Abstract:Polymer layered-silicate (clay) nanocomposites have not only the unique advantage of reduced flammability, but also improved mechanical properties. This is a key advantage over many flame retardants, which reduce flammability but also reduce the mechanical properties of the polymer. In our efforts to further understand the mechanism of flame retardancy with polymer-clay nanocomposites, we investigated the effect of the clay, the loading level and polymer melt viscosity on the flammability of polystyrene-clay n… Show more
“…Because of the dispersion at the nanometer level, polymer-clay nanocomposites exhibit superior properties in comparison with the pure polymers or conventional composites. These properties include lightweight [5], high modulus, enhanced physicalmechanical strength [6,7], improved gas barrier [8], increased solvent resistance [9], improved thermal stability, and flame retardancy [10,11]. Another impressive feature of nanocomposites and nano-filled composites is the concurrent improvement of multiple properties, in addition to the introduction of new functionalities [12].…”
This work presents thermal studies of nanocomposites based on the flexible polyurethane (PU) matrix and filled using montmorillonite organically modified with organophosphorus flame retardant compound. Flexible PU nanocomposite foams were prepared in the reaction carried out between reactive alcoholic hydroxyl and isocyanate groups with the ratio of NCO to OH groups equal to 1.05. The amount of an organoclay ranging from 3 to 9 vol% was added to the polyol component of the resin before mixing with isocyanate. The apparent density of PU foams was ranging from 0.066 to 0.077 g cm -1 . Thermal properties of the flexible PU nanocomposite foams were investigated by thermogravimetry and dynamical mechanical analysis. Glass transition temperatures (T g ) were defined as maximum peak on tand curve. Thermal decomposition was observed at 310-320°C (calculated from the onset of TG curve). Tensile strength of the PU foams was determined using mechanical test. The microstructure of the nanoparticles and the composites was investigated by X-ray diffraction. Finally, it was confirmed that the thermal and mechanical properties of flexible PU nanocomposite depend on the amount of nanoclay.
“…Because of the dispersion at the nanometer level, polymer-clay nanocomposites exhibit superior properties in comparison with the pure polymers or conventional composites. These properties include lightweight [5], high modulus, enhanced physicalmechanical strength [6,7], improved gas barrier [8], increased solvent resistance [9], improved thermal stability, and flame retardancy [10,11]. Another impressive feature of nanocomposites and nano-filled composites is the concurrent improvement of multiple properties, in addition to the introduction of new functionalities [12].…”
This work presents thermal studies of nanocomposites based on the flexible polyurethane (PU) matrix and filled using montmorillonite organically modified with organophosphorus flame retardant compound. Flexible PU nanocomposite foams were prepared in the reaction carried out between reactive alcoholic hydroxyl and isocyanate groups with the ratio of NCO to OH groups equal to 1.05. The amount of an organoclay ranging from 3 to 9 vol% was added to the polyol component of the resin before mixing with isocyanate. The apparent density of PU foams was ranging from 0.066 to 0.077 g cm -1 . Thermal properties of the flexible PU nanocomposite foams were investigated by thermogravimetry and dynamical mechanical analysis. Glass transition temperatures (T g ) were defined as maximum peak on tand curve. Thermal decomposition was observed at 310-320°C (calculated from the onset of TG curve). Tensile strength of the PU foams was determined using mechanical test. The microstructure of the nanoparticles and the composites was investigated by X-ray diffraction. Finally, it was confirmed that the thermal and mechanical properties of flexible PU nanocomposite depend on the amount of nanoclay.
“…With the advancement of nanotechnology, research regarding hybrid polymeric materials containing nanoparticle fillers has attracted much attention because some nanoparticle fillers dispersed in the polymer matrices can improve mechanical [2][3][4] and incombustible [5][6][7][8][9][10][11][12][13] properties. In addition, they are environmentally benign compared with conventional flame-retardant compounds.…”
mentioning
confidence: 99%
“…In addition, they are environmentally benign compared with conventional flame-retardant compounds. Nanoparticle fillers for flame-retardant compounds include clays, 5,6 nanoparticles, 7,8 carbon nanotubes (CNT), [9][10][11] and polyhedral silsesquioxanes. 12,13 Of these, clays are one of the most practical materials with respect to cost.…”
Exfoliated polystyrene (PS)/magadiite nanocomposites with a high suppression effect on thermal degradation were successfully prepared by in situ nitroxide-mediated radical polymerization of styrene monomer from the magadiite interlayer surface. Surface-initiated polymerization of styrene was conducted from the radical initiators immobilized on magadiite at 398 K. The number-average molecular weight (M n ) of the grafting PS increased with monomer conversion keeping a relatively low polydispersity index. The initiator efficiency was estimated to be less than 10% by size exclusion chromatography analysis. The results of X-ray diffraction and transmission electron microscopy suggested that the nanocomposites provided exfoliated structures. The fine dispersion state of magadiite in PS matrices contributed to effective suppression of the thermal degradation of PS. In addition, an interesting difference in the shape of the final residues was observed. Thermal decomposition of exfoliated PS/magadiite nanocomposites gave a substantial rigid solid as a residue, the shape of which largely depended on the concentrations of magadiite in the PS matrices. For instance, the thermal decomposition of nanocomposites produced a seamless residue that can effectively retard the decomposition rate. In contrast, the simple mixture of PS and magadiite was thermally decomposed to be powdery ash in the final residues.
“…These properties are published in previous papers. (Lakatos and Kalmár 2013a, Lakatos and Kalmár 2013b, Farhranieh et al 2006, Yucel et al 2009, Hourston et al 1996, McCormick et al 1959, Xiao et al 2006, Morgan et al 2002, Mihlayanlar et al 2008, Nussbaumer et al 2006, Changhai et al 2008. Several methods (e.g.…”
Abstract:As it is known that nowadays, reduction of the heating energy loss of buildings is achieved mainly by thermal insulation. This is one of the most important objectives of buildings constructions and retrofitting of buildings. Therefore research, calculation and simulation on the energy efficiency of buildings are of great importance. In this paper we give an expansive presentation about the measurements of the thermal conductivity, heat flux and thermal resistance of individual insulation materials as well as in-built wall constructions executed in our laboratory. Thermal diffusion coefficients and wall delaying ability of the systems will be given resulting from the measurements. First of all, thermal conductivity measurement results of individual insulation materials achieved by a Holometrix type Heat flow Meter (HFM) will be presented. Afterwards, two different steady-state methods for measuring thermal resistance of wall structures (Calibration hot box method (CC) and Heat Flux measurements by Hukseflux (HF) apparatus) will be introduced. These measurements were accomplished through either an inbuilt plaster/brick/plaster wall construction insulated internally at the first time and later externally with different materials. The main target of this paper is the presented theoretical procedure for the estimation of the retardation time of wall structures. Furthermore in this publication the determination of thermal performance of Expanded Polystyrene Insulation (EPS) applied to walls in building constructions can also be found. Moreover numerical predictions for thermal resistance are presented. Besides, infrared thermographs were used to visualise the insulation ability of the layer structures.2
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