Volume 15 Issue 4

The application of Fused Filament Fabrication (FFF) 3D printing for offices, educational institutions, and small prototyping businesses has recently attracted increased attention. Thermal-fused filaments could emit potentially hazardous atmospheric particulate matter (PM) and volatile organic compounds (VOCs). This study evaluated the particle and VOCs emission characteristics of an FFF 3D printer with lignocellulose/polylactic acid (PLA) filament to reduce emissions. The PM2.5, PM0.2-10, and VOCs emission behaviors of the FFF 3D printer with a lignocellulose/PLA filament were investigated in a test chamber under different printing conditions. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was applied to analyze the formation of VOCs from lignocellulose/PLA filaments. Analysis indicated that particle formation dominated the heating process, whereas VOCs were mainly released during the printing process. The results further showed that printing at higher relative humidity and high filament feeding temperatures triggered higher VOCs emissions. In addition, high humidity facilitated particle agglomeration and reduced PM concentration. Printing at higher filament feeding temperatures also resulted in high particle emissions. Finally, Py-GC/MS analysis determined the decomposition products of the lignocellulose/PLA filament corresponding to the main ingredients of VOCs.

Geopolymer binders show great potential in the application of eco-friendly wood composite adhesives. The applicability of organic-inorganic hybrid-reinforced geopolymer composites as plywood binder was investigated. In this study, a geopolymer-based wood adhesive was fabricated by mixing a matrix-geopolymeric slurry; a toughening agent, waterborne polyurethane; and a silane coupling agent, that served as the covalent “bridge” between the waterborne polyurethane with a geopolymer matrix. The results showed that the waterborne polyurethane exhibited excellent compatibility with the geopolymer and served as a flexibilizer, which transformed the matrix from a microfractured structure to a denser morphology. Moreover, the shear strength of bonded plywood and the morphology of the fracture surface after the tensile measurement were measured. The resulting geopolymer/wood interface was well bonded, and the interfacial bonding strength was higher than the wood strength matrix after modification. The introduction of waterborne polyurethane and silane coupling agent improved the water resistance of the composites and increased the wet shear strength of plywood from 0 MPa to 0.35 MPa. Notably, a weak wood/alkali interface was formed under alkaline conditions due to the strong diffusion of alkali metal ions between the interfaces.

Renewable and eco-friendly pig blood adhesives (PBAs) were obtained by modifying PBAs with a mild alkaline solution and glutaraldehyde and exposing them to an ultrasound treatment. The PBAs were subjected to thermogravimetric (TG) analysis and Fourier transform infrared (FTIR) spectroscopy, and the bonding strength and bonding interface of plywood were analyzed to evaluate bonding performance. The results showed that the alkaline solution unfolded the structure of blood proteins, and the glutaraldehyde crosslinked the blood protein. In addition, the ultrasound greatly increased protein expansion under weak alkaline conditions. The thermal stability of the PBAs exposed to ultrasound treatment under weak alkaline conditions was improved, but the crosslinking agent was not used, and the permeability, which was analyzed by a fluorescence microscope, improved. Further, the average and effective penetration depths on the bonding interface increased 53% and 55%, respectively. The bonding strength of plywood prepared with modified PBAs was greatly improved and compliant with relevant requirements.

The utilization of branchwood as lignocellulosic raw material source for paper production may have the potential of solving the problem of the availability of raw material in the pulp and paper industry. This study therefore compared the chemical composition and fiber morphological indices (according to Franklin’s method) of stemwood and branchwood in Eucalyptus camaldulensis and Pinus halepensis trees grown in Egypt. The statistical analysis showed a significant effect of species, wood type (stem and branchwood), and their interaction on the measured chemical constituents and fiber morphological indices at 0.05 significance level. In both genera, the stemwood exhibited a higher percentage of cellulose and hemicellulose and was lower in lignin, total extractives, and ash than those measured in branchwood. Also in both genera, the stemwood was higher in fiber length, Runkel ratio, rigidity coefficient, Muhlsteph ratio, and Luce’s shape factor, and lower in basic density and flexibility coefficient than those in branchwood. Based on the chemical analysis and the fiber morphological indices, the stemwood and branchwood of both species were suitable for paper production with various qualities. Moreover, good correlations were found in both stem and branchwood between the basic density and the fiber wall thickness and fiber lumen diameter. ln contrast, there was an independent association between the stemwood basic density and the fiber length, and this relationship in branchwood was positive for both genera.

2-Hydroxy-3-isopropoxypropyl guar gum (HIPGG), which is a novel polysaccharide-based thermo-responsive polymer, was synthesized via grafting a hydrophobic reagent (isopropyl glycidyl ether (IPGE)) onto a hydrophilic main backbone (guar gum (GG)). The HIPGG exhibited reversible and tunable thermo-responsive properties. Changing the molar substitution (MS) of the hydrophobic side chain enabled the lower critical solution temperature (LCST) to be adjusted within the range of 29.6 °C to 43.7 °C. Fluorescence spectrometry, dynamic light scattering (DLS), and transmission electron microscopy (TEM) were used to investigate the self-assembly behavior of HIPGG and the thermo-dependent size of its aggregates. It was demonstrated that HIPGG formed stable aggregates in aqueous solution, and the diameters of the aggregates increased as temperature increased. Subsequently, Nile red was used as a model to investigate the encapsulation and temperature-controlled release behaviors in HIPGG aggregates. The results indicated that Nile red was easily encapsulated in the hydrophobic region of HIPGG aggregates, and its release at 36 °C, 38 °C, and 42 °C revealed that temperature had a remarkable impact on release behavior.

