Newsflash

The drive for lightweight materials to reduce overall cost and environmental impact for automotive manufacturers is nothing new.  Fuel economy attracts car buyers too. That is how majority of steel parts have been replaced in F-150 pickup truck by aluminum parts, reducing overall weight over 500 pounds. Then there are alloys, carbon fiber and plastics composites.The ambition for lighter vehicles did not stop with alloys (magnesium, aluminum), and/or composites (glass, carbon fibers).  Recently, Japanese researchers at Kyoto University led by Professor Hiroaki Yano along with its industrial partners (Denso Corporation and Daikyo-Nishikawa Corporation) reported that they were developing cellulose nanofiber based materials for automotive as well as aircraft parts to reduce environmental footprint while increasing product performance.Inevitable questions are: 1) would these materials be cost effective? 2) What would be the service life of these products compared to the current ones? 3) How about the parts’ safety in situations like crash or fire?A final question that an automaker has to ask is: what would be the pay back time to replace current production line (machinery) to CNF based plastics line?Reference: https://www.japantimes.co.jp/news/2017/08/15/business/researchers-japan-use-wood-make-cellulose-nanofiber-auto-parts-stronger-lighter-metal/#.WbAIKeTXuUm...
We know polycarbonates mostly from its use in plastics water bottles, safety goggles, smart phones, structural panels (glazing) and the list goes on.  A quick look at Wikipedia gives a spectrum of applications.However, polycarbonates have its weaknesses along with the BPA (bis-phenol) controversy. Polymers such as polysulfates and polysulfonates have similar if not better mechanical properties than polycarbonates.  The issue has been how reliably scale-up the manufacturing process of polysulfates and polysulfonates?“Click chemistry” is a concept in organic chemistry by which highly reactive reactions provide high yielding products and require little to no purification.  The concept was introduced by Nobel Prize winner Professor K. Barry Sharpless in 2001.A recent work published in Nature Chemistry, by a team of researchers from The Scripps Research Institute (La Jolla), Lawrence Berkley National Laboratory (Berkley), California and Shanghai Institute of Organic Chemistry & Soochow University, China claimed that reduced cost of catalyst, product purity, and by-product recycling make their work ready to move from laboratory research to industrial process.Chemists are at work indeed!References:https://en.wikipedia.org/wiki/PolycarbonateK. Barry Sharpless et al; Nature Chemistry, 2017 DOI: 10.1038/nchem.2796...
In a recent The Atlantic interview Bill Gates made a wish on an energy miracle, “Here’s a source of energy that is cheaper than your coal plants, and by the way, from a global-pollution and local-pollution point of view, it’s also better”.  The race is on to find that source. One such energy source is solar energy. We all know that solar energy can be harnessed to generate thermal energy or electrical energy for use in the residential and/or in the commercial applications.  Any material that can store Solar Thermal Energy is called Solar Thermal Fuel (STF).  The quest to harvest solar energy, store the same and use it when needed has been the focus of research in industry and academia alike. For the first time, Professor Grossman’s team at MIT, Cambridge (USA) has come up with a new approach which uses polymer Solar Thermal Fuel (STF) storage platform utilizing STF in its solid-state.  According to the published article, researchers stated, “Closed cycle systems offer an opportunity for solar energy harvesting and storage all within the same material. This approach enables uniform films capable of appreciable heat storage of up to 30 Wh kg?1 and that can withstand temperature of up to 180 °C.”How the STF process works?Certain molecules (chemicals) can have 2 different stable structural forms. These structures are called conformations.  When original molecular conformation is exposed to sunlight, the molecule gets charged and the original conformation changes to the other and stay in that charged conformation for a long period.  The charged molecule snaps back to their original shape (conformation), when triggered by a very specific temperature or other stimulus generating heat in the process. Currently, developed polymeric film can release heat about 10 degree C above the surrounding temperature. Film property improvements are underway. German auto company BMW, has sponsored this research. Where the potential application lies - your guess is as good as mine.References:The Atlantic, p 56, November 2015Zhitomirsky, D., Cho, E. and Grossman, J. C. (2015), Solid-State Solar Thermal Fuels for Heat Release Applications. Adv. Energy Mater., 1502006. doi:10.1002/aenm.201502006...
In a recent The Atlantic interview Bill Gates made a wish on an energy miracle, “Here’s a source of energy that is cheaper than your coal plants, and by the way, from a global-pollution and local-pollution point of view, it’s also better”.  The race is on to find that source. One such energy source is solar energy. We all know that solar energy can be harnessed to generate thermal energy or electrical energy for use in the residential and/or in the commercial applications.  Any material that can store Solar Thermal Energy is called Solar Thermal Fuel (STF).  The quest to harvest solar energy, store the same and use it when needed has been the focus of research in industry and academia alike. For the first time, Professor Grossman’s team at MIT, Cambridge (USA) has come up with a new approach which uses polymer Solar Thermal Fuel (STF) storage platform utilizing STF in its solid-state.  According to the published article, researchers stated, “Closed cycle systems offer an opportunity for solar energy harvesting and storage all within the same material. This approach enables uniform films capable of appreciable heat storage of up to 30 Wh kg?1 and that can withstand temperature of up to 180 °C.”How the STF process works?Certain molecules (chemicals) can have 2 different stable structural forms. These structures are called conformations.  When original molecular conformation is exposed to sunlight, the molecule gets charged and the original conformation changes to the other and stay in that charged conformation for a long period.  The charged molecule snaps back to their original shape (conformation), when triggered by a very specific temperature or other stimulus generating heat in the process. Currently, developed polymeric film can release heat about 10 degree C above the surrounding temperature. Film property improvements are underway. German auto company BMW, has sponsored this research. Where the potential application lies - your guess is as good as mine.References:The Atlantic, p 56, November 2015Zhitomirsky, D., Cho, E. and Grossman, J. C. (2015), Solid-State Solar Thermal Fuels for Heat Release Applications. Adv. Energy Mater., 1502006. doi:10.1002/aenm.201502006...
