Volume 12 Issue 3

The potential usefulness of an invasive common reed as biomass feed to a biorefinery was investigated. This investigation focused on the cellulosic fiber and a comparison of with and without a hot-water extraction (HWE) pretreatment process step. Handsheets were made before and after bleaching and compared to handsheets made from other pulped grass family (Poaceae) fibers. Machine-made simulated copy-grade paper was compared with and without HWE at varied percentages of reed replacement for hardwood fiber in the furnish. The HWE appeared to cause a dramatic increase in the tensile and burst strength while the tear strength reduced slightly. The effects of HWE on woody biomass strength properties were compared.

Flax shive and hemp hurd residues were characterized, and the feasibility of manufacturing three-layered particleboards was evaluated using 2.5% and 5% polymeric diphenyl methane diisocyanate resin loadings. The flax shive and hemp hurd residues had lower bulk densities and higher aspect ratios compared with the wood residues. Their higher aspect ratios offered greater overlap in bonding, which led to consistently higher bending properties that exceeded the American National Standards Institute (ANSI) requirements for low-density (LD2) particleboard and, in some cases, medium-density (M2) particleboard. Because of their particle geometry, the flax shive and hemp hurd particleboards also showed minimal linear expansion with changes in the moisture content at 20 ± 3 °C and between 50% and 90% relative humidity. The high absorption capacity of the flax shive and hemp hurd residues resulted in higher thickness swell and water absorption properties than the wood residues. The results indicated that low-density flax shive and hemp hurd particleboards (500 to 620 kg/m³) can be manufactured using isocyanate resin quantities as low as 2.5% to produce panels that conform to ANSI specifications with a greater mechanical performance than that of wood residue particleboards.

To improve the compatibility between rice straw and reinforcing polymers, rice straw (RS) was pretreated by an anaerobic process, and its biogas residues (BR) were acetylated with acetic anhydride (AA) to prepare acetylated biogas residues (ABR). The optimum conditions of acetylation were determined by orthogonal experiments. When acetylation was performed at 140 °C with 10 mL AA/g BR and 0.08 g catalyst/g BR, the maximum weight gain rate (WGR) obtained was 23.7%. Fourier transform infrared (FTIR) analysis showed that many hydroxyl groups were displaced by acetoxy groups. Scanning electron microscopy (SEM) showed that many defects of BR were filled by the acetylation, and an ester layer was formed over the BR surface. However, the lower crystallinity of ABR than the BR and RS affected the mechanical properties of acetylated biogas residue/low density polyethylene (ABR/LDEP) composite. Interestingly, the BR and ABR showed higher onset decomposition temperature, but they exhibited faster decomposition rates because of the lower crystallinity of BR and ABR. Furthermore, the mechanical properties of the RS/LDEP, BR/LDEP, and ABR/LDEP composites were analyzed. Compared with RS/LDEP composites, the BR/LDEP and ABR/LDEP composites showed obviously better tensile and flexural properties. Consequently, rice straw fibers attained excellent compatibility with non-polar polymers.

Coconut shell, a natural biopolymer, is available in high amounts as waste in many countries. It could potentially be a crucial renewable source of raw materials for the carbon fiber industry. In this study, a series of aprotic ionic liquids, [Bmim][Ace], [Bmim]Cl, [Emim][Ace], and [Emim]Cl, were used in the dissolution and regeneration process of coconut shell. The results indicate that the dissolution of coconut shell (up to 70 mg of coconut shell per g of solvent) can occur in aprotic ionic liquids under a nitrogen atmosphere at 110 °C (6 h) and 150 °C (2 h). The extraction efficiency was greatly influenced by temperature, time, particle size, and types of cations and anions in the ionic liquids. At 150 °C, 10% regenerated lignin was obtained in [Emim][Ace], which was higher compared with [Emim]Cl, [Bmim][Ace], and [Bmim]Cl. The recyclability of the ionic liquids during the dissolution process (up to four times) was also scrutinized. The structure and properties of the untreated coconut shell and regenerated lignin were characterized by Fourier transform infra-red (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, and proton nuclear magnetic resonance (¹H NMR).

Non-crystal microporous starch (NCMS) containing microporous and amorphous structures was prepared from native corn starch by heat treatment and solvent exchange. NCMS can be used as fillers, coatings, and raw materials in the preparation of various denatured starch because of its specific surface area and amorphous region. However, the hydrophilicity of NCMS limits its applications in papermaking. Thus, in this study, NCMS was reacted with alkyl ketene dimer (AKD) to prepare hydrophobic NCMS (H–NCMS), which is more stable, and convenient for storage and use in surface sizing. The optimal preparation conditions were selected using single-factor tests. The product, which was prepared at 55 °C for 3 h with an AKD dosage of 80%, had a sizing degree of 67 s. Characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy confirmed that NCMS, H–NCMS, and sized paper were obtained. The thermal stability and hydrophobicity of the paper were measured using thermogravimetric analysis (TGA) and water contact angles, respectively. The results indicated that the sized paper has excellent thermal stability and hydrophobicity after surface sizing with 0.9% H–NCMS. Food wrapping paper with excellent strength and hydrophobicity was successfully prepared using H–NCMS and ultrasonic-assisted wheat straw pulp (UWP).

