Traditional Flame Retardants Research Articles

A Study on the Effect of Nano-Magnesium Hydroxide on the Flammability of Epoxy Resins

In this work the effect of nano-magnesium hydroxide (nano-Mg(OH)2) on the flammability of epoxy composites is presented and compared with the traditional flame retardant used in just small amounts for epoxy resins, ammonium polyphosphate (APP). The fire reaction properties of epoxy composites were obtained by cone calorimeter tests. It was observed that the flammability of the unfilled resin is significantly changed with nano-Mg(OH)2 addition and reductions of 33, 22 and 23% in the epoxy composite heat release rate peak (PHRR) by incorporating 10%, 5 % and 1% of nano-Mg(OH)2, respectively, were achieved. Cone calorimeter analyses confirm the better behavior of APP composites compared with nano-Mg(OH)2 composites. SEM micrographs show some agglomerations on the distribution of nano-Mg(OH)2 in the epoxy matrix.

Chemically modified flame retardant polymers

The increased attention to safety requirements has accelerated the investigation of flame retardant plastics, but the proportion of flame retarded types among commercial polymers is still lower than desirable. Nevertheless, certain segments of the industry started to recognize the importance of flame retardancy. According to a market study the annual consumption of flame retardants is currently over 1.8 million tonnes, which is the equivalent of a sales volume of approx. 3 billion C =. The total flame retardant (FR) market will continue to increase with average annual growth rate of 3.7%, which is due in part to the fact that the use of plastics in the past few years has increased significantly. FRs are also of increasing importance due to the growing miniaturization of electronic and electrical equipment, which may imply high power density and areas with excessive heat. The heat concentration and fire threat associated with this miniaturization needs novel FR solutions. There exist two main approaches to achieve flame retardancy: the additive and the reactive approach. Lately the reactive type was given much attention, especially in case of polycondensation or polyaddition type polymers, where monomers can be exchanged by components possessing both functionality and flame retardant moiety in the same molecule. The reactive FRs have numerous advantages: they provide more stable effect, as they are chemically incorporated into the polymer structure, so they do not migrate to the matrix surface either during high temperature processing or application. Due to these reasons less FR is needed to achieve same level of flame retardancy, which leads to reduction of toxic gas emission compared to the additive approach. Moreover, as they perform properly in low percentage, they do not influence considerably the properties of the matrix, which is a great advantage compared to the traditional FRs, such as metal-hydroxides. In addition, reactive FRs can be cost-effectively integrated in the production process, simply by replacing the original non-FR component; which is essential nowadays. The sustainable development concept applied to this field implies that FRs should involve a low impact on health and environment during the entire life cycle including recycling and disposal. The increasing focus on these issues has drawn the attention to halogen-free additives, especially to phosphorous reactive FRs. Phosphorus can act both in gas phase, mainly at the beginning of degradation, and later on principally in solid phase as intumescent FR, providing an outstanding FR effect supported by this combined mechanism.

Self-extinguishing polymer/organoclay nanocomposites

We demonstrated that self-extinguishing polymer nanocomposites, which can pass the stringent UL 94 V0 standard, can be successfully prepared by combining modified organoclays with traditional flame retardant (FR) agents. Using secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM), we determined that the addition of modified clays, which can intercalate or exfoliate in the matrix, also improved the dispersion of the FR agents. Dynamic mechanical analysis (DMA) indicated that the clays increased the modulus of the polymer above T g, which prevented dripping during burning. Cone calorimetry test showed that the nanocomposites with both FR and organoclay, had a lower peak heat release rate (PHRR) and average mass loss rate (MLR) than those with only clay or the FR agents. Extended X-ray absorption fine structure (EXAFS) data confirmed that no FR/clay interactions occurred in the solid phase, and that the synergistic effects were due to gas phase reactions. Since this mechanism is not specific, it opens the possibility of formulating self-extinguishing materials from a large class of polymers.

Polymer Nanocomposites: How to Reach Low Flammability?

AbstractThe paper investigates critically the feasibility to make fire proof polymer using nanoparticles. It includes organoclay, polyhedral oligomeric silsesquioxanes (POSS) and carbon nanotube (CNT). It is shown that they can be used to make material exhibiting low heat release rate (HRR) when they undergo heat. We have developed novel approaches to characterize quantitatively the nanodispersion by solid state NMR and by TEM associated with image analysis and we have demonstrated that the dispersion at the nanoscale is essential to achieve the best performance. On the other hand, low flammability of nanocomposites is only achieved in terms of HRR but they fail in terms of UL‐94 and limiting oxygen index (LOI). To overcome this problem, we have combined nanoparticles with traditional flame retardants (intumescents) or with plasma treatment. The nanofillers act as synergists and offer an exceptional way for making fire safe polymers.

Flame retardancy and antidripping effect of OMT/PA nanocomposites

The organically modified montmorrillonite (OMT) was extruded with PA6 and PA66, respectively to manufacture polymer layered silicate nanocomposite (PLSN). A set of OMT/PA66–PPO PLSN-alloys were synthesized. Flame retardancy of them was evaluated by conventional liming oxygen index (LOI) approach. Experimental results show that there is no dripping-melt when OMT/PA PLSN is burning. There is a kind of synergistic effect between OMT and traditional flame retardant (FR). LOI of 5% OMT–10% RPM/PA66 is 30.8, 5% OMT–15% RPM/PA66 achieves UL94-V0. LOI of 5% MMT/PA66–PPO PLSN-alloys is 30. The flame retardancy mechanism of OMT/PA is also discussed.

Flame Retardancy of Nanocomposites - from Research to Reality

Nanocomposites are a new class of polymer systems. Modified layered silicates as fillers are dispersed at a nm-level within a polymer matrix. For nanocomposites new and extraordinary properties are observed. The thermal stability and the flame retardancy of polymers forming nanocomposites are improved. The flame retardancy mechanism of layered silicate nanocomposites is based on the char formation and its structure; the char insulates the polymer from heat and acts as a barrier, reducing the escape of volatile gases from the polymer combustion. The cone calorimeter is a very useful tool to investigate the properties of flame retardancy. The combination of organoclays with traditional flame retardants is a general way to improve the flame retardant properties of polymers.

Nanocomposites. 2. a New Flame Protection System for Polymers

Nanocomposites contain only a very small amount of modified layered silicates as fillers. The flame retardant mechanism in nanocomposites is based on the extremely effective char formation during decomposition as a result of combustion. This char provides a thermal protection for the polymer, prevents further decomposition, and also delays the release of flammable gases during combustion. The cone calorimeter is the most suitable instrument for measuring these effects. Nanocomposites have significant advantages over traditional flame retardant systems such as aluminium hydroxide or magnesium hydroxide.

LEXAN FLAME RETARDANT 920/940/950 SERIES RESINS

Abstract LEXAN FLAME RETARDANT RESINS 920, 940 and 950 have decreased smoke emission and toxic gas evolution relative to traditional flame retardant grades and provide properties similar to standard grades of LEXAN resin. LEXAN 920A, 940A and 950A grades provide high flame retardance at a lower cost with improved surface appearance. They are available in opaque colors and in transparent and translucent tint colors. This datasheet provides information on physical properties, hardness, tensile properties, and compressive and shear strength as well asfracture toughness, deformation, and fatigue. Filing Code: P-19. Producer or source: G. E. Plastics.