Recent research & development in flame retardants has been focused on nanomaterials as a part of the non halogenated flame retardant systems with nanoclays and carbon nanotubes as an aid. Nanoclays, in commercial use for the past several years, reduce relative heat release, promote surface char, create an anti-dripping effect and reduce smoke generation. Nanoclays allow a lower loading of mineral flame retardant in non-halogenated formulations. This is significant, because the high loadings of halogen-free flame retardant (HFFR) typically needed (up to 65% for ATH or MDH) adversely affect mechanical properties and processing. Nanoclays are also used in halogenated systems to reduce the amount of brominated or ATO flame retardant needed, providing lower density, low blooming and better mechanical properties as per Special Chem. AkzoNobel Polymer Chemicals introduced Perkalite synthetic layered double hydroxide (LDH) organoclays in 2008, using fatty-acid modifiers that do not create undesirable color, have higher temperature stability and are more compatible with polymers than the cationic quaternaries typically used to modify other nanoclays. Polyhedral oligomeric silsesquioxanes (POSS) are used commercially as flame retardant aids in phenolics (under the tradename Thermalguard), as well as in PPE and COC. POSS are not nanoparticles, but nanostructured, single molecules whose cage-like shape has an inorganic central core functionalized by organic groups. A key advantage of POSS is that it acts as both an intumescent synergist and as a dispersion aid for halogen-free flame retardants (HFFR), which may allow lower levels of HFFR and improve flow. A lithiated POSS aids dispersion, provides thick intumescent char and mitigates loss of mechanical properties compared to using phosphate FRs alone in thermosets such as vinyl esters. Multi-walled carbon nanotubes (MWCNTs), which are used commercially for their electrostatic dissipative (ESD) and strength properties, are now being considered for their flame retardant properties. Arkema notes that customers are interested in CNTs for HFFR formulations because they affect change at very low concentrations. Research at the US National Institute of Standards and Technology (NIST) found that 1-2% CNT in epoxy was as effective in improving flame retardancy as 10-15% nanoclay. CNTs are effective at forming char, retard onset of combustion by drawing heat away, increase viscosity to help prevent dripping, and do not contribute to depolymerization. CNTs are expected to find use in electronics, where they can provide both ESD and flame retardant properties. Recent research at NIST found that carbon nanofibers were more effective than nanoclay FRs in polyurethane foam, creating an entangled network that effectively prevented the foam from dripping. A new research area at NIST is looking at flame retardancy of nanoparticles like graphene and cellulosic nanofibers in natural polymers like PLA and cellulose. Jammed networks may cause upheaval in phone systems, but among wispy carbon nanotubes or nanofibers, a similar phenomenon may greatly improve flammability resistance and, perhaps, other properties in polymers, report researchers from the National Institute of Standards and Technology and the University of Pennsylvania. Results achieved with two types of carbon nanotubes (single- and multi-walled) and with carbon nanofibers could help to eliminate trial-and-error in designing and producing nanocomposite materials with flame-retarding and other desired properties optimized for applications in areas ranging from packaging and electronics to construction and aerospace. Nanoparticle fillers, especially clays, have been shown to reduce the flammability of plastics and other polymers. Previous work on these nanoclay flame retardants indicates that the additives are most effective when they migrate to form a continuous surface layer, creating a "heat shield" on top of the more flammable polymer matrix. The shield suppresses the "vigorous bubbling" that can occur as the matrix breaks down. However, if the plate-like nanoclay particles cluster into islands, heat escapes through cracks between them, compromising their performance as flame retardants. To get around this problem, the team chose to investigate carbon nanotubes and nanofibers, which tend to be narrower and longer than nanoclays. These structures also have been shown to enhance strength, electrical conductivity and other material properties. The researchers reasoned that the extended, sinuous geometry of the tiny tubes and fibers might lend itself to forming a "continuous, network-structured protective layer" that is free of cracks. When the researchers heated polymethyl methacrylate (PMMA) dispersed with carbon nanotubes or nanofibers, the material behaved like a gel. In a process dictated by their type, concentration and other factors, the nano additives dispersed throughout the PMMA matrix and eventually achieved a "mechanically stable network structure." The “jammed networks" formed as the nanocomposites underwent a change in identity, a transition from liquid to solid. The shift occurred at an optimal composition that the team called the "gel concentration." For single-walled carbon nanotubes--sheets of carbon atoms rolled into cylinders--top fire retardant performance was achieved when the fillers made up only 0.5% of the total mass of the material. For multi-walled carbon nanotubes, which are nested sets of carbon cylinders, the gel concentration was 1%. Both types of nanotubes have the potential to surpass nanoclays as effective fire retardants. Results suggest that the gel concentration also may mark the point at which other nanotube-enabled improvements in material properties are maximized.