The potential energy balance of the sawing logs for Eucalyptus lumber production was determined. Eucalyptus grandis logs (n = 10) were sawn with a band saw, and the planks were re-sawed with a circular saw. The sawing yield was calculated with the volumes of logs, lumbers, and wastes. The consumption of electric energy was measured using a multifunctional meter. The energy stored in the wood was determined by the lower calorific value of wood; the superior calorific value was calculated and converted into the respective active energy (kWh) value. The potential energy balance was calculated using the values of the consumed electricity in the saws and that of the energy stored in the waste. Another energy balance was calculated by considering the energy stored in the timber. The potential energy balance for sawing 1 m³ of log was equal to 1,206 kWh, considering only the energy stored in the waste. When added to energy stored in the timber, the energy balance was 2,671 kWh. The positive results of energy balances demonstrate the potential of energetic self-sufficiency of timber production.

Recycled polypropylene (RPP) and lignin represent by-products produced in enormous amounts worldwide that remain underutilized. This study used rice straw lignin as a filler at various concentrations (0% to 70% w/w) in RPP and virgin polypropylene (PP) composites by melt blending. Structural and morphological alterations of lignin were analyzed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), respectively. Mechanical properties were evaluated using a universal testing machine (UTM). Results revealed that the tensile strength of the composites decreased as the lignin content increased, presumably due to the low of compatibility degree of lignin and MAPP, as well as the crack formation due to the agglomeration of lignin. However, composites with lignin as a filler showed higher moduli and water absorption capacities, as well as thickness swelling; using lignin as a filler caused a drastic reduction of the elongation at break values. The results indicated that the physical and mechanical properties of RPP and its virgin PP composites had no substantial differences. This indicated that virgin PP could be substituted by recycled polypropylene (RPP) for composite applications with the addition of MAPP.

Structural performance of chemically modified oriented strand board (OSB) has drawn great attention from builders, home insurance companies, and panel manufacturers. This study was conducted to provide time-dependent creep and moisture change-induced mechano-sorptive (MS) effect data from borate-treated and randomly formed strand board. The strand boards were lab-fabricated with flakes from southern yellow pine and mixed hardwoods. Commercial liquid phenol-formaldehyde resin was used as the binder. The treatments involved in the study were one level of zinc borate, one level of calcium borate, and two species groups that included separate controls. The load level, equivalent to 25% of the static bending modulus of rupture, was selected as a long-term constant load. Creep at 65% constant relative humidity (RH) developed in a normal time-dependent fashion and the Burger body creep model with four spring-dashpot elements was found appropriate to predict the creep response of borate modified strand board. Noticeable influence of borate modification on the fractional deflection was demonstrated under changing RH for both the absorption and desorption cycles. The measured fractional deflection due to the MS effect followed a linear relationship with moisture content change. The established material constants for various strand boards provided a way to predict the structural performance of treated strand board under varying RH conditions.

A facile method is reported to prepare nanocellulose fibers from oil palm trunk fibers. The fibers were pretreated 2 hours with NaOH/urea solution, and the fully swelled fibers were mechanically treated through high-pressure homogenization to obtain nanocellulose. The nanocellulose fibers were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR results revealed that there was no obvious difference between the spectra of the bleached fibers (BF), pretreated cellulose fibers (PCF), and cellulose nanofibers (NCF), which indicated that the pretreatment process is a non-derivative reaction. The crystallinity of PCF and NCF decreased and contained the cellulose I crystal structure. The PCF presented both a distorted structure and a coarser surface. The resulting NCF were approximately 10 nm to 100 nm in diameter with the length varying from hundreds of nanometers to several micrometers, as observed by SEM. The thermal degradation of NCF was 223 °C with about 20% weight loss, and the maximum degradation temperature was 338 °C. NaOH/urea showed potential as a mild solvent for preparing nanocellulose fibers.

Reconstituted square lumber (RSL) was fabricated using mulberry branch as the raw material and polymeric diphenylmethane isocyanate (P-MDI) as the adhesive, and its mechanical properties were investigated. By using single factor and orthogonal experiments, the optimal parameters to produce RSL had 10% glue content, 160 °C hot-press temperature, and a 45 min hot-press time. The density distributions along with width, thickness, and length directions were scanned with DENSE-LAB X (density profile measuring system). Density was a significant factor that influenced the performances of mulberry branch RSL. The amount of glue also greatly affected the internal bond strength (IB), modulus of elasticity (MOE), modulus of rupture (MOR), and the 2-h thickness swelling rate of water absorption (TS2h) of RSL. Hot-press time affected the TS2h of RSL, but did not have a significant effect on the MOE, MOR, and IB of RSL. Hot-press temperature had an effect on the MOR of RSL, which significantly influenced the TS2h of RSL and slightly affected its MOE and IB. The density distribution of RSL was steep and flat in the width direction, steep in the thickness direction, and uniform in the length direction.