This new biocomposite door leaf product has been specifically designed and fire rated for both over-ground and underground rail use; the composite structural system easily passes BS 6853 and BS 476, as well as being EN 45545 HL3 compliant. TRB can now offer the rail industry a sustainable, ‘green’ composite material option for carriage door leaves at a comparable cost to aluminium bonded door leaves, with a 35% weight saving. This has been achieved by TRB applying its in-house understanding of composite materials technology and expertise to railway applications, broadening its product offering to its established rail industry customer base to meet a growing global market need to use greener, more energy efficient products.
The design and engineering team at TRB has worked closely with a resin partner to develop a new, proprietary carbon fibre compatible bio prepreg resin. Key criteria for TRB was that the new system had to be highly sustainable and enable them to cost effectively manufacture lighter weight composite parts that would meet even the most demanding fire, smoke and toxic fumes (FST) specifications in subterranean rail applications. The new ‘bio’ prepreg, which is non-toxic and does not use volatile organic solvents, is based on a Polyfurfuryl alcohol (PFA) resin derived from a renewable alcohol produced from a natural waste bi-product from refined sugar production.
This new biocomposite prepreg system, which TRB state is the first sustainable fire rated material of its type on the market, has been developed exclusively for TRB to manufacture components for FST rail applications; as well as carriage door leaves, the TRB bio prepreg based system can be used for other rolling stock parts.
The foam core used in the rail door leaf composite structure is produced from 100% recycled consumer plastic. It was selected by TRB as the recycled foam core meets its key ‘high sustainability’ specification objective and delivers the desired overall material properties performance of the sandwich panel construction when used in combination with the woven carbon fibre fabric on both sides and the bio resin prepreg. Other matrix design options for other applications using glass fibres, natural fibres, or aramid fibres can be custom made by TRB on request. Depending on rail customer needs, door leaves are supplied with a gelcoat, finish painted or primed ready to paint.
The fire performance of TRB’s new biocomposite based system specified for rail carriage door leaves is outstanding. According to independent data, the sandwich panel system when tested to BS 476 Part 7: 1977 for ‘Spread of Flame’ easily achieved a Class 1 Category 1a rating, with a 30% less recorded flame spread of only 50mm in the 1.5 minute test time; the maximum allowable is 165mm for the Class 1a rating.
Lyndon Newman, chief engineer for TRB commented: “We are extremely pleased with the overall performance data for the new biocomposite carbon fibre prepreg sandwich panel system, in particular the FST specifications achieved. In the 30 years I have been in the industry I have never seen such impressive fire performance test results for a non-phenolic based thermoset system, achieving the BS standard so comfortably. Our PFA bio resin prepreg has fire retardant properties greater than phenolics, plus excellent temperature and chemical resistance.”
