Volume 11 Issue 3

Lignosulfonate and lignosulfonate hydrolyzed under alkaline conditions were used as the polyol components in polyurethane foam formulations. Although the treatment increased hydroxyl group abundance, it did not improve the applicability of hydrolyzed lignosulfonate in polyurethane foam. Thus, the use of original lignosulfonate yielded foams of thermal stability and mechanical properties comparable to other types of bio-based foams (Young’s moduli 0.95 to 4.42 MPa, 50% weight loss, and temperature ca. 500 °C). Lignosulfonates can be a renewable polyol component for the formulation of rigid, semi-rigid, and flexible foams.

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) was subjected to chemical extraction treatments with sodium chlorite (NaClO2) for delignification, as well as sodium hydroxide (NaOH) at various concentrations for extracting hemicelluloses gradually. Nanoindentation tests, X-Ray diffraction (XRD, and Fourier transform Raman (FT-Raman) spectroscopy studies revealed the changes in the mechanical properties and the nanostructure of the cell wall. The X-ray analysis indicated that delignification had only a moderate effect on the structure of the cell wall, while further alkali treatment led to major changes in the nanostructure. The nanoindentation tests showed that the indentation modulus and the hardness decreased after delignification and further alkali treatment, respectively. The indentation modulus of the cell wall with delignification decreased by 6.4% compared with the native cell wall, and the hardness decreased by 16.3%. After further alkali treatment, the indentation modulus and the hardness of the cell walls were 14.8% and 18.4% lower than that of the native cell walls, respectively. Additionally, the indentation modulus and the hardness of Chinese fir treated by NaOH decreased by 8.4%, and 2.1% in comparison with delignification, respectively. The results indicated that removal of hemicelluloses resulted in more damage to the mechanical properties of the cell wall compared with lignin.

The preparation and functionalization of cellulose microgels (CMGs) has been presented. Only a trace concentration of CMGs (< 0.2 wt.%) stabilized oil-in-water (O/W) emulsions and produced high internal phase emulsions (HIPE). The size and morphology of the CMGs were characterized with dynamic light scattering (DLS) and atomic force microscopy (AFM), and the structural properties were discussed. Based on the experimental results,the correlation between the amphiphilicity, and adsorption of the CMGs, and their capability to stabilize the emulsions, which are closely related to the cross-linking density of the CMGs, were elaborated. Having a porous percolating structure and being rich in free hydroxyl groups, the CMGs were functionalized by Fe3O4. The unique dispersibility of the Fe3O4-CMGs and their ability to stabilize the emulsions were investigated in detail. The results pave the way to a deeper understanding of Pickering emulsions stabilized by soft solvent-swollen materials and are expected to further expand the application of cellulose.

Sustainability and eco-efficiency are presently directing the development of the next generation of acoustic materials. In this work, foamed cellulose-polymer microsphere (PM) hybrid materials, having sound-absorbing capability, were prepared by incorporating the PMs into cellulose fibers by dehydration and foaming processes. The evolution in morphology of PMs during foaming process was investigated for different heating temperatures. The beating process disintegrated the microscopic cellulose fiber into the smaller fibers, which connected the PMs by a unique fibrous network. The influences of foaming temperature, PM content, and total areal density on the sound absorbing property of composites were studied. The results showed that incorporating the acoustic unit of elastic PMs into the porous cellulose fiber-based network significantly improved the sound absorbing ability of the composites. The sound-absorbing hybrid materials appear to be a promising alternative to non-degradable organic or inorganic acoustic composites, being economical, simple, and eco-friendly.

Fly ash-based calcium silicate (FACS), which has a large surface area (121 m2/g) and porous structure, has the potential to be used as a filler for the production of high-bulk paper. In theory, paper with a higher bulk has a lower strength. This work explores the possibility of improving paper strength without compromising its bulk through co-flocculation of cellulosic fines and FACS. To investigate the effect of co-flocculation on paper properties, composites made with various ratios of fines to FACS were studied. Results showed that paper bulk and tensile strength increased with increasing ratio of fines to FACS, up to 0.3 at 17% filler content. To further confirm these findings, the structures of composites were studied with a light microscope and scanning electronic microscope (SEM). Images showed that the composite formed at the ratio of 0.3 exhibited a larger size and looser structure than other composites, which can be attributed to the improvement of the paper’s strength and bulk. Schemes for the composite formation process and its interactions with fibers were also proposed.

