Volume 10 Issue 3

Promising controlled release systems were prepared from renewable natural products. Paper, used as the system core, was made with commercial kraft pulp and with bleached lignocellulosic pulps extracted from local plants. The characteristics of those pulps (fines content and fiber length) as well as paper thickness, porosity, and roughness, were evaluated. Alginate served as the protective membrane. The releasability of Diclofenac as a function of time and pH was studied under constant temperature (37 °C) and constant stirring (200 rpm). Also the influence of the type of paper and the calcium alginate concentration in the protective layer were highlighted. The extent of release reached 80% in a basic medium in a variable time interval 7 to 16 h, whereas in an acid medium it did not exceed 24% in 33 h. Diffusion, Fickian diffusion, and diffusion-erosion were judged to be important contributing mechanisms based on the Korsmeyer-Peppas kinetic model for those various matrixes. Different formulations were found to have significant controlled release properties that could be used in the prolonged release of the active ingredients. Because of the low release in acidic medium, the formulated system could be a good candidate to protect the active ingredient from acidic medium.

This preliminary study developed a novel cellulose pretreatment method for cost-effective cellulosic utilization using a modified cuprammonium solution as a solvent to dissolve cellulose followed by molecular oxygen/Fenton depolymerization. The modified cuprammonium solution is composed of cuprammonium solution and a special catalyst that could efficiently enhance cellulosic oxygen sensitivity and therefore improve cellulosic depolymerization. The molecular oxygen depolymerization and Fenton depolymerization of cellulosic biomass dissolved in the modified cuprammonium solution were investigated. The results demonstrate that the Fenton reaction efficiently depolymerized the cellulose dissolved in the modified cuprammonium solution and reached the monomers with no loss of organic carbon, and almost all the cellulose maintained solubility without reagglomeration after cuprammonium was removed. Molecular oxygen oxidation reduced the cellulose average degree of polymerization (DP) to approximately 4 with less cost, and the oxygen pre-oxidation increased the H2O2 utilization in the Fenton depolymerization and remarkably reduced the H2O2 requirement.

This study investigates methods for improving the heat resistance of polyvinyl alcohol/alkali lignin foam material (PLFM). Tetraethoxysilane (TEOS) was used as a precursor to prepare PLCFM by a sol-gel method. The PLCFM, prepared with different levels of TEOS, was characterized by Fourier Transform Infrared spectrometry (FTIR), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). The results indicated that the addition of silica notably improved the heat resistance properties and the initial decomposition temperature of the foam and exhibited good biocompatibility with the polyvinyl alcohol (PVOH) and alkali lignin. The melting temperature of the PLCFM also increased significantly. It reached 268 °C when the silica content was 10%, which was 110 °C higher than that of PLFM. The mechanical properties were also improved to 27.42 MPa.

The catalytic hydrothermal carbonization (C-HTC) method is proposed as a way to convert renewable feedstocks into carbon nanomaterial, using α-cellulose as the model compound. In this study, cellulose reacted with a controlled amount of Lewis acid catalyst (FeCl2 and FeCl3) under hydrothermal conditions, at temperatures ranging from 180 to 220 °C, for 6 to 24 h. The Lewis acid catalyst’s effect on the formation of carbon nanomaterials in the C-HTC reaction was investigated. This study showed that Lewis acid catalysts promoted the complete carbonization of cellulose at a reduced temperature of 200 °C. The addition of FeCl2 in C-HTC also promoted greater C=O functionality compared to FeCl3. Furthermore, the surface area of the carbon nanomaterials derived from the hydrothermal carbonization of cellulose increased from 7.92 to 15.87 and 12.96 m2 g-1 for the uncatalysed, FeCl2 and FeCl3-catalysed HTC, respectively. The findings in this study shed light on the effect of Lewis acid properties on the tunability of functional groups in the preparation of carbonaceous materials for high-end applications.

This study explored the chemical properties of heat-treated bamboo. Oriented bamboo fiber mats (OBFMs) of Phyllostachys iridescens bamboo, as units of a bamboo fiber-reinforced composite (BFRC), were heat-treated in saturated steam at 0.40 MPa (150 °C) for 110, 140, or 170 min. After heat treatment, the color of oriented bamboo fiber mats changed noticeably. The chemical properties of the bamboo were examined. The results revealed that the contents of holocellulose and hemicelluloses decreased, while the contents of α-cellulose and water extractives and buffering capacity increased. The pH value decreased compared with control samples. The change in the chemical properties of the OBFMs would have an effect on the properties of the BFRC.

