Today's KNOWLEDGE Share:
LCA:
Have you ever thought that life cycle assessment (LCA) is a bit of a minefield? Let’s start with a cup of tea!
Whether you want to benchmark your product against another, find the hotspots in your supply chain or comply with your customer’s Environmental Product Declaration (EPD) requirements, understanding the basics of LCA methodology is increasingly important to avoid greenwashing.
Source:Enrique J Garcia
Today's KNOWLEDGE Share:
European Chemicals Agency (ECHA) adds nine chemicals in the Candidate List because of their hazardous properties. They are used for example in flame retardants, paints and coatings, inks and toners, coating products, plasticizers and in the manufacture of pulp and paper.
233 Entries in the Candidate List:
ECHA’s Member State Committee confirmed the addition of these substances to the Candidate List. The Candidate List now has 233 entries – some are groups of chemicals, so the overall number of impacted chemicals is higher.
These substances may be placed on the Authorisation List in the future. If a substance is on that list, its use will be prohibited unless companies apply for authorization and the European Commission authorizes them to continue its use.
Entries added to the Candidate List on 17 January 2023 are as follows:
1) 1,1'-[ethane-1,2-diylbisoxy]bis[2,4,6-tribromobenzene]
2) 2,2',6,6'-tetrabromo-4,4'-isopropylidenediphenol
3) 4,4'-sulphonyldiphenol
4) Barium diboron tetraoxide
5) Bis(2-ethylhexyl) tetrabromophthalate covering any of the individual isomers and/or combinations thereof
6) Isobutyl 4-hydroxybenzoate
7) Melamine
8) Perfluoroheptanoic acid and its salts
9) reaction mass of 2,2,3,3,5,5,6,6-octafluoro-4-(1,1,1,2,3,3,3-heptafluoropropan-2-yl)morpholine and 2,2,3,3,5,5,6,6-octafluoro-4-(heptafluoropropyl)morpholine
Consequences of the Candidate List:
Under REACH, companies have legal obligations when their substance is included – either on its own, in mixtures or in articles – in the Candidate List.
Suppliers of articles containing a Candidate List substance above a concentration of 0.1 % (weight by weight) have to give their customers and consumers information to be able to use them safely. Consumers have the right to ask suppliers whether the products they buy contain substances of very high concern.
Importers and producers of articles will have to notify ECHA if their article contains a Candidate List substance within six months from the date it has been included in the list (17 January 2023). Suppliers of substances on the Candidate List, supplied either on their own or in mixtures, have to provide their customers with a safety data sheet.
Under the Waste Framework Directive, companies also have to notify ECHA if the articles they produce contain substances of very high concern in a concentration above 0.1 % (weight by weight). This notification is published in ECHA’s database of substances of concern in products (SCIP).
Source: ECHA/SPECIALCHEM
Today's KNOWLEDGE Share:
Reinforcements:
What is the effect of reinforcement type on the strength properties of fiber reinforced composites?
This insightful graph shows how different reinforcements (like short fibers, mats, fabrics, and unidirectional fibers) can increase the strength properties of composite materials!
Source:managingcomposites
Today's KNOWLEDGE Share:
TGA
Thermogravimetric analysis (TGA) is a common thermal analysis technique that provides composition information for polymeric materials. Most often, we associate TGA with quantitative data. However, I was reminded during a recent material analysis that TGA can also provide insight into the qualitative analysis.
I was analyzing a rubber O-ring. My first test, as usual, was Fourier transform infrared spectroscopy (FTIR). The FTIR indicated that the material was a nitrile rubber (NBR) compound. Additional absorption bands associated with aluminum silicate clay were also present. Weak bands indicated an ester-based plasticizer. The general form of the spectrum was suggestive of a moderate loading of carbon black.
I conducted the TGA analysis and found all of the expected weight loss events for the quantification of the plasticizer, polymer, and carbon black, as well as the residue for the mineral filler. However, one additional weight loss stood out. A weight loss of 4.4% centered at approximately 280 C. The temperature and relatively sharp nature of the weight loss were characteristic of dehydrohalogenation – in this case, the evolution of HCl from poly(vinyl chloride) (PVC). PVC is often added to NBR rubber compounds to modify the mechanical properties of the rubber and increase the ozone resistance and improve the weathering resistance.
