Increase In Concentration Of Cellulose Research Articles

Development of superhydrophobic hybrid silica-cellulose aerogel as promising thermal insulation and sound absorption

AbstractA cost-effective and facile synthesis method is developed for hybrid aerogels using recycled cellulose fiber concentration of 1–4 wt.% and methoxytrimethylsilane (MTMS). The developed hybrid aerogel was modified with surface hydroxyl groups to achieve superhydrophobic behavior with a contact angle as high as 163.4°. This excellent three-dimensional reticular structure with various cellulose concentrations provides a thermal conductivity of 0.039–0.041 W m−1 K−1. However, the thermal degradation of the hybrid aerogels exhibits a superior improvement with minimum weight loss. A comparatively good sound absorption coefficient of 0.392–0.504 was achieved with the inclusion of cellulose fiber concentration from 1 to 4 wt.% in comparison with silica aerogels (0.303–0.512). The experimental results also show an increase in compressive Young’s modulus of hybrid aerogels up to 96%, with an increase in cellulose concentration. This work delivers a facile approach to developing hybrid aerogels with an industrial application to replace polymer-based insulations.

Improving the Tribological Performance of MAO Coatings by Using a Stable Sol Electrolyte Mixed with Cellulose Additive.

In this study, micro-arc oxidation (MAO) of aluminum 6061 alloy was carried out within a silicate base electrolyte containing 0.75 g/L of cellulose, and the tribological properties of the coating were investigated. The as-prepared coating was detected by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), a scanning electron microscope (SEM) and an energy-dispersive spectrometer (EDS), respectively. The results suggested that cellulose filled in the microcracks and micropores, or it existed by cross-linking with Al3+. In addition, it was found that the cellulose had little effect on the coating hardness. However, the thickness and roughness of the coating were improved with the increase in cellulose concentration. Moreover, the ball-on-disk test showed that the friction coefficient, weight loss and wear rate of the MAO coating decreased with the increase in cellulose concentration. Further, the performances of the coatings obtained in the same electrolyte, under different preserved storage periods, were compared, revealing that the cellulose was uniformly dispersed in the electrolyte and improved the tribological properties of the MAO coating within 30 days.

Phase transition and dielectric relaxation of a mixed ferroelectric composite from cellulose nanoparticles and triglycine sulfate

The work is devoted to the study on electrophysical properties of a novel ferroelectric composite consisting of triglycine sulfate (TGS) and cellulose nanoparticles at different composition weight ratios from 25 to 120 °C under a weak electric field at frequencies of 102–106 Hz. The obtained results indicated that an increase in cellulose concentration in the composite led to increasing the phase transition temperature by three to a few tens of degrees Celsius higher than those for single crystal TGS (+49 °C) and led to decreasing characteristic relaxation frequency of TGS inclusion in the studied frequency range.

Preparation and dielectric properties of a mixed ferroelectric composite from nanoparticles of cellulose and triglycine sulfate

In this study, a novel ferroelectric composite consisting of triglycine sulfate (TGS) and cellulose nanoparticles (NCCP) prepared from waste cotton was synthesized and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Zetasizer analyzer. The study on electrophysical properties of the composite were performed from 25 to 120 ˚C under a weak electric field with an amplitude of 1 V/cm at low and infra-low frequencies (10−3 to 103 Hz) with different weight composition ratios. The obtained results indicated that the increase in cellulose concentration in the composite led to increasing the phase transition temperature in TGS component by 3 to 63 °C higher than those for single crystal TGS (+49 °C). The corresponding increase of the Curie temperature in composites was presumably connected with the strong interaction between TGS and cellulose nanoparticles through the system of hydrogen bonds. In the temperature range 100–115 °C, where the structural changes in pure triglycine sulfate were recorded earlier in the case of high-temperature annealing, a characteristic growth of the dielectric permittivity was also observed. The study on low and infra-low dispersion of dielectric permittivity was carried out and explained by Maxwell-Wagner-Sillars interfacial mechanism.

