Aramid fibre epoxy resin composites

The properties of some unidirectional aramid fibre epoxy resin composites are given in Table 5.7. 

Resin transfer moulding (RTM) is a low-pressure variation of transfer moulding where, instead of granules or preforms, a pre-mixed resin and catalyst (hardener) is injected into a closed mould containing dry glass, carbon or aramid fibre reinforcement. When the resin has cooled, the mould is opened and the composite part ejected. The resins used include polyester, vinylester, epoxies, phenolics and methyl methacrylate combined with pigments and fillers. Applications include small complex aircraft and automotive components as well as automotive body parts, baths and containers. 

As shown in the previous section, most polymer composites used in construction involve highly flammable matrices, such as polyester, vinylester or epoxy resins. Besides, if glass and carbon fibres are generally considered heat resistant, other type of fibres used for specific applications may also exhibit poor fire behaviour (aramid, polyolefins or other polymer fibres, for instance). Therefore, to meet the safety requirements specified in building codes and... 

The shifts in the peak position of the 1610cm aramid Raman band, shown in Figure 8.4, can be used as calibration curves to monitor the ddbrmation of fibres in a composite under any state of stress or strain. Previous studies have shown [77-81] that it is possible to map out the distribution of stress or strain along a single short, discontinuous fibre in a low-modulus epoxy resin. This is described in detail next. 

We have developed different nonwoven stmctures with para-aramid fibres, and produced thick 3D stmctures by associating several nonwoven monolayers with a consolidation treatment. Porous composites were afterwards manufactured by impregnating the fibrous stmctures with an epoxy resin. Both dry and impregnated materials were characterized in terms of stmcture (density, fibre volume fraction), and compression tests were used to evaluate mechanical properties. Equivalent pore size and distance between fibre contacts were determined using theoretical models. They help to provide some insight on the mechanical behaviour of the different stmctures. 

Carbon (sometimes referred to as graphite) fibre is the reinforcement material of choice for advanced composites. Carbon fibres have a higher fatigue resistance than glass or aramid. Carbon fibre properties depend on the structure of the carbon used and are typically defined as standard, intermediate and high modulus fibres. Several thousand fibres are twisted together to form a yarn which may be used by itself or woven into a fabric. The yarn or fabric is combined with a resin, usually epoxy, and wound or moulded to shape to form a wide variety of products. 

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