959 resultados para Acrylonitrile rubber


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Foram realizados ensaios no CNPSD visando-se obter postura de Erinnyis ello em cativeiro. O resultado obtido atestou a viabilidade da técnica de obtenção de postura da E. ello.

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Monografia apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciada em Medicina Dentária

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This paper describes hybrid mathematical model which couples the mechanics of the mass/spring model to the acoustic wave propagation model for use in generating the acoustic signal emitted by complex structures of paper fibres under strain. A discussion of the coupling method is presented including remarks on the errors encountered intrinsic to the discretisation scheme. The numerical results of a vibrating rubber band and a vibrating paper fibre are compared to their experimental counterparts. The fundamental frequencies of the acoustic signals are compared showing a close agreement between the experimental and numerical results

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In this paper we investigate a number of gas flames for fire polishing borosilicate glass capillaries used in the manufacturing of IVF micro-pipettes. Hydrofluoric acid (HF) was also used as an alternative to finish the pipette end. Glass micro tools in the IVF industry are drawn from hollow glass capillaries of diameter 1 mm. These capillaries are cut manually to a length of 100 mm from hollow glass rods resulting in sharp and chipped edges. These capillaries are held in a customised holder having padding of soft silicone or rubber. Sharp and uneven edges of these capillaries pick up particles of rubber or soft silicone shavings, rendering them ineffective for IVF treatments. The working range of borosilicate glass is 800-1,200 degrees C. The experiments involved analysis of fire polishing process for borosilicate glass capillaries using candle, butane, propane, 2350 butane propane, oxyacetylene gas flames, finding the optimum distance of the capillary relative to the flame, optimum time for which the capillary should be held in the flame and optimum region of the flame which gives the required temperature range. The results show that 2350 butane propane gas mix is optimum for fire polishing of borosilicate glass capillaries. The paper is concluded by comparing the results of fire polishing with the results of acid polishing, in which HF of 1.6% concentration is used to etch the ends of the borosilicate glass pipettes.

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During free surface moulding processes such as thermoforming and blow moulding heated polymer materials are subjected to rapid biaxial deformation as they are drawn into the shape of a mould. In the development of process simulations it is therefore essential to be able to accurately measure and model this behaviour. Conventional uniaxial test methods are generally inadequate for this purpose and this has led to the development of specialised biaxial test rigs. In this paper the results of several programmes of biaxial tests conducted at Queen’s University are presented and discussed. These have included tests on high impact polystyrene (HIPS), polypropylene (PP) and aPET, and the work has involved a wide variety of experimental conditions. In all cases the results clearly demonstrate the unique characteristics of materials when subjected to biaxial deformation. PP draws the highest stresses and it is the most temperature sensitive of the materials. aPET is initially easier to form but exhibits strain hardening at higher strains. This behaviour is increased with increasing strain rate but at very high strain rates these effects are increasingly mollified by adiabatic heating. Both aPET and PP (to a lesser degree) draw much higher stresses in sequential stretching showing that this behaviour must be considered in process simulations. HIPS showed none of these effects and it is the easiest material to deform.

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