Nano-size structures, nanotubes/multi-layer graphene (CNT/MLG), were dispersed into epoxy system by a combination of sonication and high shear mixing. To avoid CNT/MLG agglomeration, a non-covalent functionalization were performed using surfactants, CO890 - Polyoxyethylene (40) nonylphenyl ether and SDBS - sodium dodecyl benzene sulfonate. Raman spectroscopy and Fourier transformed Infra-red analysis indicated that CO890-MLG and SDBS-CNT have strong chemical interactions. Atomic force microscopy revealed formation of "spike-like" nanostructures for SDBS-CNT combination and "wall-like" nano-shape structures for the CO890-MLG ones. Tensile tests data indicate no significant change on stiffness. In average, the ultimate stress increased around 18%, while toughness had an improvement close to 62%. SDBS-CNT and CO890-MLG at small concentrations (0.075 wt. %) are probably the best options for nano-reinforcement of carbon/epoxy composites.

This paper addresses the performance study on, low viscosity, nano-modified adhesives by graphene. For achieving this goal, single-lap joints following ASTM D 5868-01 were manufactured and tested. X-ray diffraction, scanning electron microscopy and nanoindentation were employed for graphene based nanostructures characterization. The increase on joint strength was around 57% when compared against the control group. Furthermore, all failures for the nano-modified adhesive were cohesive failure for the carbon fibre/epoxy composites indicating that the adhesive was tested. X-ray diffractions signatures indicate formation of nano-structures with 17-19 nm diameters. Moreover, nanoindentation tests revealed a homogeneous dispersion of graphene.

This paper focuses on the synthesis of super-hydrophobic membranes. The polymer used in this research is polystyrene (PS), which has low surface energy but not low enough to be characterized as a superhydrophobic material. As hydrophobicity is based on low energy surface and surface roughness, the electrospinning technique was selected as the manufacturing technique. N, N' dimethylformamide (DMF) was employed as the PS solvent. Two groups of PS/DMF solutions were investigated i.e. 20/80 and 35/65. To increase even more the hydrophobicity, nanoparticles of silica, graphene, cadmium, and zinc were dispersed into the PS/DMF solutions. In contrast to results previous published in literature, the PS/DMF weight ratio of 20/80 led to water contact angles (WCA) of 148º, which is higher than the contact angle for the 35/65 ratio, i.e. 143º. This fact seems to be due to the presence of non-evaporated solvent into the PS surface as the 35/65 solution was more viscous. The WCA for membranes with 0.5 wt. (%) of graphene reached 152º, 149º-153º for membranes with nanosilica addition, 151º with 5.0 wt. (%) CdS, and 153º, 163º and 168º with the addition of 5 wt. (%), 10 wt. (%) and 15 wt. (%) of ZnS, respectively.

This paper deals with the post fire behavior of hybrid nanocomposites under dynamic loadings. A series of tests were performed to investigate how nanoparticles (i.e. nanoclay and graphene nanosheets) affect the post-fire overall composite behavior. Carbon fiber/epoxy-nanoclay and carbon fiber/epoxy-graphene nanosheets were manufactured. The nanoparticles employed were Cloisite 30B nanoclay, and surface modified graphene nanosheets. The epoxy system used was RemLam M/HY956. The nanocomposites were made using ultrasonic mixer for nanoparticle dispersion in acetone followed by a shear mixing of acetone/nanoparticle/hardener. The following steps involved degassing, the addition of resin to the mixture and, the hand lay-up with vacuum assisted cure. Thermo gravimetric analysis (TGA) indicates an average decrease on peak mass loss around 41% with the addition of small amount of nanoparticles. The sample plates were exposed to a heat flux of 800 kW.m-2 for a period up to 120 seconds. The post-fire low velocity impact tests indicated the impact resistance degraded as a function of heat exposure. However, the addition of nanoclay leads to an increase on impact peak force of 11.69%. The carbon oxidation could be the main cause of the increase on impact peak load is lower than expected, only 6.72%. The model predictions are overestimated by approximately 8%. Even though, it can be a good tool for composites design.

Single-walled carbon nanotubes, with stiffness of 1.0 TPa and strength of 60 GPa, are a natural choice for high strength materials. A problem, however, arises when experimental data are compiled. The large variability of experimental data leads to the development of numerical models denominated molecular mechanics, which is a "symbiotic" association of molecular dynamics and solid mechanics. This paper deals with molecular mechanics simulations of single-walled carbon nanotubes. To be able to evaluate the molecular mechanics model, the three major carbon nanotube configurations (armchair, zigzag and chiral) were simulated. It was proven that the carbon nanotube configuration has influence on stiffness. By varying the radius, hence the curvature, the Young's modulus changed from 0.95 TPa to 5.5 TPa, and the Poisson's ratio ranged from 0.15 to 0.29. The numerical simulations were in good agreement with those presented in the literature.

The present paper describes an integrated micro/macro mechanical study of the elastic-viscoplastic behavior of unidirectional metal matrix composites (MMC). The micromechanical analysis of the elastic moduli is based on the Composites Cylinder Assemblage model (CCA) with comparisons also draw with a Representative Unit Cell (RUC) technique. These "homogenization" techniques are later incorporated into the Vanishing Fiber Diameter (VFD) model and a new formulation is proposed. The concept of a smeared element procedure is employed in conjunction with two different versions of the Bodner and Partom elastic-viscoplastic constitutive model for the associated macroscopic analysis. The formulations developed are also compared against experimental and analytical results available in the literature.