A hydrogen peroxide (H2O2) solution was adapted for microwave pretreatment of microcrystalline cellulose, which can be further used for heavy metal adsorption. The H2O2 concentration, temperature, and retention time were the key factors affecting the microwave/hydrogen peroxide pretreatment process. A Box-Benhken design (BBD) with response surface methodology (RSM) was employed to design and optimize the microwave-hydrogen peroxide pretreatment process (H2O2 pretreatment) of cellulose. After the H2O2 pretreatment, the crystallinity of cellulose decreased by 20% and the degree of polymerization (DP) decreased by up to 30%. The optimal conditions obtained by BBD were a H2O2 concentration of 8.37%, a temperature of 90 °C, and a retention time 5.33 min. Under these conditions, a minimum DP of 91.74 was achieved. The results indicated that all three of the factors notably affected the reduction of cellulose polymerization degree and pronounced interactions existed among the response variables. The predictive model developed was able to optimize the pretreatment process for the reduction of cellulose polymerization degree, which could improve the cellulose modification reactivity.

A methodology is presented for the determination of elastic material properties on laminated and non-laminated decorative veneers of a variety of wood types. For the uniaxial tensile tests performed, at various temperatures and wood moisture values, the metrological challenges as well as the test results are described and discussed. Subsequently, the characteristic values are transferred into corresponding material models. Also, as the inverse, model-based determination of characteristic values that cannot be determined experimentally is carried out.

The price of raw material, energy demand in the pretreatment step, and enzyme usage rate are the major cost factors in the process of converting biomass to bioethanol. Unwashed furfural residues (FRs) possess great potential for application in bioethanol production. Surfactant addition is an effective method to enhance the fermentation rate. In this study, unwashed FRs were used directly as raw materials to produce bioethanol. Tea-seed cake (TSC), tea seed residues that contained protein and saponin, was added in the simultaneous saccharification and fermentation (SSF) process. The effect of TSC dosage on SSF was compared. TSC was added at the dosage of 10 g/L, which resulted in a final ethanol yield of 87.2%. However, a high concentration of TSC could induce cytotoxicity in yeast. The surface tension (approximately 33.92 mM/m) at SSF using TSC-medium was much lower than that of other fermentation systems (about 64.67 mN/m). Further contact angle testing showed that TSC-medium (21.7°) had better wetting capacity than FRs (45.6°). This study provided a proposed process strategy that SSF with the addition of TSC could be a minimum consumption of chemicals and enzymes for future cellulosic ethanol production process.

This paper presents a kinetic model of the laccase-aided chlorine dioxide bleaching of bagasse pulp. The kinetic model was based on the rate of reduction of adsorbed organic halogen (AOX). The effects of the laccase enzyme dosage, the mediator 1-hydroxybenzotriazole (HBT) dosage, and the reaction temperature on the AOX content of the bleaching effluent are discussed. Good fits were obtained for the experimental data obtained from the different laccase enzyme dosages, HBT dosages, and reaction temperatures, indicating the feasibility of the kinetic model as a means of predicting the optimal operation conditions for the laccase-aided chlorine dioxide bleaching of bagasse pulp in the future.

Hazelnut husk was considered as a potential filler for thermoplastic composites. Different amounts of hazelnut husk flour and the recycled high-density polyethylene (R-HDPE) were used as the filler and polymer matrix, respectively. The composite compounds were produced using single-screw extrusion compounding, and then composite panels were prepared by hot-press compression molding. The morphological, physical, mechanical, and thermal properties, as well as the biological durability of the composites, were evaluated. The flexural and tensile modulus of the composites improved with increasing hazelnut husk filler content, whereas the physical properties, biological durability, and the flexural and tensile strengths were reduced. With the addition of a maleic anhydrite-grafted polyethylene (MAPE), the hazelnut husk filler was more finely dispersed within the polymer matrix and the degree of crystallinity was lower than that of the R-HDPE. This research revealed that hazelnut husk flour has potential for use as a filler in R-HDPE composites.