Toward the cottonization of hemp fibers by steam explosion. Flame-retardant fibers

Maria Moussa (1, 2) , Roland El Hage (1) , Rodolphe Sonnier (3) , Laurent Chrusciel (2) , Isabelle Ziegler-Devin (2) , Nicolas Brosse (2)

1 LCPM - Laboratoire de Chimie Physique des Matériaux
2 LERMAB - Laboratoire d'Etude et de Recherche sur le Matériau Bois
3 PCH - IMT Mines Alès - Polymères Composites et Hybrides

The goal is to produce cottonized hemp fibers with improved thermal stability. It was first found that the fine hemp fibers produced from technical non-retted hemp fibers by steam explosion exhibited an enhanced thermal stability. An efficient and low-cost process was developed using a mixture of urea/etidronic acid in aqueous solution in order to achieve a high phosphorus content and produce flame retardant fibers by chemical grafting. ICP, 31P and 13C NMR, SEM, thermogravimetric, Pyrolysis-Combustion Flow Calorimetry analyses and a flame test were used to characterize the grafted fibers. Fibers modified with relatively high P and N contents have been produced (≈ 6 wt % and ≈ 4 wt % respectively) but lower grafting rates (P ≈ 0.5 % and N ≈ 0.35 %) are sufficient to produce non-flammable fibers. A synergistic effect between N and P has been proposed to induce the formation of a stable char.

Mots clés: HEDP/urea; Thermal grafting; Steam explosion; Hemp fibers

Domaines: Polymères; Génie des procédés; Matériaux; Chimie organique

Maria Moussa, Roland El Hage, Rodolphe Sonnier, Laurent Chrusciel, Isabelle Ziegler-Devin, et al.. Toward the cottonization of hemp fibers by steam explosion. Flame-retardant fibers. Industrial Crops and Products, 2020, 151, pp.112242. ⟨10.1016/j.indcrop.2020.112242⟩. ⟨hal-02676818⟩