Treatment of chenevotte, a co-product of industrial hemp fiber, by water or hydrochloric acid: impact on polymer mobility in the lignified cell walls

The impact of water- and of mild acid impregnation with hydrochloric acid (HCl) on the viscoelastic and breaking properties of woody hemp core (chenevotte) was studied from the polymer to the macroscale level. We have shown that transition temperature (T (g)) values of lignin and hemicelluloses were not affected by the acid treatment, whereas the relaxation mechanism of hemicelluloses, expressed by the apparent activation energy, was modified. The opposite impacts were observed in the water extraction. Changes in the sample strength were also noted, as the chenevotte treated with mild HCl became more brittle, as opposed to the samples extracted with water. It is suggested here that the moderate HCl treatment impacts chenevotte micro- and macro-properties through acid depolymerization of polysaccharides and extraction of low molecular mass entities, whereas water immersion contributes solely to the later mechanism.