The effect of mixing procedure on rheological properties of glass flake-epoxy vinyl ester composites

15 wt. % Glass flake (GF) was incorporated into epoxy vinyl ester resin by the mechanical agitation and sonication. The particles were extracted by solution extraction method and then the particle size and aspect ratio of the GF distribution were calculated. A particle size analyzer was used to investigate whether or not the GF breaks down to smaller particles. The breakage into the smaller particles was confirmed by the microscopic image analysis. Two mechanisms were found in the breaking process: the mechanical agitation and/or the abrasion of particles together. Recent studies show that the mechanical agitation has a larger effect on the breaking of the three GF types. On the other hand, it is shown that in order to minimize the necessary mixing time, surface coating of the particulates can limit mechanical or high shear breaking action. The GF with larger circular diameter and length were more sensitive to shear than the smaller particles. The effect of glass flakes treatment and particle size distribution on the interaction between the polymer matrix and the glass flakes were investigated by rheology including the amplitude and rate sweep experiments. These studies showed that the treatment of glass flake improves interaction between the polymer matrix and the GF. The results indicated that the finer GF filled specimens display richer rheological properties. Furthermore, the rheological properties of three vinyl ester/GF composites prepared using three types of GF at different mixing time were monitored. Here, the properties depend strongly on the flow-induced morphology and on the yield phenomena or orientation. The rheological experiments indicated that the power law exponent (n) was lower for the sample with larger mixing time, while this sample showed higher zero shear viscosity, which confirmed that the filler-matrix network formed in the breaking process became more elastic with tighter structure as a result of the use of finer particles in the GF composites.

کلیدواژه ها:

Glass flake ، epoxy-vinyl ester ، sonication ، rheological measurements ، amplitude ، Angularfrequencies ، aspect ratio