Reliable and high performance lithium ion batteries commonly known as LIBS are highly sought after product by industries. We all have heard stories about laptops, electric vehicles, airplanes catching fires due to LIBS. Underlying problem is the battery overheating. Preventing batteries from overheating is crucial to the public safety.  Now a team of researchers at Stanford University designed a thermo-responsive (heat sensitive) plastic composite film made from polyethylene and spiky nickel microparticles coated with graphene which shuts down the battery if the temperature is too high.         In a recently published work led by Yi Cui and Zhenan Bao of Stanford University, USA concluded “Safe batteries with this thermoresponsive polymer switching (TRPS) materials show excellent battery performance at normal temperature and shut down rapidly under abnormal conditions, such as overheating and shorting.” How practical this design approach is? Time will tell.References: Y. Cui, Z. Bao et al Nature Energy vol.1, Article number: 15009 (2016); DOI: 10.1038/nenergy.2015.9Chemical & Engineering News, Page 7, January 18, 2016...
In aviation industry, the focus is how to improve fuel safety and handling. Mike Jaffe and Sahitya Allam gave their perspective on safer fuels by integrating polymer theory into design (Science, 350, No. 6256, p. 32, 2015).Mist (generated from the fuel) is much more flammable than the liquid and that is why anti-misting kerosene interferes with mist formation when a low percentage of a polymer is added into it.  The problem however, is that the polymer chain undergoes scission during handling and can’t assist in suppressing mist formation. The answer comes from a recent paper published in the Journal Science by Professor Julia Kornfield and her cross-functional team at Caltech, Pasadena, USA. The group designed a megasupramolecules having polycyclooctadiene backbones and acid or amine end groups (telechelic polymer) which is short enough to resist hydrodynamic chain scission while protecting covalent bonds through reversible linkages. Yes, polymers can be designed to suit our societal needs including aviation fuel safety.Reference: M-H Wei, B. Li, R.L. Ameri David, S.C. Jones, V. Sarohia, J.A. Schmitigal and J.A. Kornfield; Science, 350, (6256), pp. 72-75 (2015)...
At the TED conference, Carbon3D, a Vancouver based company touted a radical 3D printing technology and named it CLIP or Continuous Liquid Interface Product. CLIP grows parts instead of printing them layer by layer. It harnesses light and oxygen to continuously grow objects from a pool of resin.  The result: make commercial quality parts at game-changing speed.  CLIP is 25 to 100 times faster than traditional 3D printing technique.  To make the point, Carbon3D web site provides a head-to-head comparison of CLIP to Polyjet, SLS and SLA.[Press release: March 16, 2015, Vancouver, Canada.  www.carbon3D.com]...
Self-healing plastics has been around for a while. Applications include self-healing medical implants, self-repairing materials for use in airplanes and spacecrafts. Even scientists have made polymeric materials that can repair itself multiple times. A recent report in Science describes a significant advance in self-healing plastics. The authors describe a product that mimics how blood can clot to heal a wound. When the plastic is damaged a pair of pre-polymers in channels combines and rapidly forms a gel, which then hardens over 3 hours.The authors demonstrated that holes up to 8 millimeters wide can be repaired. The repaired parts can absorb 62% of the total energy absorbed by undamaged parts.  Science never stops.Reference:S. R. White, J. S. Moore, N. R. Sottos, B. P. Krull, W. A. Santa Cruz, R. C. R. Gergely; Science, Restoration of Large Damage Volumes in Polymers, Vol. 344 no. 6184 pp. 620-623; (9 May 2014). ...
Knowingly or unknowingly, flexible electronics has become a part of our daily life.  Transparent conductive films (TCFs) are used in mobile phones, tablets, laptops and displays.  Currently, Indium Tin Oxide or commonly known as ITO is the material of choice.  But use of ITO has some major disadvantages and these are brittleness, higher conductivity at greater transparency, and supply of Indium.  This is where non-ITO materials come into play. Based in St. Paul, Minnesota (USA), Cima NaoTech’s uses its SANTETM nanoparticle technology, a silver nanoparticle conductive coating which self-assembles into a random mesh like network when coated onto a flexible substrate such as PET and PC.  According to a recent press release, the company stated SANTETM nanoparticle technology enabled transparent conductors in a multitude markets from large format multi-touch displays to capacitive sensors, transparent and mouldable EMI shielding, transparent heaters, antennas, OLED lighting, electrochromic and other flexible applications.  Cima NanoTech is working with Silicon Integrated Systems Corp. (SIS) of Taiwan and using its highly conductive SANTE FS200TM touch films to develop large format touch screens.References: Press release, San Diego, June 03, 2014; www.cimananotech.com ; http://www.cimananotech.com/sante-technology ; http://www.sis.com/...
