Preparation of TiO2/epoxy nanocomposites by ultrasonic dispersion and their structure property relationship

Abstract

By the insertion of nanoparticles into a polymer matrix a considerable improvement of mechanical properties can be achieved. Therefore, a homogeneous distribution of fillers within the matrix is required. In the present paper the dispersion of TiO(2)-nanoparticles in a DGEBA (diglycidyl ether of bisphenol A) epoxy resin by means of an ultrasonic horn was studied. The systematic examination of process parameters of a previous study was completed in order to determine the optimum processing window leading to a good dispersion result without degrading the molecular structure of the epoxy resin. Therefore, particle sizes were examined using a dynamic light scattering device, and the effect of the ultrasonic treatment on the resin was surveyed by FT-IR spectroscopy (Fourier transform infrared spectroscopy). Furthermore, the mechanical performance of the nanocomposites was examined for various contents of TiO(2)-nanoparticles to show that the materials prepared by ultrasonic dispersion show an improved property's profile. In order to understand the reinforcing mechanisms of nanoparticles in the polymer matrix providing improved mechanical properties, scanning electron microscope (SEM) pictures of the fracture surfaces of the samples were carried out, which revealed that nanocomposites show a significantly rougher surface than the neat epoxy resin. This indicates a change in the fracture mechanisms.

Preparation of TiO2 epoxy nanocomposites by ultrasonic dispersion and resulting properties

“…As shown in Ref. 13, this is not always true. In the nanocomposite, crystal bonded aggregates are also encountered, which cannot be broken up by conventional dispersion techniques.…”

“…In addition, a previous study revealed that there are also crystal bonded aggregates bigger than the primary particles, which cannot be broken up by conventional dispersion techniques. 13 The sonication induced particle size reduction can be described in both the cases by the model developed in Ref. 6:…”

“…13. Samples were prepared by adding epoxy resin to dilute the prepolymer to the desired particle content.…”

Nanocomposites for Vehicle Structural Applications

“…TiO 2 (Bittmann et al, 2010) were found to yield the best balance of toughness, modulus and strength. The same investigators highlighted that when the nanoclay particles were used to enhance the polymer matrix in a conventional glass fiber-reinforced composite, the interlaminar fracture toughness of the composite was less than that of the unreinforced composite.…”

Fracture toughness modelling of polymers filled with inhomogeneously distributed rigid spherical particles

“…Surprisingly, toughness is higher for the inhomogeneoulsy distributed particles. Bittmann et al [31] reported that in nano-composites toughness can be increased when the fillers become more dispersed, i.e. if agglomeration can be avoided.…”