Abstract
This study investigates new intumescent formulations based on lignin and phosphinates to improve the flame retardant properties of Polyamide 11, while preserving the bio-based characteristics of this latter. Lignin has the advantage of being a bio-based compound and can be effectively used as carbon source for the design of intumescent systems in combination with other flame retardant additives. Metal phosphinates belong to a novel class of phosphorus flame retardants. Despite their increasing use, there is lack of scientific understanding as far as their fire retardancy mechanism is considered, especially in char forming polymeric materials. In this context, Polyamide 11 was melt blended with lignin and metal phosphinates. The possibility of melt spinning the prepared blends were assessed through melt flow index (MFI) tests; thermogravimetric (TG) analyses and cone calorimetry tests were exploited for investigating the thermal stability and the combustion behaviour of the obtained products, respectively. MFI results indicate that some formulations are suitable for melt spinning processes to generate flame retardant multifilament. Furthermore, the combination of lignin and phosphinates provides charring properties to polyamide 11. Finally, cone calorimetry data confirmed that the designed intumescent formulations could remarkably reduce PHRR through formation of protective char layer, hence slowing down the combustion process.
Highlights
Recently, bio-based polymeric materials are being exploited for various textile applications to address growing environmental concerns due to the shortage of petroleum resources and pollution caused by synthetic polymers
Polyamide 11 (PA11) is one of the bio-based polyamide increasingly used for various applications including manufacturing of textile fibers [1]
The low flame retardant properties of PA11 limit its applications in electronics, in the automotive sector and for high performance textiles
Summary
Bio-based polymeric materials are being exploited for various textile applications to address growing environmental concerns due to the shortage of petroleum resources and pollution caused by synthetic polymers. Polyamide 11 (PA11) is one of the bio-based polyamide increasingly used for various applications including manufacturing of textile fibers [1]. The low flame retardant properties of PA11 limit its applications in electronics, in the automotive sector and for high performance textiles. Lignin has shown great potential as bio-based flame retardant additive because of its high char yield after decomposition ascribable to its aromatic framework. It is well known that the ability to form char during the thermal degradation is a fundamental aspect of flame retardant intumescent systems. Charring properties make lignin an important candidate as a carbon source in combination with other
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