Research Articles

Self-tapping screws are commonly used to connect critical structural components, such as legs to rails in chair construction, using laminated bamboo lumber (LBL) materials. The loosening of a connection is commonly seen in self-tapping screwed LBL connections before actual breakage of connections happens. The loosening of connections, especially those associated with chair legs, can significantly affect chair stability. Current furniture performance test standards have not address this issue, i.e., the minor loosening of a connection is not treated as a failure in the current standard because of the lack of better understanding the load-rotation-time behavior of various connections subjected to the cyclical loads. The effects of cyclic loading magnitude and orientation on the load-rotation-time behavior of L-shaped, end-to-side, single self-tapping screwed LBL connections were investigated. Results indicated that the Burger and Kelvin models could be used to describe the cyclic and recovery behavior of studied connections. Increasing the cyclic loading magnitude resulted in a decreasing trend for all viscoelastic constants. The most significant decrease in all viscoelastic constants occurred when the cyclic loading magnitude applied to connections increased from 50 to 60% of its corresponding ultimate static resistance loads.

Two kinds of thermoresponsive 2-hydroxy-3-alkoxypropyl hydroxyethyl celluloses (HAPEC) were prepared by grafting butyl and isopropyl glycidyl ethers onto hydroxyethyl celluloses (HEC). The HAPEC was characterized by 1H NMR, 13C NMR, and 2D HSQC NMR. The lower critical solution temperature (LCST) of HAPEC can be tuned by changing the molar substitution (MS). The LCST decreased with the increasing MS of the alkyl chains. The HAPEC concentration, salt concentration, and organic solvent concentration had a marked influence on LCST. In addition, the differences of thermoresponsive properties between the two kinds of HAPECs were investigated. 2-Hydroxy-3-butoxypropyl hydroxyethyl cellulose (HBPEC), which has longer hydrophobic side chains, demonstrated a lower LCST when both HBPEC and 2-hydroxy-3-isopropoxypropyl hydroxyethyl cellulose (HIPEC) possessed similar MS values. HBPEC, which has longer hydrophobic side chains, exhibited thermoresponsive flocculation behavior, and the critical flocculation temperature (CFT) was adjusted in the range from 27.3 to 51.2 °C by changing the molar substitution.

As a great amount of chemicals are employed to carry out the coating process of paper, the wastewater from paper mill making coated products is characterized by high levels of chemical oxygen demand (COD), colour, and total suspended solids (TSS). In this study, wastewater from a paper mill making coated products was treated by a sequencing batch biofilm reactor (SBBR) after a lab-scale coagulation, resulting in COD, colour, and TSS removal efficiencies of 87.7 ± 1.0%, 33.5 ± 5.2%, and 41.4 ± 3.7%, respectively, which exceeded the biological treatment performance in the paper mill. The removal of COD and colour was attributed to the removal of recalcitrant organic matter, and the removal of TSS was attributed to the biofilm.

As the by-product of biomass pyrolysis, wood vinegar (WV) possesses numerous beneficial properties and has been used in many fields. The properties and utilization of WVs are primarily influenced by the type of biomass feedstock and the production techniques. In this paper, WVs were pyrolyzed from fir sawdust waste at 350 to 650 °C to study their growth regulation effect on wheat seed and to investigate the underlying mechanisms. The highest yield of WV was at 450 °C with major components of phenols (37.92%) and acids (24.59%). The concentration of WVs has a major influence on regulation effect, which mainly affected the development of lateral roots. Compared with sterile water (CK), the WV-2 showed the highest seed germination rate and lateral roots growth, which increased nearly 65% and 92%, respectively. The lower concentration of WVs increased the roots vigor (RV) and promoted growth, while the higher concentration increased the content of malondialdehyde (MDA) and inhibited growth. The increased MDA indicated that wheat roots were suffering from oxidative stress. The findings revealed the suitability of WV as growth regulator in sustainable agriculture and also provided an efficient way for biomass waste utilization.

Many academic studies over the years have confirmed that mechano-sorptive (MS) creep is an inherent characteristic of wood. Unlike solid wood, bond lines are introduced into laminated veneer lumber (LVL), creating a laminated structure with different hygroscopicity. What are the effects of these differences on the MS creep of LVL? In this study, three groups of well-matched LVL samples were subjected to four-point bending loading within different relative humidity cycles. For each group, the applied load ranged from 15% to 35% of the short-term fracture load. The results showed that after the first hygroscopic process, LVL showed irreversible expansion (0.11 mm) and a relatively slow moisture adsorption rate. These made it difficult for LVL to show partial creep recovery during the first adsorption process no matter how low the load level was, while solid wood showed partial creep recovery when the load level was ≤ 25%. The following creep behavior of LVL was similar to that of solid wood: partial creep recovery started from the second adsorption stage when a moderate load level was applied.

