIGMASOFT Virtual Molding, Moldex3D, Vero VISI Flow, Simcon CadMould, and Solidworks Plastics.

Thanks for reading and till next time!

Greetings,

Herwig 

#findoutaboutplastics

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature: 

[1] https://www.findoutaboutplastics.com/2015/04/injection-molding-filling-simulation-my.html

[2] https://www.findoutaboutplastics.com/2018/01/data-is-new-plastic-data-algorithms-in.html

[3] https://www.findoutaboutplastics.com/2021/03/the-future-of-plastics-manufacturing.html

[4]https://www.3erp.com/blog/how-injection-molding-simulation-software-helps-you-design-better-parts/

[5] https://www.downloadcloud.com/injection-molding-software.html


Tuesday, 19 April 2022

Design Properties for Polymer Engineering: Dynamic Mechanical Analysis (DMA) of Reinforced Engineering Polymers

Hello and welcome to a new blog post in which we continue with the DMA data. Today we discuss  reinforced engineering polymers (pls. find here the DMA data of neat resin, and here of high performance polymers)Here you can find the collection of all my posts on design properties for plastics engineering - engineering and high performance polymers.

Reinforcement such as glass fibers can increase thermal and mechanical properties of amorphous and semi-crystalline thermoplastics. 

Example Polyamide 6 (PA 6): neat vs. reinforced polymer

Figure 1 [1] shows an unreinforced Polyamide 6 which has a glass transition temperature of 65°C and a heat deflection temperature (HDT) of 65°C at 1.82 MPa. It can be shown that the modulus declines from 2.81 GPa (pre- Tg) to 0.56 GPa (post-Tg), resulting in a decrease of 80%. 

In the next step we add 14% glass fiber as reinforcements. This amount of glass fibers increases the HDT from 65°C to 200°C at 1.82 MPa. Also, modulus is almost doubled and the decline from pre- to post-Tg is 55% (from 4.46 GPa to 1.98 GPa).

In the last step we add 33% glass fiber reinforcements. In this final case, HDT can be slightly increased to 210°C at 1.82 MPa. However, modulus can be increased to 7.87 GPa and the decline is now below 50% (from 7.87 GPa to 3.99 GPa). 

Figure 1: DMA results of an unreinforced Polyamide 6 and glass fiber reinforced Polyamide 6.

DMA of reinforced engineering polymers (PBT, PA, PC and POK)

Figure 2 shows the elastic modulus of glass fiber reinforced PBT-GF30 (Valox® 420; SABIC), PC-GF20 (Lexan® 3412; SABIC), PA 6-GF30 (Ultramid® B3EG6; BASF), and POK-GF30 (RIAMAXX® HR; RIA-Polymers). 

PBT-GF30 and PA 6-GF30 have a similar elastic modulus behavior over the temperature range. Polyketone with glass fiber reinforcement is superior at lower temperatures, however above room temperature the behavior is similar to Polycarbonate. At higher temperatures (above 150°C), Polyketone is similar to reinforced PA 6 and PBT. 

Figure 2: Elastic modulus of glass fiber reinforced PBT-GF30 (Valox 420; SABIC), PC-GF20 (Lexan 3412; SABIC), PA6-GF30 (Ultramid B3EG6; BASF), and POK-GF30 (RIAMAXX® HR; RIA-Polymers).

All in all, DMA data allow you to decide if the selected material is suitable to fulfill the requirements of your application.

Thanks for reading and #findoutaboutplastics

Greetings, 
Herwig

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature: 
[1] https://www.findoutaboutplastics.com/2020/10/rule-of-thumb-for-plastic-part-design.html
[2] M. Sepe: Dynamic Mechanical Analysis for Plastics Engineering, Elsevier
[3] https://www.findoutaboutplastics.com/2020/07/design-properties-for-engineers-dynamic.html
[4] https://www.findoutaboutplastics.com/2018/12/dynamic-mechanical-analysis-dma-as.html

Sunday, 10 April 2022

Carbonated PET Bottles - Saving Material by Optimization Calculation

PET bottle - Learn how to optimize the wall thickness

Hello and welcome to a new post. Today I will discuss with you how to optimize the wall thickness of well- known PET bottles by using safety factors and the stress equations.

