Volume 11 Issue 1

An attempt to introduce assistive vibration into the process of biomass briquetting was carried out, with a focus on lowering the energy requirement and improving product quality. The effects of assistive vibration on the surface morphology of briquettes using corn stalk and wheat straw as the experimental materials was investigated, and it was found that assistive vibration can increase the flow capacity of the material and improve the press transmission as well as the uniformity of internal stresses to facilitate the inner-layer-material compression and lower the springback of the compressed material. The biomass particles were still bonded primarily by mechanical interlocking and solid bridges, but the distribution range and size of the voids or gaps between adjacent particles were reduced, and the particles or fibers of thicker layer appeared to be “lying down” instead of “standing,” indicating a higher density of the product compared with the case of compaction without vibration assistance.

This study aims to investigate the ultraviolet (UV) absorption property of palm fiber and to reveal the mechanism underlying its UV-shielding behavior. The UV spectra of various solvent extracts of palm fiber were investigated. Fourier transform infrared spectroscopy (FTIR) and UV spectra were used to analyze the treated palm fiber, 100% α-cellulose, and raw palm fiber. The UV absorbances of palm, bamboo, and ramie fibers and their lignin extracts were comparatively investigated. The results showed that lignin is the main contributor to the UV absorption property of palm fiber. UV spectroscopy of the solvent extracts showed that a dioxane solution exhibited an excellent extraction capacity. The analysis of the FTIR and UV spectra of treated palm fiber, 100% α-cellulose, and raw palm fiber confirmed that there was a strong correlation between the UV absorption property and the chemical components. The results showed that the palm fiber exhibited superior UV absorption properties and that the lignin content noticeably affected the UV absorption degree.

Rubber seed shell (RSS) was modified by grafting treatment using glycidyl methacrylate (GMA) at various concentrations. The RSS was then used to reinforce high-density polyethylene (HDPE). The effects of modification on the mechanical, water absorption, and thermal properties of the RSS/HDPE composites were studied using a mechanical testing instrument, weighing method, Vicat softening temperature (VST) testing, thermogravimetry, and dynamic mechanical analysis. The results showed that the GMA grafting produced an improvement in the flexural and tensile properties of the composites. The water absorption rate of the composites also had an obvious decrease. While a slight increase in VST was found, the various concentrations of GMA showed no improvement in VST. GMA modification also could elevate the thermal stability of the composites at the initial decomposition stage. The optimum grafting concentration of GMA (2.5%) led to the lowest thermal weight loss (37.07% and 26.56%) during the first and second decomposition stages. The E’ values of the composites had a significant increase with the addition of GMA. There were two peaks of tan δ for the untreated samples, but the modified samples exhibited a shift in the transition peak at higher temperatures; moreover, the second peak disappeared.

Suspensions of bleached bagasse pulp at 0% to 15% mass concentrations were sheared in a concentric cylinder rotary device to study the pulp suspension’s fluidization properties. The use of a baffled chamber, with blade rotors, imposed shear stress within the suspensions and prevented slip at the chamber walls. Linear-type, hollow-type, and screw-type rotors were used to explore the influence of rotor structure on fluidization properties. The torque was measured as a function of rotational speed. The torque vs. rotational speed curves and flow phenomenon were found to depend on the mass consistency of the pulp suspensions and the gap between the rotor and chamber. The structure of the rotor had little influence on the fluidization of the pulp suspensions, and the critical rotational speed that makes the pulp suspensions turbulent was similar for all rotor types. The gap between the rotor and chamber should be small to let pulp suspensions fluidize at low rotational speed.

Deep drawn shapes with orthogonal wall components are usually evaluated by shape accuracy and visual quality. There have been only a few investigations on the stability of such structures; however, the effect of the wrinkles on the stability of the wall is important for packaging applications and can support the shape accuracy. This paper focuses on the influences of process parameters on the stability of orthogonal walls of shapes produced by deep drawing with rigid tools and immediate compression. The wall stability was evaluated by tensile testing orthogonal to the direction of the wrinkles. The stability distribution was characterized with regard to the drawing height, and a comparison was made between the two different materials. The wall stability decreased with increases in the forming height. Furthermore, a blank holder force design and z-directional compression level improved the wall stability. Together with an elevated moisture content of the material and thermal energy supply that delivered two to three times higher resistance against wrinkle extension, these effects drastically improved the wall stability.

