Effect of Particle Size on the Thermal Stability and Flammability of Mg(OH)2/EVA Nanocomposites

Abstract

The effect of the Mg(OH) 2 particle size on the thermal degradation and flammability of a model nanocomposite is presented. In order to investigate the effect of particle size on the flammability and thermal stability of materials intended for cable coatings, the ethylene-vinyl acetate copolymer (EVA) was filled with two types of magnesium hydroxide (Mg(OH) 2 ) with the average particle size 20 nm and 2000 nm. The thermogravimetric experiments performed under nitrogen and air atmosphere did not reveal any substantial effect of particle size on the mechanisms and kinetics of Mg(OH) 2 decomposition. Both types of Mg(OH) 2 , at temperatures above 350 • C, decomposed endothermally to MgO and H 2 O. At the same filler volume fraction, composites with the larger Mg(OH) 2 particles exhibited greater value of the limiting oxygen index (LOI) compared to Mg(OH) 2 nanocomposites. It is proposed that the reduction of Mg(OH) 2 particle size below 200 nm results in the catalytic effect of Mg 2+ to become more prominent compared to coarser particles. In the case of nano-sized Mg(OH) 2 , a large portion of polymer matrix is in direct contact with filler surface due to the high specific surface area of the filler used. Large filler-matrix contact area most probably resulted in the surface-induced catalytic effects of the Mg 2+ ion on degradation of polyolefins, already described in the literature, accelerating thermal degradation of EVA matrix. This process acts against the flame retarding effect of the Mg(OH) 2 thermal decomposition. Furthermore, larger filler surface of nano-filler led to the indispensable change of the deformation response of EVA compared to the micro-filled composite.

Thermal Decomposition Kinetics of High Impact Polystyrene/Organo Fe‐montmorillonite Nanocomposites

“…The decomposition reaction of HIPS and HIPS/Fe-OMT nanocomposites could be best modeled via reactions A→B of the Fn type f(α)＝(1-α) n . [16] This trend coincided with the thermal analysis results. However, from the calculation and nonlinear regression, a single-step reaction model was obtained, which forced E to be constant.…”

“…[14][15][16] Although the thermal behavior of HIPS/Fe-OMT nanocomposites has been studied in our previous reports, [11] the kinetic aspects of the thermal degradation remain practically unknown. [14][15][16] Although the thermal behavior of HIPS/Fe-OMT nanocomposites has been studied in our previous reports, [11] the kinetic aspects of the thermal degradation remain practically unknown.…”

Influences of organic montmorillonite on the combustion behaviors and thermal stability of polyamide 6/polystyrene blends

“…Nano-magnesium hydroxide and nano-aluminum hydroxide are the most popular nanopowder FRs and have been investigated in detail due to their excellent properties and low cost. [3][4][5][6] However, in order to achieve the desired FR performances, the high loading (over 50 wt%) are required. Compared with conventional filled polymers, polymer layered silicate nanocomposites (PLSNs) have a lot of unique properties in the presence of a small amount of silicate, such as enhanced mechanical properties, increased heat distortion temperature, improved thermal stability, decreased gas/ vapor permeability, and reduced flammability.…”

Preparation of Different Diameter Nano-Mg(OH)2Powders and Their Non-isothermal Kinetics of Thermal Decomposition

“…Recently, much interest has been attracted into its application as a flame retardant [5]. Many reports have described magnesium hydroxide as a new inorganic retardant which is more effective and environment friendly than the widely used traditional inorganic retardant-aluminium hydroxide [9][10][11][12][13][14][15][16][17][18][19]. The capability of its firepreventing is usually attributed to the absorption of heat during its thermal decomposition when the produced water molecule turns from liquid state into gas phase.…”