Air-dried rosewood (Aniba rosaeodora) samples with sizes of 50 mm (length) by 50 mm (width) by 20 mm (thickness) were pretreated with NaOH to increase their permeability. The specimens were then impregnated with microcrystalline wax at a temperature of 100 °C to obtain various weight gains at four treatment durations. After impregnation, the swelling and shrinkage extents and surface hardness of the rosewood were measured. The results showed that, compared with untreated specimens, the linear swelling extent, volumetric swelling extent, and linear shrinkage extent of the impregnated specimens decreased by 75.23%, 59.85%, and 80.70%, respectively, and the surface hardness of the treated specimens increased by 43.36%. The impregnation with wax significantly increased the dimensional stability and surface hardness of the rosewood.

ZnO nanoparticles (NPs) were reduced by treatment with chitosan oligosaccharide (COS) and loaded on organic zirconium phosphate (OZrP) by electrostatic self-assembly in an aqueous medium. The size and morphology of the ZnO NPs was modified using OZrP, which was applied to disperse the ZnO NPs and act as a stabilizer. The synthesized nanocomposites (NC) were used as fillers, and the surface coating method was applied to prepare cellulose-based composite papers having antibacterial properties. The composites were characterized using UV/vis spectroscopy, transmission electron microscopy (TEM), energy dispersion X-ray (EDX) spectrometry, X-ray diffraction (XRD), zeta potential measurements, and scanning electron microscope (SEM). Results indicated that the average diameter of ZnO NPs was less than 50 nm. ZnO NPs was dispersed on the surface and in the interlayer of the OZrP. The physical properties of the finished papers were improved by coating with ZnO/COS/OZrP (ZCO) NCs. Paper that was coated with ZCO yielded good antibacterial properties.

The goal of this study was to collect up-to-date data on the properties of Canadian and United States-manufactured particleboard (PB) and medium density fiberboard (MDF). Sixty-three manufacturers were contacted and asked to participate in a mechanical and physical properties comparison study. This is the first of two papers presenting the results of the PB evaluation. Samples from five different manufacturing facilities from Canada and the United States were evaluated. Each manufacturing facility provided 5 full-sized, (2440 x 1220 mm) M2-grade panels. These were tested according to North American standards. The performed tests included internal bond (IB), bending and elastic moduli (MOR/MOE), thickness swelling (TS), linear expansion (LE), vertical density profile (VDP), and face and edge screw withdrawal resistance (SWR). Four out of 5 press lines exceeded the American National Standards Institute (ANSI) A208.1 (2009) recommendation for IB. Only one of the tested particleboard sets reached the recommended ANSI standard for MOR. Results for the edge SWR showed that none of the tested particleboard manufacturers reached the ANSI recommended value.

The properties of medium density fiberboard (MDF) derived from different manufacturing plants were compared. Each plant provided 5 full-sized (2440 by 1220 mm) 155-grade panels that were tested according to ANSI A208.2-2009. None of the panels met the recommended value for Internal Bond (IB). Mean values for Thickness Swell (TS) were all significantly different, with one manufacturer below the standard. Three manufacturers exceeded the recommended face Screw Withdrawal Resistance (fSWR) values, one was equal to it, and one failed. Three manufacturers exceeded the edge SWR (eSWR) standard, and the remaining two fell below. Two manufacturers met the standard for Modulus of Rupture (MOR), and only one manufacturer failed to meet the Modulus of Elasticity (MOE) requirements. Linear Expansion (LE) was evaluated for a RH change from 50 to 90%. The panels made with pMDI-resin consistently had some of the highest mean values for MOR, MOE, fSWR, and IB and exhibited good performance in the TS test.

The drying kinetics of mango were examined as a first step of pretreatment for biofuels production. This method exploits the potential of the carbohydrate present in the raw material, where the concentration for fermentation was adjusted to 20 g/L of reducing sugars. Dehydration was carried out by natural convection using a solar dryer. The solar dryer employed was made of transparent acrylic, and it had an internal volume of 0.125 m3. The dehydration was performed through natural convection. The dehydration achieved 95.6% moisture removal in 28 h and reached maximum temperatures of 52 °C and 56 °C, corresponding to first and second phases, respectively. The minimum temperature reached was 21 °C. The rate of drying was evaluated during the first stage, between 0 to 4 hours, with radiation maxima of 991 and 1014 W/m2 for that day. At the peak of radiation the drying rate was 0.060 g H2O/ g dry mass/ min.