摘要:

This paper presents techniques for the functionalization of polymer materials with alkoxy-silane groups. Alkoxy-silane groups are key intermediates in bonding organic materials onto glass-fibre surfaces. Two reaction routes are described: (1) Chain copolymerization of butyl acrylate (BuA) and γ-methacryloxypropyltrimethoxy-silane (MPS) and (2) grafting of MPS onto polyethylene (PE) and poly(styrene-block-ethylene-co-1-butene-block-styrene) (SEBS). It is concluded that chain copolymerization is the superior route since it gives almost unlimited possibilities of adjusting the degree of alkoxy-silane functionality. The paper also demonstrates the advantage of performing graft copolymerization in the melt instead of in solution. Solution grafting is of low efficiency and is probably directed to chains having reactive sites, e.g. branch points. It is proposed that the primary cause is the lower temperatures used in solution grafting in comparison to the melt reaction.

DOI:10.1163/156855496X00164

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

—This paper presents an interphase engineering technique suitable for grafting silane-modified polymers onto glass fibres to be used in composites with enhanced impact tolerance. The silane-modified polymers include ethylene polymers grafted with γ-methacryloxypropyltrimethoxysilane (MPS) and a copolymer of butyl acrylate (BuA) and MPS. The grafting of functionalized interphase materials onto glass fibres is performed in solution. By changing the concentrations of the solutions, different amounts of polymer can be deposited on the fibres. Water crosslinking of the polymer gives the possibility of producing stabilised interfacial polymer coatings over a range of thicknesses. It is concluded that acidic conditions (1) promote the grafting of silane-modified polymers on glass fibres and (2) for a given reaction time, increase the amount of crosslinked polymer in the interphase, i.e. yield more stable interphases. It is also likely that preserving acidic conditions at the fibre/polymer interface is important for maintaining bonding across the interface. It is shown that polystyrene/glass-fibre composites having SEBS at the interface are promising candidates for high-impact-tolerance composites.

DOI:10.1163/156855496X00173

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

K2O 6TiO2whiskers have been used to prepare 6061 alloy and pure A1 matrix composites by a squeeze casting process. The flexural strength and microhardness test have been performed for as-cast composites and in the T6 treated state. The interfacial microstructures of composites and the effect of interface reaction on composite properties have been studied with high resolution transmission electron microscope (HRTEM), energy dispersive spectrum (EDS) and X-ray diffraction (XRD). The results showed that the flexural strength of 6061A1 composites was 518 MPa in the as-cast state and decreased to 490 MPa in the T6 state. The tensile strength of pure A1 matrix composites was 238 MPa (as-cast) and 212 MPa ('T6'). In K2O. 6TiO2/A1 composites, the whisker was found to react with matrix easily, thus forming a continuous interlayer. In the case of 6061A1 matrix, the interlayer consisted of TiO, MgTi2O4, MgAl2O4, some 10-20 nm in thickness, which increased a few nanometers after T6 treatment. In the case of pure A1, besides a TiO layer, α-KO2particles were found near the interlayer. The degradation of composite strength following the T6 treatment was a result of the interfacial reaction which consumed the whiskers more intensively.

DOI:10.1163/156855496X00182

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor