摘要:

A comparative study of interfacial effects due to styrene-butadiene-based triblock copolymer (SEBS) addition and to corona treatment has been investigated for blends of polyethylene (PE) and polystyrene (PS). Blends of PS/PE covering a wide range of weight composition have been prepared in the molten state. Scanning electron microscopy demonstrated that moderate amounts of SEBS copolymer addition (2-5%) resulted in finer particle dispersion and in better interfacial adhesion between PE and PS phases. Tensile strength and elongation at break were also significantly improved. In the case of corona treatment of both polyethylene and polystyrene, the tensile strength of the blends increased while their elongation at break remained almost unchanged. The same trend was found when small amounts of corona-treated blend (5%) were added to the non-modified PS/PE blends. Rheological measurements revealed that corona treatment resulted in a decrease of dynamic shear viscosity of both PE and PS. From a view-point of morphological and mechanical properties, the triblock copolymer was found to be the more efficient modifier. Nevertheless, much higher tensile strengths, but lower elongations at break were obtained when the blends were modified by corona-treated SEBS copolymer. The results suggest that a combination of the two modification methods may be a promising route to enhance performance properties in the immiscible PS/PE system.

DOI:10.1163/156855494X00076

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The use of composite materials has increased considerably in the past 30 years. However, many of the molecular level processes occurring in the interfacial region have yet to be investigated. In this regard, an in situ Fourier transform near infrared technique has been demonstrated herein. This technique utilizes a seven-fiber bundle to examine monolayer and sub-monolayer level surfactant adsorption at the silica optical fiber/solution interface. It is felt that this technique will greatly increase the knowledge of the processes involved in the improvement of mechanical properties of silane treated composites.

DOI:10.1163/156855494X00085

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Continuous fiber, high-performance composites have found increased use in the design of a large number of civilian and military aircraft. However, the brittle nature of the carbon fiber and the resins used as matrices have restricted the full utilization of these materials in aerospace application. Hence, the development of toughened composites has a great potential for expanding the use of current materials, and a major effort is being undertaken in order to develop toughened composites. Due to several advantages of introducing a ductile or flexible material between the fiber and matrix, coating the fiber with polymers has recently received considerable interest and much effort has been done to understand the effect of the interlayer on composite properties. This paper reviews the technology of toughening composites by fiber coating, showing the composite systems, coating materials, fiber coating methods and toughness mechanisms which have been studied. Finally, a separate section is dedicated to reviewing dynamic mechanical analysis of fiber-coated composites due to the increasing importance of this technique for characterization of these materials.

DOI:10.1163/156855494X00094

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effect of functionalized short poly(ethylene-terephthalate) (PET) fibres, with free sulphonil azide groups, on the mechanical behaviour of low density polyethylene (LDPE) and polypropylene (PP) and their blends has been investigated by means of an experimental design. The addition of modified PET fibres to these polymer matrices gives rise to a considerable increase in the tensile and tlexural moduli, mainly in matrices with high LDPE percentages. The strength of the composites depends principally on matrix composition. So fibres act as a reinforcing agent in matrices with high LDPE contents. However, at PP percentages above 60% in the matrix the tensile and flexural strengths decrease or remain almost constant as fibre content increases, respectively. The impact strength mainly depends on matrix composition although a minimum is observed at high both PP and fibre percentages in the composite. A comparison between natural and modified PET fibres has been carried out and the most important effect of the modified fibres is observed in the impact behaviour of the LDPE, with increases of nearly 200%. Morphological studies have shown a better wettability between LDPE and PET fibres, and an improved adhesion at the fibre/matrix interface in the case of azide modified PET fibres.

DOI:10.1163/156855494X00102

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor