Research Articles

The vibrational frequency method was used to measure the elastic modulus of laminated veneer lumber (LVL), and the feasibility of using Weibull distribution to analyze the elastic modulus data of LVL was considered. Samples were randomly selected as test pieces at the factory. The sponge support structure was used to realize the free beam state, and the modal test results verified the accuracy of realizing the free beam. Under transient excitation, the elastic modulus of the specimen was obtained by testing the first-order bending frequency. The Weibull distribution fitting test, Weibull distribution K-S test, and normal distribution K-S test were used for the test data. The probability of LVL elastic modulus was calculated under a given value. The results showed that the LVL elastic modulus did not obey the two-parameter Weibull distribution (Eu=0). The LVL elastic modulus fit to the three-parameter Weibull distribution (Eu) was greater than half of the minimum test value and the normal distribution. When 9 GPa and 8 GPa were used as the setting values of Eu, the calculated probability value was relatively stable. At this time, Eu was 81% and 92% of the minimum elastic modulus 9.815 GPa. Therefore, it was recommended to use 80% to 90% of the minimum value of the measured data as the setting value of the position parameter Eu. The three-parameter Weibull distribution and the normal distribution calculated LVL elastic modulus have the same probability under the given value.

It was proposed that pre-hydrolysing tule (Typha domingensis Pers) would make it possible to produce handsheets with strength-related properties similar to those of conventional commercial paper, in addition to valorizable hemicelluloses. The hypothesis was tested with a biorefining scheme involving autohydrolysis. Conditions were optimized to maximize the extraction of hemicelluloses while preserving glucan integrity. The autohydrolysis at a liquid to solid ratio of 13 at 141 °C for 45 min (optimized conditions) provided a commercially useful liquor containing primarily tule hemicelluloses. The autohydrolysis of tule before alkaline extraction made it possible to obtain a valuable liquid phase comprising between 23.3% and 71.6% of all hemicelluloses in the raw material. The gross heating value for the hydrolyzed tule was increased (1.6% to 7.9 %) with respect the raw material. The solid phase was subjected to soda–anthraquinone pulping. The yield, ethanol extractives, kappa number, viscosity, glucan, xylan, Klason lignin, soluble lignins, as well as the tensile index were evaluated. Tule was found to be amenable to industrial processing for the production of quality cellulose derivatives. Autohydrolysis provided valorizable liquor in addition to solid that yielded soda–anthraquinone pulp having properties similar to those obtained in its absence, but using milder operating conditions.

As a green and sustainable packaging material, industrial sack paper has gained increased attention in recent years due to the public’s heightened environmental awareness. Practical applications for industrial packaging sack paper demands that the paper possess high physical strength properties. In this study, silicon dioxide (SiO2) nanoparticles in conjunction with poly(diallyldimethylammonium chloride) (PDADMAC) were applied to improve the physical strength of sack paper. The results showed that the physical strength properties of the sack paper increased with the addition of the SiO2 nanoparticles and PDADMAC, while the air permeability of the paper also remained high. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to characterize the sack paper with the SiO2 nanoparticle filler.

A simple, novel method was developed for synthesizing cellulose (CE) fibers doped with silver nanoparticles (Ag NPs) in the green solvent tetrabutylammonium hydroxide / dimethyl sulfoxide / H2O at room temperature. Tetrabutylammonium hydroxide accelerated the reduction of Ag+ to Ag by the cellulose chains, yielding Ag NPs in cellulose solution stabilized using polyethyleneimine (PEI). After 24 h, almost all the Ag+ was reduced to Ag NPs. The influences of silver nitrate concentration, reaction time, and stabilizer on the formation of Ag NPs were investigated by UV-vis spectrophotometry. The prepared smooth and dense cellulose / Ag NP fibers showed high mechanical properties, with a tensile strength of 304.3 MPa and an elongation at break of 22.1%. The fibers exhibited excellent antibacterial activities against Escherichia coli and Staphylococcus aureus, with more than 99% of E. coli bacteria killed by Ag NP / cellulose fibers. The synthesis procedure offers a general and mild approach to designing materials of almost any shape.

Glue shear strength and wood preservatives play an important role in the longevity of engineered wood products. The effects of factors such as UV rays, humidity, and temperature on wooden materials are known. However, it is not known what effects sub-zero temperatures have on wood material and how wood preservatives play a role. This study determined the effects of synthetic-based varnish and impregnation on shear strength in cold climatic conditions. Variables including glue type, ambient temperature, tree type, and process type were investigated. Wood laminate test samples were produced for this purpose, and water repellent impregnation material and synthetic-based varnish were used as wood preservatives. Experimental samples were kept in a cold air cabinet at (-15 °C) and (-30 °C) temperature for 90 days. Samples kept in different temperature conditions were subjected to a pull experiment in a parallel (//) direction to the fibers under static load. As the ambient temperature decreased, the shear strength decreased (-15 °C: 8,960 N/mm2 ,-30 °C: 8,025 N/mm2 ) . When the performance of wood preservation elements were examined, it was determined that the varnish process (8,875 N/mm2) and the impregnation process (8,691 N/mm2) were not statistically significant, at 12% and 10%, respectively.

