Flame Retardancy of Lightweight Sandwich Composites

Abstract

This study proposes an innovative solution to flame-retard a sandwich composite made of unsaturated polyester resin, glass fibre skins and polyester nonwoven core material. The strategy uses the core material as flame-retardant carrier, while the resin is also flame-retarded with aluminum trihydroxide (ATH). A screening of the fire-retardant performances of the core materials, covered with different types of phosphorous flame-retardant additives (phosphate, phosphinate, phosphonate), was performed using cone calorimetry. The best candidate was selected and evaluated in the sandwich panel. Great performances were obtained with ammonium polyphosphate (AP422) at 262 g/m2. The core material, when tested alone, did not ignite, and when used in the laminate, improved the fire behaviour by decreasing the peak of heat release rate (pHRR) and the total heat release (THR): the second peak in HRR observed for the references (full glass monolith and sandwich with the untreated core) was suppressed in this case. This improvement is attributed to the interaction occurring between the two FR additives, which leads to the formation of aluminophosphates, as shown using Electron Probe Micro-Analysis (EPMA), X-Ray Diffraction (XRD) and solid-state 31P Nuclear Magnetic Resonance (NMR). The influence of the FR add-on on the core, as well as the ATH loading in the matrix, was studied separately to optimize the material performances in terms of smoke and heat release. The best compromise was obtained using AP422 at 182 g/m2 and 160 phr of ATH.

Physical Properties of Glass-Fibre-Reinforced Polymer Filled with Alumina Trihydrate and Calcium Carbonate

“…The two factors, the tiny amount of resin and the role of ATH as a fire retardant, explain why the AT30 composite has the lowest combustion rate. These findings are in line with those of other researchers who used ATH as a filler that functions as a fire retardant [23,37,[39][40][41].…”

Compressive Strength and Elastic Modulus of a 3D Woven Glass/Polyester Fire-Retardant Sandwich Composite

“…Aluminum trihydroxide (Al(OH)3) (ATH) is well-known as a mineral filler material and is often loaded into a matrix to enhance fire retardancy [8,21]. ATH is recognized for its low cost and non-toxicity [22].…”

“…Samyn et al investigated the fire retardancy of a lightweight sandwich composite based on unsaturated polyester resin, glass fiber skins, and nonwoven polyester core material, with ATH used as a fire-retardant filler. The ATH loading in the matrix was shown to enhance the fire retardancy performance of the material [21]. In work by Wirawan et al, the loading of up to 40% ATH on 3D woven sandwich glass-polyester led to higher fire resistance [8].…”

Development of New Hybrid Composites for High-Temperature Applications

“…The demand for lightweight, strong and durable structures has increased in recent years [1,2]. That is why fiber metal laminates are gaining popularity in different applications: automotive, aircraft and space [3][4][5][6].…”