Today's KNOWLEDGE Share:Kevlar 29 Vs Kevlar 49

Today's KNOWLEDGE Share

Kevlar 29 vs Kevlar 49

Kevlar® 29 is used in the manufacture of body armour (panels) for lightweight military vehicles. A good example is the US Army’s ‘Bradley Fighting Vehicle’. This has been used extensively in Iraq and Afghanistan. Kevlar® 29 was selected for its armour, because it is lightweight and withstands attack from RPGs. The Kevlar® 29 panels protect the soldiers inside the vehicle.

Kevlar® 29 is ideal because it is lightweight and non-flammable and it offers protection from high temperatures (fire bombs, Molotov cocktails etc...). Kevlar® 29 can also withstand the harsh environmental conditions, found in hot climates.

Kevlar® 49 is used for specialist boat hulls and in the aerospace industry. It is popular as a material for boats because it is lightweight and can withstand a considerable amount of force (torque - twisting force), tensile stress and impact. Hulls manufactured from traditional materials, such as fibreglass, are limited in their resistance to forces and stress. Also, a lightweight boat is faster on the water and uses less fuel to complete distances.

Eurofighter is relatively light compared to other similar fighter jets, due to the selection of Kevlar ® 49 as a material in its manufacture. This means that it can fly faster and further, before in-flight refuelling is needed. It is more agile than its rivals due to excellent force (torque - twisting force) and tensile stress resistance. The plane is more likely to survive being hit by small arms fire, compared to other fighter planes, as Kevlar ® 49 has excellent impact resistance. 

FURTHER ADVANTAGES OF USING KEVLARKevlar® has a range of advantages, not only its relative low weight and high strength:

Laminated Kevlar® is very stable at high temperatures and it is impact and scratch resistant.

Kevlar® is often combined with other materials, to produce textiles with enhanced properties, such as fire resistant clothing for the Fire Services.

Kevlar is used in some quality walking boots because it is waterproof (when combined with other materials as a composite) but also breathable, ensuring comfort.

When Kevlar is used as a composite with rubber, it retains its flexibility. This composite material is used in the manufacture of Formula One Racing Car petrol tanks. The tank holds the petrol safely, even in the event of an accident. The material cannot be pieced by other car components, even during a high speed impact. The petrol does not escape / leak, avoiding fire and explosions. The lightweight tank, adds to the reduced weight of the entire vehicle, leading to a faster racing car.

source:technologystudent/heaterk

3D printing technology for tissue: Bayreuth researchers combine hydrogels and fibres in a new technology

Prof. Dr Leonid Ionov and his team at the University of Bayreuth have developed a new type of 3D printing technology that combines hydrogels and fibres. The innovative process, combined in one device for the first time, enables the production of constructs with fibrous structures and uniaxial cell alignment. The research results, published in the journal “Advanced Healthcare Materials”, harbour potential for the artificial production of biological tissue.

Biofabrication, a specialised field of medical technology that deals with the production of biologically relevant structures, aims to replicate the complex architecture of human tissues and organs. One promising approach to counteracting the global shortage of donor organs is the use of 3D (bio) printing, an advanced biofabrication technique.

This technology was integrated, in a single, with a fiber spinning technology called touch-spinning. This approach has been under development at the University of Bayreuth since 2018 and enables the production of tissue-like structures. An innovative device for this has now been invented and patented in Bayreuth and could represent a significant advance in the production of living tissue. In addition, great progress has been made in the area of efficient production of fibres and composites.

In the latest study by Prof Dr Leonid Ionov, Professor of Biofabrication, and his team at the University of Bayreuth, various types of hydrogels were extensively tested for the 3D printing of tissues. A hydrogel is a water-retaining and at the same time water-insoluble polymer. In addition, the cell containing-hydrogels, also known as bioink, are combined with fibres to create a composite material. This is achieved by using 3D (bio) printing with an integrated touch-spinning process.

Touch spinning is a scalable process for producing of fibres from a polymer solution or melt. The Bayreuth scientists have now combined 3D (bio) printing technology with touch-spinning technology in a single device for the first time.

“The insights gained in this study are of great importance for the production of tissues and in particular tissues with fibrous structures and uniaxial alignment of cells such as connective and muscle tissue,” explains Prof. Dr Leonid Ionov.

In an article recently published in the journal “Advanced Healthcare Materials”, the Bayreuth researchers Prof. Dr. Dr. Elisabetta Ada Cavalcanti-Adam, Chair of Cellular Biomechanics, Prof. Dr. Leonid Ionov, Professor of Biofabrication, Waseem Kitana, PhD student at the Chair of Biofabrication, and their colleague Dr. Victoria Levario-Diaz from the Max Planck Institute for Medical Research, report on a novel approach for the production of multilayer bioink fibre composites.

source:AM Chronicle

Today's KNOWLEDGE Share:Polydicyclopentadiene (pDCPD)

Today's KNOWLEDGE Share

Polydicyclopentadiene (pDCPD)

Polydicyclopentadiene (pDCPD) is a relatively new polymer which is formed through Ring opening metathesis polymerisation (ROMP) of  Dicyclopentadiene (DCPD).

pDCPD is a custom-engineered thermoset polymer designed to deliver an excellent combination of chemical, corrosion, and heat resistance, plus stiffness and impact strength. This material blends the molding flexibility of a thermoset with the high-performance characteristics of top engineering thermoplastics. It has a heat deflection temperature of up to 120°C.

pDCPD is unique because it has virtually no part size or weight limitations — parts with variable wall thicknesses, molded stiffening ribs, and more won’t slow down production. pDCPD is a relatively new material and its applications are limited as of yet, but it’s shown promise in corrosion-resistant chemical process equipment, septic tanks, and water treatment equipment.

