Volume 10 Issue 2

This work reported the thermomechanical and morphological properties of polyvinyl alcohol (PVA) nanocomposites reinforced with nanosilica and oil palm empty fruit bunches derived nanocellulose. The nanocomposites were characterized by mechanical, thermal, XRD, optical, and morphological studies. Uniformity dispersion of the nanofillers at a 3 wt% concentration has been shown by scanning electron microscopy, whereas the changes in crystallinity were demonstrated by X-ray diffraction analysis. Addition of nanosilica resulted in increased thermal stability of PVA/nanocellulose composites due to the reduction in mobility of the matrix molecules. Visible light transmission showed that the addition of 0.5 wt% nanosilica only slightly reduced the light transmission of PVA/nanocellulose composites with 3 wt% nanocellulose. The addition of a small concentration of nanosilica successfully improved the tensile and modulus properties of PVA/nanocellulose composite films. The increases in tensile strength and thermal stability were evidence of a nanosilica contribution in PVA/nanocellulose composites, inducing reinforcement, as detected by the thermomechanical properties.

In this study, both untreated rice straw stem fibers and fibers treated with sodium hydroxide were used. Maleic anhydride polypropylene (MAPP) was used to enhance adhesion of the fiber with the matrix. Composites were prepared with various combinations of fiber, ranging from 10 wt.% to 25 wt.%, and polypropylene in addition to 2 wt.% MAPP. These composites were then tested for acoustical, mechanical, thermal, infrared spectral, and morphological properties. The fibers were treated by being soaked in 5 wt.% NaOH solution at 30 °C for 30 min. The composites with treated fiber exhibited higher thermal stability, tensile strength, sound absorption, and fiber-matrix adhesion than the composites with untreated fiber. The results of sound absorption measurements showed that the composites with higher fiber content had better sound absorption than the composites with lower fiber content. The changes in the peaks in the Fourier transform infrared spectrum indicate that the alkaline treatment removed hemicellulose and lignin from the rice straw stem fibers.

A carbonization-sulfonation method was utilized in synthesizing sulfonated mesoporous catalysts from palm tree biomass. Brunauer-Emmet-Teller (BET), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), and field emission scanning emission microscopy (FE-SEM) analyses were used to evaluate the structural and textural properties of the catalysts. Further, Fourier transform infrared (FT-IR) spectroscopy and titrimetric analyses measured the strong acid value and acidity distribution of the materials. These analyses indicated that the catalysts had large mesopore volume, large surface area, uniform pore size, and high acid density. The catalytic activity exhibited by esterifying used frying oil (UFO) containing high (48%) free fatty acid (FFA) content further indicated these properties. All catalysts exhibited high activity, with sPTS/400 converting more than 98% FFA into fatty acid methyl esters (FAMEs). The catalyst exhibited the highest acid density, 1.2974 mmol/g, determined by NaOH titration. This is outstanding considering the lower reaction parameters of 5 h, 5:1 methanol-to-oil ratio, and a moderate temperature range between 100 and 200 °C. The study further illustrates the prospect of converting wastes into highly efficient, benign, and recyclable solid acid catalysts.

The influence of the filler content and surface modification of Elateriospermum tapos seed shell (ETSS)-filled recycled polypropylene (rPP) on the tensile, thermal, and morphological properties was investigated. Maleic acid (MA) was used for the chemical modification of ETSS. It was found that increasing the ETSS content decreased the tensile strength and elongation at break of composites. However, the modulus of elasticity increased with the addition of ETSS. The thermal properties of composites were examined using thermal analysis (TGA) and differential scanning calorimetry (DSC). The addition of ETSS indicated better thermal stability of rPP/ETSS composites. The degree of crystallinity (Xc) of the composites decreased with increasing ETSS content. The tensile strength and modulus of elasticity of modified composites was higher than unmodified composites. Surface modification with maleic acid increased the thermal stability and crystallinity of the modified rPP/ETSS composites. Scanning electron microscopy showed that the filler-matrix interaction improved with the modification of ETSS with maleic acid.

The Paulownia tree is one of the most important fast growing species in the World and is an ideal multipurpose tree. In this study, the potential use of Paulownia wood (Paulownia elongata) as a raw material for the pencil manufacturing industry is investigated. Currently, poplar, cedar, and juniper species are most commonly used in this industry. However, Paulownia wood is a fast growing species that can be used in the industry after 5 years on the plantation. Paulownia (Paulownia elongata), poplar (Populus tremula), and juniper (Juniperus excelsa) wood specimens were used in this study. The specimens were prepared according to related standards, and physical, mechanical, and technological properties were investigated. The data obtained from these measurements were compared statistically using ANOVA and Duncan’s Multiple Range Test. As a result, Paulownia wood exhibited favorable properties, suggesting that it would be a useful alternative raw material for the pencil manufacturing industry.