In an article appeared today (January 29, 2014) in The Guardian newspaper, Stuart Dredge wrote, “From jet parts to unborn babies, icebergs to crime scenes, dolls to houses: how new technology is shaking up making things”1. Mr. Dredge was speaking about 3D printing technology.  The heart of this technology is the 3D printer itself. Stratasys, a company headquartered in Minneapolis, USA is the manufacturer of 3D printers.  It recently announced the launch of Color Multi-material 3D Printer, the first and only 3D printer to combine colors with multi-material 3D printing.  According to the press release2, by using cyan, magenta, and yellow, multi-material objects can be printed in hundreds of colors.  The technology is based on proven Connex technology.  While the base materials are plastics and elastomers, they can be combined and treated to make finished products of wide ranging flexibility and rigidity, transparency and opacity.  Designers, engineers and manufacturers can create models, mold, and parts that match the characteristics of the finished production part. This includes achieving excellent mechanical properties.  According to the manufacturer, print job in the newly revealed printer can run with about 30 kg of resin per cycle and prints as fine as 16 micron layers for models.  No wonder why some call the new Color Multi-material 3D printer a groundbreaking stuff.References: 1. www.theguardian.com.technology/2014/jan/29/3d-printing-limbs-cars-selfies (January 29, 2014)2. http://investors.stratasys.com/releasedetail.cfm?ReleaseID=821134 (August 3, 2014)...
Instead of stitches or skin staples, doctors use skin glue to close wounds. The glue joinsthe edges of a wound together while the wounds heal underneath. Most of the timeskin glue is used for simple cuts or wounds. According to the paper published inScience Translational Medicine, there are no clinically approved surgical glues thatare non-toxic, bind strongly to tissue, and work well in wet and highly dynamicenvironments within the body. This is the reason why this published work is promisingwhere infants born with heart defects would benefit tremendously. Researchers at the Brigham and Women’s hospital in Boston have engineered ‘bio-inspired’ gluethat can bind strongly to tissues on demand, and work well in the presence ofactively contracting tissues and blood flow. The authors of the paper show howthe glue can effectively be used to repair defects of the heart and blood vessels during minimally invasive procedures. [References: P. J. del Nido et al; Sci. Transl. Med., DOI: 10.1126/scitranslmed.3006557; See also, www.geckobiomedical.com/news/gecko-biomedicals-co-founde.html]...
Stability of organic electronics in water is a major research challenge. For this reason,organic electronics has yet to see any sensing application in aqueous environment.However, as understanding of underlying mechanism of stability aspect is becomingclearer, new developmental efforts to make water compatible organic polymer devicesare taking place. Recently, Professor Zhenan Bao’s group in the department of chemical engineering at Stanforduniversity revealed in a paper published in the journal of Nature Communications thatsolution- processable organic polymer could be stable under both in freshwater andin seawater. Developed organic field-effect transistor sensor is able to detect mercury ionsin the marine environment (high salt environment). Researchers believe that the work hasthe potential to develop inexpensive, ink-jet printed, and large-scale environmental monitoring devices. [References: O. Knopfmacher, M.L. Hammock, A.L. Appleton, G. Schwartz, J. Mei, T. Lei, J. Pei,and Z. Bao; Nature Communications, 5, 2954, January 6, 2014; DOI: 10.1038/ncomms3954]...
Insulin, the wonder medicine for diabetes was discovered about a century ago.Since insulin does not get into the blood stream easily, diabetes patients oftenhave injected themselves with insulin. Now a group of scientists led by Dr. Sanyog Jainat the Center for Pharmaceutical Nanotechnology of National Institute of Pharmaceutical Education and Research in Punjab, India has designed a polymerbased package for oral insulin administration. The package design addresses two major obstacles, 1) digestive enzymes must notdegrade insulin prior to its action and 2) the insulin gets into the blood stream.The package contained folic acid functionalized insulin loaded in liposomes.To protect the liposomes (lipids or fat molecules) they were alternately coated withnegatively charged polyacrylic acid (PAA), and positively charged poly allylamine hydrochloride. Studies were conducted to compare the efficacy of bothdelivery systems: designed polyelectrolyte based insulin and standard insulinsolution. Effects of oral administration lasted longer than that of injectedinsulin, authors reported in a recent article in Biomacromolecules. [Reference: A.K. Agarwal, H. Harde, K. Thanki, and S. Jain; Biomacrmolecules, Nov. 27, 2013;DOI: 10.1021/bm401580k]...
Research in the area of stretchable electronics is heating up!  Thanks to polymers. Led by Professor George M. Whitesides of Harvard University (USA), a team of researchers have demonstrated in a recently published paper in Science that ionic conductors can be used in devices requiring voltages and frequencies much higher than commonly associated with devices using ionic conductors.  The team showed for the first time that electrical charges carried by ions and not electrons, can be utilized in fast-moving, high voltage devices.As a proof of concept, the authors of the study built a transparent loudspeaker that produces sound across the full audible range i.e., 20 Hz to 20 kHz.  Components [such as VHB 4910 tape (acrylic tape with PE liner), polyacrylamide hydrogel containing NaCl electrolyte] used for the high speed, transparent actuators are described in the paper.Tissues and cells are soft and require stretchable conductors for biological systems. Many hydrogels are biocompatible which makes this work particularly an important one. The design of gel-based ionic conductors is highly stretchable, completely transparent and offer new opportunities for designers of soft machines.   [Reference: C.Keplinger, J-Y. Sun, C.C. Foo, P. Rothemund, G.M. Whitesides, and Z. Suo; Science, 341 (6149), pp. 984-987 (2013); DOI: 10.1126/science.1240228]...
Interweaving biological tissue with functional electronics, one can make bionic ears.  NASA has tested 3D-printed rocket engine part.  Then why not 3D print yourself?Well, Twinkind, a German start-up company is now offering enthusiasts statues of themselves for display.  How this works?  A full body scanner takes an image of the customer’s body, transfers the file to the printer after which 3D printer laser sinters a composite powder layer by layer into the customer image.Can we dare to say that Madame Tussauds wax figure of Voltaire can now be 3D printed in polymers soon!  [Reference: www.twinkind.com ]...
