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Sisal nanowhiskers were used as novel reinforcement to obtain nanocomposites with polyvinyl acetate (PVAc) as matrix phase. They are seen as attractive materials due to the widespread availability and low cost of the sisal source material. Statistical analysis of the sisal whisker length and diameter resulted in average values of 250 nm and 4 nm, respectively, resulting in an average aspect ratio...
Nanocomposites were produced with NaOH aqueous solution-treated microfibrillated cellulose (MFC) and phenolic resin, and the mechanical properties were compared with their microcomposite counterparts based on pulp fiber. Tensile tests showed that strong alkali-treated MFC nanocomposites with resin content around 20 wt.% achieved strain at fracture values two times higher than those of untreated MFC...
A new method to obtain composites of phenolic resin reinforced with microfibrillated cellulose with a wide fiber content was established and the mechanical properties were evaluated by tensile test. A linear increase in Young’s modulus was observed at fiber contents up to 40 wt%, with a stabilizing tendency for higher fiber percentages. These results were ratified by measurements of the coefficient...
Utilization of TEMPO-oxidized celluloses in bio-based nanocomposites is reported for the first time. TEMPO-oxidized wood pulps (net carboxylate content 1.1 mmol/g cellulose) were fibrillated to varying degrees using a high intensity ultrasonic processor. The degree of fibrillation was controlled by varying sonication time from 1 to 20 min. The sonication products were then characterized independently...
The mechanical properties, morphologies, and gas barriers of hybrid films of cellulose with two different organoclays are compared. Dodecyltriphenyl-phosphonium-mica (C12PPh-mica) and hexadecyl-mica (C16-mica) were used as reinforcing fillers in the fabrication of the cellulose hybrid films. The cellulose hybrid films were synthesized from N-methyl-morpholine-N-oxide (NMMO) solutions with the two...
The chemical composition and morphology of Syngonanthus nitens (Capim Dourado) fibers were investigated. An unusual low lignin content and high holocellulose content have been observed. High aspect ratio cellulose whiskers were prepared from these lignocellulosic fibers by an acid hydrolysis treatment. The average diameter and length were 4.5 nm and 300 nm, respectively, giving rise to an aspect ratio...
Due to their abundance, high strength and stiffness, low weight and biodegradability, nano-scale cellulose fiber materials (e.g., microfibrillated cellulose and bacterial cellulose) serve as promising candidates for bio-nanocomposite production. Such new high-value materials are the subject of continuing research and are commercially interesting in terms of new products from the pulp and paper industry...
Bionanocomposites of hydroxypropyl cellulose (HPC) and nanofibrillated cellulose (NFC) were prepared by solution casting. The various NFC were in form of powders and were prepared from refined, bleached beech pulp (RBP) by mechanical disintegration, optionally combined with a pre- or post mechanical carboxymethylation. Dynamic mechanical analysis (DMA) and tensile tests were performed to compare the...
Polylactic acid (PLA) in a crystallized state has mechanical properties at high temperatures superior to PLA in an amorphous state. However, a long annealing time is required to fully crystallize PLA. In this study, microfibrillated cellulose (MFC)-reinforced partially crystallized PLA composites were produced, with the goal of reducing the time required to fabricate PLA parts. A series of PLA/MFC...
Synthesis of Ag nanopaticles was carried out with carboxylated cellulose nanocrystals as the scaffolds by reducing metallic cations using NaBH4. Ag particles with a size less than 10 nm were readily prepared and dispersed well. The carboxyl and hydroxyl groups of carboxylated cellulose nanocrystals supplied a coordination effect to adsorb metallic cations and Ag nanoparticles, which prevent the aggregation...
In a previous work (Siqueira et al. 2010b) the preparation of cellulosic nanoparticles from sisal fibers using different processing routes, viz. a combination of mechanical shearing, acid and enzymatic hydrolysis was reported. It was shown that the pre-enzymatic hydrolysis treatment of bleached sisal pulp helps the preparation of well individualized rod-like nanocrystals. An amorphous polymer (natural...
Cellulose-synthetic polymer nanocomposite films were prepared by immersion of cellulose gel in polymer solutions followed by dry casting. The cellulose hydrogel was prepared from aqueous alkali-urea solution. As the synthetic polymer, polystyrene (PS) and poly(methyl methacrylate) (PMMA) were used. The polymer content could be changed between 10 and 80% by changing polymer concentration of immersing...
This study evaluates the effects of nucleants phenylphosphonic acid zinc (PPA-Zn) and talc, mold temperature, and microfibrillated cellulose (MFC) reinforcement in the acceleration of injection molding cycle of polylactic acid (PLA). PLA was dissolved in an organic solvent, mixed with nucleant and MFC, and dried compounds were injection molded into molds at temperatures ranging from 40 °C to 95 °C...
A series of resole-type phenolic resin-based nanocomposites, uniformly filled with cellulose nanowhiskers (CNWs), was successfully fabricated via direct solution mixing, then solvent-exchange with DMF and finally stepwise thermal curing. Dynamic mechanical analysis evidenced a moderate reinforcing effect with a minimum CNWs weight content of 5.0 wt% especially above the resin glass transition temperature...
The microstructure and chemical composition of alfa (Stipa tenacissima) were investigated. The polysaccharide and lignin contents were around 70 and 20 wt%, respectively. From the bleached and delignified fibers, two types of nanosized cellulosic particles were extracted, namely cellulose nanocrystals and microfibrillated cellulose (MFC). The former correspond typically to the elementary crystallite...
Nanofibrillated cellulose offers new technological solutions for the development of paper products. Here, composites of nanofibrillated cellulose (NFC) and Ag nanoparticles (NP) were prepared for the first time via the electrostatic assembly of Ag NP (aqueous colloids) onto NFC. Distinct polyelectrolytes have been investigated as macromolecular linkers in order to evaluate their effects on the building-up...
Polyvinyl alcohol (PVOH) and its nanofibrillated cellulose (NFC) reinforced nanocomposites were produced and foamed and its properties—such as the dynamic mechanical properties, crystallization behavior, and solubility of carbon dioxide (CO2)—were evaluated. PVOH was mixed with an NFC fiber suspension in water followed by casting. Transmission electron microscopy (TEM) images, as well as the optical...
This study reports the use of solid state ball milling (SSBM) for dispersing cellulose nanowhiskers (CNWs) in starch-based thermoplastics. Prior to conventional drying, interwhiskers agglomeration was minimized by coating the CNWs with pectin, a vegetable hydrocolloid polysaccharide. SSBM and melt-processing were employed to prepare the nanocomposites. A strong correlation between mechanical reinforcement...
Cellulose nanowhiskers (CNWs) were chemically modified by acetylating to obtain acetylated cellulose nanowhiskers (ACNWs) which could be well dispersed in acetone. The chemical modification was limited only on the surface of CNWs which was confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Surface substitution degree of ACNWs was evaluated to be 0.45 through X-ray photoelectron...
Thin nanocomposite films of thermoplastic starch, chitosan and cellulose nanofibers (bacterial cellulose or nanofibrillated cellulose) were prepared for the first time by solvent casting of water based suspensions of the three polysaccharides. The role of the different bioploymers on the final properties (thermal stability, transparency, mechanical performance and antimicrobial activity) of the films...
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