What are some requirements for carbonated bottles?

In general, PET drink containers need to contain the pressure of dissolved C02 safely, easy processing via moulding / blow moulding, transparent or translucent, and must be recyclable. PET bottles are the cheapest solution to fulfill the aforementioned requirements. Next best alternative would be PLA which has the lowest embodied energy [1]. 

What equations do we need?

Figure 1 shows the internal pressure situation of a carbonated drink bottle. Tensile stresses along the walls are created  due to the internal pressure p inside the bottle. There are two stresses, the circumferential stress (𝛔c = pr/t) and the axial stress (𝛔a = pr/2t). t is the wall thickness and r is the radius of the bottle. Based on those, we can derive the must-have wall thickness so that the stresses are not leading to bottle failure: t= S [(pr)/(𝛔y)]. S is representing a safety factor and 𝛔y is the yield strength of the wall material. 

Figure 1: internal pressure situation of a carbonated drink bottle. 


Example: wall optimization of carbonated  PET bottle

In literature it can be found that the working pressure of a standard soda PET bottle is 0.5 MPa and has a diameter of 2r = 64 mm. As a safety factor we take 2.5. 70 MPa is the tensile strength of PET at room temperature. 

How thick do we need to make the walls to handle the pressure safely?

We start with our equation from before: t= S [(pr)/(𝛔y)]

t= 2.5 [(0.5x0.032)/(70)] = 0.00057 m = 0.57 mm

The required wall thickness t is 0.57 mm. After consuming your next soda drink in a PET bottle, you can check the wall thickness and see if the bottle already uses as little PET as possible. 

In another post I show how to select the optimal polymer material for an injection / blow moulded water bottle.

Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig Juster

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature:

[1] Michael Ashby: Materials and the Environment. Eco-informed Material Choice


Thursday, 7 April 2022

Design Properties for Polymer Engineering: Dynamic Mechanical Analysis (DMA) of Unfilled Engineering Polymers

Hello and welcome to a new post. Today I present to you dynamic mechanical analysis (DMA) data of most used unfilled engineering polymers. 

In a previous post we discussed the storage modulus vs. temperature behavior of different high performance amorphous and semicrystalline polymers. Also how DMA can be used as a polymer material selection tool. Here you can find the collection of all my posts on design properties for plastics engineering - engineering and high performance polymers.

In general, the DMA is a thermo-analytical method that estimates the viscoelastic properties of a given material over the course of different temperatures. It steps away from a single point view toward a multipoint data view which is beneficial for polymer material selection tasks.

Figure 1 shows the elastic modulus of ABS, POM, PBT, and PA 6.6 and Figure 2 shows it for PMMA, POK, PC, and mPPE. 

Figure 1: Elastic modulus of ABS, POM, PBT, and PA 6.6 (all unfilled)

Figure 2: Elastic modulus of PMMA, POK,PC, and mPPE (all unfilled)


Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature: 

[1] M. Sepe: Dynamic Mechanical Analysis for Plastics Engineering, Elsevier

[2] https://www.findoutaboutplastics.com/2020/07/design-properties-for-engineers-dynamic.html

[3] https://www.findoutaboutplastics.com/2018/12/dynamic-mechanical-analysis-dma-as.html


Monday, 28 March 2022

Dimensional Stability of Polymer Based Parts after Processing: 3 Considerations

 Hello and welcome back to a new blog post. Today we discuss three considerations for optimal dimensional stability of plastics parts after processing.

Polymer based parts have a dimensional stability which is not equal to that of metals. It can vary with several factors which we discuss in the following in more detail. If it is a critical part, this needs to be considered during the polymer material selection.

Definition dimensional stability

In short, dimensional stability means that the required dimensions are kept after processing and when the application is in use. Three considerations help to keep the dimensional stability of your part: moisture, mechanics, and thermal stability (Figure 1). 

Figure 1: Plastic part design - three considerations help to keep the dimensional stability of your part.