Polymer membranes have become a leading contender in numerous separation processes.  Be it in gas (air, hydrogen etc.) or be it in water purifications (salinated water, waste water etc.).  Not only polymer membrane technology helps reducing the environmental impact but also it is cost-effective.  Fracking in shell gas is one of many examples. New advances in drilling technology (such as horizontal drilling) have led to new hydraulic fractures called fracking.  Hydraulic fracturing requires about 2.5 to 5 million gallons of water per well.  Water management and its disposal are major costs for producers.One major challenge, however, of the membrane technology is the fouling (damage caused by contaminants) mitigation.  This has been recently studied by a group of researchers from University of Texas at Austin led by Professor Benny Freeman to address efficiency and reuse of water for fracking in shale gas plays.Researchers modified polydopamine coated UF (ultrafiltration) module by grafting polyethylene glycol brushes onto it.  The result is more hydrophilic surfaces which in turn improved cleaning efficiency relative to unmodified modules. The coating improves the membrane life, and can easily be applied to membrane surface by rinsing it through the recycling system.[References: D.J. Miller, X. Huang, H. Li, S. Kasemset, A. Lee, D. Agnihotri, T. Hayes, D.R. Paul, and B. Freeman; J. Membrane Sci., 437, pp. 265-275 (2013); Also see www.advancedhydro.net ]...
Flexible electronics can change the way we use electronic devices.  It is a term used for assembling electronic circuits by mounting electronic devices on a flexible plastic. A recent review article captured the advancement of CNT and graphene based flexible thin film transistors from material preparation, device fabrication to transistor performance control compared to traditional rigid silicon1. Silicon is used almost exclusively in electronic devices.Now Prof. Ali Javey led a team at the University of California, Berkley to develop a printing process to make nanotube transistors at room temperature with gravure printer.  The plastics used is polyethylene terephthalate (PET). The device exhibited excellent performance with mobility and on/off current ratio of up to ~9 cm2/ (V s) and 105 respectively.  Also, maximum bendability is observed.  The paper authors conclude that this high-throughput printing process serves as enabling nanomanufacturing scheme for range of large-area electronic applications based on nanotube networks2. References:1. D-M. Sun, C. Liu, W-C. Ren and H-M Cheng; Small, DOI: 10.1002/smll.2012031542. P.H. Lau, K. Takei, C. Wang, Y. Zu, J. Kim, Z. Yu, T. Takahashi, G. Cho, and Ali Javey; Nano Letters, 13 (8), pp. 3864-3869 (2013); DOI. 10.1021/nl401934a...
Drinking coffee from paper cups are as common as drinking water from plastics bottle. The issue however, is recycling of disposable cups. The disposable cups are made up of 90-95% of high strength paper (fibers) with a 5% thin coating of plastic (PE).To address the recycling issue, James Cropper Speciality Papers of UK have developed a process which involves softening the cup waste, and separating the plastic coating from the fiber.  After skimming off the plastic, remains are pulverised and recycled, leaving water and pulp behind.  According to the company news release, the high grade pulp is reused in luxury papers and packaging materials.An innovative approach to address a common problem.[Reference: www.jamescropper.com/news ]...
A search for an alternative to rigid silicon wafers gave birth to the area of flexible or bendable electronics. Research has been intense for the past few years in the area flexible electronics as it opens up multitude of new applications. Polymers play an important role to exciting field of flexible electronics.In a recent research report, a team of scientist led by Prof. Ali Javey of University of California, Berkeley (USA)  has shown for the first time user-interactive electronic skin or e-skin can conformally wrap irregular surfaces and spatially map and quantify various stimuli through a built-in active matrix OLED display.  Three electronic components namely thin film transistor (uniform carbon nanotube based), pressure sensor, and OLED arrays (red, green, and blue) are integrated over a plastic substrate.  Spin coated and cured polyimide on a silicon wafer is used as the flexible substrate.  Details are in the paper.This work essentially provides a technology platform where integration of several components (organic and inorganic) can be done at a system level on plastic substrates. According to the paper, this e-skin technology could find applications in interactive input/control devices, smart wallpapers, robotics, and medical/health monitoring devices.    [Ref: C. Wang, D. Hwang, Z. Yu, K. Takei, J. Park, T. Chen, B. Ma, and Ali Javey; Nature Materials, Published online July 21, 2013; DOI: 10.1038/NMAT3711]...
Recent buzz in the technology world is 3D printing.  Researchers to designers are creating new products everyday using 3D printing technology.  Even eBay has unveiled its services to those looking to make their own creations using 3D printing App.Since ages composites have played a crucial role in our society. Inspired by natural (biological) composites such as bone or nacreous abalone shell, researchers from MIT (USA) and Stratasys have developed composite materials that have fracture behaviour similar to bones.  Using computer model with soft and stiff polymers, the team has come up with a specific topological arrangements (hierarchical structures) of polymer phases to boost the mechanical behaviour in the composites.Interestingly, the team has been able to manufacture (thanks to 3D printing) a composite material that is more than 20 times larger than its strongest constituent.  The referenced paper showed that one can use computer model to design composite materials of their choice, tailor the fracture pattern and then use 3D printing technology to manufacture the composites.[Ref: L.S. Dimas, G.H. Bratzel, I. Eylon, and M.J. Buehler; Advanced Functional Materials, Published online June 17, 2013; DOI: 10.1002/adfm.201300215]...

