69 research outputs found
Laccase-assisted approach to graft multifunctional materials of interest: keratin-EC based novel composites and their characterisation
This study focuses on the evaluation of raw keratin as a potential material to develop composites with novel characteristics. Herein, we report a mild and eco-friendly fabrication of in-house extracted feather keratin-based novel enzyme assisted composites consisting of ethyl cellulose (EC) as a backbone material. A range of composites between keratin and EC using different keratin: EC ratios were prepared and characterised. Comparing keratin to the composites, the FT-IR peak at 1,630 cm-1 shifted to a lower wavenumber of 1,610 cm-1 in keratin-EC which typically indicates the involvement of ÎČ-sheet structures of the keratin during the graft formation process. SEM analysis revealed that the uniform dispersion of the keratin increases the area of keratin-EC contact which further contributes to the efficient functionality of the resulting composites. In comparison to the pristine keratin and EC, a clear shift in the XRD peaks was also observed at the specific region of 2-Theta values of keratin-g-EC. The thermo- mechanical properties of the composites reached their highest levels in comparison to the keratin which was too fragile to be measured for its mechanical properties. Considerable improvement in the water contact angle and surface tension properties was also recorded
Les urgences médicales au cabinet dentaire
BORDEAUX2-BU Sci.Homme/Odontol. (330632102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
Different compatibility approaches to improve the thermal and mechanical properties of EVA/starch composites
Biocompostable composites based of ethyleneâcoâvinyl acetate (EVA) copolymer were prepared by using a twinâscrew extruder. The compatibility between EVA/starch composites were improved either by addition of polyethyleneâgrafted maleic anhydride (PEâgâMA), or by reactive extrusion with maleic anhydride (MA) and benzoyl peroxide. The crystallinity of the nonâcompatibilized composites increased with the starch content. The addition of PEâgâMA increased the crystallinity of the composites made with up to 20 wt% of starch. The thermal stability of EVA/starch composites decreased with increasing the starch content, and the addition of PEâgâMA compatibilizer enhanced the thermal stability of the composite. The inâsitu grafting with MA and PBO led to an increase in the thermal stability of the composites containing higher amounts of starch. Further, the mechanical properties of the compatibilized EVA/starch composites were improved with increasing the starch content and this was ascribed to the improved interfacial interactions between starch and EVA
Valorisation des dĂ©chets ligno-cellulosiques pour la prĂ©paration dâun nouveau matĂ©riau composite PVC/farine des noyaux de dattes
Afin de limiter lâutilisation des Ă©nergies fossiles et de valoriser les dĂ©chets ligno-cellulosiques, les composites Ă fibres naturelles sâinscrivent dans un contexte favorable qui permettra de rĂ©pondre Ă des enjeux environnementaux, Ă©conomiques et sociaux grĂące Ă leurs propriĂ©tĂ©s de faible coĂ»t, faible densitĂ©, renouvelables et de biodĂ©gradabilitĂ©. Lâobjectif de cette Ă©tude est de dĂ©velopper un nouveau matĂ©riau composite constituĂ© dâune matrice thermoplastique, le polychlorure de vinyle (PVC), renforcĂ©e par des fibres naturelles Ă base des noyaux de dattes (FND) avec des taux de charge allant de 10 Ă 40â% massique. DiffĂ©rentes techniques dâanalyses ont Ă©tĂ© utilisĂ©es pour Ă©tudier les propriĂ©tĂ©s mĂ©caniques, morphologiques et la permĂ©abilitĂ© dâeau des Ă©chantillons obtenus. Les rĂ©sultats enregistrĂ©s indiquent que la contrainte Ă la rupture diminue avec lâaugmentation du taux de charge en FND tandis que la rigiditĂ© augmente. Lâanalyse morphologique par microscopie Ă©lectronique Ă balayage (MEB) montre une meilleure dispersion pour de faible taux de charge en FND. Une trĂšs faible absorption dâeau a Ă©tĂ© enregistrĂ©e
Chemical modification of olive pomace by various esters and silane
International audienceThe olive pomace was modified chemically to improve the interface between the polymer matrix and the cellulosic fillers. The modification was done using various ester types having the same nature, however, with different chain lengths and one silane. Before the surface treatment, the olive pomace was extracted with acetone to remove contaminants on the surface, using Soxhlet apparatus. The transesterification of olive pomace with the different ester components, i.e., vinyl acetate, vinyl propanoate, and vinyl butanoate, and the condensation reaction with dichlorodimethylsilane was confirmed by Fourier transform infrared (FTIR) analysis. Moreover, the treatment of olive pomace with vinyl acetate improves the thermal stability and the sample records higher onset temperature of degradation as measured by thermogravimetric analysis (TGA). The results obtained indicated also that the reaction between the hydroxyl groups of waste flour and the acetyl, propionyl, pivalyl, and silane groups have occurred. The modified wood flours exhibited a decrease in the hydrophilicity as supported by the lower moisture content
Effect of compatibilizing agents on the mechanical properties of high-density polyethylene/olive husk flour composites
International audienceThe main objective of this research was to investigate the effect on the thermal and mechanical properties of the addition of two different compatibilizing agents, malefic anhydride-grafted polyethylene (PE) [synthesized in a solution state (MAPE) and commercial (XA255)], to olive husk flour, high-density polyethylene (HDPE) composites. The composites contain 30 wt % of olive husk flour and a variable proportion of compatibilizer (3, 5, and 7 wt %). The grafting reaction was followed by Fourier transform infrared, and the grafting degree was evaluated by means of titration. The effect of grafting on the thermal properties of MAPE was observed by ATG/DTG. The mechanical and thermal properties of the composite were investigated. A morphological study of the composite reveals that there is a positive effect of compatibilizing agent on interfacial bonding
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