Consideration 1: Residual moisture and moisture uptake during use

General rule of thumb is that when materials are exposed to moisture, dimensional changes are likely to occur. In case your application has tight tolerance requirements, polymers with low moisture absorption should be taken. For example, an aliphatic Polyamide was specified for an application with tight tolerances. Due to the moisture uptake, part performance decreased and a replacement material is needed. In such a case, a semi-aromatic Polyarylamide (PARA) can be an alternative, since it has the lowest moisture uptake of Polyamides. There are also other polymers such as PEI, PPS, and PEEK, which have excellent mechanical, and moisture performance. PPS, PPA, and PEI can be used for applications, which are exposed to high temperature and moisture during the use of the application (water pumps in cars for example). Also during processing, keeping a maximum allowed moisture level is essential to not harm the polymer during processing. In this post, different maximum moisture levels after resin drying to ensure proper processing are shown.

Consideration 2: Mechanical strength

In case of structural applications, loading strength of the selected polymer is important and can influence the dimensional stability. For complete evaluation, short-term property data such as tensile and compression strength, together with long-term data such as tensile creep should be considered. Examples of high performance polymers which show high dimensional stability are PPS, PAI, and PEEK.

Consideration 3: Thermal stability

Temperature load can have a severe impact on the plastic part dimensions. Therefore, it is critical to evaluate the maximum use temperature and the continuous use temperature, together with the environment (air, water-glycol) of your application. For evaluation of the temperature impact, dynamic mechanical analysis (DMA) data, as well as head deflection data (HDT) of the selected polymers are helpful.

Overall, there are some factors, which influence the polymer part performance. In this post, I show you additional factors to consider for your plastic part design.



Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig 

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature: 

[1] https://apex-intl.com/2017/02/24/engineering-plastics-understanding-dimensional-stability-in-material-selection/


Monday, 21 March 2022

Decision Making in the Plastics Industry – Avoid the Survivorship Bias Trap

Hello and welcome to a new post. Today we have a look at a well-known cognitive bias that psychologists refer to as “survivorship bias” and how to use this information for better decision making in our daily plastics operation.

The focus on people, companies, or products that have themselves successfully established and forgetting about other important factors such as failure is referred to as survivorship bias.



Let us put this bias in relation to some examples

Analyzing of World War II bomber airplanes

Most famous example is the US Air Force dilemma of lost airplanes during World War II. They investigated the returning airplanes and found out that the wing tips, body and tail had the most holes. Their plan was to reinforce those areas for better protection. Luckily they had Mr. Abraham Wald as part of the Statistical Research Group (SRG) on their team. He explained to the military leader that this would be a terrible mistake since they did not look at the airplanes, which were shot down. The weakest parts are not the wing, tail or body. It is the engine and once you get a hit there, the airplane will hit the ground quite fast.

Example plastics industry

Looking at the engineering polymer Polyamide, it is a well-established and successful material, which is used in lots of applications. Material manufacturers, which have their focus on other polymer resins, may want to add such Polyamide resin and compounds to their portfolio to gain a share of the cake. However, it is better to look at companies which failed to enter the market place with their new Polyamide resin or compounds, followed by companies which have mediocre sales and profit numbers when they entered with their new Polyamides. Tendency is to look at the market leaders and established companies. 

In conclusion, it pays off to look at not successful launches of products too and not only the successful ones. It is harder to find the stories of failing products, however it is worth taking the extra step and fighting the survivorship bias. 

Thanks for reading and #findoutaboutplastics

Greetings

Herwig Juster

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature

[1] http://blog.idonethis.com/7-lessons-survivorship-bias-will-help-make-better-decisions/

Tuesday, 15 March 2022

Engineering Biopolymers - Using the 3P-Triangle to Select Them

Hello and welcome to a new post. Today I show you how you can use the 3P (price, performance, and processing)-triangle to select engineering biopolymers.

An overall summary on bio-based polymers can be found in this three part bio-based polyamide series.

