Tribological issues in engineering Teflon

Institute of Chemical Technology, Mumbai, Marathawada Campus, Jalna.

Teflon, scientifically known as polytetrafluoroethylene (PTFE), is one of the most versatile materials known to history of material science; this invention was done by the Dupont research team. It was an accidental invention made by the team working to find the coolant material; they ended up with a white slippery material- Teflon. The C-F bond is termed the strongest organic bond, making Teflon inert in various operating conditions such as thermal, mechanical, surface, and chemical. It shows almost negligible water absorbance due to its hydrophobic surface, making it durable. It is a carbon-based polymer due to the absence of charge carriers. i.e., electrons. Teflon is a bad conductor of electricity and heat. These properties can be regulated by adding conducting inorganic fillers.

Along with all these properties, Teflon blends and composites are famous for their outstanding tribological performance. Tribology is the branch of material science that deals with the study of the performance of a surface by calculating its coefficient of friction and wear loss. A wide range of Teflon-derived products based on their tribological properties, conveyor belts, chain lubes, cleaner kits for increasing the performance of automobiles, etc., are available in the market. The selection of appropriate material at the industrial level significantly affects the cost of operation positively. Industries appreciate polymeric material and their derived products as an alternative to other traditional materials such as metal and inorganic ceramics due to their durability and lighter weight. Though we have a long-range of polymeric materials available at the current date, we must choose wisely as per our requirements to get the most efficient output with the same process. One should select the most appropriate materials, and its periodic maintenance significantly impacts energy consumption and the cost-efficiency of the process. According to information from HMSO, 1966. Lubrication (Tribology) Education and Research, UK Department of Education and Science a quantitative analysis of savings is as shown in the figure below –

                      (Percentage-wise distribution of savings achieved after good tribological practice)

The tribological performance of any material can be examined by comparing and analyzing the contact between the surface of that material and the reference material. All these studies of tribological performance are called tribotesting, and the instrument used for it is called tribotesters. There are four main configurations of tribotesters: Pin on the plate, Pin on disc, Ring on the plate, and Ball on the ball. Tribological performance is determined by varying different parameters such as sliding distance, sliding time, and RPS for the tip of the tribotester. The material undergoes various levels of tribotesting to get permitted for the particular application.
These levels are as mentioned in the figure given below –  

      (Different levels of tribotesting and their respective consequences)

There are some demerits of Teflon, such as low dimensional stability with temperature rise; Insolubility in a long-range solvent, which limits the ease of processing; low thermal and electric conductivity; releases toxic gases at high temperatures (above 320 ⁰C). 

Teflon blends and composites-
Teflon shows a low coefficient of friction and excellent wear performance with high durability due to its chemically inert nature; thus, PTFE is considered as one of the most promising tribological materials known. It also exhibits some results, such as low dimensional stability with increasing load and temperature; the load-bearing capacity value is also low for PTFE. In order to improve these characteristics and overcome the limiting conditions, high-performance engineering polymeric materials such as PEEK and PI are mixed with virgin PTFE. Improvement in creep performance of PTFE is also a topic of research. The operating environment also plays a crucial role in the tribological performance of Teflon; with an experimental study, it was observed that when Teflon is operated in marine water conditions, it shows better results as compared with dry and normal water environments. In a marine water environment, deposition of salts and minerals results in reduced wear loss of the surface. According to researchers, the creep performance of virgin PTFE can be improved by adding glass fiber and carbon fiber. The addition of glass fiber was also found to enhance the performance of PTFE in the oxidizing environment while mixing carbon fibers with virgin PTFE enhances its hardness as well as thermal and electrical conductivity. It is pretty apparent from the above discussion that mixing virgin Teflon improves the individual performance, so to enhance such set of properties; we have to select groups of polymers or fillers to obtain desired results. 

Gujarat Fluorochemicals Ltd (GFL), Chemours, Arkema, and Hindustan Fluorocarbons Limited are the leading industries producing fluoro polymers and derived products. According to the survey conducted, around 200,000 tons of Teflon is manufactured worldwide annually, this number keeps on increasing. From this we can see the increasing demand of Teflon as well as its domain of application. 

Acknowledgment- I would like to express my immense gratitude to Prof. Dr. Girish M. Joshi sir, and thank him for motivating and guiding me to complete this article. Also, I would like to thank the Institute of Chemical Technology, Mumbai, Marathwada Campus, Jalna.  

