Research Articles

The rheological properties of the compression process of sweet sorghum straw were studied. The selected experimental factors comprised of the compression density, cutting length, compression speed, and moisture content, and specific energy consumption were selected as the evaluation index of the compression characteristics. The Box-Behnken test scheme was used to analyze the response surface test. The results showed that the selected compression model and specific energy consumption model of the sweet sorghum straw compression process were obtained. The primary factors contributing to energy consumption were the cutting length, moisture content, and compression density. The optimal parameters were as follows: a compression density of 500 kg/m3, a cutting length of 20 mm to 30 mm, a moisture content of 60.06%, and a specific energy consumption of 66 kJ/kg. The results provided methods for reducing the total energy consumption of the compression process and a theoretical basis for the compression and bundling of sweet sorghum.

Novel bio-based composite wood panels (CWPs) that consisted of distiller’s dried grains and solubles (DDGS) flour adhesive bound to a wood filler/reinforcement were subjected to high strain-rate compression loading, and their behavior was investigated. Specimens of DDGS-Paulownia wood (PW) or DDGS-pinewood (Pine) composites made using DDGS with fractions of 10%, 15%, 25%, and 50% were tested at high strain-rates using a modified compression Split Hopkinson Pressure Bar (SHPB). Both DDGS-PW and DDGS-Pine composites displayed strain-rate sensitivity, and DDGS-PW had a 25% fraction, which showed the highest ultimate compressive strength of 655 MPa at approximately 1600/s. The 90%-PW had the highest specific energy of 19.24 kJ/kg at approximately 1600/s when loaded via dynamic compression. The CWPs constructed of DDGS-PW had higher strength and energy absorption than DDGS-Pine with the exception of the 50% DDGS composites.

The goal of this study was to develop an eco-friendly removal technology for fluorescent whitening agents (FWAs) using enzymes suitable for each type of FWA. Internally treated paper with internal FWA (D-FWA) and surface-sized paper with surface-sizing FWA (T-FWA) were made as model papers in a laboratory. The enzymatic treatments were applied to the stock prepared using these model papers by disintegration. Cellulase and (alpha-) amylase treatments were performed at 50 °C under the conditions of pH 3 to 4 and pH 7 to 8, respectively. After disintegration and enzymatic treatments, handsheets were made, and the fluorescence index and FWA reduction of these handsheets were determined for evaluating FWA removal during recycling. Because D-FWA gets strongly attached to cellulosic fibers, it could not be easily separated from the internally treated paper by disintegration. Up to 8.1% of D-FWA was removed by enzymatic treatment with high-activity cellulase. Amylase could not separate D-FWA from cellulosic fibers. In the case of T-FWA, ca. 41% was separated by disintegration, and an additional 24% was detached from surface-sized papers by high-activity amylase treatment. Therefore, cellulase was effective in removing internal FWA (D-FWA), and amylase was required for removing surface-sizing FWA (T-FWA) during recycling.

The efficiency of clove (Eugenia caryophyllata) essential oil (C-EO) for the curative antifungal treatment of historic wood was investigated in comparison with two classical biocide products: a boron-based preservative (Diffusit S) and a formulation containing quaternary ammonium salts and isothiazole (Biotin T). A combined approach was adopted that consisted of implementation of C-EO in a practical case study on a degraded beech (Fagus sylvatica) wood artifact and evaluation of the treatment efficacy via an original laboratory mycological test. Small samples, extracted from the degraded wood material before and after curative treatments, were placed as inoculum on sterile culture medium and incubated for periodic monitoring of the emerging fungal growth for 140 d. Direct observation was supplemented with digital quantification of the fungal coverage area via ImageJ software and calculation of the absolute and relative indices of fungal development reduction. The results indicated that the C-EO solutions at both tested concentrations (10%, 5%) were more efficient than the considered reference products at similar concentrations (Diffusit S (10%) and Biotin T (5%)) for curative antifungal treatment. However, none of the treatments applied entirely prevented reactivation of the severe and complex fungal attack, which was highlighted by the mycological tests conducted on the control samples.

A thermogravimetric method was used to study the combustion of bituminous coal (BC), diverse biomass (wood chips: WC, chaff: CH), and their blends under non-isothermal conditions and isothermal conditions. A higher blending amount of WC or CH under non-isothermal conditions resulted in a lower ignition temperature, burnout temperature, and a greater comprehensive combustion characteristic index. Meanwhile, the co-combustion of BC, WC, and CH all showed inhibiting effects. The inhibition effect was prominent when the blending ratio of WC was below 30%. Under isothermal conditions, with the increase of oxygen concentration and blending amount, the combustion performance of BC improved gradually. The synergistic effect between BC and biomass dominated, and the interaction was more distinct when WC content exceeded 50%. Under both non-isothermal and isothermal conditions, the interaction between CH and BC did not vary at diverse blending ratios. The dynamic results suggested that the chemical reaction model O1 was suitable for stage 1 of the co-combustion of WC and BC, the model diffusion controlled D4 controlled the co-combustion of CH and BC and stage 2 of the co-combustion of WC and BC. The blending ratio of WC or CH with the lowest activation energy was 50%.

