Thermal and viscoelastic property of epoxy-clay and hybrid inorganic-organic epoxy nanocomposites

Abstract

ABSTRACT:The properties of nanostructured plastics are determined by complex relationships between the type and size of the nanoreinforcement, the interface and chemical interaction between the nanoreinforcement and the polymeric chain, along with macroscopic processing and microstructural effects. In this article, we investigated the thermal and viscoelastic property enhancement on crosslinked epoxy using two types of nanoreinforcement, namely, organoion exchange clay and polymerizable polyhedral oligomeric silsesquioxane (POSS) macromers. Glass transitions of these nanocomposites were studied using differential scanning calorimetry (DSC). Small-strain stress relaxation under uniaxial deformation was examined to provide insights into the time-dependent viscoelastic behavior of these nanocomposites. Since the size of the POSS macromer is comparable to the distance between molecular junctions, as we increase the amount of POSS macromers, the glass transition temperature T g as observed by DSC, increases. However, for an epoxy network reinforced with clay, we did not observe any effect on the T g due to the presence of clay reinforcements. In smallstrain stress relaxation experiments, both types of reinforcement provided some enhancement in creep resistance, namely, the characteristic relaxation time, as determined using a stretched exponential relaxation function increased with the addition of reinforcements. However, due to different reinforcement mechanisms, enhancement in the instantaneous modulus was observed for clay-reinforced epoxies, while the instantaneous modulus was not effected in POSS-epoxy nanocomposites.

Nanostructured High-Performance Materials Consisting of Bismaleimide and Functional Liquid Crystal Monomer

“…There are too many papers to cite them all here. Thus some selected papers are cited here [1][2][3][4][5][6][7][8][9]. Although epoxy composite materials have successfully been used for certain structural applications (e.g., airplanes), they suffer from two weaknesses.…”

Controversial effects of fumed silica on the curing and thermomechanical properties of epoxy composites

“…The mechanical properties of epoxy resins can, however, be improved by incorporating inorganic particles [1]. It is well known that particle volume, shape, size, surface characteristics and particle dispersion within the matrix have an influence on the mechanical properties of the composites [2][3][4][5]. Specific surface area can promote stress transfer from matrix to nanoparticles and improve the Young's modulus of polymers to a higher extent than micro-fillers.…”

Surface energetics, dispersion, and nanotribomechanical behavior of POSS/PP hybrid nanocomposites

“…In general, hybridization of an organic polymer matrix with inorganic POSS results in improved thermal and mechanical properties along with increase in oxidative and flame resistance. [3][4][5][6][7][8]11 Recently Nanda et al 12 synthesized well dispersed polyurethane/POSS hybrid materials utilizing a solution polymerization process. Ordered morphologies with homogenously distributed POSS domains ($100-150 nm) were observed.…”