The global demand for wood as a building material is steadily growing, while the availability of this natural resource is diminishing. This situation has led to the development of alternative materials. Of the various synthetic materials that have been explored and advocated, polymer composites claim a major participation as building materials. There has been a growing interest in utilizing natural fibres as reinforcement in polymer composite for making low cost construction materials in recent years. Natural fibres are prospective reinforcing materials and their use until now has been more traditional than technical. They have long served many useful purposes but the application of the material technology for the utilization of natural fibres as reinforcement in polymer matrix took place in comparatively recent years. Economic and other related factors in many developing countries where natural fibres are abundant, demand that scientists and engineers apply appropriate technology to utilize these natural fibres as effectively and economically as possible to produce good quality fibre reinforced polymer composites for housing and other needs. Among the various natural fibres, sisal is of particular interest in that its composites have high impact strength besides having moderate tensile and flexural properties compared to other lignocellulosic fibres. The present paper surveys the research work published in the field of sisal fibre reinforced polymer composites with special reference to the structure and properties of sisal fibre, processing techniques, and the physical and mechanical properties of the composites.Key words: sisal fibre, polymer, composites, structure, properties COMPÓSITOS POLIMÉRICOS REFORÇADOS COM FIBRAS DE SISAL RESUMOO uso da madeira como material de construção continua crescendo mundialmente enquanto a disponibilidade deste recurso natural está diminuindo. Esta situação tem conduzido ao desenvolvimento de materiais alternativos. Dentre os vários materiais sintéticos que têm sido explorados, os compósitos poliméricos reivindicam e buscam uma maior participação como material de construção. Nos últimos anos tem se observado um crescente interesse na utilização de fibras naturais como reforço de matrizes poliméricas para a produção de materiais de baixo custo. As fibras naturais são reforços com grande potencialidade e seu uso tem se dado de forma mais tradicional do que científica. Elas têm se prestado a inúmeras aplicações ao longo do tempo, mas a aplicação da tecnologia dos materiais visando a sua utilização como reforço de matrizes poliméricas é relativamente recente. As dificuldades econômicos e sociais observadas em muitos dos países em desenvolvimento, onde as fibras naturais são abundantes, requerem que cientistas e engenheiros apliquem tecnologias apropriadas para utilizar estas fibras da forma mais eficiente possível, de tal maneira que se possa produzir materiais compósitos poliméricos de boa qualidade visando a atender a demanda da população por habitações e componentes habi...

Pressure burst tests gave measured tensile strengths between 230 and 410 MPa for a total of six chemical-vapor-deposited (CVD) diamond disks in both transparent ‘‘white’’ and opaque ‘‘black’’ forms obtained from three different sources. The disks were nominally 0.635 cm in diameter and 254 μm thick. These strengths are explained by a theoretical model using a Young’s modulus of 1.05×106 MPa and a fracture surface energy of 5.3 J/m2, appropriate for natural diamond, and with critical crack lengths between 33 and 105 μm. The latter lengths can fit, either on or inside, the tapered columnar crystal grains that grow vertically in synthetic CVD diamond films. The model is consistent with the observed inverse dependence of measured tensile strength on film thickness and with tensile strengths between 180 and 5190 MPa reported by other workers for synthetic CVD diamond.