Sarang Subhashchandra Shindalkar – currently studying Integrated M. Tech in Chemical Engineering with minor material science at ICT, Mumbai, Marathwada Campus Jalna since 2019. Presently working as a student intern at Century paper and pulp, Lal Kuan, Uttarakhand.

Plastic used in Fertilizer Industry

Institute of Chemical Technology, Mumbai, Marathwada Campus Jalna.

The main objective of employing various types of plastic (packaging material) in the fertilizer sector is to meet the specific needs of the fertilizer being packaged. Plastic is also utilised to make fertilizer-related equipment, in addition to packaging. Fertilizers are made by a variety of companies all over the world, and while their formulas may differ, their packing materials are very similar.

The primary goal in choosing an appropriate material for fertilizer packaging is to ensure that the fertilizer chemical does not lose its properties due to reactions with environmental exposures such as moisture, reactive gases, and biological factors such as fungal growth, among others. To accomplish this, the packaging material should be chemically stable in normal natural circumstances, recyclable, and inexpensive. The packaging material used must have some properties which are important because lack of these properties can affect the fertilizer or it can react with the plastic packaging material and can contaminate the product. The properties of these materials should be durable, flexible, waterproof, surface non-reactant, cost-efficient and eco-friendly.

The type of fertilizer packaging includes polyethylene derivatives such as LDPE, LLDPE, and HDPE Other derivatives include burlap, cloth, and PP woven bags; however, while cloth and burlap do not contain plastic material, the PP woven bag does contain polypropylene, which is also a type of plastic material used in the fertilizer industry. The PE material is used because of its exceptional qualities such as flexibility, durability, water resistance, tear resistance, and leak resistance. Although almost all PE materials almost contain the same composition, their properties differ for example LDPE (low density polyethylene) consist of short, branched chains that are evenly distributed throughout the polymer structure. HDPE (high density polyethylene) has produced by very less branching during the process of polymerization; HDPE is used for heavy loads safely and easily as it is tear resistant polymer. LLDPE (linear low-density polyethylene) production requires significantly less energy than LDPE. LLDPE is used whenever it is necessary to produce bags with a thickness less than LDPE. Nowadays, the most common bags used in the market for fertilizer packaging are LLDPE.

Because of the polypropylene strips that are waved into one another, PP woven bags are noted for their extreme strength. These bags are incredibly cost effective, and they also let air to circulate inside the bag, preventing it from expanding due to fertilizer gas production.

Many fertilizer companies utilise PP woven bags for packaging because of their qualities. BOPP stands for Biaxially oriented zolypropylene – modified version of PP. BOPP bags are long-lasting and easy to use because the polypropylene is stretched in a machine and in a transverse orientation, it provides excellent resistance to dirt, moisture, and contaminants.

Aside from industry, agricultural plastics such as ethylene vinyl acetate copolymer (EVC), polyvinyl chloride (PVC), and polycarbonate are used for a variety of applications such as crop shielding, UV filtering, and so on. Though plastic is used in these Fertilizer bags it can be recycled, allowing the plastic to be reused. The bag has been emptied, but it still contains traces of the fertilizer material, which is not harmful if it is used with precautions.

Proper disposal of these packaging bags is critical, however due to a lack of awareness, this material is generating major environmental problems. These plastic packaging materials will be replaced in the future with dissolvable packaging, which could be a more Environmentally Friendly option. Nano fertiliser synthesis is also a major research issue; thus, a more particular packing material will be needed to ensure that the Nanoparticles do not decay and can be stored for a significant duration.

Acknowledgement – Firstly, I would like to express my heartfelt gratitude to Prof. Dr. Girish M. Joshi sir for inspiring and mentoring me to accomplish this article. I would also like to convey my gratitude to the Institute of Chemical Technology, Mumbai, Marathwada Campus Jalna.

Sarika Ravindra kulkarni – is a student at ICT, Mumbai, Marathwada campus Jalna, pursuing an Integrated MTech in chemical engineering with a minor in material science. Currently working as a student Intern at Century Pulp and Paper, Lalkuan, Uttarakhand.

Cars could get a ‘flashy’ upgrade

The part of an old car that gets turned into graphene could come back as a better part for a new car.

Rice University chemists working with researchers at the Ford Motor Company are turning plastic parts from “end-of-life” vehicles into graphene via the university’s flash Joule heating process.