fr_figure  Fire safety is crucial to our modern society. Flame retardants play an important role in the fire protection strategy.  In recent years, regulatory demands have put enormous pressure on developing environments friendly flame retardants for thermoplastics. The aim of this series of articles is to review new flame retardant technology and trends in their use with thermoplastics.  It describes advances in non-halogenated flame retardant technologies, new polymeric flame retardant additives, and advances in testing and fire risk evaluation.

Background

Flame retardants are a class of chemicals designed to provide passive fire protection to polymers under specific fire risk scenarios. The fire protection provided by the flame retardant can vary from ignition resistance to slowing of flame spread/heat release growth to smoke and toxic gas reduction.  There is a very wide range of actions flame retardants can perform if chosen and implemented properly.  It is important to note that every flame retardant solution must be tailored for a specific polymer and for a specific test.

In 2009 the global market for flame-retardant chemicals was more than 3 billion pounds, with a value of over $4 billion. This was expected to reach $6.1 billion by 2014. Detailed breakdowns of this market are only available in proprietary marketing reports such as those produced by the Business Communications Company . Important applications include aerospace, automotive, electronics & electrical goods, carpeting, textiles, mass transport (train, ships, subways), building & construction, military, and wire & cable. 

A flame retardant will normally be used in a particular product if fire safety engineers anticipate a significant risk of fire exposure that threatens loss of life or property and which cannot be addressed with active fire protection (sprinklers or replacement with non-flammable materials). The amount of flame retardants used in each application will vary depending upon the flammability of the polymer and the severity of the fire risk. 

Significant environmental events have captured the public’s attention and led to a general phobia of chemicals in the Western World. These include the Great Smog of London (United Kingdom, 1952 ), which caused numerous deaths due to emissions and the Cuyahoga River fire (near Cleveland, Ohio, USA, 1969 ) where the water ‘caught fire’ due to incorrect chemical disposal.

