Improvement of the fire behavior of poly(1,4-butanediol succinate)/flax biocomposites by fiber surface modification with phosphorus compounds: molecular versus macromolecular strategy
Résumé
The grafting of phosphorus compounds onto natural fibers has been investigated as a strategy for improving poly(1,4-butanediol succinate)/flax biocomposite fire behavior. Three phosphorus compounds - dihydrogen ammonium phosphate, poly(methacryloyloxy) methyl phosphonic acid homopolymer and poly(methacryloyloxy) methyl phosphonic acid methylmethacrylate copolymer - were selected. The aim of this work was to compare the fire performance conferred by the grafted compounds depending on whether phosphorus is brought by a molecule or a macromolecule. TGA, pyrolysis combustion flow calorimetry and cone calorimetry were used to characterize the thermal stability and fire behavior of the samples. The pyrolysis combustion flow calorimetry results showed that in all cases the presence of phosphorus changes the degradation pathway and thus the flammability properties of flax. The ability of the grafted flame retardant to promote char formation and residue formation was found to be dependent on the nature and quantity of phosphorus covalently bonded to flax. Conversely, cone calorimeter tests revealed similar fire behavior whatever the grafting agent. A significant increase of the char amount and a global enhancement of fire parameters were observed with increasing grafting rate. Moreover, phosphonated polymers promoted a charred sheath around the fibers which acts in addition to their charring, conferring a fire performance close to that of dihydrogen ammonium phosphate for the biocomposite.
Origine : Fichiers produits par l'(les) auteur(s)