The dynamic viscoelasticity of bamboo kraft pulping black liquor under various temperatures (ranging from 50 to 80 °C) and solids concentrations (60 to 80 wt.%) was studied. Rotational rheometer analysis data indicated that the viscoelastic motion law with a high solids concentration in black liquor was in accordance with the Kelvin model, and black liquor with a medium concentration conformed to the Maxwell model. As a result, the temperature and solids concentration greatly influenced the dynamic viscoelasticity of bamboo kraft pulping black liquor. For instance, the modulus increased as the solids concentration increased, indicating that the viscous component of black liquor was prominent. For this reason, it was easier to soften the bamboo black liquor, providing a favorable condition for the pure viscosity of black liquor. Steady shear thinning was apparent during the frequency shear process. The dynamic viscosity, storage viscosity, and complex viscosity of the black liquor decreased as the shear frequency increased. The quantitative relationship between dynamic viscosity and angular frequency can be described using the Power Law model.

Natural–synthetic fiber hybrid composites offer a combination of high mechanical properties from the synthetic fibers and the advantages of renewable fibers to produce a material with highly specific and determined properties. In this study, plain-woven kenaf/glass reinforced unsaturated polyester (UP) hybrid composites were fabricated using the hand lay-up method with a cold hydraulic press in a sandwich-configuration laminate. The glass was used as a shell with kenaf as a core, with an approximate total fiber content of 40%. Three glass/kenaf weight ratios percentages of (70/30)% (H1), (55/45)% (H2), and (30/70)% (H3) were used to fabricate hybrid composites. Also pure glass/UP and kenaf/UP were fabricated for comparison purposes. Monotonic tests, namely tensile, compression, and flexural strengths of the composites, were performed. The morphological properties of tensile and compression failure of kenaf and hybrid composites were studied. In addition, uniaxial tensile fatigue life of hybrid composites were conducted and evaluated. The results revealed that the hybrid composite (H1) offered a good balance and the best static properties, but in tensile fatigue loading (H3) displayed low fatigue sensitivity when compared with the other hybrid composites.

To illustrate the effects of nano-bamboo charcoal (NBC) on the properties of bamboo plastic composites (BPC), nano-bamboo charcoal-bamboo plastic composites (NBC-BPC) were prepared at 0%, 2.5%, 5%, 7.5%, 10%, and 12.5% (w/v) NBC and characterized. The effects of NBC on the water absorption, fractured surfaces, mechanical properties, and thermal properties of the composites were investigated. NBC had strong interfacial interaction in the BPC, which greatly improved the interfacial adhesion of bamboo flour (BF) and high-density polyethylene (HDPE). The water resistance, flexural strengths, and tensile strengths of the composites were enhanced compared with traditional BPC when the volume of NBC reached a specific loading. These results demonstrated that the incorporation of NBC slightly improved the thermal properties of the synthesized composites.

Cellulose-graft-poly(p-dioxanone) copolymers (cellulose-g-PPDO) were homogeneously prepared via ring-opening graft polymerization (ROP) between p-dioxanone (PDO) and hydroxyl groups of cellulose using the catalyst 4-dimethylaminoptridine (DMAP) in the ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl). Chemical structures and physical properties of the cellulose-g-PPDO copolymers were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (1H, 13C, 1H-13C 2D heteronuclear single quantum correlation (HSQC)-NMR)), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) techniques. By adjusting the reaction conditions, including the molar ratio of PDO to the anhydroglucose unit (AGU), amount of DMAP, and reaction temperature and time, the structure of the graft copolymers could be altered, and a series of copolymers with molar substitutions (MSs) in the range of 1.09 to 6.97 and polymerization degrees (DPs) varying from 1.85 to 2.88 were obtained. The graft copolymers exhibited a noticeably lower thermal stability than cellulose. After the attachment of PPDO groups, the crystalline structure of cellulose was disrupted because of the elimination of the inter- and intra-molecular hydrogen bonds of cellulose chains.

The commercial method for isolation of ampelopsin, one of the most common flavonoids isolated from the plant species Ampelopsis grossedentata, is a simple hydrothermal extraction at high temperature. To develop an improved process to isolate ampelopsin, the effects of treatment of cellulase on hydrolysis of the dried fruit of A. grossedentata were investigated. The treatment of cellulase was found to decrease the temperature and time for hydrolysis of the dried fruit of A. grossedentata. The conditions of the filter press and continuous flow centrifuge for removal of insoluble materials from the hydrolysate of the dried fruit of A. grossedentata were optimized. The recovery yield of ampelopsin from the dried fruits of A. grossedentata was 39.4%, as determined by HPLC chromatographic analysis. A safe and economical process at low temperature with treatment of cellulase for the isolation of ampelopsin was developed in this study.