Our society has responded to events like these and made great strides in improving the balance between technological advancement and environmental protection. One result is our ability to detect picogram quantities of pollutants with the help of modern analytical techniques such as gas chromatography – mass spectrometry (GC-MS) and high performance liquid chromatography – mass spectrometry (HPLC-MS).  This has shown that flame retardants are wide spread in the environment.

Other work has shown that some flame retardants can be persistent, bio-accumulative, and toxic (PBT). This has led to calls for bans on their use and to regulation in the European Union and United States, where the use of some brominated flame retardants is banned.

Plastics containing brominated flame retardants can be difficult to recycle. The first problem is that the flame retardant may migrate out of the plastic as a dust during regrinding. The second one occurs when brominated flame retardant containing plastics are recycled, they can contaminate non-flame retardant plastic waste streams. Finally, in the case that the brominated flame retardant polymer goes to incineration for final disposal, the incinerators must have afterburners and acid capture systems to deal with any dioxin and hydrogen bromide formed.  However, some brominated flame retardant containing polymers have shown that they can be reground and remelted into parts many times before losing flame retardant effectiveness.  So while there are difficulties in recycling halogen flame retardant containing plastics, it can be done.  

Along with chemical phobia and some of the difficulties in dealing with brominated flame retardants at the end of their life cycle, flame retardants seem to have lost in the court of public opinion. For example in May, 2012, a wide-ranging article was published by the Chicago Tribune  calling for a ban on an entire chemical class of flame retardants. The perception is that flame retardants serve no purpose. This is based upon a lack of awareness of the balance between the benefits of modern plastics and the fire risks that they bring into the home and workplace.

Flame retardants are a class of chemicals, which are added to combustible materials to provide passive fire protection for specific fire risk scenarios. These additives are designed to minimize the risk of a fire when a plastic comes in contact with a small heat source such as cigarette, candle or an electrical fault. The fire protection provided by the flame retardant can vary from ignition resistance to slowing of flame spread/heat release growth to smoke and toxic gas reduction.  Flame retardants can provide this wide range of mechanisms if chosen and used correctly.

Flame retardants are examples of polymer additives, which as their name implies, are materials that are added to the plastic at some point during its manufacture, to bring a specific benefit to a plastic (such as improved mechanical, thermal or electrical properties, color, oxygen or UV protection) that the base polymer could not provide on its own.

A wide range of materials are used as flame retardants. There is no such thing as a universal flame retardant, since a material that works well with a polymer in one test may not be appropriate for the same polymer in another test, or for a different polymer in that same test.  Every flame retardant application must be tailored for a specific polymer in a specific test.  Development of new flame retardant applications requires careful attention to polymer chemistry, polymer thermal decomposition behavior, and the flame retardant mechanism. This is discussed in a number of introductory books and guides , , .

The most common flame retardants are the brominated flame retardants, which are used due to their great efficacy in a wide range of polymers and applications and their low cost.  These materials have been known since the 1930s, and have proved to be effective. However this is an old technology and as we have learnt more about their environmental impact, their risks and benefits have had to be reassessed. At the same time a new class of brominated flame retardants which are polymeric in structure has been appearing in the market place. Their rate of acceptance is being determined by a mix of technical and political factors.

The Regulatory Situation:  Flame Retardant Bans

The EU has been investigating the PBT issues of this class of chemicals for quite some time. The issue has also been discussed and debated in the US and Canada and over the past 20 years.  The greatest change has occurred in the past year; flame retardants that have been in use for decades (such as brominated diphenyl ethers and hexabromocyclododecane (HBCD)) will no longer be allowed after the end of 2013 or 2014.  Even with some national regulatory exceptions, the extended use time for these flame retardants is unlikely exceed one or two years.

fr_figure1

In 2006 Pentabromodiphenyl ether and Octabromodiphenyl ether were voluntarily withdrawn by the last major manufacturer of these chemicals (Great Lakes Chemical Corporation, now part of Chemtura) and regulated heavily in the US by the Environmental Protection Agency (EPA), thus ensuring that there would be no new major use of these chemicals. 

In 2012, all brominated diphenyl ethers have been voluntarily withdrawn by the main flame retardant manufacturers and also placed under EPA regulatory control for phase-out and banning of import or use in the US.   These rules effectively eliminate the use of these flame retardant additives in any new product sold in the US, but this flame retardant may be present in many existing products that already contains that flame retardant.  HBCD, used mostly for expanded polystyrene foam insulation, has also been selected for phase out in the USA  and Canada. 

In one year, two widely used classes of flame retardants have been voluntarily withdrawn by the manufacturers and put under regulatory ban.  This has had two major effects, one political, one technical. It has given companies the impetus to develop viable safer commercial alternatives and it has emboldened non-governmental organizations (NGO) to push for further bans.