In this study, 130 uniform ‘Flame Seedless’ grape trees were selected for and subjected to the same cultural practices. The trees were sprayed three times, before flowering, during full bloom, and three weeks later with the following treatments: control (water only), 250, 500, and 750 ppm glycine; 50, 100, and 150 ppm folic acid (FA); 2%, 4%, and 6% leaf moringa aqueous extract (MLAE); and their combinations. High-performance liquid chromatography (HPLC) analysis of moringa leaf aqueous extract (MLAE) showed the presence of the phenolic compounds ellagic acid, vanillic acid, p-hydroxy benzoic acid, catechol, and gallic acid with values of 54.18, 18.79, 14, 12.32, and 12.12 mg/100 g, respectively. The obtained results showed that the foliar spraying of 250, 500, and 750 ppm glycine, 4% and 6% MLAE, and their combinations of glycine 500 ppm + FA 100 ppm + MLAE 4% and glycine 750 ppm + FA 150 ppm + MLAE 6% significantly increased the shoot length, shoot thickness, leaf chlorophyll content, yield, and fruit quality over the control. Glycine at 750 ppm was the best treatment followed by glycine at 500 ppm compared with the other applied treatments and the control in both experimental seasons.

Short carbon fiber (SCF), rice straw powder, and high-density polyethylene (HDPE) were melted, mixed, and compounded into composites by compression molding. The effects of carbon fiber content on the mechanical properties of rice straw-high density polyethylene composites (RHCs) were studied. The carbon fibers were characterized by a universal capability test machine (UCTM), scanning electron microscope (SEM), DMA dynamic mechanical analyzer, and a Fourier infrared spectrometer. The results showed that the addition of carbon fiber was beneficial to reduce the creep of RHCs. Meanwhile, the carbon fibers were broken after strength testing. The functional group types of rice straw WPC composites did not change, and the skeleton structure of WPC materials was still retained. When the content of carbon fibers was 9%, a large number of carbon fibers were surrounded by the HDPE matrix; the fibers were broken and rarely pulled out. The results showed that good interfacial bonding took place between the carbon fibers and the composites. The maximum tensile strength of the RHC/S9 was 15.15 MPa, which was 20.7% higher than that of default RHC, and the modulus of elasticity was 52.5% higher than that of default RHC. However, due to the large content of carbon fiber, the distribution of the carbon fibers was uneven in the matrix, and the toughness was reduced.

Poplar 69 (Populus deltoides Bartr. cv. ‘Lux’ (I-69/55)) was chosen for a pot experiment to study the growth and the extraction of Cd from soil to various parts of the one-year-old trees growing in upright and artificial leaning (45°) patterns under different Cd stress. The results indicated considerable tolerance of both upright poplar (UP) and leaning poplar (LP) to Cd stress in the soil, though with significant inhibition from Cd application. LP demonstrated significantly lower height and basal diameter growth than UP. Cd concentrations in different parts of both UP and LP increased with the increase of Cd in the soil and it followed a general order as Bark > Leaf > Root > Stem. Different parts of poplar had average bio-concentration factor (BCF) ranges between 0.08 to 2.36, and average translocation factor (TF) between 0.67 to 7.92, indicating a big difference of phytoextraction ability among the parts, among the treatments, and between LP and UP. Average Cd concentration, BCF, and TF for each part of LP were higher than that of UP, but the difference was not significant. Significantly higher Cd concentration was found in the tension zone of stem wood than that in the opposite zone for LP.

Bamboo-wood composite cross-laminated timber (BCLT) is a new kind of wood structure material. Studies of the mechanical properties of BCLT have the potential to improve its utilization. Compared with the traditional testing method, this paper designs a fast and effective nondestructive testing method. Three types of composite BCLT plates were designed and made. Multi-point sampling of unit-converted timber was done using a 900-1700 nm NIR spectrometer. Mechanical properties of the unit converted timber were obtained through a four-point bending experiment. The data set consisted of near-infrared spectrum data and mechanical property data. The NIR prediction model was obtained by partial least squares method. The coefficients of determination for the density, MOR and MOE prediction models were 0.88, 0.88, and 0.85, respectively. Finally, the finite element modeling analysis of BCLT plate was carried out according to the element material prediction model, and the prediction of mechanical properties of BCLT plate was achieved. For the three BCLT plates, the prediction error of the finite element model was less than 10%, showing that the finite element analysis method is feasible to predict the mechanical properties of BCLT plate.

To improve the utilization rate of pineapple leaf and crop straw, and provide technical support for making biodegradable fiber mulch paper through organic cultivation, the process and properties of the degradable fiber mulch paper made from pineapple leaf and rice straw were studied. The degradable fiber mulch paper was prepared as a hybrid composite in which pineapple leaf fiber and rice straw fiber were used as raw materials, and environmentally friendly agents were added. A four-factor five-level quadratic orthogonal rotation central composite design of the response surface method was employed. The beating degree of pineapple leaf fiber, basis weight, addition ratio of pineapple leaf fiber, and wet strength agent content were process parameters; dry tension strength, wet tension strength, and bursting strength were objective functions. The optimal technology parameters of pineapple leaf and rice straw fiber mulch paper were 70 to 90 g/m2 basis weight of pineapple leaf fiber, 17% to 25% addition ratio of pineapple leaf fiber, 55 °SR beating degree, and 1.5% wet strength agent content. According to the tensile strength and bursting strength standards, the degradable fiber mulch paper made from pineapple leaf and rice straw was feasible. The results provide theoretical basis and technical support to use pineapple leaves and rice straw to make degradable mulch paper.