Spartina anglica, a plant that controls coastal erosion, is widely distributed throughout the world and is rich in cellulose, hemicellulose, and lignin. The hemicellulose from Spartina anglica can be extracted and hydrolyzed into monosaccharides and xylooligosaccharides under acid or enzymatic digestion conditions. In this study, an effective PMP(1-phenyl-3-methyl-5-pyrazolone)-derivatized HPLC (High performance liquid chromatography) method was developed for monitoring monosaccharides and xylooligosaccharides of Spartina anglica. With phosphate buffer (0.04 M, pH 8.06) as mobile phase A, and acetonitrile as mobile phase B, in which the elution gradient was set as A:B/79:21, the monosaccharides (glucose, xylose and arabinose) and xylooligosaccharides (xylobiose, xylotriose, xylotetraose, xylopentaose, xylohexaose) could be separated completely using the C18 column. This provides an economical, rapid, and efficient method for process monitoring in the bioconversion of Spartina anglica.

Porous carbons with a high porosity were successfully produced from fast pyrolysis pine wood char via a thermochemical method in which KOH was used as chemical activator. The effects of various weight ratios of KOH to pyrolysis char (0.65:1, 0.7:1, 1.0:1, 1.35:1, and 1.7:1) on the physical properties of activated carbons were investigated. When the weight ratio of KOH to pyrolysis char was 1.35:1, the prepared activated carbon had the highest surface area of 1140 m2/g with a total pore volume of 0.71 cm3/g, a microporous surface area of 957 m2/g, and a microporous specific volume of 0.51 cm3/g. As the weight ratio of KOH to pyrolysis char increased from 0.65 to 1.35, the prepared activated carbon had increases in total surface area, total pore volume, microporous surface area, and specific volume of micropores. However, there was a reverse trend when the weight ratio of KOH to pyrolysis char was higher than 1.35. The use of nitrogen as a flow gas resulted in much more developed activated carbon than without nitrogen. The experiment results suggested that activated carbon with high surface area could be prepared from pyrolysis char by adjusting the activation conditions.

Surface characteristics were studied for particleboards produced from hydro-thermally treated (HTT) and non-treated (NT) wheat stalk (WS). Wood and wheat stalk particles were used as experimental materials. The wheat stalk particles were subjected to HTT at a temperature of 180 °C for 8 minutes in a steam explosion machine. HTT and NT WS particles were added at 10%, 20%, 30%, and 40% to the wood particles. The surface roughness and wettability of the produced panels were determined. The roughness measurements, average roughness (Ra), maximum roughness (Rmax), and mean peak-to-valley height (Rz) were performed using a fine stylus tracing technique. The wetting behavior of the panels was characterized by the contact angle method (goniometer technique). The contact angle (CA) measurements were obtained by using a KSV Cam-101 Scientific Instrument connected with a digital camera and computer system. Statistical analyses showed significant differences in the surface roughness and wettability of the particleboards following hydro-thermal modification. The addition of WS to the panels significantly decreased the roughness values. However, all of the HTT groups exhibited higher roughness compared to NT groups. The CA values decreased when the WS content increased. The wettability of the particleboard containing HTT WS particles was improved.

The properties of wood charcoal layers have an effect on the performance of small-scale blast furnaces. In order to characterize the mechanical behavior of a fixed bed of eucalyptus charcoal, a specific uniaxial compression test was designed and used with charcoal layers of different characteristics. This layer test has the potential to be standardized, and it made it possible to consider the bulk properties of randomly layout charcoal pieces, which was better adapted than single specimen tests in the fiber direction. A total of eight charcoal layers were prepared with two carbonization temperatures (500 °C and 900 °C), two granularities (10 mm and 20 mm), and two different testing temperatures (20 °C and 300 °C). Characteristic parameters of the compression tests were then determined as the particle size distribution, the mechanical energy, and the mean power. The charcoal produced at 900 °C and with a granularity of 20 mm was more resistant to breakage than the others were, and a high quantity of large particles remained after the tests. Significant correlations existed between the carbonization temperature, granularity, and mechanical power of the compression test. The mechanical power was the main parameter that determined the resistance to breakage of a charcoal bed in compression.

Waste wood-plastic composite (WPC) was used in this work as a raw material to produce recycled WPCs reinforced with carbon fiber and nanoclay. To evaluate the synergistic effects of carbon fiber and nanoclay, various performances (i.e., microstrucural, mechanical, thermal, water absorption, and electrical properties) were investigated. Scanning electron micrographs and X-ray diffraction analysis of the fillers (carbon fiber and nanoclay) present in the recycled WPCs showed that the nanoclays were properly intercalated when filled with carbon fibers. According to mechanical property analysis, hybrid incorporation of carbon fibers and nanoclays improved impact strength, tensile strength, and flexural strength. However, further incorporation of nanoclays reduced the impact strength and did not improve the tensile modulus or the flexural modulus. The carbon fibers present in the recycled WPCs improved the electrical conductivity of the composites, despite the various fillers that interfered with their electrical conduction. In addition, carbon fibers and nanoclays were mixed into the recycled WPCs to improve the thermal stability of the composites. Finally, the presence of nanoclays in recycled WPCs led to increased water uptake of the composites.