Current Trends

As indicated in the previous section, the three main manufacturers of brominated flame retardants - Albemarle Corporation, Great Lakes Solutions (Chemtura), and Israel Chemicals Limited - have voluntarily withdrawn HBCD and brominated diphenyl ethers from the market.  However, each company also has a variety of replacements for these chemicals.  In many cases, the replacement is a polymeric brominated polymer.  This is notable in that polymeric materials tend to have a much lower environmental impact (low bio-accumulation and toxicity factors) than small molecules do.  This trend of polymeric flame retardants is one that is likely to continue as the flame retardant manufacturers advance this technology.  Indeed, polymeric flame retardants may present some superior benefits from a manufacturing perspective, compared to the flame retardants they are replacing.  Specifically, they will likely be easier to melt-compound into a plastic, and may give better balance of properties in final plastic products as the final product will be a polymer/polymer blend, not a polymer with fillers/additives present. These polymeric additives, with trade names such as GreenArmor (Albemarle), Emerald Innovation (Great Lakes), and FR122 (Israel Chemicals), are a new trend for 2012 and one that is likely to continue. 

Companies outside North America and Europe have no chemical-production bans in their home country, and so continue to manufacture the banned flame retardants, which might continue to appear in imported goods.

The long term future of brominated polymers is not clear. Their commercial viability is threatened by the chemical phobia discussed above, exacerbated by pressure from NGOs, who cast doubt on their value and efficacy while emphasizing perceived health risks associated with the small molecule flame retardants.  This is important, as the chemical structures of small molecule brominated flame retardants and brominated polymers may share some similarities (aromatic Carbon-Bromine bonds for example) but a polymer and a small molecule containing the same type of chemical bond will have an entirely different PBT profile.  Therefore one should not just assume that all chemical structures have the same environmental and toxicity/health effect.  Each structure has to be tested and verified for toxicity.

Every plastic manufacturer must carry out a difficult balancing act when selling a product.  The product must meet end-use performance requirements (mechanical, electrical, appearance, thermal, fire, etc.), marketing targets (cost, availability), and customer demands, which can at times be rather fickle.  The trend for many consumers of plastics in regards to flame retardants is to go towards non-halogenated technologies.  This is due to the perception that halogenated materials (brominated flame retardants, poly(vinyl chloride), etc.) are bad for the environment, whether right or wrong.  Therefore customer perception that halogen compounds are always bad may slow the commercialization of new brominated polymers for use in the marketplace.  The plastics manufacturer must give the customer what they want or they are not going to make a sale, and very likely we will see continued increases in non-halogenated flame retardant sales and use over the next decade.  A significant educational campaign on the part of the flame retardant manufacturers is needed here, and one should expect more discussion on the topic over the next several years.  This discussion carries into the next topic, the effects of politics on fire vs. environmental safety. 

The Situation:  Fire Safety vs. Environmental Safety

With the Chicago Tribune article and two successful bans of flame retardants, some groups are now turning their focus promoting bans on the use of flame retardants in many applications. If the chemical cannot be banned, then these organizations fight to prevent their use in specific applications, whether or not this position is supported by scientific data. An example is provided by efforts to revise the fire safety standards for upholstered furniture in the US, starting with a revision of California Technical Bulletin 117 (TB-117), which governs the response of polyurethane foam to small open flames. 

In this author’s opinion, not all flame retardants should be used at all costs.  If there is good data showing that the fire protection benefits from a flame retardant are outweighed by environmental damage, then that flame retardant should not be used. If there is good scientific data showing that there is a satisfactory replacement for the old flame retardant which provides good fire safety performance and lowered environmental impact, then the old flame retardant should be removed and the replacement inserted. The wrong approach would be to ban flame retardants with no consideration of fire safety.  For the TB-117 revision, the push is to focus on removing the small open flame ignition source and instead use a smoldering cigarette ignition source.  However, since cigarettes in the US are mostly self-extinguishing (with the exception of hand-rolled cigarettes) the standard revision seems to be focusing on what could be a less common fire risk; ignition by cigarettes.  TB-117 began long ago as a way to provide fire safety against cigarette ignition by testing with a fire source worse than a smoldering cigarette. If the argument is that the fire risk scenario has changed, then it’s time to look at both the regulatory standard and the fire risk.  If cigarette ignition is not really the hazard, but the heat release of polyurethane foam can cause major fire losses, then one should focus on instead on overall material flammability tests, like heat release requirements via calorimetric measurements.  The furniture industry does not need to be literally and figuratively burned again by fire standards that open them up to liability suits. Similarly, the path away from the lawsuits will not be met by abandoning flame retardants.  The fire risks associated with polyurethane foams are quite obvious , but so far in the discussion these fire risks seem to be ignored. 

