• biocomposites
• composites
• dion 9500
• flax fibers
• glass fibers
• laminated composites
• marine
• naval
• rubber toughening
• toughening
• vinyl ester resins

Vinyl esters resins are currently extensively used as thermosets matrix materials for laminated composites, principally in naval and automotive applications, due to their good mechanical strength, outstanding resistance to chemicals and easy processing. However, vinyl esters resins suffer from inherent brittleness that limits their application, especially in cold environment. Substantial improvement of the toughness of brittle materials may be achieved by dispersing core shell rubber particles (CSR) in the polymeric matrix. Modifications in vinyl esters matrix are being experimentally studied in the current work of thesis, characterizing a commercially available rubber-modified vinyl ester resin and comparing it with the unmodified one.
Different thermal curing treatments have been studied to enhance mechanical properties of the neat resins and, to select the best temperature protocol for satisfying industry’s quality requirements, the matrices with different curing pathways were compared through thermal tests, mechanical tests, and fracture mechanics evaluation.
Once the process to optimize the curing of the resin with the catalyst has been established, this work of thesis, also, intends to understand the effect of such matrix modifications on the final mechanical properties of laminated composites obtained with vacuum bagging process using as reinforcement both with flax and glass fibers in form of fabrics. Flax fibers have been selected to be a renewable and sustainable alternative to glass-vinyl ester panel yet maintaining high quality standard.
The composites obtained have been mechanically tested and the results have been compared to understand if flax can be a valuable green alternative; moreover, water absorption of flax composite has been also studied following ISO62.
Interlaminar shear strength and SEM micrography studies have been also carried out to study their morphology, to understand the adhesion between fibers and matrix and to correlate the microscopic structure to the macroscopic mechanical results.