We have developed a novel process to convert low molecular weight microcrystalline cellulose into stiff regenerated cellulose fibers using a dry-jet wet fiber spinning process. Highly aligned cellulose fibers were spun from optically anisotropic microcrystalline cellulose/1-ethyl-3-methylimidazolium diethyl phosphate (EMImDEP) solutions. As the cellulose concentration increased from 7.6 to 12.4 wt %, the solution texture changed from completely isotropic to weakly nematic. Higher concentration solutions (>15 wt %) showed strongly optically anisotropic patterns, with clearing temperatures ranging from 80 to 90 °C. Cellulose fibers were spun from 12.4, 15.2, and 18.0 wt % cellulose solutions. The physical properties of these fibers were studied by scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD), and tensile testing. The 18.0 wt % cellulose fibers, with an average diameter of ∼20 μm, possessed a high Young's modulus up to ∼22 GPa, moderately high tensile strength of ∼305 MPa, as well as high alignment of cellulose chains along the fiber axis confirmed by X-ray diffraction. This process presents a new route to convert microcrystalline cellulose, which is usually used for low mechanical performance applications (matrix for pharmaceutical tablets and food ingredients, etc.) into stiff fibers which can potentially be used for high-performance composite materials.

This study is focused on recycling potential of some waste materials, such as olive pits, i.e. the solid phase derived from an olive oil mill, blended with thermoplastic polymers and used for the production of new materials applied in manufacturing containers and formworks. The olive pit powders are described and characterized. Then the powder is introduced in a bio-based and biodegradable matrix (polylactic acid, PLA) at various percentages. In this study, a comparison of the size distribution and the densities of olive pit powders according to the grinding methods (planetary mill and centrifugal mill) was made. The analyses showed that olive pits can be further studied as additive for the production of green materials. The development of an agricultural based polymer matrix compatible with olive pits and consequently a fully biodegradable composite system is the future and ultimate goal of the research undertaken. For that purpose, composite samples made out of PLA matrix, reinforced with olive pit powders were manufactured and mechanically characterized. With filler loading, an increase in the tensile modulus but a decrease of the flexural strength may be due to the poor interfacial bonding between olive pit powder and PLA.

We report a method to extract lignin from willow, using triethyl ammonium hydrogen sulphate [Et3NH][HSO4. This method is used to manufacture fibers with a range of compositions.. This extraction achieved an 18% yield of lignin as characterized by ATR-IR and elemental analysis indicated a high carbon yield. 1-Ethyl-3-methylimidazolium acetate [C2C1im][OAc] was then used as a solvent to manufacture lignin-cellulose fiber blends. The Young's modulus of a 75:25 lignin:cellulose fiber was found to be 3.0 ±0.5 GPa which increased to 5.9 ±0.6 GPa for a 25:75 lignin:cellulose blend. From a characterization of the surface morphology using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) it was observed that a rich lignin content in the fiber blend increased the surface roughness. FT-IR analysis confirmed the presence of aromatic groups of lignin from the presence of peaks located at ~1505 cm -1 and ~1607 cm -1 . The presence of lignin improves the thermal stability of the fiber blends by allowing them degrade over a wider temperature range. This is potentially useful for the utilisation of renewable lignocellulosic biomass derived fibers as carbon fiber precursors. Although the mechanical properties of the regenerated fibers were diminished by the addition of lignin, the blends prepared produced a solution suitablefor a stable fiber spinning process.

This study is focused on the investigation of the effect of thermal shock cycling on the mechanical properties of cellulose based reinforced polymer composites. Polymer composites reinforced with olive pits powder at different filler-volume fractions were manufactured. An increase in the bending modulus on the order of 48% was achieved. On the other hand, results showed that the bending strength remained almost unaffected from the amount of filler introduced. Next, the effect of thermal shock cycling on the mechanical behaviour of the thus manufactured composites was investigated. Theoretical predictions for both the properties variation with number of thermal shock cycles applied as well as with filler-volume fraction were derived using the residual properties model (RPM) and the modulus predictive model (MPM), respectively. Predicted values were compared with respective experimental results. In all cases, a fair agreement between experimental findings and theoretical predictions was found. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: [67][68][69][70][71][72][73][74][75][76] 2012