Non-treated and silane-treated kenaf bast/natural rubber latex foam (NRLF) were prepared using the Dunlop method at different filler loading (0, 3, 5, and 7 pphr). The properties were investigated in terms of mechanical properties, tensile, compression, hardness, and swelling behavior. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize kenaf bast/NRLF. With the modulus at 100% elongation (M100), the compression strength and hardness showed increments in value with increments of kenaf loading. However, different results showed in tensile strength, elongation at break, swelling percentage, and recovery percentage, which decreased at higher filler loading. Silane-treated kenaf bast/NRLF showed higher value in all properties except for elongation at break, swelling, and recovery percentage. The improvement of properties was supported by SEM surface morphological studies that showed better adhesion between the rubber matrix and kenaf filler.

Flattened and crushed fiber-bundles of moso bamboo (Phyllostachys pubescens) were dyed with a water or alcohol-based dye at 20 °C, 75 °C or 90 °C for 72 h, followed by drying and coating with PF resin. Hot-pressed bamboo fiber composites (BFC) were manufactured, and the weathering performance of the composites made from dyed and natural bamboo material were tested over 90 days of the Autumn/Winter season in Beijing. Dye was able to penetrate the bamboo tissue to create a rich red color that degraded in color faster than BFC made from un-dyed bamboo. BFC made from un-dyed tissue remained a lighter but more consistent color over the weathering period. Dying the bamboo in ethanol-based dye was effective at pigmenting the product, but made it more susceptible to color degradation as well as greater mass and thickness loss due to the chemical degradation of the lignin caused by ethanol. Higher temperature of water dying treatment (90 °C) gave the greatest resistance to mass and thickness loss during outdoor exposure, and the bamboo may have benefitted from the longer period of ‘heat treatment’ during dyeing. Further work is needed to quantify dye leaching from bamboo tissue and to develop more water-tight and color-fast, weather resistant dyes for bamboo products.

The moisture content of corn stover during the harvest season in the Huang-Huai-Hai region of China is approximately 50%. To achieve rapid off-field transportation and to prolong its shelf life, a method suitable for corn stover with medium-high moisture content was considered based on the stover multistage continuous cold roll forming method. An orthogonal experiment was adopted by taking the moisture content, sterilization method, and inhibitor addition method as experimental factors and taking the shelf life, percent rebound, and density of the molding blocks as the experimental indices. It was found that the steam sterilization method can prolong the shelf life of the molding block the most. The percent rebound and the density were primarily affected by the moisture content, followed by the sterilization method. A comprehensive analysis indicated that the optimal treatment mode was a moisture content of 45%, and the optimal sterilization method was steam sterilization with no inhibitor. In this mode, the molding block can be stored for 72 h without mildew with an average temperature of 32 °C and an average humidity of 48% during the day. The percent rebound was 24.3%, and the density can reach 310 kg/m3 after the completion of rebound.

Polyalthia bullata is a woody medicinal plant that contains antioxidant compounds. Finding a suitable solvent is important to obtain a high yield of antioxidants in the phenolic, flavonoid, and terpenoid families. In this study, from different solvent extracts, the leaf methanolic extract exhibited the highest total phenolic content (TPC), total flavonoid content (TFC), total terpenoid content (TTC), and total antioxidant activity. For woody parts of stem and roots, methanol was the best solvent for all phytochemicals except for phenolics, which accumulated in the roots and were extracted more efficiently using ethanol. However, the methanolic extracts from both tissues displayed the best antioxidant capacity. Gas chromatography-mass spectrometry (GC-MS) profiling data showed the presence of antioxidant compounds such as thymol, phytol, and neophytadiene in the leaf; trans-farnesol, n-hexadecanoic acid, and 9-Octadecenamide in the stem; and fatty acid (cis-vaccenic) and its methyl ester (11-Octadecanoic acid, methyl ester and [1,1’-bicyclopropyl]-2-octanoic acid, 2’-hexyl-methyl ester) in the roots. These findings reveal important compounds that are present in different plant parts of P. bullata.

In some respects the safest food packaging material is paper that is completely free of chemical additives, made only from primary cellulosic fibers. There is no information in the literature on giving paper barrier properties using nanocellulose without any additives, especially bacterial cellulose, by applying a coating to a fibrous semi-product. In order to prepare paper-layered composites, paper sheets made of beaten or non-beaten softwood or hardwood cellulose pulp, or their 50/50 (wt./wt.) mix, were used in the experiment. After the application of bacterial cellulose onto the sheets, the paper became completely impermeable to air, which means that fine microbial fibers had filled the voids (pores) between plant cellulose fibers. The results of the experiment could be regarded as a perfect, biodegradable packaging material.