The average SUV contains up to 350 kilograms (771 pounds) of plastic that could sit in a landfill for centuries but for the recycling process

The goal of the project led by Rice chemist James Tour and graduate student and lead author Kevin Wyss was to reuse that graphene to make enhanced polyurethane foam for new vehicles. Tests showed the graphene-infused foam had a 34% increase in tensile strength and a 25% increase in low-frequency noise absorption. That’s with only 0.1% by weight or less of graphene.

And when that new car is old, the foam can be flashed into graphene again.

“Ford sent us 10 pounds of mixed plastic waste from a vehicle shredding facility,” Tour said. “It was muddy and wet. We flashed it, we sent the graphene back to Ford, they put it into new foam composites and it did everything it was supposed to do.

“Then they sent us the new composites and we flashed those and turned them back into graphene,” he said. “It’s a great example of circular recycling.”

The researchers cited a study that estimates the amount of plastic used in vehicles has increased by 75% in just the past six years as a means to reduce weight and increase fuel economy.

Segregating mixed end-of-life plastic by type for recycling has been a long-term problem for the auto industry, Tour said, and it’s becoming more critical because of potential environmental regulations around end-of-life vehicles. “In Europe, cars come back to the manufacturer, which is allowed to landfill only 5% of a vehicle,” he said. “That means they must recycle 95%, and it’s just overwhelming to them.”

Much of the mixed plastic ends up being incinerated, according to co-author Deborah Mielewski, technical fellow for sustainability at Ford, who noted the U.S. shreds 10 to 15 million vehicles each year, with more than 27 million shredded globally.

“We have hundreds of different combinations of plastic resin, filler and reinforcements on vehicles that make the materials impossible to separate,” she said. “Every application has a specific loading/mixture that most economically meets the requirements.”

“These aren’t recyclables like plastic bottles, so they can’t melt and reshape them,” Tour said. “So, when Ford researchers spotted our paper on flash Joule heating plastic into graphene, they reached out.”

Flash Joule heating to make graphene, introduced by the Tour lab in 2020, packs mixed ground plastic and a coke additive (for conductivity) between electrodes in a tube and blasts it with high voltage. The sudden, intense heat — up to nearly 5,000 degrees Fahrenheit — vaporizes other elements and leaves behind easy-to-solubilize, turbostratic graphene.

Flash heating offers significant environmental benefits, as the process does not require solvents and uses a minimum of energy to produce graphene.

To test whether end-of-life, mixed plastic could be transformed, the Rice lab ground the shredder “fluff” made of plastic bumpers, gaskets, carpets, mats, seating and door casings from end-of-life F-150 pickup trucks to a fine powder without washing or pre-sorting the components.

The lab flashed the powder in two steps, first under low current and then high current in a heater Wyss custom designed for the experiment.

Powder heated between 10 to 16 seconds in low current produced a highly carbonized plastic accounting for about 30 percent of the initial bulk. The other 70% was outgassed or recovered as hydrocarbon-rich waxes and oils that Wyss suggested could also be recycled.

The carbonized plastic was then subjected to high-current flashing, converting 85% of it into graphene while outgassing hydrogen, oxygen, chlorine, silicon and trace metal impurities.

The chance to incorporate life-cycle analysis (LCA) into a Rice research project was also a draw for Wyss. “I’m driven by sustainability, and it’s where I want to focus in my career,” he said.

The LCA involved comparing graphene from flashed car parts to that produced by other methods, and evaluating recycling efficiency. Their results showed flash Joule heating produced graphene with a substantial reduction in energy, greenhouse gas emissions, and water use when compared to other methods, even including the energy required to reduce the plastic shredder fluff to powder.

Ford has been using up to 60 pounds of polyurethane foam in its vehicles, with about 2 pounds of that being graphene-reinforced since 2018, according to co-author Alper Kiziltas, a technical expert at Ford research who focuses on sustainability and emerging materials. “When we got the graphene back from Rice, we incorporated it into our foam in very small quantities and saw significant improvement,” he said. “It exceeded our expectations in providing both excellent mechanical and physical properties for our applications.”

Graphene clearly has a future at Ford. The company first introduced it into a variety of other under-the-hood components and in 2020 added a graphene-reinforced engine cover. Kiziltas said the company expects to use it to reinforce hard plastics as well.

