Research Articles

A biodegradable, environmentally friendly starch-based wood adhesive with cassava starch as a raw material and butyl acrylate (BA) as a co-monomer was synthesized. Results revealed that this cassava starch-based wood adhesive (SWA) was more stable than corn starch-based wood adhesive, and its bonding performance was close to that of commercial PVAc emulsion, even after 90 days of storage. Further analysis found that the improved stability of the adhesive could be attributed to its low minimum film forming temperature (MFFT) and glass transition temperature (Tg) of cassava starch. Moreover, the amount of total volatile organic compounds (TVOCs) emitted by the cassava starch-based wood adhesive were much lower than the Chinese national standard control criteria. Therefore, cassava SWA might be a potential alternative to traditional petrochemical-based wood adhesives.

The main objective of this research was to study the potential uses of almond shell flour (ASF) in the production of thermoplastic composites containing montmorillonite (MMT). Thirty, 35, and 40 wt% ASF was used, and 2.0 wt% maleic anhydride-grafted polypropylene was used as the compatibilizer. Two levels of MMT nanoclay, 2.5 and 5.0 wt%, were mixed with polypropylene (PP). The effects of MMT on the thermal properties of the blended composites were evaluated using thermogravimetric analysis (TGA), morphological characterization, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The XRD data showed that the relative intercalation of the composites with 2.5 wt% MMT was higher than that of the 5.0 wt% nanoclay composites. The TGA results indicated that by increasing the MMT percentage, the degradation temperature and the thermal stability were enhanced. The MMT exhibited better dispersion in the clay layers of the polymer-matrix composites when increased from 2.5 to 5.0 wt%, and at the 5.0 wt% MMT loading, the size of MMT became larger. The total weight loss of the ASF/PP/MMT composite decreased as the filler content increased, and the thermal stability increased as the MMT content increased.

A free radical chain initiation reaction was exploited to prepare poly(acrylonitrile)-grafted Khaya cellulose. The synthesis of the poly(amidoxime) ligand was also performed using oximation reactions. Transition metal cations formed some complexes with the polymeric ligand. The pH of the solution played an important role in the optical detection of Cu2+ ions. The highest absorbance (approximately 94%) of the [Cu-ligand]n+ complex was at pH 6. The sorption quantity increased with increasing Cu2+ ion concentration, which was reflected by a broad peak at 600 nm that was attributed to the charge transfer (- transition) process. The equilibrium sorption capacity of 282 mg/g, with faster adsorption rates (t1/2 = 8 min), suggested that copper possessed excellent adsorption capacity compared with the other cations (Fe3+, Co3+, Cr3+, Ni2+, and Zn2+). The sorption data for all of the cations followed the Freundlich isotherm model, with a high coefficient of determination, reflecting a heterogeneous sorption process by the cellulose-based, poly(amidoxime) adsorbent. The feasibility for recycling of adsorbent was evaluated by the sorption/ desorption study, and the results suggest that a new type adsorbent can be reused in seven cycles without any significant loss in its original sensing and removal performances.

The aim of this study was to determine the pentosan content in pulps by a dual-wavelength spectrophotometric method. The method was based on the boiling reaction between pentosan and 12% hydrochloric acid, in which pentosan was subsequently converted to furfural. The concentration of furfural in the distillate was determined by the absorbance at 280 nm and 290 nm. Several different simultaneous equations were solved to obtain the concentrations of furfural in the distillate. The results showed that the method had an excellent accuracy (RSD ≤ 0.61%) and reproducibility (RSD = 3.25%). The spectral interference of the 5-hydroxymethyl-2-furaldehyde in the distillate was eliminated by the dual-wavelength measurement technique. Compared with the TAPPI method (colorimetric method), this method is simple, user-friendly, and practical and has high detection sensitivity.

An improved system for hydrogen production by the steam reforming of simulated bio-oil was developed. The coal ash was packed in front of nickel-based catalysts, acting as a guard catalyst. The model compounds passed through coal ash and were preliminarily reformed to smaller molecular intermediates containing more CO and CH4, which were then further reformed over the following nickel-reforming catalyst. The improved reaction system succeeded in effectively converting the complex simulated bio-oil into hydrogen and exhibited high activity. For 15 wt.% Ni/γ-Al2O3 catalyst with coal ash packing, the catalyst lifetime was extended to 8 h, with simulated bio-oil almost completely converted into hydrogen. In addition, coke deposition was suppressed.

