Avient Introduces PFAS-free Fiber Solution for Ballistic and Personal Protection

Dyneema®, owned by Avient Corporation, to provide ultra-high-molecular-weight polyethylene (UHMWPE) fiber, unidirectional (UD) composite fabric, and film materials that are manufactured without intentionally added per- and polyfluoroalkyl substances (PFAS) for hard and soft ballistic armor, helmets, and vehicle armor.

Also, unlike para-aramid alternatives, the unique properties of Dyneema®, enable personal protection products that can achieve desirable levels of water, liquid, and oil-repellency without a need for PFAS-based surface treatments.

Addressing Supply Chain Uncertainty of PFAS Materials:

Certain PFAS are often used in a range of personal protection products, including in their manufacturing processes or surface treatments. However, a growing body of research suggests that many PFAS break down very slowly over time and can persist in water and soil in the environment. As a result, authorities in the United States and beyond are considering actions to limit PFAS.

At the North Carolina FEDTEX 2024 Conference, the US Army Combat Capabilities Development Command (DEVCOM) Soldier Center warned that solutions containing PFAS are becoming less readily available because of regulatory and supply chain uncertainty. According to the DEVCOM Soldier Center, there is an urgent need to move toward non-PFAS alternatives within the personal protection industry.

One material currently used to make personal protective products is para-aramid. However, para-aramid-based solutions require a surface treatment, which typically is PFAS-based, to repel liquids, such as water and oils, because moisture and oil can negatively affect the ballistic performance of para-aramid fibers. In contrast, the unique properties of Dyneema® materials make them inherently resistant to moisture and easy to wipe clean – meaning there is no need to apply a PFAS-containing surface treatment.

Offering Ultra-low Weight with Maximum Stopping Power:

Thanks to its unique manufacturing process and performance properties, the Dyneema® brand signifies that its fiber, UD material, and film are made without intentionally added PFAS. For the American market, Dyneema® fiber – with its unrivaled strength-to-weight ratio – is manufactured in Greenville, North Carolina. The Greenville site employs more than 400 American workers, 10% of whom are military veterans. The facility is also close to the Dyneema® business’s US Technical Service Center, where its ballistic experts support armor manufacturers in developing next-generation products capable of standing up to legacy and emerging threats.

Source: Avient Corporation/www.polymer-additives.specialchem.com

Today's KNOWLEDGE Share :Thermochromic Polymer Blend Enables Energy-efficient Indoor Space Cooling

Today's KNOWLEDGE Share

New Smart Thermochromic Polymer Blend Enables Energy-efficient Indoor Space Cooling

Rice University researchers have developed a smart material that adjusts its transparency with changes in temperature, outperforming similar materials in terms of durability, transparency and responsiveness.

The new polymer blend could significantly enhance energy efficiency for indoor space cooling, according to a new study published in Joule.

Becomes Less Transparent as the Day Gets Warmer

Cooling off can be a matter of life or death, but air conditioning ⎯ when and if available ⎯ already accounts for 7% of the world’s energy use and 3% of carbon emissions. With temperatures hitting record highs and heat waves growing more frequent worldwide, the need for more efficient ways to keep indoor temperatures in check has also grown more urgent.

One way to mitigate the issue involves coating windows with materials that keep heat out while still allowing light to pass through. One such class of materials is thermochromics, yet existing varieties are still too expensive and short-lived to make a feasible choice for use in buildings, vehicles and wherever else needed.

The new salted polymer blend system developed by Rice engineers in the Nanomaterials Laboratory led by Pulickel Ajayan overcomes these challenges, potentially enabling the large-scale deployment of thermochromics as an energy-efficient indoor space cooling technology.

“Imagine a window that becomes less transparent as the day gets warmer, keeping interiors cool without consuming energy,” said Sreehari Saju, a materials science and nanoengineering doctoral student at Rice who is a co-lead author on the study. “Our formulation leverages both organic and inorganic components to overcome the limitations of existing thermochromic materials such as short lifespans and high costs.

“Moreover, this material’s thermic response is well-matched to real-world environmental demands. We think that smart windows made from this material could significantly reduce energy consumption in buildings, making a tangible impact on both energy costs and carbon footprint.”

Mixed Two Polymers with a Salt

The researchers combined experimental methods with computational simulations to understand the material’s behavior under different environmental and architectural settings. For instance, they assessed how the material would perform in specific urban areas around the world to get a sense of its potential impact when deployed at scale.

The researchers synthesized the material by mixing two polymers with a type of salt and worked on optimizing the composition to achieve smooth transitions between transparent and opaque states with temperature fluctuations. Their findings show that the new thermochromic blend is not only highly effective in regulating solar radiation but also remarkably durable with an estimated lifespan of 60 years.

Source: Rice University/www.omnexus.specialchem.com

Today's KNOWLEDGE Share :Frozen Layer thickness

Today's KNOWLEDGE Share

When trying to model Injection Molding one has to determine the transient frozen layer thickness.

And it is more tricky than most might think.

