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Algerian palm groves, a key component of oasis ecosystems, generate significant volumes of natural waste. In the present study, leaflet and rachis derived date palm fibers (DPFs) produced from the pruning of date palm trees were used as an effective filler to reinforce composites consisting of polyvinyl chloride and high-density polyethylene (PVC-HDPE) (20:80). Composites with an untreated and treated DPFs loading of 30 wt.% were prepared using a twin-screw extruder and compression molding. The DPFs surface was modified using various treatments, including NaOH, 3-aminopropyltriethoxysilane, combined alkali-silane, bleaching with NaClO2, and H2O2+HNO3. The successful surface modification of the DPFs, including delignification and the extraction of cellulose microcrystals (CMCs), was verified using infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG). The results revealed an improvement in the morphological, thermal, mechanical, dynamical-mechanical, rheological, and water uptake performance of the composites with the addition of the modified DPFs. It was concluded that it was the CMCs that primarily enhanced the thermo-physical properties of the PVC-HDPE composites, making them suitable for several industrial applications.

Biocomposites have major advantage in term of weight saving thanks to lower densities compared to conventional materials; this property also allows a reduction of environmental impacts which is beneficial for the automotive industry. In addition, they maintain rather good mechanical properties after recycling cycles which makes possible to consider other end-of-life scenarios than incineration or landfill. In this work, we studied two potential routes for the recycling of moulding wastes from poly (propylene)-flax nonwovens. By representing close to 25%-wt, these wastes are a major industrial problem, inducing additional recycling or treatment costs. In a first step, the parts were grinded and reincorporated at different weight fractions into virgin nonwovens. Up to 30%-wt of reincorporated wastes, results showed good mechanical performances for recycled nonwovens, especially in bending mode. In a second stage, scraps were grinded and then compounded for injection moulding applications. Their good rheological behavior and ability to conserve fibre lengths during extrusion made possible to formulate competitive materials in terms of tensile performances. (C) 2017 Elsevier Ltd. All rights reserved.

The role of the main cell-wall polysaccharide-constituents of flax fibres on their mechanical behaviour has been investigated. One sample of scutched flax fibres underwent a successive sequence of extractions (boiling water, EDTA, HCl, NaOH), and tensile tests on elementary fibres were carried out after each step. Results indicated a role of the primary cell-wall in the tensile performance of the fibres. Indeed, an increase of the TIII mechanical behaviour proportion was observed after the boiling water extraction. Furthermore, after EDTA extraction, a significant decrease of the strength at the tangent modulus threshold (312–153 MPa) and a significant increase of the strain at rupture (2.3–2.9%), occurred. Additionally, it was highlighted that the strength at rupture and the Young’s modulus of flax fibres decreased after each extraction. In the secondary cell-wall, it was deduced that the matrix polysaccharides were involved in the load transfer whereas structuring polysaccharides enhanced the cohesion between cellulose microfibrils. At the end of the extraction sequence, fibres still had mechanical performances close to those of regenerated cellulose ones and exhibited a typical non-linear mechanical behaviour. Thus, it was hypothesized that microfibril reorientation phenomena can still occur after a NaOH extraction when fibres are mostly composed of cellulose.

International audience; Ultrasound-assisted synthesis of diglycidyl ethers of isosorbide (DGEI) with different epoxy equivalent weight (EEW) with isophorone diamine (IPD) hardener have been performed. Interestingly, it was found that one specific epoxy formulation exhibits high reactivity with amine hardener inducing high glass transition and indentation stiffness. Associated with flax fibres, this new bio-based resin has made it possible to develop performing and promising unidirectional biocomposites with characteristics comparable to commercial petroleum-based epoxy resins.

International audience; The purpose of the present article is to evaluate the real fibre surface involved in the practical adhesion of a flax/epoxy system. The difference in practical adhesion evaluated by microbond tests between Hermes (τapp = 22.5 ± 1.5 MPa) and Electra (τapp = 13.2 ± 3.2 MPa) flax fibres varieties/epoxy systems could not be explained by their superficial surface chemistry evaluated by XPS. FTIR spectroscopy highlights a difference in biochemical composition and Laser Confocal microscopy evidences a resin penetration for the two flax fibres systems (1.7 ± 0.7 μm for Hermes and 2.2 ± 0.8 μm for Electra). Thus the effective surface or complex interphase will be by consequence the overall area where the resin and fibre are in contact, i.e. the entire area penetrated by resin.