Research Articles

Bioderived poly(lactic acid) (PLA) is a promising alternative for fossil-based polymers, but its poor hydrophilicity, high brittleness, and low heat-resistance are problems for its utilization. In this work, bleached softwood kraft pulp (BSKP) fiber was adopted to modify PLA with MAPP as the coupling agent, with BSKP accounting for 10 wt% to 50 wt%. Internal mixing (IM) was applied to mix the PLA/fiber blend instead of screw grinding. The thermal and mechanical properties of the composites were assessed. The IM process was proven qualified for its effective dispersion of BSKP fibers in the PLA matrix. At a fiber loading of 50 wt%, IM-processed composites acquired satisfactory tensile strength (50.49 MPa, slightly higher than PLA) and Young’s modulus (2.56 GPa, 45.8% higher than PLA). The pulp fillers matched PLA matrix well for the characteristic temperatures in thermal decomposition. The BSKP/PLA composites were thermally strengthened by pulp fibers characterized by higher content of residues. The fibers improved the interfacial crystallinity of PLA in the composites (i.e., from 5.22% to 11.86%). The increased crystallinity resulted in enhanced stiffness or weaker damping performance of the composites. In conclusion, natural plant fibers are a feasible option to modify PLA for extended applications.

The surface morphology of biomass pellets can provide data for the contact mechanics fractal model between the molding pellet and hole in biomass molding machines and for predicting wear of the molding hole. In this study, desert caragana (Caragana korshinskii) was mixed with residue from maize production, crushed, and compressed into pellets, which were used to collect data on their circumferential surface roughness profile, density, diameter, and hardness. The results showed that frictional wear occurs during contact between the forming hole and the molding particles, increasing the diameter d₀ of the forming hole and the diameter d of the molding particles. The density ρ and hardness HD of the molded pellets decreased as their diameter d increased, and the ρ and HD of caragana were higher in autumn than in summer. The values of the roughness parameters R_a, R_c and R_z of the molded particles increased with their diameter d. The maximum material rate M_r2 value of the roughness’s central profile remained at 86% with the increase of diameter d. Molded particles had surface roughness kurtosis R_ku>3 and roughness skew R_sk<0 with the increase of diameter d. The surface of molded particles was spiky and negatively skewed, and with a low number of spikes.

A wooden matched-die mold was manufactured to develop wood-based corrugated panels. Wood veneers brushed with resin were cold pressed between the mold halves and formed into a corrugated geometry. The corrugated panels were used as a core and bonded to flat veneer-based facesheets to develop sandwich panels. The whole manufacturing process involved a cold-forming technique that allowed panels to be produced with no heat. Specimens cut from both corrugated and sandwich panels were submitted to a four-point bending test to evaluate their structural performance. Adopting the same number of layers used to make the sandwich panels, flat panels were fabricated and tested to find the effect of this corrugated geometry and cold-forming process on the load-carrying capacity of the sandwich structures. A comparison with flat panels made with the same stacking of veneers showed an increase of 272% of the bending stiffness of the sandwich panels, which is known as the sandwich effect. Comparison between the bending results of the panels developed in this study with those manufactured using thermoset resin and hot-pressing technique indicated that the cold-forming process using the wooden mold is an effective and inexpensive method to develop wood-based corrugated sandwich panels.

As a consequence of increasingly serious environmental problems, many researchers are highlighting biomass materials. Cellulose, the most abundant bioresource, is becoming a key consideration for alleviating environmental pollution. Characterization of cellulosic materials is fundamental to exploring their structures and elemental contents. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are frequently employed to study the structure of cellulose. Thus, it is urgent to combine traditional means with new ones. This study focused on the characterization of the all-cellulose composites (ACCs) model prepared via partially dissolving filter paper using 40% benzyltrimethylammonium hydroxide (BzMe₃NOH) aqueous solution. Characterized by SEM, XRD, Fourier transformation infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, the unique transformation from cellulose I to cellulose II of the ACCs model was explored. These characterization methods exhibited respective features, which could be universal ways to investigate ACCs.

A rotary kiln is a central piece of equipment for the calcination of clinker in the  production of cement. Biomass energy has been applied to rotary kilns, and solar energy has been introduced to assist the energy supply. Coupled optimization results for biomass energy and solar energy applications are compared to the single fossil energy used in the base period. A field survey and statistical analysis and integration of cement clinker production sites in China’s Central Plains Economic Zone revealed a negative linear correlation between the consumption of raw coal in the cement production process and the environmental temperature and humidity parameters of the production lines.  The energy consumption is large and the energy utilization of the system is low, with goodness of fit of R=0.962.  Coupled solar and biomass energy use in the audit period and single energy use in the base period comparison revealed a 19.5% reduction in electricity consumption, a 25.4% reduction in coal consumption and a 4.39% increase in heavy oil consumption. From 2017 to 2020, the average annual consumption cost of electricity and raw coal decreased, while the average annual consumption cost of heavy fuel oil slowly increased. After verification during the audit period, compared with the base period, the total production cost of the case enterprise can be reduced approximately 5.17%, in which the energy cost decreased 0.9%.

