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Posted on 22/05/2018 in 32 News
Ecological flame retardant textiles and composites

Marc Vanhoomissen, Veramitex SA, Belgium, presented the LIFE-FARBioTY project: Fire and Ageing Resistance Biocomposite for Transportation industry (see pinfa Newsletter n°83). This project aims to develop new composite materials based on renewably-sourced flax fibres. Epoxy and polyester resins are being tested with flax fibres and THPC + ammonia treatment for flame retardancy.

This is a classical textile process, in which the chlorine is removed in the process, leaving a phosphorus-nitrogen flame retardant treatment. Results to date show that treated flax can achieve M1 fire performance, similar to glass-fibre based products.  Besides, the impregnation of resins is much easier after flame retardancy treatment. Further testing of ageing, weathering and UV resistance are underway.

Giulio Malucelli, Politecnico di Torino, presented experimental studies of bio-based PIN materials as flame retardants for cotton fibres. Bio-based materials tested include dairy-derived whey proteins and casein protein (S+N), chitosan protein (C, N), hydrophobin proteins produced by filamentous fungi (S+N) and nucleic acids (C, P, N). Tests show that low molecular weight nucleic acids (which are less expensive) are effective. LBL (layer-by-layer) deposition of 20 alternate layers of chitosan and nucleic acids rendered cotton textile self-extinguishing, including after washing (durable), without deteriorating fibre mechanical properties. This is considered to be because chitosan is negatively and nucleic acids positively charged, enabling LBL deposition, and chitosan reacts to a 3D network ensuring durability. Scale up is now being studied to reduce costs. See also pinfa Newsletter n°84.

Sebastian Rabe, BAM Germany, summarised research testing of a Novamont thermoplastic starch – polyester blend polymer with various natural fibres as filler material (industrial processes wastes from various Mexican industrial sectors): keratin fibres from bovine skin hair during leather tanning, coconut, blue agave and henequen agave fibres. These were tested with different PIN FRs: ATH (aluminium tri hydrate), APP (ammonium polyphosphate), expandable graphite. In some cases, the fibre showed synergistic fire performance with the PIN FRs.  10 wt.-% APP and 20 wt.-% fibre achieved UL94-V2 (3.1 mm) and achieved a lower PHRR and THE in cone calorimeter than 30 wt.-% APP alone.

Roland El Hage, Lebanese University, presented experiments on PIN fire safing of a mixture of bio-sourced miscanthus fibres and recycled textile fibres, intended as sustainable construction insulation materials. Chitosan polysaccharide based binder and aluminium hydroxide (ATH) PIN flame retardant were tested, showing good surface adhesion to the fibres and achieving Euroclass E (“non flammable”) with 3.5% total fillers loading. No significant deterioration of mechanical properties were observed and good thermal insulation values were achieved.

Maude Jimenez, University of Lille, France, presented experimental development of a single-step coating method to fire protect polycarbonate, to replace the current coating methods usually involving three layers: adhesive, base and topcoat. Spray-on self-stratifying epoxy resin / silicone coatings were tested with the PIN FRs: RDP (bis(diphenyl phosphate), iron oxide Fe2O3 and calcium carbonate. Presence of iron oxide and calcium carbonate, which probably modifies the structure of the silicon network, allowed achieving UL94-V0 (3mm) at 2.5% FR loading (within a 50µm coating). Fire performance showed to be resistant to UV and ageing. Life cycle analyses of this one pot process and of the three-layers processes were compared, showing improved environmental impact for the one-step process.

Raymond Hajj, Lebanese University / IMT – Mines Alès, presented experiments in binding phosphorus FRs to flax fibres by impregnation and radiation fixing. Vinyl phosphonic acid showed to be effective, using water as the impregnation solvent. Radiation breaks the compound’s carbon double bond, so fixing into the flax fibres. Flax fibre textile was rendered self-extinguishing with > 0.5% phosphorus loading, but the temperature of thermal degradation of the fibres was significantly reduced.

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