The objective of this work was to degrade lignocellulosic components in un-pretreated vinegar residue (VR) using a fungal consortium. Consortium-29, consisting of P. chrysosporium, T. koningii, A. niger, and A. ficuum NTG-23, was constructed using orthogonal design combined with two-way interaction analysis. After seven days of cultivation, the reducing sugar yield reached 35.57 mg per gram of dry substrate (gds-1), which was 108.01% higher than the control (17.10 mg gds^-1). Additionally, the xylanase and CMCase activity reached 439.07 U gds^-1 and 8.15 U gds^-1, which were 432.08% and 243.88% higher than that of pure cultures of A. niger (82.52 U gds-1) and P. chrysosporium (2.37 U gds^-1), respectively. The cellulose, hemicellulose, and lignin contents decreased by 17.11%, 68.61%, and 14.44%, respectively, compared with that of the raw VR. The optimal fermentation conditions of consortium-29 were as follows: incubation temperature 25 °C, initial pH 6, initial moisture content 70%, inoculum size 1 ´ x 10⁶ spores/mL, incubation time 5 days, urea/VR 1%, and MnSO4×H2O/VR 0.03%. This study suggests that consortium-29 is an efficient fungal consortium for un-pretreated VR degradation and has a potential application in lignocellulosic waste utilization with a low cost of operation.

The feasibility of heat treatment of Masson pine veneers (MPVs) was evaluated based on mass loss, tensile strength, bending strength, and water absorption of the heat-treated MPVs, and its application in plywood was explored. Fourier-transform infrared and X-ray diffraction results showed that heat-treated MPVs contained a lower amount of hydrophilic groups and had an increased crystallinity. The maximum tensile strength was 59.2 MPa when MPVs were heat-treated at 210 °C for 5.0 min. The corresponding mass loss, water absorption (384 h), and bending strength values were 1.72%, 105.44%, and 83.1 MPa, respectively. Plywood produced from heat-treated MPV (210 °C, 30 min) with the best fungal durability and the lowest shear strength (1.07 MPa) still met the requirements of the Chinese National Standard (GB/T 9846.3-2004, ≥0.80 MPa) for exterior plywood. These results indicate that products based on heat-treated MPV will have increased fungal durability.

The sorption capacity of untreated and alkaline-treated coconut shaft biosorbents for the removal of Pb2+ from aqueous solution was investigated in batch experiments. Effects of contact time, biosorbent dose, initial metal concentration, and pH on the sorption capacity were investigated. Optimum Pb2+ removal of 17.6 and 22.1 mg/g by untreated and alkaline-treated biomass was achieved at an initial metal concentration of 150 mg/L, a biomass dose of 0.7 g, a contact time of 80 min, and a pH of 4.0. The sorption data fitted well into the Langmuir isotherm, while kinetic modeling of the data from untreated biomass indicated conformity with the Lagergren pseudo-first-order model, whereas data from the treated biomass fit well with the Elovich model. FT-IR results gave indications of possible functional groups on the cell walls of the coconut shaft, including alcohols, amines, carboxylic acids, ester, and ethers. Thus, alkaline treatment of the coconut shafts enhanced the biosorption ability of Pb2+ onto the coconut shaft biomass.

The purpose of this work was to determine the optimal welding time for linear friction welding of birch (Betula pendula L.) wood while keeping the other parameters constant and at similar levels compared to other species in a similar density range. Specimens with dimensions of 20 × 5 × 150 mm3 were welded together, and the influence of welding time (2.5, 3.0, 3.5, and 4.0 s) on the mechanical properties of the specimens was determined. The studies included a tensile-shear strength test as well as visual estimation of wood failure percentage (WFP). Additionally, X-ray microtomographic imaging was used to investigate and characterise the bond line properties as a non-destructive testing method. The highest mean tensile-shear strength, 7.9 MPa, was reached with a welding time of 3.5 s. Generally, all four result groups showed high, yet decreasing proportional standard deviations as the welding time increased. X-ray microtomographic images and analysis express the heterogeneity of the weld line clearly as well. According to the averaged group-wise results, WFP and tensile-shear strength correlated positively with an R2 of 0.93. An extrapolation of WFP to 65% totals a tensile-shear strength of 10.6 MPa, corresponding to four common adhesive bonds determined for beech.

An approach is demonstrated for the manufacturing of a microfibrillated cellulose (MFC) composite paper. A key element in the manufacturing paradigm is the use of high consistency suspensions to improve retention and minimize the need for water removal after forming. The rheological characterization of the composite furnish, which contained 70% structured pigment, 20% MFC, and 10% pulp fibers, revealed a gel-like shear thinning behavior of the suspension, which differs greatly from traditional fiber-based papermaking furnishes. The results from laboratory and pilot scale studies show that the headbox consistency range from 5 to 10% offers the best combination of processing, forming characteristics, retention, and dewatering. While the furnish dewatering in laboratory scale was very problematic, under suitable dynamic conditions the wire section dewatering was excellent. The results of this study suggest that the MFC composite can be manufactured on a modified paper machine and that the final product will have an attractive cost structure.