Water Uptake Of Nanocomposites Research Articles

The effect of aligning graphene‐oxide nanoplatelets on moisture absorption and thermal stability of polymeric nanocomposites

AbstractThis article investigates the effect of aligning graphene‐oxide nanoplatelets (GONPs) on the moisture absorption and thermal stability of polymeric nanocomposites. Various nanocomposite specimens were fabricated using different GONP contents to improve water uptake resistance and thermal stability by aligning GONPs using an AC electric field during manufacturing. The results showed that aligning 0.3 wt% GONPs resulted in the most significant improvements, with the reductions of 76% and 54% observed in the water uptake of nanocomposites at the initial and saturation stages, respectively. The thermal stability of the nanocomposite specimens was also investigated using thermogravimetric analysis, in which nanocomposites containing 0.3 wt% randomly dispersed GONPs demonstrated improved performance compared with the neat epoxy specimen. However, aligning GONPs resulted in a marginal effect on the thermal stability parameters of nanocomposites. Moreover, Fourier transform infrared spectroscopy was conducted to investigate the chemical nature and hydrophilicity of the specimens. In addition, the freeze‐fractured surfaces of the neat and nanocomposite specimens were investigated using scanning electron microscopy. The results indicated the role of nanoparticle alignment in enhancing the performance of nanocomposites under hygrothermal conditions in terms of water uptake, which is of high importance in the marine industry.

온도와 나노 첨가제 함량이 나노복합소재의 흡습거동에 미치는 영향

온도와 나노 첨가제 함량이 나노복합소재의 흡습거동에 미치는 영향

Anomalous water diffusion in epoxy/carbon nanoparticle composites

Water absorption-desorption-resorption and swelling were studied for a DGEBA-based amine-cured epoxy resin filled with four types of carbon nanoparticles: multiwall carbon nanotubes (MWCNT), graphite nano-platelets (GnP), expanded graphite platelets, and carbon black. Nanocomposites are characterised by lower diffusivity (down to 20% for epoxy/GnP) and increased water sorption capacity compared to the neat epoxy. Anomalous water absorption and swelling of nanocomposites is finely described by the diffusion-relaxation model. The relaxation times, considered as quantitative indicators of changes in segmental mobility of the polymer, increased with addition of nanoparticles and decreased with temperature. Epoxy/MWCNT composites are characterised by the longest relaxation times (twofold increase) and highest Deborah numbers compared to the neat epoxy and other nanocomposites. Hydrothermal ageing effects and efficiency of nanoparticles on thermal and thermomechanical properties of the epoxy were estimated. Water uptake in nanocomposites is accompanied by several competing processes: plasticization, after-cure, and physical ageing of the polymer matrix.

Improving of the Mg-Co nanoferrites efficiency for crude oil adsorption from aqueous solution by blending them with chitosan hydrogel.

The efficiency of the as-prepared Mg0.25Co0.75Fe2O4 spinel nanoparticles for adsorption of crude oil from aqueous solution was improved by blending them with chitosan hydrogel (CH) prepared using epichlorohydrin as cross-linker resulting (CH/Mg0.25Co0.75Fe2O4) nanocomposites. Mg0.25Co0.75Fe2O4 nanocrystals was prepared by the chemical co-precipitation method and characterized by using X-ray diffraction (XRD), infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), and differential thermal analysis (DTA)/thermogravimetric analysis (TGA). DTA/TGA results showed that the net weight loss of the samples heated from room temperature up to 1000°C lies in the range 2.2-26.5% weight, where the maximum weight loss appeared at 100°C and 614°C. The blending nanocomposites prepared, were characterized by FT-IR and SEM micrographs. The effect of the nanoparticles ratio on the water uptake of nanocomposites and their capability to adsorb the crude oil was estimated by the gravimetric method. TEM results showed that the average nanoparticle size (Z) of Mg0.25Co0.75Fe2O4 is 30.06nm and the SEM illustrated the presence of a very clear and rough layer of pores which are homogenously arranged structures that could play an important role in the adsorption and stability of crude oil on polymers. The adsorption ability of crude oil from waste water on the CH/Mg0.25Co0.75Fe2O4 nanocomposites hydrogel was reported and it was found that the CH/Mg0.25Co0.75Fe2O4 with 95/5% ratio showed the improvement in the oil adsorption (72.5%) than the 0/100% one (50.2%). As a consequence, it is highly suggested that the potential of blending CH with Mg0.25Co0.75Fe2O4 to obtain CH/Mg0.25Co0.75Fe2O4 for enhancing crude oil adsorption in oily waste water treatment with a low cost.

Preparation and characterization of light‐cured methacrylate/montmorillonite nanocomposites

AbstractPolymer/clay nanocomposites were prepared from dimethacrylate monomers, commonly used in dental restorative resins, and an organically modified silicate (montmorillonite). The photopolymerization process was hardly affected by the presence of the silicate filler, and thus 2 mm thick samples containing 3 wt% clay were extensively cured. Transmission electron microscopy revealed that the montmorillonite platelets were either intercalated or exfoliated. Nevertheless, for all formulations, intermediate‐sized aggregates of about 1 µm were present and their fraction increased as the amount of filler increased. The presence of the clay was found to have no major effect on the flexural modulus and compressive yield strength of the nanocomposites. Moreover, the water uptake of nanocomposites containing 3 wt% clay was about 10–15% higher than that of unfilled monomers. Modification of the clay surface with alternative organic cations is certainly necessary in order to achieve an optimal dispersion of the clay in the polymer matrix. Copyright © 2010 Society of Chemical Industry