Microstructure of wood fibre-plaster composites

Microstructure of wood fibre-plaster composites

literature survey I resurvey Prepared by M.E Adams, L Boniface, M.C. Hill and 7". Nensi CARBON FIBRES Thermal and oxidative stability of carbon fib...

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literature survey I

resurvey

Prepared by M.E Adams, L Boniface, M.C. Hill and 7". Nensi

CARBON FIBRES Thermal and oxidative stability of carbon fibers and composites Sheppard, C.H. SAMPE Quarterly Vol 18 No 2 (January 1987) pp 14-17 Having established in an earlier study that commercially-available PMR-15 resin is a suitable candidate matrix material for composites subjected to temperatures > 260°C, the author has investigated a number of carbon fibres for their suitability as reinforcement for this matrix. The thermal oxidative stability and the effects of the surface sizing on five commercially-available carbon fibres were investigated. It is concluded that it is necessary to establish the effects of both these properties of carbon fibres for the successful development of polymeric composites for long-term use at elevated temperatures, and that TGA kinetic studies may prove to be a useful tool in the qualitative ranking of fibres, resins and composites for this purpose.

CARBON MATRICES Tensile and compression test methods for cylindrical weave carbon-carbon composite materials Adams, D.F. and Odom, E.M. SAMPE Quarterly Vo118 No 4 (July 1987)pp 25-31 Methods are presented for testing cylindrical weave carbon/carbon composite materials in both tension and compression, using specially developed specimen configurations and test fixtures. Specimen preparation is discussed and test data are presented. The compressive test method is shown to be a promising method of determining axial properties of the threedimensionally reinforced composite materials, as is the tension testing method using a back-toback dual arc specimen.

CEMENT MATRICES The influence of fibre-matrix interfaclal bond strength on the mechanical properties of steel fibre reinforced mortars Gray, RJ. and Johnson, C.D. The International Journal of Cement Composites and Lightweight Concrete Vol 9No I (February 1987)pp 43-55 The influence of the shear strength of the fibre/ matrix interfacial bond on the mechanical properties of steel fibre-reinforced cementitious mortars under uniaxial tensile and fiexural loading was investigated. It is shown that the effect of interfacial bond strength associated with mortar mix proportions on the properties of the composite is limited but significant with respect to uniaxial tensile and first--crack ftexural strengths. Variations in the bond strength associated with the surface texture of the fibre affect the post-crack properties of the composite. It was further found that the aspect

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ratio of the reinforcing fibres and their concentration have a significant effect on the fibre/ matrix interracial bond strength. Microstructure of wood fibre-plaster composites Coutts, R.S.P. and Ward, J.V.Journal ofMaterials Science Letters Vol 6 No 5 (May 1987) pp 562-564 The effect of fibre content on fracture toughness of a wood fibre/plaster composite is examined by investigating failure in individual fibres by SEM. A tenfold increase in toughness is found on addition to the plaster of 2 wt% wood fibres, and up to twenty times for 8-10 wt% fibres. This is explained by the contribution to energy absorption of both fibre pull-out and fibre fracture by tension buckling of the wood fibres. The interfacial bond between the fibres and the matrix is good.

CERAMIC FIBRES Corrosion of glass fibres Rodriguez, E.L Journal of Materials Science LeUers Vol 6No 6 (June 1987)pp 718-720 The surfaces of two types of glass fibres are examined by SEM after immersion in 5% H 2SO4 for 336 and 1200 hours at room temperature. Spiral cracks are observed in E-glass fibres after 336 hours' exposure whereas there is no damage in EC-glass fibres even after 1200 hours. Effect of thermal and chemical treatments on carbon and silica contents in rice husk Patel, M., Karera, A. and Prasanna, P.Journal of Materials Science Vo122 (1987) pp 2457-2464 An evaluation of carbon and silica in both thermally treated and chemically treated rice husks has been conducted and conditions for achieving a carbon/silica ratio of 2:1, required for the production of solar grade silicon, have been determined. Acid leaching of rice husks was found to produce a 99% pure silica. The results have been interpreted in terms of the bonding nature between carbon and silica. Mechanical properties of glass fibres containing aluminium dispersoids Shrivastava, A., Agrawal, D.C. and Ch akravorty, D. Journal of Materials Science Vol 22 (1987) pp 2465-2469 The strength and Young's modulus of single glass fibres containing metallic aluminium dispersoids (7.5 at %) have been investigated. It was found that the presence of aluminium particles (which ranged from 5 to 40 nm) increases the Young's modulus but decreases the strength due to stress concentration effects.

The fatigue (tension-tension) and stress-rupture properties of two different types of lithium aluminosilicate glass-ceramic matrices (LAS-I and LAS-II) reinforced with Nicalontype silicon carbide fibre were investigated at a range of temperatures. In tensile tests, the LAS-I matrix composites showed linear elastic behaviour up to fracture, whilst the stronger, LAS-II matrix composite displayed a non-linear stress/ strain curve. Fatigue of the LAS-I matrix composite at room temperatures did not alter the stress/strain behaviour of the composite. However, fatigue testing of the LAS-II matrix composite above the proportionallimit showed a significant reduction in the proportional limit stress but residual strength was not significantly altered. This behaviour is attributed to the occurrence of matrix microcracking. At high temperatures (circa 600 - 900°C) this matrix microcracking allowed oxygen-induced embrittlement to occur.

GENERAL Analysis of thermoviscoelastic behavior of unidirectional fiber composites Hashin, Z,, Humphreys, E.A. and Goering, J. Composites Science and Technology Vol 29 No 2 (1987) pp 103-131 A method of analysis of the thermoviscoelastic properties of unidirectional fibre composites consisting of transversely isotropic elastic fibres and thermorheologically complex matrix is presented. The composite is modelled by the composite cylinder assemblage to obtain certain properties and by the periodic hexagonal array model to obtain others, Analysis capability includes any temperature variation and any thermorheological matrix. Specific numerical results were obtained for relaxation and creep functions and for material response associated with cyclic temperature variations as occurs in an orbiting space structure. (Authors' abstract) Characterisation of off-axis laminates made by folding Tan, S.C. Journal of Composite Materials Vol 21 (June 1987)pp 536-552 The fabrication of off-axis plies in rectangular module and other shapes for patches using a technique of folding is reported. The difference between laminates made by folding and conventional means has been investigated in terms of the stress/strain relations, the ultimate strength and failure mechanisms. Both tension and compression tests showed that folded laminates are significantly stiffer and stronger than conventional laminates made by cutting. The applications of this folding method for delamination control and structural design are proposed.

CERAMIC MATRICES Fatigue and stress rupture of silicon carbide fibrereinforced glass-ceramics Prewo, K.M. Journal of Materials Science Vol 22 (1987) pp 2695-2701

Current status of the losipescu shear test method Adams, D.F. and Walratb, D.E. Journal of Composite Materials Vo121 (June 1987)pp 494-507 This paper is a review of the Iosipescu shear test with particular emphasis on the correlation and contradictions resulting from published works

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