Volume 13 Issue 2

The mechanical characteristics of cellulose fibres in biocomposites (epoxy resin/Musa textilis) were investigated relative to the microstructure of these fibres as determined by porosimetry and electron microscopy in terms of their utilization in composite systems. The influence of the chemical treatment via alkali (NaOH) on the change in surface properties and the interfacial interaction of fibres with an epoxy resin was investigated as well as mechanical characteristics of abaca/epoxy composites. The porosity of abaca fibres reached 57% on average, and the averaged tensile strength value was 641 MPa and a Young modulus of 26 MPa. Evaluated composite systems were prepared through a vacuum infusion in which various orientations of long ordered fibres in these composites were evaluated along with the influence of a 6% NaOH chemical treatment on the resultant mechanical properties. The alkali treatment increased the tensile strength of the observed composite systems by up to 16 MPa. The chemical treatment of the abaca fibres led to an increase in the interfacial interaction, which was evaluated with electron microscopy.

Silica nanoparticle (SiNP)-poly(vinyl alcohol) (PVOH) coating is an important material system in paper coating applications, where particle distribution critically affects coating performance. In the present study, the authors investigated a role of physicochemical interaction between SiNP surface and PVOH chain in SiNP distribution in the coating layer, with a comparison of the suspension at pH 3 (good interaction) and pH 10 (poor interaction) as PVOH concentration was varied. Rheological properties and sedimentation behavior of the suspensions showed the dispersion stability of SiNP at pH 3 was improved by the addition of PVOH, whereas it was independent of the PVOH concentration at pH 10. Scanning electron microscopy and small angle x-ray scattering intensity of dried coating layer showed the uniform and dense structure with homogeneous distribution of SiNPs at pH 3, where spatial arrangement of SiNPs depended on the addition of PVOH. However, non-uniform and porous structures with SiNP aggregates were observed at pH 10, where the spatial arrangement of SiNPs was independent to the addition of PVOH. The stress development during drying of the coating suggested that the mechanical property was related to the spatial arrangement of individual SiNPs at pH 3, whereas to the distribution of SiNPs aggregates at pH 10.

Water contamination by heavy metal ions is a worldwide problem. In this work, a type of hydrogel, based on hemicellulose, was prepared via graft copolymerization. The reaction time and cost were reduced by modifying the traditional preparation process. The hemicellulose-based hydrogel was an opaque, smooth, well-distributed, and high resilience hydrogel. To better understand the application of hemicellulose-based hydrogel as an absorbent for the removal of Pb(II) (lead nitrate) from heavy metal contaminated water, the hydrogel was used to adsorb Pb(II) from aqueous solution. The various factors that influenced the Pb(II) removal efficiency were studied, including concentration and temperature. The results showed that the hemicellulose-based hydrogel was assessed as an ideal absorbent towards Pb(II), showing maximum monolayer adsorption capacity of 5.88 mg/g. The Pb(II) adsorption isotherm was determined to further understand the adsorption mechanism. The results demonstrated that the adsorption of the hemicellulose-based hydrogel on Pb(II) belongs to the monolayer adsorption and that adsorption conforms to the Langmuir model better than the other model. It revealed that the adsorption process of Pb(II) on hemicellulose-based hydrogel was spontaneous and endothermic in nature. The hemicellulose-based hydrogel was proven as a good material for potential application.

Novel thermoplastic composites filled with wheat straw (WS) and enzymatic-hydrolysis lignin (EHL) were developed and characterized. The three-dimensional melt blending system of WS, EHL, and high-density polyethylene (HDPE) was optimized via orthogonal experiments. The mechanical properties and melt index of the composites were measured and the optimum ratio of the composites was determined. Based on the optimum ratio of the composites’ blending system, identified through compounding granulation and extrusion molding process links, pilot products of the composites were produced. The thermal behavior, polar groups, and surface structures of the fibers and developed thermoplastic composites were assessed by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) analysis, respectively. The addition of EHL, an abundant renewable resource, improved the dispersity of the matrix as well as the mechanical and thermal properties of the composites. The results provide a theoretical basis for the application and development of new composites and illustrate a potential industrial application of EHL.

Time and motion studies are often used to evaluate the performance of various product systems. However, traditional studies are characterized by a series of technical limitations, and they require many resources. This study tested the capability of a low-cost Global Positioning System (GPS) receiver and an accelerometer unit to automate the field data collection for characterizing motor-manual felling of willow short rotation coppices. The results were promising. By thresholding the acceleration data, the running and stopped engine states were accurately separated. Also, by combining the GPS speed with the acceleration data, followed by threshold setting and data visualization in the Geographic Information System software, detailed time categories, such as productive, working, and non-working times, could be separated. The methods described herein could be used to manage long-term field data collection, as such operations are affected by many operational factors.

