Efeito da radiação gama sobre as propriedades mecânicas de compósito de fibras de sisal/poliuretana sem uso de agentes de acoplamento

Abstract

Natural fiber composites with polymeric matrix has been the focus of studies by having good mechanical properties and low weight, which allows its use in various environments, including hospital, radiotherapy and radiology rooms. Its major difficulty is the lack of affinity of the component materials, causing detachment of the interface and lower load transfer between matrix and reinforcement. An alternative may be composites based on natural fibers and polyurethane derived from castor oil. The incidence of radiation can lead to degradation of polymeric material and change its mechanical properties. The objective of this study was to obtain and characterize composites of dispersed sisal fibers and sisal fabric with polyurethane matrix based on castor oil without addition of compatibilizing agents, which may be used in environments that receive radiation at high intensity. The composites were obtained by cold pressing, irradiated with gamma radiation, dose of 25 kGy, and evaluated before and after irradiation with thermal, infrared, surface and mechanical testing. It was observed that there may be chemical affinity between the reinforcing material and the matrix, since was not observed detachment from the fiber / polymer interface. The materials can be considered hydrophilic by contact angle analysis. Maximum values of bending stress of 80.33 MPa and elastic modulus in bending of 4.40 GPa for the sisal fabric / polyurethane composite without irradiation were obtained, such as impact resistance of 13.14 kJ / m2 for the dispersed sisal fibers composite after irradiation. It can be concluded that the materials are suitable for use in radiotherapy and radiology rooms.