Method of forming an article from resin-impregnated plastics material

Method of forming an article from resin-impregnated plastics material

exhibit an Arrhenius type of behaviour. Viscoelastic analysis of the residual stress in glass fibre-reinforced plastics Roy, A. and Murthy, P. N. Fib...

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exhibit an Arrhenius type of behaviour.

Viscoelastic analysis of the residual stress in glass fibre-reinforced plastics Roy, A. and Murthy, P. N. Fibre Science & Technology, Vol 9, No 2 (April 1976) pp 81-101 A theoretical analysis is presented, which studies the effects of different types of curing schedules on the relaxation of residual stresses. The resin is characterised as a thermorheologically simple material. Using an elasticoviscoelastic analogy, elastic

solutions are transformed into fiscoelastic solutions, and these are applied to different curing schedules to enable a suitable choice for a given practical situation. Single fibre solutions are extended to multifibre models using the principle of superposition. It is found that a multistep temperature drop gives relatively lower residual stresses than a single-step drop. WOOD

Determination of modulus of elasticity of wood from vibrating reed measurements

Vafai, A., Parshad, M. and Ahmadieh, A. Fibre Science & Technology, Vol 6, No I (Jan 1976)pp 1-10 The modulus of elasticity of two types of wood was determined using a vibrating reed test. This procedure is based upon the resonance method of determining vibration characteristics and, in conjunction with a simple mathematical model, yields information regarding the material properties of the wood. The modulus of elasticity was also determined, in three directions (longitudinal, radial and tangential), as a function of specific gravity.

Abstracts of patents UK patents are prepared by V. Edwards, QMC Industrial Research Ltd, London UK PA TEN TS

Method of forming an article from resin-impregnated plastics material (Shell Internationale Research Maatschappij NV) UK Pat I 412 465 (5 Nov 19 75) 10 to 35% of the voids of an open cell foam material are impregnated with a thermosetting resin and pieces are mixed with pieces of an unimpregnated foam. The mix is placed in a mould where pressure is applied to distribute the resin which is then allowed to cure. A composite material (Alexei Tikhonovich Tumanov et al) UK Pat 1 412 498 (5 Nov 1975) High strength at temperatures up to 500°C is produced by reinforcing a matrix consisting of 90 to 40% by volume of sintered powdered aluminium with 10 to 60% of stainless steel fibres. Composite materials comprising carbon with a surface which has been modified by electrolysis (Rhone-Progll) UK Pat 1 412 846 (5 Nov 19 75) Carbon fibres, Films, tapes etc are subjected to a two-stage electrochemical treatment, first by electrolysing an aqueous solution with the carbon forming the anode and second by electrolysing the same solution with the current reversed such

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that no metal is deposited on the carbon. Improved mechanical performance of resin composites is claimed.

Reinforcement of polyamide moulding compositions (Dynamit Nobel Aktiengesellschaft) UK Pat 1 412 980 (5 Nov 1975) Glass fibre and/or powder and a polyamide produced from the dimethyl ester of terephthalic acid and 2, 2, 4and/or 2, 4, 4- trimethyl hexa methylenediamine having a viscosity number (DIN 53 727) of 116 to 150 ml/g may be blended together in an extruder to give homogeneous moulding materials. Mesh reinforced elastomeric polymers (Comalco (J and S) Pty Limited) UK Pat 1 413 778(12Nov 1975) Low-cost reinforced sheets are made by interposing a metal grid between two larger sheets of elastomer coated with an adhesive, extracting the air from between the sheets so that they meet through the holes in the grid and allowing the adhesive to cure.

Process for the production of highquality cement-bound wood chip or similar boards especially wall panels made of wood, bagasse or other wood-

like material (Branko Simunic) UK Pat I 414 310 (19 Nov 1975)

Greater strength results from treating the mixture of fibrous material, cement and water with an aqueous dispersion of a vinyl chloride copolymer containing 5 to 50% of vinyl chloride, the remainder being a vinyl ester and/or an alkene. The dispersion may be added to the mix before moulding or as a coating for the surface before pressing and drying.

Method of producing synthetic resinimpregnated paper (Rohm GmbH) UK Pat I 414 361 (19 Nov 1975) Paper containing over 30% resin can be made in a paper-making machine by treating pulp with a dispersion of a non-ionic synthetic resin, such as a polymer of an acrylic ester, methacrylate ester or styrene, containing a cationic dispersion agent. Rubber articles reinforced with high modulus fibre cords, pneumatic tyres reinforced with such fibre cords and a method for producing the same (Bridgestone Tire Kabushiki Kaisha) UK Pat 1 415 573 (26 Nov 1975) High speed durability and stability follows the use of steel or glass fibre cords which have been covered at the ends and at least part of the peripheral surface with a hard, high modulus rubber and a further softer rubber layer, with a modulus 20 to 90% of that of the first layer, at least covering the ends and in contact with the first layer.

COMPOSITES.JULY 1976