Most research on biomass-filled plastic composites (BFPCs) mainly focuses on their formulation and physical/mechanical properties, but studies on the connection performance of BFPCs are very rare. However, such performance is vital in the quality assessment of BFPCs products and plays an important role in improving product quality and promoting its application in the field of architecture and furniture. Therefore, the behavior of L-type BFPCs structure under the interaction of fatigue-creep was investigated. Results suggested that the fatigue-creep curve is a typically three-region curve at 80% and 60% failure load, and only first two stages at 40% failure load. But the damage caused by fatigue-creep interaction was not a simple superposition. Fatigue damage dominated when the holding time was short, and creep damage occupied a dominant position gradually when the holding time was longer. In addition, the lifespan of the BFPC component increased initially and then decreased as holding time increased. The component joint exhibited the least integrated damage when the holding time was 60 s and the lifespan was longer.

Magnesium hydroxide (Mg(OH)₂) nanosheets were explored as an effective material for the restoration and conservation of paper-based cultural archives and compared with the commonly used Ca(OH)₂ nanoparticles. The (Mg(OH)₂) nanosheets were applied to filter paper as a reference, as well as to new and old paper samples. The effectiveness of Mg(OH)₂ nanosheets was evaluated by (i) a pH test of the surface and the bulk extracts, (ii) measuring the alkaline reserve and correlating it with the enhancement in life expectancy, and (iii) in terms of mechanical strength. The alkaline reserve test indicated an increase in the alkaline buffer, which resulted in markedly reduced acidic content of the samples. It was inferred from the improved properties that Mg(OH)₂ nanosheets coated the paper as a lamination sheet and protected it as the first line of defense against acidic environmental attack. Moreover, its presence within the paper acted as an alkaline reserve and also as reinforcement in the form of an inorganic nanosheet. The results suggest that the nanosheets are an innovative, compatible, and efficient material for the consolidation and restoration of old and new paper samples.

Fish glue prepared from swim bladders has been used in China to glue wooden parts together since ancient times. It is also used as an important natural glue for wooden artifact and building restoration, musical instrument fabrication, as well as many other fields. Microorganism contamination is a major concern for fish glue preservation. In this research, fish glue was prepared from swim bladders using two methods, namely, heat treatment and enzymatic hydrolysis. Then, the molds that germinated in both samples were analyzed. Light microscope and scanning electron microscopy (SEM) observations of the molds’ hypha morphology identified Alternaria in both glue samples. The antimicrobial efficiencies of borax, sodium diacetate, and Antim AL-D (an organic/inorganic composite antimicrobial) were then compared. The results demonstrated that all antimicrobial agents in the research effectively inhibited Alternaria germination in both fish glue samples. A 0.3% (by weight) solution of Antim AL-D was sufficient for preserving fish glue. As for borax and sodium diacetate, the addition of a minimum of 1.0% was adequate to inhibit Alternaria growth. Results also revealed that the addition of Antim AL-D minimally affected the shear strength of glued wooden parts.

Genetic modification of plant lignin composition is an important strategy for improving biomass enzymatic digestibility without sacrificing the normal growth of the plant. However, the absence of fast and convenient methods for rapid determination of lignin composition has impeded corresponding research. Near-infrared reflectance spectroscopy (NIRS) analysis has potential as a solution for this dilemma, while the NIRS measurement for expediently assaying lignin composition in rice straws is still lacking. In this study, visible and near-infrared reflectance spectroscopy (VIS/NIRS) and modified partial least squares (MPLS) method were combined to develop calibration models for predicting the lignin monomer contents in a diverse rice population. Four optimal equations for predicting the content of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) lignin units and their total amount (H + S + G) were generated with acceptable determination coefficients for calibration (0.85 to 0.93), cross-validation (0.75 to 0.88), and external validation (0.82 to 0.88), and the ratio performance deviation (RPD, 2 to 3.01). This study was the first to demonstrate that VIS/NIRS could give a sufficiently accurate prediction of lignin monomer contents in rice and could be applied for rapid assessments of large-scale rice straw samples.

This research investigated the use of reclaimed rubber (RR) from waste tires to partially replace the rubber compound (RC) when making wood fiber-rubber composites (WRCs). Ninety panels of WRC containing RR were manufactured with RR contents of 0% to 40%, mixing times of 6 min to 14 min, and vulcanizing temperatures of 150 °C to 170 °C. There were three steps, which were the fiber-rubber mixing, tabletting, and vulcanization molding processes. Four regression equations for the tensile strength, elongation at break, hardness, and rebound resilience as functions of the RR content, mixing time, and vulcanizing temperature were derived, and a nonlinear programming model was developed to obtain the optimum panel properties. It was found that when the RR content was within 20%, the wood fibers were well encapsulated and embedded in the RC/RR blends, and the processability of the WRCs were improved by adding RR. The incorporation of RR into the WRCs increased the average tensile strength and hardness by 33.9% and 2.3%, respectively, while the swelling ratio in toluene and 24-h water absorption were reduced by 13% and 42%, respectively.