EFFECT OF THE MORPHOLOGY ON FRACTURE TOUGHNESS OF THERMOPLASTIC/THERMOSET/CLAY HYBRID NANOCOMPOSITES

摘要

Unsaturated polyester resins (UPRs) are thermosetting polymers with high crosslink density which leads to superior properties for them. On the other hand, it results in their brittleness. In order to improve their fracture toughness, incorporation of an inclusion is a common method. The inclusion can promote energy dissipating processes during crack propagation such as localized plastic deformation of the matrix, matrix void formation, cavitation of soft inclusions (e.g. rubbers), and particle/matrix debonding. In addition, the inclusion located in the front of the crack tip can perturb crack front during propagation. Perturbation of crack front leads to crack deflection and/or crack bowing (pinning) resulting in an increase in fracture toughness [1]. Rubber toughening is used as a common technique to improve fracture toughness of thermosets. The rubbery dispersed phase can result in a significant improvement in fracture toughness but at the cost of Young's modulus, compressive strength, and thermal stability [2]. Thermoplastic additives and nano-reinforcements also can be used for this purpose without the expense of other properties, but they are not as effective as rubber additives [2].