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2015-06-30 - Colloque/Présentation - poster - Anglais - 1 page(s)

Costes Lucie , Laoutid Fouad , Rose Gwendoline, Khelifa Farid , Brohez Sylvain , Delvosalle Christian , Dubois Philippe , "Cellulose – Phosphorus combinations as Flame Retardant additives for Poly(lactic acid)" in 2nd Researcher's Day of the Materials Research Institute, Mons, Belgium, 2015

  • Codes CREF : Matériaux composites (DI2726), Chimie (DI1300)
  • Unités de recherche UMONS : Matériaux Polymères et Composites (S816), Génie des Procédés chimiques et biochimiques (F505)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux), Institut des Sciences et du Management des Risques (Risques)
  • Centres UMONS : Centre d’Innovation et de Recherche en Matériaux Polymères (CIRMAP)

Abstract(s) :

(Anglais) The use of bio-based additives as sustainable solutions for the improvement of polymer properties such as fire performances are more and more considered, particularly for bioplastics which are increasingly used for technical and durable applications. With this view, this study evaluates the flame retardant effect of microcrystalline cellulose (MCC) and cellulose nanocrystals (CNC) associated with phosphorus in PLA. Cellulose is the most abundant raw material in nature and it exhibits char forming potential when associated with phosphorus. Many studies relate flame retardant treatments of cellulosic materials by using phosphorous compounds. The improvement of fire performances lies on the capacity of treated cellulose to form carbonaceous char during the combustion. In the present study, two different pathways were considered to combine cellulose with phosphorus keeping the bio-based characteristic features of the flame retardant system. The first pathway consisted in a reactive approach by functionalizing cellulose with phosphorous acid. The second pathway concerned the combination of cellulose with a metallic phytate as bio-based phosphorus compounds. The combination of phosphorylated cellulose with metallic phytate has been also investigated. Cellulose was successfully phosphorylated with phosphorous acid in urea4. A high phosphorus content (18 wt%) was reached when CNC was treated (CNC-P). The phosphorylation of the cellulose modifies the degradation pathway of cellulose by reducing its onset degradation temperature and by promoting the formation of high amount of char residue. PLA composites containing the different cellulose-based fire retardant systems were fire tested by cone calorimetry under a heat flux of 35 kW/m². The use of phosphorylated cellulose, alone or in combination with aluminum phytate leads to significant decrease of the peak of heat release rate (pHRR) during cone calorimeter test thanks to the formation of an insulating char layer during the combustion. PLA containing 10 Al-Phyt/10 CNC-P proved to be the best fire retarded composition owing to its high phosphorus content and some synergistic effect due to the presence of Al. During the combustion, an insulating, cohesive and continuous char layer is rapidly formed limiting the release of volatile degradation products in the gas phase and hence reducing the heat released.Cellulose associated with phosphorus by reactive pathway or by combination pathway exhibits flame retardant efficiency in PLA. The efficiency of the cellulose-based flame retardant system is related to the phosphorus content, which leads the cellulose thermal degradation towards the formation of stable char residues acting as an insulating barrier. The combination of cellulose-based flame retardant system with Al phytate enhances the barrier effect thanks to the faster formation of the carbonaceous layer.