Microstructures of cellulose coagulated in water and alcohols from 1-ethyl-3-methylimidazolium acetate: contrasting coagulation mechanisms

Coagulation of cellulose solutions is a process whereby many useful materials with variable microstructures and properties can be produced. This study investigates the complexity of the phase separation that generates the structural heterogeneity of such materials. The ionic liquid, 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25 wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water → 2PrOH → butanone → cyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep electron microscopy images of 50 k magnification reveal open-pore fibrillar structures. The crystalline constituents of those fibrils are estimated using wide-angle X-ray spectroscopy and specific surface area data. It is found that the crystalline order or crystallite size is reduced by an increase in cellulose concentration, by the use of the co-solvent DMSO, or by the use of 2PrOH instead of water as the coagulant. Because previous theories cannot explain these trends, an alternative explanation is presented here focused on solid–liquid versus liquid–liquid phase separations.Graphical abstract

Effect of film constituents and different processing conditions on the properties of starch based thermoplastic films

The main aim of this study is to examine the different film preparation methods (Hot air oven method, Microwave oven method, and UV irradiation method) for development of Bio-thermoplastic films from agro waste polysaccharides. The rheological properties were also studied for different combinations of tamarind seed starch (T), okra mucilage polysaccharide (OK), Residual rice bran starch (R) and sugarcane bagasse cellulose (C). Increase in concentration of okra mucilage polysaccharide and sugarcane bagasse cellulose found to highly influence the rheological viscous properties of tamarind starch solution. Increase in concentration of okra mucilage (above 1.5%) in tamarind film matrix solution significantly increased the elongation properties of starch films. Increase in concentration of cellulose (above 1%) in tamarind film matrix solution significantly increased the tensile strength of starch films. The microwave oven method was found to be the quickest method (~10 to 20 min) for biopolymer film preparation. SEM and AFM analysis revealed that UV – irradiation method produces stable bio-thermoplastic films with low surface roughness and high barrier properties. The interaction of starch molecules with other natural polysaccharide produces stable thermoplastic biopolymer films, that can be developed under different processing conditions to eradicate environmental pollution caused by petrochemical plastics.

Thermal assisted alkaline pretreatment of rice husk for enhanced biomass deconstruction and enzymatic saccharification: Physico-chemical and structural characterization

Thermal assisted alkaline pretreatment (TAAP) of rice husk (RH) was investigated to facilitate enzymatic saccharification by enhancing the enzyme accessibility to cellulosic components. Statistically guided experiments based on the Box-Behnken design involving four factors viz. biomass loading, particle size, NaOH loading and reaction time was considered for optimization. The maximum sugar yield of 371 mg g−1 biomass was obtained at optimized pretreatment condition [biomass loading (10% w/w), particle size (0.25–0.625 mm), NaOH loading (2% w/w), and reaction time (40 min)]. The TAAP of RH resulted in the efficient removal of lignin (14.9–54% (w/w)) with low hemicellulose solubilization [10.7–33.1% (w/w)] and with a simultaneous increase in cellulose concentration [32.65–51.65% (w/w)]. The SEM analysis indicated increased porosity and biomass disruption during TAAP. The FTIR analysis showed progressive removal of noncellulosic constituents, and XRD analysis revealed an increase in cellulose crystallinity post-TAAP indicating the effectiveness of pretreatment.

Effect of Punica granatum peel extracts on antimicrobial properties in Walnut shell cellulose reinforced Bio-thermoplastic starch films from cashew nut shells

The main aim of the present study is to extract and characterize cashew nut shell (CNS) starch and walnut shell cellulose (WNC) for development of cellulose reinforced starch films. Moreover, the extraction and characterization of pomegranate peel extract, for incorporation with CNS-WNC films, was investigated. CNS starch was examined to be a moderate amylose starch with 26.32 ± 0.43% amylose content. Thermal degradation temperature of CNS starch was found to be 310 °C. Walnut shell cellulose was found to have high crystallinity index of 72%, with two thermal degradation temperatures of 319 °C and 461 °C. 2% WN cellulose reinforced CNS starch films were examined to have good oxygen transfer rate, mechanical and physical properties. Thermal degradation temperature of CNS-WNC starch films were found to be at the range of 298–302 °C. Surface roughness of CNS-WNC starch films were found to be increasing with increase in concentration of cellulose in films. Hydroxymethylfurfurole, Benzene, 2-methoxy-1,3,4-trimethyl and 1,2,3-Propanetriol, 1-acetate were found to be major active compounds present in hydrophilic extracts of Punica granatum peels. 2% WN cellulose reinforced starch films infused with hydrophilic active compounds of pomegranate peel was examined to be having good active package properties.

