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Polyester resin based composite materials are widely used in the manufacture of fiberglass boats. Production time of fiberglass laminate components could be strongly reduced by using an intense energy source as well as microwaves. In this work a polyester resin was used with 2% by weight of catalyst and reinforced with chopped or woven glass fabric. Pure resin and composite samples were cured by microwaves exposition for different radiation times. A three point bending test was performed on all the cured samples by using an universal testing machine and the resulting fracture surfaces were observed by means of scanning electron microscopy (SEM). The results of mechanical and microscopy analyses evidenced that microwave activation lowers curing time of the composite while good mechanical properties were retained. Microwaves exposition time is crucial for mechanical performance of the composite. It was evidenced that short exposition times suffice for resin activation while long exposure times cause fast cross linking and premature matrix fracture. Furthermore high-radiation times induce bubbles growth or defects nucleation within the sample, decreasing composite performance. On the basis of such results microwave curing activation of polyester resin based composites could be proposed as a valid alternative method for faster processing of laminated materials employed for large-scale applications.

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Laser scanning vibrometry (LSV) is a non-contact technique for precise measurements of elastic wave parameters. In particular, the measurements of the wave velocity and dissipation deliver information on a material's stiffness and imperfections. In this paper, LSV was applied to monitor the stiffness and density of defects in composite laminate specimens cured at various exposures to microwave radiation. The specimens were supported by nylon wires and excited by a loudspeaker. Its driving frequency was swept and the frequency response of the specimens was measured by a laser vibrometer. The frequency shift of the fundamental flexural mode due to stiffness variation was measured as a function of the microwave exposure. To evaluate the dissipation factor, which is related to the density of defects, a short pulse was used for acoustic excitation. The temporal decay of the vibrations (reverberation) was measured by LSV and interpolated with an exponential function. The results obtained enable monitoring of the deterioration of the composite properties with the increase in the microwave exposure.