Morphological, mechanical, and thermal features of PMMA nanocomposites containing two‐dimensional Co–Al layered double hydroxide

Abstract

The focus of the current study is to investigate the influence of Co-Al layered double hydroxide (LDH) on the morphological, thermal, and mechanical features of poly(methyl methacrylate) (PMMA)-based nanocomposites. Sodium dodecyl sulfate modified Co-Al LDH was synthesized by single step coagulation method. The PMMA nanocomposites containing different loadings of nanofiller (1-7 wt %) and polystyrene-grafted maleic anhydride compatibilizer (5 wt %) were melt intercalated via twin screw extruder and later subjected to injection molding to prepare mechanical testing samples. The different properties of PMMA nanocomposites were studied by using XRD, TEM, FTIR, DSC, TGA, tensile, flexural, impact, and flammability analysis. The result of XRD analysis suggested the exfoliated morphology of the nanocomposite while the TEM demonstrated the intercalated structure at higher loading of LDH. The thermal characterization results revealed that thermal properties were improved by the addition of Co-Al LDH, whereas the flammability test exposed that dripping was minimum at 7 wt % loading. The mechanical properties exhibited that optimum results were obtained at 1 wt % loading of Co-Al LDH.

Thermal properties and electric modulus approach to the analysis of dielectric relaxation of nanocomposites based on carbon dots

“…This result indicates that C‐Dots have a plasticizing effect on the polymer structure‐giving rise to an increase in the mobility of PMMA chains . The obtained T g values do not show any dependence on the nanofiller loading in the polymeric matrix in the investigated filler concentration range, as already observed in the literature using different nanoparticles α relaxation of the polymer, and give rise to an immobilized polymer layer surrounding the nanoparticles .…”

“…It corresponds to a reversible phase transition of the second order from a glassy state to an elastic one. The value obtained for PMMA is in good agreement with that reported by Manish [24] and quite close to other values reported in the literature. [20,[25][26][27] As described in Table 1, for the composites with filler concentration in the range from 0.5 to 4%wt, the values of T g are lower than the corresponding value for the bare PMMA.…”

“…[28] The obtained T g values do not show any dependence on the nanofiller loading in the polymeric matrix in the investigated filler concentration range, as already observed in the literature using different nanoparticles. [20,24] A recent published paper indicates that, in most cases, the presence of nanoparticles, in particular oxides, causes an increment of T g thanks to the formation of interactions, primarily hydrogen bonds, between the nanoparticles and the polymer chains, which slow down the α relaxation of the polymer, and give rise to an immobilized polymer layer surrounding the nanoparticles. [29] Other studies on PMMA nanocomposites, mainly prepared using solvent based methods, point out a decrease in the glass transition temperature.…”

Effect of layered double hydroxide on the flame retardancy of intumescent flame retardant thermoplastic polyurethane composites prepared by selective laser sintering

“…The formula of LDHs is [M 2+ 1− x M 3+ x (OH) 2 ] x + A m − x / m ▪nH 2 O, where M 2+ are divalent cations, M 3+ are trivalent cations and A m− are the changeable interlayer anions. LDHs offer a robust synergistic effect in flame retardant polymer composites as a consequence of their layered structure and metal hydroxide components 27–30 . During combustion, LDHs can release water vapor due to its chemical structure being bound with water, after which it will absorb a mass of heat to break the layers into metal oxides at higher temperature.…”

“…LDHs offer a robust synergistic effect in flame retardant polymer composites as a consequence of their layered structure and metal hydroxide components. [27][28][29][30] During combustion, LDHs can release water vapor due to its chemical structure being bound with water, after which it will absorb a mass of heat to break the layers into metal oxides at higher temperature. The physical layered structure of LDHs may obstruct the transfer of heat flow and mass between the flame and polymer matrix.…”