Motivation of Engineering Biopolymer Usage

Engineering polymers represent much lower volumes compared to commodity plastics and bio-derived engineering polymers represent a niche within this engineering plastics segment. Packaging materials are much more visible to consumers on a daily basis compared to for example under the hood automotive applications. Therefore, research focus was more directed towards replacing high volume single use polymers with recycled and bio-based materials solutions. However, consumer perspective is shifting towards all different polymer applications to have recycled content or be bio-based. In addition, more and more OEMs demand recycling and bio-based content in their plastic parts. Material suppliers work on drop-in bio-based solutions for traditional polymer applications. One way are hybrid materials out of a 100% bio based polymer blended with a traditional engineering polymer such as PC (Table 1). Often biopolymers show a brittle behaviour. Blending a bio-copolyester such as Polybutylene adipate terephthalate (PBAT) with a Polylactic acid (PLA) will result in a ductile (derived from PBAT) and stiff (derived from PLA) material. Polyamides are among the most used engineering polymers and there are already several short- and long chain bio-based Polyamides available, where one or both monomers are derived from bio sources (Table 2).

Table 1: hybrid materials out of a 100% bio based polymer blended with a traditional engineering polymer

Table 2: overview bio-based Polyamides

Material Selection – Visual approach using the 3P-triangle

The price, processing and performance triangle allows to compare similar plastics and how well they measure up against each other in a visual way. Incorporation of environmental sustainability values is done over “processing” where the nature of feedstock is included and over “performance” which takes the materials impact during use-life and recycling phase.

With bio-based engineering polymers, the balance between fulfillment of rigorous property requirements of the target application and life-cycle impact need to be found during material selection. I developed three steps to achieve such a balance.  

1. Step: We define the maximum allowed environmental impact of the material which can be provided by the customer (numerical value – example: GWP)

2. Step: Incorporate this value into the semi-quantitative polymer comparison triangle together with price, processing and performance.

3. Compare different polymers to each other and make a decision which to investigate further

Example: injection / blow moulded water bottle

In the following, an example helps to better understand the 3P-triangle approach. For an injection moulded water bottle, the incumbent material is most of the times PET and can be placed more towards the price vertex due to its low costs. As a next alternative, bio-based PET can be used  which improves towards the processing vertex. PLA, on the other hand will improve processing, however will increase material costs. This may change in the future too, due to more availability of bio-based materials. Altogether, the 3P-triangle is a tool which can be put into your polymer material selection tool box and supports selecting bio-based polymers.

I made also a short training video on this topic: 


Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig 

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature: 

[1] Plastics and Sustainability: Towards a Peaceful Coexistence between Bio-based and Fossil Fuel-based Plastics, Michael Tolinski


Thursday, 10 March 2022

Polymer Material Selection - My New Book is Coming Soon!

 

Polymer Material Selection - my new book

Hello and welcome to this project reveal post. 

My latest project is a book called *Polymer Material Selection*.

Currently I'm previewing it and I can tell you it looks already promising.

In the book I will show you how to select polymers in a systematic way using my polymer selection funnel method.

We will go over the entire selection process, from how to establish part requirements, gather material data, rank different polymers all the way to how to select a vendor after selecting the polymer.

After reading the book, you know everything you need to select the optimal polymer material for your project, save thousands of dollars by preventing part failure, and have fun in the process.

Leave your email on my site to be the first to be informed as soon as the book launches. 

Sign up here to be informed about the book launch

I'll exclusively send you my product requirement checklist which is part of the polymer material selection funnel.

Thank you and stay tuned.

Greetings and #findoutaboutplastics

Herwig 


Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Tuesday, 8 March 2022

Bio-Based Polyamides – Part 3: Sustainability Facets (Bio Sourcing, LCA, Certifications) and Example Polyamide 6.10

 Hello and welcome to part 3 of our bio-based Polyamide series. 

Check out part 1: PA 5.6 and 5T (Chemical Structure, Production, Properties, Applications, Value Proposition) here and part 2: Short and Long Chain Aliphatic Polyamides (PA 6, PA 11, PA 6.10, PA 10.10) here

In this post, I focus on three topics under the sustainability umbrella: bio sourcing, LCA, and certifications

Bio sourcing for polyamides

Materials based partially or complete on renewable biomass fall into this definition. Castor beans, trees, and crops are major examples of this category. Fossil based or biomass based materials have all carbon atoms in their back. This allows a distinction of bio-based polyamides in terms of their bio content. For functional groups and inorganic groups, this is not possible and a mass-based approach is used.