This example illustrates the power of thermogravimetric analysis, both quantitative and qualitative.
Source:Jeffrey A.Jansen
Today's KNOWLEDGE Share:
Geometric lattice cores
When talking about geometric lattice cores, most people think about a core with hexagon shaped cells, which is the basic and most common cellular honeycomb configuration. However, we have other options currently available on the market, such as Flex-Core, Ox-Core and Double-Flex to name a few!
But how to select between them?
The Flex-Core cell configuration provides for exceptional formability in compound curvatures with reduced anticlastic curvature and without buckling the cell walls. Curvatures of very tight radii are easily formed. When formed into tight radii, Flex-Core provides higher shear strengths than comparable hexagonal core of equivalent density.
The “OX” configuration is a hexagonal honeycomb that has been over-expanded in the “W” direction, providing a rectangular cell configuration that facilitates curving or forming in the “L” direction. The OX process increases “W” shear properties and decreases “L” shear properties when compared to hexagonal honeycomb.
Double-Flex is a unique large cell Aluminum Flex-Core with excellent formability and high specific compression properties. Double-Flex formability is similar to standard Flex-Core.
Source: Hexcel/managingcomposites/thenativelab
Today's KNOWLEDGE Share:
Which was the first composite material manufactured by humans?
As you may already know, a composite material is, by definition, ''a material that is made of two or more different materials, differentiable at a microscopic level, whose specific properties are better than their separated properties''.
Just like any topic related to discovering the first application of any new technology, there is still some debate about which was the first composite material developed by humankind. The answer heavily depends on your own interpretation of the definition aforementioned, and also the reliability when dating ancient discoveries.
Many researchers point out that the first uses of composites date back to 1500 B.C. when early Egyptians and Mesopotamian settlers used a mixture of mud and straw to create strong and durable buildings. The mud acted as a matrix for the random straw reinforcements! Mesopotamians also used straw to provide reinforcement to ancient composite products including pottery and boats.
Funny to think that, 3500 years ago humans manufactured the first composite material, at a time when this definition was far away from even existing!
Source:managingcomposites/thenativelab
Today's KNOWLEDGE Share:
Composite Essentials!
What are the most common failure modes for carbon fiber composites? Let's check them out in detail!
This microscopy shows three different failure modes: delamination, tensile fiber fracture, and tensile/shear matrix cracks in a cross-ply laminate!
Fracture analysis when zoomed-in can reveal a lot of info to engineers!
Bibliographical Reference:
Article ''On the Effective Constitutive Properties of a Thin Adhesive Layer Loaded in Peel'', written by Andersson T and Biel A.
Source:managingcomposites/thenativelab
Today's KNOWLEDGE Share:
Composite Essentials
Let's learn more about the different weave patterns in woven fabrics!
Woven fabrics are woven yarns, rovings, or tows in mat form in a single layer, in which the amount of fiber in different directions is controlled by the weave pattern. The most common are Plain, Twill and Harness Satin!
In a plain-weave pattern, fibers in 0° and 90° directions are equally distributed. A plain weave carbon fiber sheet looks symmetrical with a small checkerboard style appearance. In this weave the tows are woven in an over/under pattern.
In a twill weave, the tow strand passes over a set number of tows and then under the same number of tows. The over/under pattern creates a diagonal arrowhead look, known as a “twill line”. 2×2 Twill is likely the most recognizable carbon fiber weave in the industry. It is used in many cosmetic and decorative applications, but also has great functionality, it has both moderate formability and moderate stability. As the 2×2 name implies, each tow will pass over 2 tows then under two tows.
The number in the Harness Satin names indicates the total number of tows passed over then under. For 4HS, it will pass over 3 tows then under 1. For 5HS, it will pass over 4 then under 1, and 8HS will pass over 7 and under 1. Common harness satin weaves are 4 harness satin (4HS), 5 harness satin (5HS) and 8 harness satin (8HS). As you increase the number of the satin weave, formability will increase and fabric stability will decrease.
In this picture you can see how the weaving process can yield many different patterns!
Bibliographical Reference:
Composite Manufacturing - Materials, Product and Process Engineering - Page 54
Elevated Materials Article "Carbon Fiber Weaves: What they are and why to use them"
Source:managingcomposites/thenativelab
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