This study documented the current status of wood pallet repair in the United States by identifying the types of processing and equipment usage in repair operations from an automation perspective. The wood pallet repair firms included in the study received an average of approximately 1.28 million cores (i.e., used pallets) for recovery in 2012. A majority of the cores received were stringer-style pallets. The most common pallet size received and repaired was 48 x 40 inch. The most commonly used stringer repair method was the application of companion stringers. It was found that most firms utilized high levels of manual labor, with limited machinery support. The board trimming and pallet sorting/stacking processes had the highest level of automation, while the inspection, nailing, and painting processes utilized manual labor.

This study reports the moment resistance, stiffness, and numerical analysis of various sizes of round-end mortise and tenon joints. L-shaped and T-shaped specimens were constructed. Joints were manufactured using three tenon widths and three tenon lengths with 10 replications for each combination. Specimens were constructed of Turkish beech, and the joints were assembled with polyvinylacetate (PVAc) adhesive. Bending tests were carried out in compliance with accepted test methods. Numerical analyses were performed with finite element method (FEM) software. At the end of the study, the joints became stronger and stiffer as either tenon width or length increased. Tenon length had a more significant effect on moment resistance, while tenon width had a more significant effect on stiffness. Ultimate moment resistances were obtained with L-shaped joint construction of 50 × 50 mm tenons and T-shaped joint construction of 40 × 50 mm tenons. Strength of a chair could be increased by considering these results in engineering design process. Results showed that the numerical analyses gave reasonable estimates of mechanical behavior of joints. Analytical calculations and numerical simulations confirmed that the maximum stress in the glue line was concentrated at the edge and corners, and that the modeled joints had a shape-adhesive nature.

Cellulosic fibers from the bast of Pueraria lobata (P. lobata) vine were separated using a “green” and efficient method that combined steam explosion (SE) and a laccase mediator system (LMS). The chemical components, structure, and thermal alterations in the fibers were evaluated. The SE performed at 180 °C for 10 min did not change the chemical composition of P. lobata; however, SE did alter the fiber structure and rendered its surface more accessible to the laccase enzyme. Treated and untreated samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and chemical methods. The cellulose content of the processed fibers was approximately 68.2%, and the lignin content was 11.8%, which was much lower than the 22.98% lignin content of the raw material. The cellulose fibers exhibited higher cellulose crystallinity and thermal stability compared with the untreated samples. This combined treatment approach may be useful for the isolation of cellulose fibers for composites, textiles, and other industrial applications.

The effect of hydrothermal conditions on enzymatic hydrolysis lignin (EHL) degradation in water-isopropyl alcohol co-solvent and optimal conditions were investigated. The yields and reactivity toward formaldehyde of degraded enzymatic hydrolysis lignin (DEL) were determined. The optimal conditions of temperature, time, and ratio of solids to liquids were 250 °C, 60 min, and 1:10 (w/v), respectively. The EHL and DEL were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H NMR), thermal gravity (TG), and differential scanning calorimetry (DSC) analyses. The results revealed that the molecular weight and polydispersity of DEL were lower than that of EHL. Although the fundamental structure of lignin before and after hydrothermal degradation was retained, the ether (β-O-4, α-O-4, etc.) content decreased, while that of hydroxyl (phenolic and aliphatic) increased. The DTGmax and Tg values shifted from 334 and 117 °C to 304 and 105 °C, respectively.

Hybrid composites were fabricated with 4-methylcatechol-treated jute and bamboo fiber at different pH levels. The effects of different pH levels on the thermal, mechanical, and morphological properties of jute-bamboo hybrid composites were investigated. Fabricated hybrid composites were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and adhesion test analysis. Additionally, surface morphology and tensile testing were reported. Fourier transform infrared spectroscopy (FTIR) revealed that the peak intensities at 1634 and 1643 cm-1 disappeared in treated jute and bamboo fibers. This resulted from the removal of hydroxyl groups on the treated fibers. A higher pH (9 or 10) resulted in the effective modification of bamboo and jute fibers. The TGA results showed that the presence of hybrid fiber led to an earlier degradation of the hybrid composite. The DSC results showed that the crystallinity index declined by 7% to 8%, which improved the adhesion between the fiber and the polymer. According to these finding, the pH level contributed to an improvement in the mechanical properties of the composites. The pH 10-treated hybrid composites exhibited the highest tensile strength and modulus. The surface morphology revealed that at higher pH, the treated hybrid composites exhibited strong adhesion characteristics.