ASTM D6866 and EN 16640 are used for the determination of bio-based carbon content in polyamides and other polymers. Base working principle is the radiocarbon analysis which allows to determine the carbon fraction (C14 measurement) [1].

Life Cycle Assessments

Life Cycle Assessments (LCAs) are used to identify the environmental impact of a certain material or produced good thorough their life cycle and currently two major standards are used for LCAs: ISO 14040:2006 (Environmental management — Life cycle assessment — Principles and framework) and ISO 14044:2006 (Environmental management — Life cycle assessment — Requirements and guidelines).

The structure of a LCA contains a scope section and the impact categories. Within the scope section distinctions between three variations is done: gate-to-gate, cradle-to-gate, and cradle-to-grave. For polymers the preferred scope is cradle-to-gate and this scope covers all processes as well as environmental impacts (buying feedstock and making the polymer). Often high performance bio-polyamides are tailored to the specific customer requirements by compounding selected additives into the base polymer. End-of-life disposal is more complex and harder to access for the polymer manufacturer. Environmental impact can be estimated using following metrics:

-greenhouse gas emissions,

-ozone depletion,

-human toxicity (cancer effects),

-human toxicity (non-cancer effects),

-photochemical ozone formation,

-ionizing radiation, particulate matter,

-terrestrial acidification,

-terrestrial eutrophication,

-marine eutrophication,

-ecosystem toxicity,

-resource depletion (fossil),

-resource depletion (abiotic),

- and water resource depletion.

For customers and polymer manufacturers, the global warming potential (GWP expressed over CO2 equivalent) is the most interesting value as well as the most frequently requested value within the LCA report.

Example Polyamide 6.10

Manufacturing of a long chain Polyamide PA 6.10 is made as shown in Table 1 by sebacic acid (C10H18O4) and HMDA (C6H16N2). For bio-based Polyamide 6.10, the sebacic acid is bio-sourced. In general, bio-sourced products have a lower carbon footprint since they contain locked atmospheric (biogenic) carbon in the product. In case of combustion or degradation of sebacic acid (based on castor oil) at the end-of-life, this would result in approximately 1.5 kg of CO2 equivalent release. The whole Polyamide 6.10 would lead to a release of 2.2 kg of CO2 equivalent. The total carbon footprint (from raw material, polycondensation of Polyamide minus the biogenic carbon of sebacic acid) of Polyamide 6.10 is 4.6 kg Co2/kg. In case Polyamide 6.10 is made 100% out of petrochemicals, the carbon footprint would be 7.3 kg CO2/kg. The aforementioned 2.2 kg of CO2 equivalent are most probably released before 100 years since end-of-life is reached before 100 years (GWP calculations use a 100 year time frame).

Table 1: overview of bio based Polyamides

Certifications

As already mentioned under the section “Bio-sourcing”, radiocarbon dating is a good method to distinguish between fossil based carbon and bio based carbon. The C14 isotopes for fossil based material display a different set compared to bio based ones. Standard is DIN ISO 10694. Other certifications are ISCC PLUS and REDcert². Both are leading sustainability certification systems for bio-based and recycled materials. Certifications and proper labeling get more and more important since the end customers are demanding such distinctions more and more.

What are some trends in 2022?

We see more and more the use of recycled plant based oils and fats to produce Polyamides which reach a carbon footprint of only 0.5 kg Co2/kg [2]. Also, 100% bio-based carbon content is possible with Polyamides. PA 11 uses only 11-aminoundecanoic acid which can be won from castor oil. This enables a 100% bio-based carbon content. Also PA 5.10 can be produced in a 100% bio based carbon way using pentamethylene diamine and sebacic acid out of corn and castor oil.

Thanks for reading and #findoutaboutplastics

Greetings, 

Herwig 

Interested to talk with me about your plastic selection, sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section

Literature: 

[1] https://www.findoutaboutplastics.com/2021/07/biopolymers-difference-between-bio.html

[2] https://akro-plastic.com/compound-overview/akromid-next/

[3] Stephan Kabasci: Bio-Based Plastics: Materials and Applications