ETD

• composite materials
• core-shell
• glass fibers
• thermoset
• toughened

The following thesis originates from the idea of optimizing fiberglass composite materials for naval applications, increasing toughness properties, in collaboration with the company Baglietto Spa and the Centro Tecnologico Sperimentale (CTS) of La Spezia. The main aim of this work is to compare the performance of composites manufactured using a commercial vinyl ester resin pre-toughened, with a commercial urethane vinyl ester resin both not toughened and toughened with core-shell rubbers (CSR) in the laboratories of the University of Pisa.
After developing the composite materials, adding fiberglass reinforcements, the focus was placed on analyzing their mechanical properties both at room temperature and at low temperatures, in order to enable their use in harsher marine environments, such as those in Northern Europe.
The first phase of this work involved measuring the grammage of the two glass fiber fabric types supplied by the company. Subsequently, both fabrics underwent mechanical testing to evaluate their properties, and the one with higher grammage was selected to meet the company’s requirements for the final product.
In the second phase, the commercial pre-toughened resin, Daron® 120 and the untoughened Atlac ® 580 were subjected to tensile and impact tests to evaluate their mechanical properties, to viscosity analysis to check if they were suitable for the infusion process and to DSC thermal analysis for investigating their thermal behavior.
In the third phase, rubber particles were added to the Atlac® 580 resin to increase its toughness. The same tests conducted on the other resins were also performed on this one, and SEM analysis was used to compare the toughening particles present in this resin with those in the commercial Daron®120. In the fourth phase, composite panels were manufactured using the vacuum-bagging technique. First, two panels measuring 200 × 200 mm were produced for each type of resin using the selected glass fiber fabric. Subsequently, three 300 × 300 mm panels were manufactured for each resin type to be supplied to the Centro Tecnologico Sperimentale (CTS) in La Spezia.
The smallest panels were examined in the Laboratories of the University of Pisa, conducting different tests to evaluate the effectiveness of the vacuum-bagging process: flexural test, ILSS test, porosity evaluation and SEM characterization. The other panels were deeply analyzed in CTS, where one composite panel for each type of resin was conditioned with a cycle of 12 hours at 25°C and 12 hours at -40°C to check their resistance in extreme conditions.
Each panel was mechanically characterized through tensile testing, impact testing, flexural testing, interlaminar shear testing, laminar shear testing and compression testing. In addition, calcination was used to obtain an accurate measurement of the reinforcement content, and the glass transition temperature was determined by DSC. Finally, the results obtained indicate an increase in the toughness of the Atlac® 580 resin, particularly at low temperatures, making it comparable to the commercial Daron® 120 resin without compromising its mechanical properties.