“Our collaborative discovery with Rice will become even more relevant as Ford transitions to electric vehicles,” Mielewski said. “When you take away the noise generated by the internal combustion engine, you can hear everything else in and outside the vehicle that much more clearly.”

“It’s much more critical to be able to mitigate noise,” she said. “So we desperately need foam materials that are better noise and vibration absorbers. This is exactly where graphene can provide amazing noise mitigation using extremely low levels.”

https://www.rice.edu/

LanzaTech, with the support of Danone, Discovers Method to Produce Sustainable PET Bottles from Captured Carbon

A consortium, including LanzaTech and Danone, led to the discovery of a new route to monoethylene glycol, (MEG), which is a key building block for polyethylene terephthalate, (PET), resin, fibers and bottles. The technology converts carbon emissions from steel mills or gasified waste biomass directly into MEG. The carbon capture technology uses a proprietary engineered bacterium to convert carbon emissions directly into MEG through fermentation, bypassing the need for an ethanol intermediate, and simplifying the MEG supply chain. The direct production of MEG was proven at laboratory scale and the presence of MEG was confirmed by two external laboratories.

“We have made a breakthrough in the production of sustainable PET that has vast potential to reduce the overall environmental impact of the process,” said Dr. Jennifer Holmgren, CEO of LanzaTech. “This is a technological breakthrough which could have significant impact, with applications in multiple sectors, including packaging and textiles!”

While there is no organism in nature known to produce MEG, through this proof-of-concept stage, LanzaTech has used Synthetic Biology and AI tools to discover multiple novel pathways to make MEG directly from carbon emissions. By combining and prototyping various sets of enzymes identified from different sources in novel ways, LanzaTech has successfully reprogrammed its ethanol producing bacteria to fix and channel carbon into MEG.

This early-stage proof of concept work shows for the first time that it is possible for a bacterium to directly produce MEG from gas. By producing MEG directly, the new technology avoids the multiple processing steps required to convert ethanol into ethylene, then ethylene oxide and then to MEG. LanzaTech anticipates that when scaled successfully after a multiyear development phase, the direct production process will lead to PET bottles and PET fibers with a reduced environmental impact.

LanzaTech is partnering with leading companies to improve the environmental impact of packaging. Given the success of this proof-of-concept phase, LanzaTech, with the support of Danone, plans to continue the scale-up phase of its direct-to-MEG technology.

“We have been working with LanzaTech for years and strongly believe in the long-term capacity of this technology to become a game changer in the way to manage sustainable packaging materials production. This technological collaboration is a key enabler to accelerate the development of this promising technology,” said Pascal Chapon, Danone R&I Advanced Techno Materials Director.

Avery Dennison and Wiliot announce strategic partnership to build and scale the future of the Internet of Things

Avery Dennison Corporation, the world’s largest provider of RFID and digital ID solutions, and Wiliot, the Internet of Things pioneer, today announced a strategic partnership dedicated to scaling the IoT to the next level, creating a new era of IoT that benefits people and the planet.

Avery Dennison will leverage its R&D capabilities and scale to design and manufacture second-generation Wiliot tags, which are stamp-sized computers powered by Bluetooth that attach to any product or packaging to embed it with intelligence and connectivity to create more agile, profitable, and sustainable supply chains.

In addition, Avery Dennison will integrate Wiliot sensing services (SaaS) with its atma.io connected product cloud, enabling tag sensing information to be added to the end-to-end item-level data of a connected product. Both companies share a vision for the future of the IoT where almost everything is connected to the internet; not just phones, computers, and homes, but also food, medicine, clothing, and nearly everything else. With an ambition to help to eliminate waste and provide unparalleled transparency and consumer connection.

The partnership will help scale the manufacturing capacity of Wiliot tags significantly, and will leverage Avery Dennison’s market development, innovation and ROI expertise to drive value and enable the company to deliver on large projects to some of the world’s largest retail, food & beverage, and pharmaceutical brands.

“Wiliot’s passive Bluetooth technology offers the ability to work with existing infrastructure and provides another accelerator to the growth of IoT. Combined with sensing capabilities and security features as standard, this expands our portfolio and opens up many new use cases for our customers and partners,” stated Francisco Melo, vice president and general manager, Avery Dennison Smartrac.

https://www.wiliot.com/

Wiliot announces a battery-assisted version of its IoT Pixel tags

Wiliot, the Internet of Things pioneer whose IoT platform is enabling trillions of everyday “things” to gain intelligence and harness the power of the cloud, today announced a milestone expansion of its product portfolio with the introduction of a Battery-Assisted IoT Pixel, developed in partnership with leading smart tag manufacturer Identiv.