Both the flame retardant manufacturers and organizations opposing them have used political hearings promote their positions.  One side promotes their products as enhancing fire safety while the other argues that the chemicals are all hazardous and do not provide any meaningful benefit. The truth of the matter is that both are partly right, and they should be working together to come up with better solutions. In some cases, the polyaromatic hydrocarbons and dioxins released from a large house fire, initiated by a non-flame-retarded product, can generate far more environmental pollution than the release of flame retardant into the environment when no accidental fire occurred . In modern homes, with many synthetic polymers present, once fires are started, they grow faster and burn hotter/quicker than fires of old,  thus leading to more large fires with significant emissions.  This is demonstrated in a recent video of a fire study conducted by Underwriter’s Laboratories and the US National Institute of Standards and Technology shows that a room with modern furnishings can burn much faster than one filled with older materials . 

Conclusions

Fire risk will always be with us, and so the question needs to be asked what level of risk are we willing to live with?  Should we accept a higher chance of loss of property and life in fires in order to reduce environmental and health damage?   As a scientist one would argue that we should be asking for and demanding a reduced fire risk without environmental harm.  Just as we have made great strides in detecting chemicals through research and innovations in analytical techniques, we have made similar strides in developing new chemicals in which adherence to green chemistry methods and environmental impact are considered.  Assuming that all participants can agree that both fire safety and the environment are important, a rational scientific approach can be developed that considers environmental toxicity and life cycle analysis in the development of new flame retardant materials. Such collaboration would be incredibly fruitful for our society, and it is sorely needed.

References

1. http://www.bccresearch.com/report/flame-retardant-chemicals-market-chm014k.html?tab=highlight&highlightKeyword=flame+retardants (accessed 5 Feb, 2013) 

2. http://www.metoffice.gov.uk/education/teens/case-studies/great-smog (accessed 18 Feb, 2013)

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5. “Flame Retardants for Plastics and Textiles:  Practical Applications” Weil, E. D.; Levchik, S. V. Hanser Publishers, Cincinnati, OH 2009, ISBN 978-1-56990-454-1

6. “Fire Retardancy of Polymeric Materials” 2nd Edition. Eds. Wilkie, C. A.; Morgan A. B.  2010, Taylor and Francis. Boca Raton, FL ISBN 978-1-4200-8399-6

7. “Fire Toxicity” Eds. Stec, A. A.; Hull, T. R. 2010, Woodhead Publishing Ltd., Boca Raton, FL ISBN 978-1-84569-502-6

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12. (a) “Thermal decomposition, combustion and fire-retardancy of polyurethanes – a review of the recent literature” Levchik, S. V.; Weil, E. D. Polym. Int. 2004, 53, 1585-1610.  (b) “Heat release and structural collapse of flexible polyurethane foam” Kramer, R. H.; Zammarano, M.; Linteris, G. T.; Gedde, U. W.; Gilman, J. W. Polym. Degrad. Stab. 2010, 95, 1115-1122

13. (a) “Fire-LCA Model:  TV Case Study” Simonson, M.; Blomqvist, P.; Boldizar, A.; Möller, K.; Rosell, L.; Tullin, C.; Stripple, H.; Sundqvist, J. O. SP Report 2000:13  ISBN 91-7848-811-7  Printed in 2000.  (b) “Emissions from Fires Part I:  Fire Retarded and Non-Fire Retarded TV-Sets” Blomqvist, P.; Rosell, L.; Simonson, M. Fire Tech. 2004, 40, 39-58.  (c) “Emissions from Fires Part II:  Fire Retarded and Non-Fire Retarded TV-Sets” Blomqvist, P.; Rosell, L.; Simonson, M. Fire Tech. 2004, 40, 59-73

14. http://www.nist.gov/el/fire_research/fire-071112.cfm (accessed 18 Feb, 2013)

15. http://www.youtube.com/watch?v=aDNPhq5ggoE (accessed 15 Feb, 2013)

 

Alexander B. Morgan, Ph.D.

After receiving a B.Sc from the Virginia Military Institute (1994) and a Ph.D. from the University of South Carolina (1998), Dr. Morgan has worked for over seventeen years in the areas of materials flammability, polymeric material flame retardancy, fire science, fire testing, and fire safety engineering with an emphasis on chemical structure property relationships and fire safe material design.  His current research areas include New Flame Retardant Technology for Polyurethane Foam and Furniture, New Flame Retardant Technology with Reduced Environmental Impact, Fire Testing Method Development, Waste-To-Energy Pyrolysis and Combustion Science and Thermal Degradation and Stability Behavior of Materials.


Dr. Morgan has helped academic, government, and industrial customers solve their flame retardant and fire safety needs in a wide range of applications.  He is on the editorial review boards for two fire safety journals (Fire and Materials, Journal of Fire Science), and is a member of ASTM, Sigma Xi, International Association of Fire Safety Scientists, and the American Chemical Society.