Polypropylene/chemically treated coir composites: optimizing coir delignification conditions using central composite design

The effect of alkaline treatment of coir on polypropylene/coir composite properties was investigated, using a two-factor central composite design where NaOH concentration and reaction time were varied. Alkaline treatment favored delignification, and at certain conditions, increased composite stiffness without loss in tensile strength. Increase in cellulose concentration likely increases the number of free hydroxyls, which is less favorable to composite mechanical properties. Treatments with 2 and 9% NaOH for 5 h resulted in cellulose concentration of about 50 and 70%, respectively. Treatments with high concentrations and for long periods are disadvantageous to composite properties, resulting in lower tensile strength likely due to the increased number of free hydroxyls as well as to possible breaks in cellulose structure. A desirability function, used to optimize the delignification process, revealed the highest tensile modulus and strength (3.5 GPa and 31 MPa, respectively) could be obtained at 5.75% NaOH and reaction time of 3 h.

Influence of temperature on the solution rheology of cellulose in 1-ethyl-3-methylimidazolium chloride/dimethyl sulfoxide

Rheological properties of cellulose solutions in 1-ethyl-3-methylimidazolium chloride/dimethyl sulfoxide ([Emim]Cl/DMSO, 7/3, w/w) in a wide range of concentration and temperature were investigated. The viscosity of cellulose/[Emim]Cl/DMSO solution agrees well with the complex viscosity suggesting Cox-Merz law is valid for the solution. The viscosity contributed by cellulose (eta (0)-eta (s) ) and cellulose concentration (c) scales as (eta (0)-eta (s) )similar to c (n) with n in the range of 2.00-1.57 and 4.52-3.79 in semidilute unentangled and semidilute entangled regimes, respectively, in the temperature of 25-100 A degrees C. Intrinsic viscosity of the solutions remains constant at temperature below 60 A degrees C and decreases linearly with the increase of temperature above 60 A degrees C. The activation energy of cellulose/[Emim]Cl/DMSO solution increases with the increase in cellulose concentration. The chain dynamics of cellulose in [Emim]Cl/DMSO follows Zimm model and Rouse model in dilute regime (lower than 0.5 wt%) and semidilute unentangled regime (between 0.5 and 2 wt%), respectively.

Dissolving and Rheological Behavior of Lignocellulose in the NaOH/Thiourea/Urea Solvent System

As one of the most abundant renewable resources and natural polymer materials, cellulose increasing peoples attention in many fields. In this paper we was firstly focus on the solubility of the wooden cellulose and cotton cellulose in NaOH/Thiourea/Urea solution, the result showed that the solubility decreased with the increase in concentration of cellulose. Then the morphology test by a polarizing microscope and the rheological properties was tested by a viscometer, both of the two different cellulose solution present the shear thinning property. Finally the experiment achieved a comparison of the solubility of two different celluloses, and the cotton cellulose presents a better solubility in this NaOH/Thiourea/Urea system.

Cellulose synthesis in maize: isolation and expression analysis of the cellulose synthase (CesA) gene family

Stalk lodging in maize results in significant yield losses. We have determined that cellulose per unit length of the stalk is the primary determinant of internodal strength. An increase in cellulose concentration in the wall might allow simultaneous improvements in stalk strength and harvest index. Cellulose formation in plants can be perturbed by mutations in the genes involved in cellulose synthesis, post-synthetic cellulose alteration or deposition, N-glycosylation, and some other genes with as yet unknown functions. We have isolated 12 members of the cellulose synthase (CesA) gene family from maize. The genes involved in primary wall formation appear to have duplicated relatively independently in dicots and monocots. The deduced amino acid sequences of three of the maize genes, ZmCesA10–12, cluster with the Arabidopsis CesA sequences that have been shown to be involved in secondary wall formation. Based on their expression patterns across multiple tissues, these three genes appear to be coordinately expressed. The remaining genes show overlapping expression to varying degrees with ZmCesA1, 7, and 8 forming one group, ZmCesA3 and 5 a second group, and ZmCesA2 and 6 exhibiting independent expression of any other gene. This suggests that the varying levels of coexpression may just be incidental except in the case of ZmCesA10–12, which may interact with each other to form a functional enzyme complex. Isolation of the expressed CesA genes from maize and their association with primary or secondary wall formation has made it possible to test their respective roles in cellulose synthesis through mutational genetics or transgenic approaches. This information would be useful in improving stalk strength.