The new Battery-Assisted IoT Pixel joins the company’s flagship Battery-Free IoT Pixel to address specific IoT applications that are best served by battery power. It is a major step forward for the company as it scales its vision for a future of the IoT, where all products are connected to the internet and embedded with cloud intelligence.

This introduction marks a rapid innovation cycle for Wiliot, following the company’s March 2022 launch of its Version 2 Battery-Free IoT Pixel – a stamp-sized computer that costs pennies and powers itself by harvesting and recycling energy from radio waves. This solution, recently recognized by the SXSW 2022 Innovation Awards, is currently being adopted by many of the world’s leading retail, food, beverage, and pharmaceutical brands.

The Wiliot Battery-Assisted IoT Pixel uses the same exceptionally-efficient chip as the Battery-Free IoT Pixel, but it augments it with a tiny printed battery. The tags are smaller than a business card and broadcast the same standard Bluetooth beacon as the company’s Battery-Free IoT Pixel.

“Wiliot was founded on the mission to transform industries by embedding everything with cloud intelligence using our IoT pixel tagging technology,” stated Roee Zeiler, Wiliot’s CFO. “We began by tackling this challenge with battery-free technology, which significantly reduced barriers to IoT adoption and will scale the IoT from billions to trillions.”

This new battery-assisted tag reduces the cost of bringing Bluetooth standards-based continuous connectivity and intelligence to things by 10X, whereas the battery-free product cuts the cost of Bluetooth standard integration by 100X.

Continued Zeiler, “We’ve always understood that certain applications are best addressed with battery-assisted technology – which is why this launch is a milestone for Wiliot, Identiv, and the industry. Now, with a portfolio that includes battery-free and battery-assisted pixels, we’re one step closer to achieving our goal of creating an Internet of Trillions of Things (IoT2).”

Unlike the battery-free version, the Battery-Assisted IoT Pixel doesn’t require bridges or any other source of radio waves to harvest energy from. All they require is a device with a Bluetooth radio to read their transmission – any phone, Bluetooth gateway, or Wi-Fi access point. As such, since any BLE reader can be configured to read a Battery-Assisted IoT Pixel, and no additional infrastructure is required, the entry price and complexity of tagging things is close to zero.

The product promises to bridge between the worlds of battery-free and battery powered tags, allowing solution providers to start using the Wiliot Cloud to deploy solutions more easily to new places that may not have been accessible before.

While Battery-Free IoT Pixels address the tracking of low-priced products – clothing, food, medicine, and more – this launch enables tracking of medium value to higher value assets such as temporary promotional signage, certain returnable transport items, IT assets, and retail assets – which benefit from the boosted connectivity yet can also better absorb the battery-assisted pixel’s higher price-point.

Compared with conventional Bluetooth tags, Wiliot’s Battery-Assisted IoT Pixel is thinner (1.3mm at its thickest), lower cost, and more physically flexible – so they can easily attach to products on a production line at speed and in volume using a label applicator. Compared with conventional Bluetooth beacons, Wiliot’s new battery-assisted beacon features extremely low power consumption that enables longer lifetime in a smaller form factor.

The first Battery-Assisted IoT Pixel will be mass-produced by leading smart tag manufacturer Identiv, which is known for focusing on more sophisticated and specialist tag designs. Limited availability of the Battery-Assisted IoT Pixels will begin next month, while larger quantities will be ready for roll-out by the end of year.

“Identiv always strives to innovate, and our contribution to this new era of Bluetooth-based IoT is an outcome of the scalable manufacturing standards, unique processes, and expertise we have mastered in the NFC and RFID ecosystem. Bluetooth is pervasive, and this new product offers the advantages of providing infrastructure-free temperature sensing, tracking, and traceability. We are proud to collaborate with Wiliot and scale solutions into many Internet of Things deployments,” said Amir Khoshniyati, VP and GM Transponders, Identiv.

The Wiliot Battery-Assisted IoT Pixel tag will be available directly from Identiv and will use the same Wiliot cloud services to manage scale, privacy and sensing, that brings intelligence to products and packaging that were previously offline.

https://www.wiliot.com/