Sharif Digital Repository

In this investigation, aluminum layers are bonded together using epoxy adhesive. The adhesive is modified using different additives and the influence of adhesive composition on interfacial fracture energy is measured via double cantilever beam (DCB) test. To characterize the mechanical behavior of the adhesive, compression and impact tests were incorporated. The results of compression and impact tests show that compressive and impact properties of adhesives are functions of type and content of modifier. In the DCB test, it was observed that while addition of rubber particles increase interfacial fracture energy of epoxy, incorporating SiC particles decrease this parameter. Also, the results... 

Laminated composites are made using different routes, including adhesive bonding. In this investigation, Aluminum layers are bonded together using epoxy adhesive (neat, rubber-modified and filled-epoxy). In phase one of this investigation, the influence of number of layers and adhesive ductility have been studied on dynamic behavior of composites. The results of impact behavior of laminates indicate that the impact energy increases with the number of layers. Also, it can be concluded that there is much more sensitivity of the impact energy of the composite to the number of the layers than that to the adhesive composition. © 2004 Elsevier B.V. All rights reserved  

The physical properties including glass transition temperature and permeability behavior of clay-filled epoxies are reviewed in this chapter. There is no consensus in the literature on how nanoclay affects the α-relaxation temperature in epoxy systems. This perhaps rises from the complexity of nanoclay morphology in polymeric resins and the interphase properties since morphology of nanoclay and interphase characteristics are two key parameters to control the glass transition process in epoxy nanocomposites. In addition, the possible existence of several α-transitions in montmorillonite-filled epoxies due to the existence of several relaxation domains may account for the controversial... 

The impact behavior of aluminum/epoxy laminates was studied by changing the number of layers and the interface strength. It should be noted that although the overall thickness did not changed, the individual layers decreased in thickness when the number of layers increased. The results indicate that the impact resistance of the laminate increases with the number of layers, while the interface strength has a less pronounced influence (50%) on the impact resistance of the laminate. It is also deducted that if the ratio of layer thickness to plastic zone size is smaller than or equal to 1, the impact behavior of the laminates is sensitive to the interface strength. © 2008 Elsevier Ltd. All... 

In this investigation, core-shell rubber particles and organically modified clay were added to an epoxy resin and the changes in mechanical behavior were studied. As expected, the yield strength of the organoclay-filled epoxies increased modestly with increasing clay content and the yield strength of the rubber-modified compounds decreased with rubber content. Interestingly, the compressive yield strength of epoxy resins containing both rubber particles and organoclay (a.k.a. hybrid nanocomposites) was found to be independent on organoclay content (up to 5 phr). The fracture toughness of organoclay-filled epoxies increased modestly with clay content and, as expected, the increases in... 

The aim of this paper is to investigate adhesion property between nano-layered filler and the polymer matrix using a combination of experimental and micromechanical models as well as the changes in yield strength and stiffness of a layered silicate-filled epoxy nanocomposite. The results indicate that addition of intercalated layered silicate particles increased Young's modulus and yield strength of the epoxy resin, although the increases in stiffness and yield strength are modest, 30% and 4%, respectively. In addition, experimental results were compared with predictive stiffening and strengthening models. The rule of mixtures provides an upper bound for the modulus in these materials, while... 

A study was conducted to report an observation on the effect of nanoclay fillers on the α-relaxation in an epoxy resin. The observation provided useful facts about glass transition processes in nanoclay-filled epoxy composites. The investigation involved the synthesis of intercalated-exfoliated clay-epoxy compounds, by swelling an organophilic montmorillonite in an aromatic epoxy resin and polymerization. The epoxy resin used in the study was a diglycidyl ether of bisphenol A (DGEBA), EPON 828, with an equivalent weight of 184-190 g/eq from Hexion Specialty Chemicals. The epoxy resin was cured with piperidine, obtained from Sigma-Aldrich. Nanomer® 1.30E. An octadecyl amine treated... 

In this investigation, the mechanical and thermal properties of the montmorillonite-epoxy nanocomposites were studied. The epoxy compounds were prepared by in situ polymerization and the intercalation dispersion were obtained as evidenced using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results reveal remarkable stiffening effect and slight toughening effect of the MMT in the epoxy resin and an insight about the crack tip and notch tip toughening mechanism. According to the DMA, the glass transition temperature increases as increasing the MMT content. © 2008 World Scientific Publishing Company  

Electrically conductive polyamide-6 (PA6)/poly(phenylene oxide) (PPO) nanocomposites containing conductive nanofillers such as carbon nanotubes (CNTs) and conductive carbon black (CCB) have attracted considerable interest from both academia and industry. Despite their importance in applications such as electrostatic painting, only a few studies have been reported. In the current study, the effects of the morphological structure and selective localization of CNTs/CCB (into the PA6 or at the interface of the PA6/PPO) on the electrical conductivity of the nanocomposites have been investigated. The PA6/PPO ratio and mixing sequence are the two parameters that control the morphology and the... 

In this paper, we review recent progress made in the field of epoxy-based binary and ternary nanocomposites containing three-, two-, and one-dimensional (i.e., 3D-, 2D-, and 1D) nano-size fillers with a special focus on their fracture behaviors. Despite investigations conducted so far to evaluate the crack-resistance of epoxy nanocomposites and attempts made to clarify the controlling toughening mechanisms of these materials, some questions remain unsolved. It is shown that silica nanoparticles can be as effective as rubber particles in improving the fracture toughness/energy; but incorporation of carbon nanotubes (CNTs) or clay platelets in epoxy matrices delays crack growth only modestly....