For amorphous polymers the best transition temperature would be available straight from the PvT data and will even include the important pressure dependence. It will however not include any cooling rate dependence and Tg is extremely sensitive to cooling rate, as people observe daily with DSC

PvT is essentially measured in a quiescent state close to thermodynamic equilibrium (very slow heat/cool rates).

For semi-crystalline materials the problem is worse. We need to capture the crystallization temperature which is pressure dependent also (that can be seen in PvT) but extremely dependent on cooling rate (crystallization kinetics aspects).

Furthermore, the strong nucleation effect of shear-stress close to the outer layers will dramatically increase, locally, this transition temperature. Which means the transition temperature will be very different from skin to core.

In essence, there is not such a thing as ONE no flow temperature or transition temperature.

To preserve mass balance in molding simulation it will also be of key importance to perfectly "sync" the phase change for all physical properties (PvT, thermal data, viscosity,...).

We still have a long way to go to fully capture this complex physics in our beloved commercial software tools.

The best attempt I know of, was an old Research Release version of Moldflow, work I was involved in) including explicit crystallization kinetics and implementing "dynamic" PvT (transition zone driven by real kinetics), with full sync of all other variables.

source:Vito leo

Today's KNOWLEDGE Share Renegade Materials earns NCAMP certification for low-dielectric prepreg

Today's KNOWLEDGE Share

Renegade Materials earns NCAMP certification for low-dielectric prepreg:

Thermoset prepreg using quartz fabric, well suited for aircraft manufacturers and aircraft part suppliers, has completed qualification and will be listed in the NCAMP database and CMH-17.

Renegade Materials (Miamisburg, Ohio, U.S.), a global provider of aerospace composite materials and a subsidiary of Teijin Holdings USA Inc., a member of the Teijin Group, announces National Center for Advanced Materials Performance (NCAMP) qualification of the company’s high-performance low-dielectric prepreg material, made by impregnating woven quartz fabric with epoxy resin. The development and execution of the test plan was completed in under 12 months.

Renegade Materials’ RM-2014-LDk-Tk-4581 prepreg has successfully completed qualification and design property testing through Wichita State University’s (WSU) National Institute for Aviation Research (NIAR), enabling it to be listed in the NCAMP database and CMH-17. This data is vital for accelerating the adoption of composite material systems for aircraft manufacturers, ultimately reducing production costs and enabling rapid transition to production.

These materials are used for aircraft radar domes (radomes) as they provide optimal electrical insulation and enhanced signal integrity, but also has value-added capabilities such as reducing electromagnetic interference (EMI).

The RM-2014-LDk-Tk prepreg system is part of a suite of compatible low-dielectric products offered by Renegade Materials, including prepregs on quartz, glass, peel plies, syntactic foams and low dielectric adhesive. B-Basis design allowables are now available for 4581-style quartz in the statistical analysis report. Dielectric properties (X-band) are available alongside mechanical properties. Prepreg is available under the NMS201/1 NCAMP material specification.

source:Teijin/www.compositesworld.com

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:terlene

Global Silicone Trends in Germany

 Seize the final opportunity to get on board!!

#GlobalSiliconeTrends2024

#GST2024 #Germany

Feel free to contact the Organizing Committee:

Sharon Hsiung +86-13811366249 xiongshuang@acmi.org.cn

Justin Dou   +49 21325813130 douweiyu@acmi.org.cn

Nicole Tang   +86-18210097596 tangnaimei@acmi.org.cn

#Silicone #SiliconeConference #GlobalEvents

Today's KNOWLEDGE Share :Improving mechanical and flame retardant properties of Vinyl Ester Resin

Today's KNOWLEDGE Share

Improved mechanical and flame retardant properties of vinyl ester resin composites by combination of lithium-containing polyhedral oligomeric phenyl sesquisiloxanes and phosphorus-containing ionic liquid...

Vinyl ester resin (VER) are widely used in various applications, including automotive parts, yachts, wind turbine blades, and cooling towers, due to their excellent properties. However, the high flammability of VER limits its application in fields requiring stringent fire resistance. In this work, we used ionic liquid containing phospholipid structures (VIDHP) in combination with lithium-containing polyhedral oligomeric phenyl sesquisiloxanes (Li-POSS) to improve the mechanical and flame retardant properties of VER. The coordination between the VIDHP and Li-POSS increases the thermal stability of VIDHP and improve the solubility of Li-POSS in VER. The experimental results show an increase in initial decomposition temperature of VIDHP4/POSS1/VER compared to VIDHP/VER, while the solubility of Li-POSS in VER is improved. The Cone calorimeter results show that the total heat and smoke release of VIDHP4/POSS1/VER are reduced by 29.37 % and 36.55 % compared with the pure VER. The investigation of the flame retardant mechanism shows that the combined use of VIDHP and Li-POSS exhibits flame-retardant activity in both the gas and condensed phases, effectively enhancing the flame-retardant property of Vinyl Ester Resin.

source: https://www.sciencedirect.com

Authors:Zeqi Zhang, Liang Qiao, Xue Bi, Keshan Zhang ,Wenchao Zhang,Rongjie Yang