A biocomposite was successfully prepared by blending montmorillonite (MMT)/hemicellulose from oil palm empty fruit bunches (OPEFB) with carboxymethyl cellulose (CMC) through solution casting. The composite was characterized by scanning electron microscopy (SEM), Fourier transmission infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The results displayed good compatibility between the mixtures of the blended MMT/hemicellulose and CMC due to the hydrogen bonding and electrostatic interaction. There was an improvement in the thermal analysis through their thermogravimetry analysis (TGA), derivative thermogravimetry (DTG), and differential scanning calorimetry (DSC), mechanical properties (tensile strength and tensile modulus),and water vapor permeability (WVP). The best values of tensile strength and tensile modulus of 47.5 MPa and 2.62 MPa, respectively, were obtained from 60H-40CMC-MMT nanocomposite films. The results showed that the mixture of the blended MMT/hemicelluloses and CMC produced a robust nanocomposite film with improved physical and mechanical properties, demonstrating that it is a promising candidate for green packaging applications.

Thermally treated wood is widely used for construction, furniture, and flooring because it has better dimensional stability in outdoor conditions. There is a close relationship between the mechanical properties of thermally treated wood cell walls and the performance of its products. The hardness (H) and reduced elastic modulus (Er) of larch (Larix gmelinii) and red oak (Quercus rubra) wood cell walls were investigated via nanoindentation. The results showed that the larch and red oak wood specimens had different nanomechanical properties. The Er in the larch wood initially increased with a maximum value of 22.4 GPa at 225 °C, then rapidly decreased after 300 °C with a minimum value of 5.7 GPa at 350 °C. The Er in the red oak wood appeared to have a mild decline. The H in both wood species visibly increased with the thermal treatments due to the reduction of organic wood polymers and the increase of inorganic carbon materials.

The material basis and degradation of the terpenoids were investigated in Pinus massoniana sawdust during the composting process. In order to better utilize P. massoniana sawdust for the culturation of edible fungus, three treatments were designed according to the amount of brown sugar that was added: 4% (A1), 5% (A2), and 6% (A3). The brown sugar was added based on the dry weight of the P. massoniana sawdust. The results showed that the brown sugar addition of 5% yielded the fastest heating rate of composting and the longest temperature duration above 60 °C. The gas chromatography-mass (GC-MS) analysis showed that the amount of brown sugar did not affect the degradation of the terpenoids. The relative terpenoid content decreased from 3.89% to 2.10% and 0.31% after 30 d and 60 d of composting, respectively. Fourier transform infrared (FTIR) analysis indicated that the terpenoids decomposed a lot throughout the composting process. The mycelium cultivation demonstrated that the P. massoniana sawdust treated with 30 d of composting promoted the growth of edible fungi.

In order to promote plantation establishment of Larix gmelinii var. olgensis (syn. L. olgensis A. Henry), a ‘near threatened’ species, the wood and lumber properties were preliminary investigated for five trees from two clones of 57-year-old trees planted in Japan. The mean value of dynamic Young’s modulus of logs was 10.16 GPa. The mean values of annual ring width, latewood percentage, basic density, MOE, and MOR of five sample trees were 2.1 mm, 29.3%, 0.47 g•cm-3, 8.06 GPa, and 60.4 MPa, respectively. In addition, the MOE and MOR of 2 by 4 lumber were 10.43 GPa and 42.4 MPa, respectively. These values were similar to those obtained from other Larix species. Thus, construction lumber could be produced from the wood from plantation grown L. gmelinii var. olgensis.

Changes in chemical composition and structure of corncob lignocellulosic biomass were investigated relative to pretreatment and anaerobic digestion. The pretreatment involved 1% and 3% sodium hydroxide, 3% and 7% sulphuric acid, as well as medium and high temperature extrusion (in 110 °C and in the range from 140 °C to 160 °C). The chemical components content was studied using a gravimetric method, whereas structure and relations between the carbohydrate and lignin participation were investigated using Fourier transform infrared spectroscopy. It was determined that the chemical treatment, both acidic and alkaline, changed the chemical composition of corncob more significantly than the extrusion. Alkaline pretreatment contributed to significant delignification, while acidic pretreatment reduced the share of hemicelluloses and increased the proportion of lignin, the so-called “pseudolignin”. The composition of corncob (control and after pre-treatment) was changed after anaerobic digestion, i.e., a decreased carbohydrate substance content and a significantly increased lignin content. FTIR analysis showed changes in their structure. Although the control corncob differed from that processed by various pretreatment methods, the chemical composition of the digested pulp obtained from them was similar. The NaOH pretreatment was judged to be the preferred method for delignification of the raw material.