Equipment

DCPD resins are transformed using high pressure RIM equipment as used in the polyurethane industry, with some small changes to be considered. As a reference, a widely used machine to inject DCPD resins is the Cannon A-100 fitted with a DCPD kit. The most important change is that the resin can never be in contact with air or moisture, which required a nitrogen blanket in the tanks. The tools or moulds are closed tools and are being clamped using a hydraulic press. Due to the fact that the resins shrink about 6% in volume during reaction, these presses (also called clamping units) don't have to handle high pressures such as for Sheet Moulding Compound (SMC) or expanding polyurethane.

Advantages of pDCPD:

Combines chemical, corrosion, and heat resistance

No part size or weight limitation – won’t slow down production

Blends molding flexibility with high performance

Disadvantages of pDCPD:

New material: applications are limited

Applications:

Since pDCPD is still a young material, the number of applications is quite limited. The major success story is in the field of body panels, mainly for tractors, construction equipment, trucks and buses. In the industrial applications, the main success story is components for chlor-alkali production (e.g. cell covers for electrolyzers). Other applications can be developed where impact resistance in combination with rigidity, 3D design and/or corrosion resistance is required.

source:telene

Evonik launches VISIOMER® HEMA-P 100

With the launch of VISIOMER® HEMA-P 100, Evonik introduces a Phosphate methacrylate monomer that improves adhesion, reduces corrosion, and provides flame-retardancy.

VISIOMER® HEMA-P 100 can act as a dispersant and complexing agent. Incorporated by polymerization, HEMA-P is non-migratory, and the effects are long-lasting. It can act as a dispersant and complexing agent.

Incorporated by polymerization, HEMA-P is non-migratory, and the effects are long-lasting.

Typical product applications of VISIOMER® HEMA-P include adhesives, coatings, construction and composites:

*In acrylic dispersions​, HEMA-P acts as an adhesion promoter & anti-corrosive agent (e.g. DTM)

*In structural acrylic adhesives, HEMA-P increases adhesion to polar substrates and improves corrosion resistance

*In emulsions for wood, textile or paper coatings, HEMA-P enhances the flame-retardancy

*To cast PMMA, HEMA-P brings flame-retardancy without compromising transparency or mechanical properties

VISIOMER® HEMA-P stands out due to its high monoester content which helps ensure maximum performance.

VISIOMER® HEMA-P is also available in a low viscosity 70% solution in MMA for easier handling. VISIOMER® HEMA-P 70M and the new VISIOMER® HEMA-P 100are available globally.

sourc:Evonik/jeccomposites

Today's KNOWLEDGE Share:Dynamic Rheology

Today's KNOWLEDGE Share

I praised the incredible power of Dynamic Rheology to study polymer flow behaviour and the polymer molecular structure.

To be totally fair, I have to also acknowledge the equally valuable power of Dynamic Mechanical Analysis (DMA or DMTA).

The principle is strictly the same, with an in-phase and out of phase response. The test is however conducted on solid samples (tension, torsion, bending...) and is most useful in a Temperature sweep approach, ideally from cryogenic temperatures up and above Tg.

The data produced (in addition to the Tg value) can help assess the damping characteristics of the polymer for NVH aspects for instance.

The observation of multiple sub-Tg transitions is of great spectroscopic interest to understand molecular motions and segmental movements. These transitions are the key reason for toughness observed below Tg in many polymers, a performance aspect we rely upon everyday in our plastic parts.

Subtle plasticizing or anti-plasticizing mechanisms can be studied, highlighting often dramatic changes in mechanical performance with addition of a few tenth percent of additives or just due to moisture.

source:Vito leo

Today's KNOWLEDGE Share:Artificial Worm gut

Today's KNOWLEDGE Share

Scientists Develop Artificial Worm Gut to Break Down Plastics

A team of scientists from NTU Singapore has developed an artificial ‘worm gut’ to break down plastics. This offers hope for a nature-inspired method to tackle the global plastic pollution problem.

Overcame the Slow Feeding Rate and Worm Maintenance:

By feeding worms with plastics and cultivating microbes found in their guts, researchers have demonstrated a new method to accelerate plastic biodegradation. The team included scientists from NTU’s School of Civil and Environmental Engineering (CEE) and Singapore Centre for Environmental Life Sciences Engineering (SCELSE).

Zophobas atratus worms are known for their nutritional value. It is the larvae of the darkling beetle commonly sold as pet food and is known as ‘superworms’. However, their use in plastics processing has been impractical due to the slow rate of feeding and worm maintenance.

NTU scientists have now demonstrated a way to overcome these challenges by isolating the worm’s gut bacteria. The bacteria are used to do the job without the need for large scale worm breeding.

Source:omnexus.specialchem/Nanyang Technological University, Singapore

Today's KNOWLEDGE Share: Composits

Today's KNOWLEDGE Share

Composite Essentials!

How important have composite materials been during the history of mankind?

This schematic shows the relative importance of the four classes of materials (metals, polymers, composites, and ceramics) in engineering as a function of time! 

As you can see, composite materials have been used by humans for thousands and thousands of years, however, their relative importance was considerably reduced until the advent of fiberglass composites! Since 1960, composite materials have become more and more important for the engineering world. 

This uptrend in relative importance is evident and makes us very excited about the future of composite materials! 

 

Image Source: Article ''Biomimetics and Composite Materials toward Efficient Mobility: A Review'' written by Joel Boaretto, Mohammad Fotouhi, Eduardo Tende, Gustavo Francisco Aver, Victoria Rafaela Ritzel Marcon, Guilherme Luís Cordeiro, Carlos Pérez Bergmann, and Felipe Vannucchi de Camargo.

source:managingcomposites