Novel co-blended polymer matrix systems for fire resistant structural marine composites

Fibre-reinforced composites are finding increased usage in load-bearing structures in a variety of applications in marine, automotive and rail transport industries owing to their specific strength and stiffness properties. A serious problem with these composite materials, particularly glass-reinforced polymeric composites, which are the most prevalent in marine and other surface transport applications, is that they support combustion and in fire conditions burn, most often with heavy soot and smoke. Insulation can reduce the fire hazard, but does not eliminate it. Moreover the insulation adds weight and cost to apply.The combustible part of the composite is organic resin matrix. Most common method of fire retarding the resin and hence, the overall composite is the physical and chemical modification of the resin by either adding fire retardant element in the polymer backbone or using fire retardant additives in the resin. For polyester or vinyl ester resins, usually halogenated chemicals are used. While the presence of halogen significantly reduces the flammability of the resin, due to increasing environmental awareness and strict environmental legislations thereof, halogen - containing fire retardants are being strictly scrutinised. When non-halogen flame retardants are used, invariably they are required in large quantities (>30% w/w) to achieve required level of fire retardancy. The high concentrations of additives however, can reduce the mechanical properties of the composite. Moreover, they also affect resin's processability for resin transfer moulding technique, commonly used for these types of composites. We propose here a step change in the resin matrix by reducing the combustibility of vinyl ester and/or polyester resin by co-blending with inherently fire retardant resins, such as phenolic or melamine-formaldehyde resin.This proposal is a joint attempt by 'Fire Materials' group at the University of Bolton and 'Fluid Structure Interactions Research Group (FSIRG) at the University of Southampton to develop, construct, test and model novel, fire-retardant composites, initially for marine applications. The principal focus is to develop a modified polymeric matrix to reduce the combustibility of the vinyl ester or polyester resins by blending with appropriately modified phenolic and melamine resins, which will increase the thermal stability and char-forming capacity of the matrix. The physical and chemical properties of the modified resin will be optimised to enable: (a) the resin to be infusible for moulding leading to good processing ability: (b) low temperature cure capability to maximize compatibility and bonding with glass fibres; and (c) up-scaling to produce large laminates and structures. It is proposed that two different approaches will be taken: the first one 'Material' based, mainly by Bolton, and the other 'Structure' based, to which both Bolton and Southampton will contribute. The specific tasks include resin blending, chemical / physical modification of the resin, process modelling and resin infusion, composite laminate preparation and flammability evaluation. The composite laminates and structures thus produced are expected to comply with the fire performance requirements contained in the International Convention for the Safety of Life at Sea (SOLAS) as `IMO/HSC Code (Code of Safety for High Speed craft of the International Maritime Organisation). Additionally, the structural performance of the composite would be expected to be comparable with current glass/vinyl ester. We also propose to conduct fire performance modelling, mechanical characterisation and progressive damage analysis from a structural design viewpoint.We expect these composites to find applications also in other engineering arenas for which low-weight, thermally resistant and fire-retardant structures are increasingly being sought.

Who will benefit from this research? The beneficiaries from this work will be the marine industry as a whole from suppliers through manufacturers to end users, including: 1) Boatbuilders of high volume, high value boats (e.g. Sunseeker and Sealine) 2) Shipbuilders of high value, naval ships (e.g. BVT) 3) Boat owners, such as the Royal National Lifeboat Institution (RNLI) 4) Regulatory agencies in marine and composite structure design (e.g. Lloyd's Register) 5) Government and statutory agencies (e.g. Marine and Coastguard Agency, MCA and the Ministry of Defence, MoD) 6) International Maritime Organisation, an organisation of the UN, that ultimately makes recommendations for safe design of ships How will they benefit from this research? 1) Materials suppliers will be able to discern the improved resin chemistry to improve their product range, particularly in applications where fire is an important hazard. 2) Boat and ship designers and builders will be able to generate more efficient and a wider range of designs for the market place offering enhanced safety features from the use of better, fire resistant and lightweight materials. The materials suppliers too would find a better route to world-wide markets for their product ranges thus enabling increased exports. 3) RNLI has the highest specification rescue craft in the world. Their safety design case will be further enhanced through the use of fire retardant materials, supported by structural design approaches. 4) LR will be able to be the first to develop guidelines for ship and boat design based on this work, thereby giving them an edge as compared with their main competitor such as Det Norske Veritas or American Bureau of Shipping 5) The MCA could be seen as driving the safety agenda for the benefit of the UK public at large a significant proportion of whom are into marine sports and yachting where too the product ranges offered could benefit from improved and safer resins. The MCA involvement will also underpin UK inputs into IMO and ISO debates and working groups that ultimately lead to international regulations, standards and statutes. 6) The work is highly relevant to future MoD procurements for next generation surface combatants. What will be done to ensure that they have the opportunity to benefit from this research? Enabling mechanisms and methods of communication to ensure that the industrial and government beneficiaries have the opportunity to benefit from this research are four-fold. 1) The key industrialists and government agencies are collaborators with whom the proposal has been shared before submission. 2) The industrial/government consortium will be part of the Project Management Group (PMG) that will monitor progress and identify strategic directions of work. PMG will include Scott Bader, UK BVT Surface Fleet, British Marine Federation (BMF) Royal National Lifeboat Institution (RNLI), Lloyd's Register, MoD, Maritime Coastguard Agency 3) Dissemination of the findings from the research in the two universities quickly and directly into the concerned organisations, in particular the scientists and engineers most closely associated with the disciplines underpinning this work. The fire group at Bolton have good working relationship with relevant industry, i.e., resin manufacturers, flame retardant manufacturers, commercial fire testing laboratories and composite manufacturers/users, with whom they have been engaged in different research projects over last 10 years or so. The FSIRG group at Southampton also had a track record of collaboration with main players in marine industry. 4) Use specific industrial contexts for defining case study material and test sample design when considering empirical and/or numerical modelling cases for the laboratory studies. That is, laboratory and university based work funded through this grant will be aligned closely with 'real life' scenarios as far as possible.