Flame retardant mechanism of polyamide 6–clay nanocomposites

Kashiwagi, Takashi; Harris, Richard H.; Zhang, Xin; Briber, Robert M.; Cipriano, Bani H.; Raghavan, Srinivasa R.; Awad, Walid H.; Shields, John R.

doi:10.1016/j.polymer.2003.11.036

Cited by 435 publications

(281 citation statements)

References 30 publications

(24 reference statements)

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“…The weight of the sample was continuously measured by a sensitive weight device and mass loss rate was calculated by taking the time derivative of the weight. The observed mass loss rate in this device correlates well with heat release rate (a direct measure of the size of a fire) of polymer-CNT nanocomposites [22,36] and polymer-clay nanocomposites [37]. The apparatus consists of a stainless-steel cylindrical chamber that is 1.70 m tall and 0.61 m in diameter.…”

Section: Methodsmentioning

confidence: 79%

Relationship between dispersion metric and properties of PMMA/SWNT nanocomposites

Kashiwagi

Fagan

Douglas

et al. 2007

Polymer

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169

113

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Particle spatial dispersion is a crucial characteristic of polymer composite materials and this property is recognized as especially important in nanocomposite materials due to the general tendency of nanoparticles to aggregate under processing conditions. We introduce dispersion metrics along with a specified dispersion scale over which material homogeneity is measured and consider how the dispersion metrics correlate quantitatively with the variation of basic nanocomposite properties. We then address the general problem of quantifying nanoparticle spatial dispersion in model nanocomposites of single wall carbon nanotubes (SWNT) dispersed in poly(methyl methacrylate) (PMMA) at a fixed SWNT concentration of 0.5 % using a 'coagulation' fabrication method. Two methods are utilized to measure dispersion, UV-Vis spectroscopy and optical confocal microscopy. Quantitative spatial dispersion levels were obtained through image analysis to obtain a 'relative dispersion index' (RDI) representing the uniformity of the dispersion of SWNTs in the samples and through absorbance. We find that the storage modulus, electrical conductivity, and flammability containing the same amount of SWNTs, the relationships between the quantified dispersion levels and physical properties show about four orders of magnitude variation in storage modulus, almost eight orders of magnitude variation in electric conductivity, and about 70 % reduction in peak mass loss rate at the highest dispersion level used in this study. The observation of such a profound effect of SWNT dispersion indicates the need for objective dispersion metrics for correlating and understanding how the properties of nanocomposites are determined by the concentration, shape and size of the nanotubes. conditions. We introduce dispersion metrics along with a specified dispersion scale over which material homogeneity is measured and consider how the dispersion metrics correlate quantitatively with the variation of basic nanocomposite properties. We then address the general problem of quantifying nanoparticle spatial dispersion in model nanocomposites of single wall carbon nanotubes (SWNT) dispersed in poly(methyl methacrylate) (PMMA) at a fixed SWNT concentration of 0.5 % using a 'coagulation' fabrication method. Two methods are utilized to measure dispersion, UV-Vis spectroscopy and optical confocal microscopy. Quantitative spatial dispersion levels were obtained through image analysis to obtain a 'relative dispersion index ' (RDI) representing the uniformity of the dispersion of SWNTs in the samples and through absorbance. We find that the storage modulus, electrical conductivity, and flammability † This was carried out by the National Institute of Standards and Technology (NIST), an agency of the US Government and is not subject to copyright in the US. ‡ Correspondence to: T. Kashiwagi (E-mail: takashi.kashiwagi@nist.gov) 1 property of the nanocomposites correlates well with the RDI. For the nanocomposites containing the same amount of SWNTs, the relationships betw...

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Section: Methodsmentioning

confidence: 79%

Relationship between dispersion metric and properties of PMMA/SWNT nanocomposites

Kashiwagi

Fagan

Douglas

et al. 2007

Polymer

Self Cite

169

113

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“…The situation for polyamide-6 nanocomposites is more complex; in some cases enhanced thermal stability has been seen by TGA [27], while in other cases there is no change in thermal stability [28]. No explanation has yet been offered for the changes, or lack thereof, in thermal stability.…”

Section: Thermogravimetric Analysismentioning

confidence: 99%

Benzimidazolium surfactants for modification of clays for use with styrenic polymers

Costache

Heidecker

Manias

et al. 2007

Polymer Degradation and Stability

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Abstract:Nanocomposites of polystyrene (PS), acrylonitrile-butadiene-styrene copolymer (ABS) and high impact polystyrene (HIPS) were prepared with two new homologous benzimidazolium surfactants used as organic modifications for the clays. The morphology of the polymer/clay hybrids was evaluated by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM), showing good overall dispersion of the clay. The thermal stability of the polymer/clay nanocomposites was enhanced, as evaluated by thermogravimetric analysis. From cone calorimetric measurements, the peak heat release rate of the nanocomposites was decreased by about the same amount as seen for other organically-modified, commercially available clays.

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“…In literature, usually the employ of carbon nanotubes as flame retardant additives has been well documented. Indeed, their highly elongated shape and thus the high aspect ratio play a crucial factor in the reduction of the flammability of some polymers such as polypropylene [21,22], poly methyl methacrylate [23] and poly ethylene vinyl acetate [24]. Analogously, carbon nanofibers can behave similarly to carbon nanotubes as flame retardants promoting the in situ formation of a continuous network structured protective layer from the tubes.…”

Section: -Combustion Behaviormentioning

confidence: 99%

“…One of the most promising applications involves the improvement in flame retardancy properties of polymers added with nanofillers. The possibility to reduce flammability of numerous polymers using nanoclays have been shown by many authors and several mechanisms are proposed [5][6][7][8][9][10][11][12][13][14][15][16][17]. Indeed, nanocomposite systems are a new attractive alternative to conventional commercial flame retardants.…”

Section: Introductionmentioning

confidence: 99%

“…Nowadays, the most common approach to nanocomposite fire retardants is based on the use of layered silicates characterized by a large aspect ratio. Carbon nanotubes and carbon nanofibers are suitable candidate as flame retardant: Kashiwagi and coworkers [13,14] demonstrated that multi-walled carbon nanotubes can be used for reducing the flammability properties of polypropylene, and that it is possible also to use single walled carbon nanotubes for poly(methyl methacrylate) for the same purpose [15]. These fillers are also used as reinforcement.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Poly(ethylene terephthalate)-carbon nanofiber nano composite for fiber spinning; properties and combustion behavior

Alongi¹,

Frache

2010

E-Polymers

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Carbon nanofiber (CNF)-polyethylene terephthalate (PET) blends were previously prepared by melt blending and, subsequently, melt spun in order to obtain nanostructured fibers characterized by high flame retardant properties and resistance to the combustion. The morphological analysis showed that CNFs are homogeneously distributed and finely dispersed within PET matrix. The mechanical properties in tensile testing of the fibers change in the presence of CNFs: the elongation at break increases, whereas the tenacity and the tensile strength decrease. The combustion tests by cone calorimetry reveal a relevant decrease of heat release rate, total heat evolved and total smokes released by the nanocomposites as compared to neat PET.

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Flame retardant mechanism of polyamide 6–clay nanocomposites

Cited by 435 publications

References 30 publications

Relationship between dispersion metric and properties of PMMA/SWNT nanocomposites

Relationship between dispersion metric and properties of PMMA/SWNT nanocomposites

Benzimidazolium surfactants for modification of clays for use with styrenic polymers

Poly(ethylene terephthalate)-carbon nanofiber nano composite for fiber spinning; properties and combustion behavior

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