Energy use, together with consumption of raw materials, machine clothing, and wet end chemicals, are some of the most critical aspects in successful tissue making today. This work was aimed at developing a laboratory-scale method of estimating dewatering mechanisms, vacuum efficiency, and energy use of Through Air Drying (TAD) of tissue. When compared to pilot data, the results of the new laboratory method for investigating dewatering during TAD were in the same magnitude, around 24 to 26% dryness after vacuum dewatering, and 27 to 29% dryness after TAD molding. Sheet properties, such as caliper and surface profile, were evaluated and compared to commercial tissue sheets. The results indicate that it will be possible to precisely measure accurate dryness development and penetrated air volume for tissue sheet forming and TAD molding at a laboratory scale. This can contribute to the efforts of implementing a circular forest-based bioeconomy by increasing the fundamental understanding of dewatering of tissue paper materials, which is facilitated by improvements in energy use. The new method developed in this work will make it easier to assess ideas that are difficult to bring to pilot scale or full scale before learning more of the dewatering capabilities. The authors are convinced that improved knowledge of tissue dewatering mechanisms, forming, and material transport during and after TAD dewatering can increase the efficiency of the industrial manufacturing processes.

Effects of high temperature pretreatment and inoculation of Bacillus coagulans were determined relative to the physicochemical properties and bacterial community of aerobic composting of chicken manure. Chicken manure was pretreated with high temperature for 0 h (CJ), 0.5 h (T-0.5h), 1.0 h (T-1.0h), 1.5 h (T-1.5h), and 2.0 h (T-2.0h) and then inoculated with B. coagulans. Chicken manure without high temperature pretreatment was included as control (CK). The results showed that the temperature of manure in CJ, T-0.5h, T-1.0h, T-1.5h, and T-2.0h groups was 2.2 to 8.4 °C higher than the chicken manure in CK within 1 day. On day 3, the chicken manure temperature reached a peak, which was 1.5 to 7.7 °C higher than that in the CK (56.8 °C). Both inoculation of B. coagulans and high temperature pretreatment increased the abundance and diversity of the bacterial community. The abundance of Firmicutes in T-1.5h was significantly higher than that in CJ. In the temperature decreasing period, the abundance of Bacillus in T-1.5h group was significantly higher than that in the CK and CJ. Overall, it was concluded that high temperature pretreatment and B. coagulans inoculation can accelerate the temperature elevation, increase the temperature of compost, and regulate the structure of bacterial community.

Seed health testing, using the blotter method, revealed some fungal growth on the seed surface of one accession of Indian trumpet flower/Broken bones tree (Oroxylum indicum (L.) Kurz) collected from Kokrajhar, Assam, India. The fungus was identified as Diaporthe phaseolorum (Cooke & Ellis) Sacc. based on morphological characters. Later, the identity was re-confirmed by DNA sequencing using ITS gene sequencing (NCBI Sequence Id: MT154253.1) and a large subunit of rRNA (NCBI Sequence Id: OL798081.1). Literature reveals that D. phaseolorum is a destructive pathogen causing severe yield losses in various host crops. However, detection of D. phaseolorum in Indian trumpet flower seed followed by pathogenicity on its seedlings confirms that O. indicum is a new host record. Being a destructive pathogen of several other crops, such as seed decay and stem canker in soybean, it may pose a serious threat to future cultivation of this herbal plant.

Leaf and stem fibers of Sorghum halepense L. (SH) were investigated as fillers for recycled polypropylene (RPP) at 10, 20, and 30 wt%. The effects of SH in RPP on the thermal and mechanical properties of composites were investigated by tensile and bending tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). It was found that mechanical properties of the RPP composites decreased but their elasticity modulus increased. The addition of SH fibers to the polymer matrix changed the thermal properties of RPP. A slight decrease in DSC crystallinity was observed with the addition of 10% SH leaf and stem fiber to the polymer matrix and then the percentages of crystallinity increased with the addition of 20% and 30% SH leaf and stem fiber. The SEM images showed that the SH fibers mixed well with the polymer matrix without agglomeration, and the fracture sections of the composites were less rough than that of the RPP by itself.

To eliminate toxic formaldehyde from wood-based panels, a new formaldehyde-free wood adhesive (named OL/PEI adhesive) was synthesized by a reaction of oxidized lignin (OL) and polyethylenimine (PEI) reaction in the presence of sodium periodate. The curing mechanism of the OL/PEI adhesive was clarified by Fourier transform infrared spectroscopy (FTIR) and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS¹³C-NMR) spectroscopy. The results showed that the sodium periodate could selectively oxidize wheat straw lignin to produce the ortho-quinone, and then the ortho-quinone in OL could further react with amino groups in PEI to form the OL/PEI adhesive. The as-prepared poplar particleboard was investigated with regard to hot-pressing temperature, the hot-pressing time, the OL/PEI weight ratio, and the dosage of OL/PEI adhesive. Under the optimum conditions, e.g., hot pressing temperature of 180 °C, hot pressing time of 13 min, the OL/PEI weight ratio of 1:1, and the dosage of 10%, OL/PEI adhesive was found to disperse evenly into the voids among the shavings of poplar particleboard, followed by the curing of OL/PEI adhesive using hot-pressing to form tightly bonds between the shavings. The resulting particleboard reached the requirement of mechanical properties (GB/T 4897.3-2003), higher water resistance properties, and better heating resistivity. This study demonstrated a new way to produce a formaldehyde-free wood adhesive with unique properties. This material could replace formaldehyde wood adhesive in wood bonding.