Preparation of tannic acid-reinforced cellulose nanofiber composites for all-water-based high-performance wood adhesives.

Traditional adhesives easily release toxic gases during the preparation process or apply to wood composite products, which have adverse effects on the human body and the environment. Herein, an all-water-based high-performance wood adhesive is prepared using TEMPO-oxidized cellulose nanofiber (TOCNF), acrylamide (AM), and tannic acid (TA) through free radical polymerization. Different characteristics of the prepared composites, including morphology, injectability, and adhesion properties, have been investigated. Results showed that the TA/TOCNF/PAM composite has excellent injectability. The addition of TA can enhance the lap shear strength of the TA/TOCNF/PAM composites and with the increment of TA content, the lap shear strength gradually decreases. The formation of effective hydrogen bonds and Van der Waals interaction among the rich functional groups in the composite, lead to strong lap shear strength on different substrates. The composite with 5.0 g of AM, 5.0 g of the TOCNF suspension and 0.1 g TA possesses a high lap shear strength of 10.5 MPa on wood and 1.5 MPa on aluminium. Based on strong adhesion properties and excellent injectability, the TA/TOCNF/PAM composites have great potential in the furniture construction and building industries.

Nanocellulose Composite Films in Food Packaging Materials: A Review.

Owing to the environmental pollution caused by petroleum-based packaging materials, there is an imminent need to develop novel food packaging materials. Nanocellulose, which is a one-dimensional structure, has excellent physical and chemical properties, such as renewability, degradability, sound mechanical properties, and good biocompatibility, indicating promising applications in modern industry, particularly in food packaging. This article introduces nanocellulose, followed by its extraction methods and the preparation of relevant composite films. Meanwhile, the performances of nanocellulose composite films in improving the mechanical, barrier (oxygen, water vapor, ultraviolet) and thermal properties of food packaging materials and the development of biodegradable or edible packaging materials in the food industry are elaborated. In addition, the excellent performances of nanocellulose composites for the packaging and preservation of various food categories are outlined. This study provides a theoretical framework for the development and utilization of nanocellulose composite films in the food packaging industry.

Preparation and sustained-release properties of poly(lactic acid)/graphene oxide porous biomimetic composite scaffolds loaded with salvianolic acid B.

Biomimetic scaffolds loaded with drugs can improve the osteogenesis and neovascularisation of scaffolds. A series of PLA/GO/Sal-B drug-loaded scaffolds was prepared by thermally induced phase separation. The addition of Sal-B increased the diameter of the fibres, but the scaffold showed a porous nanofibrous structure after drug release. X-ray diffraction results showed that the addition of Sal-B did not affect the formation of the nanofibre biomimetic structure of the scaffold. FTIR results indicated a certain interaction between Sal-B and PLA/GO. Water absorption and porosity test results revealed that the scaffolds had good hydrophilicity and appropriate porosity. The addition of Sal-B was also conducive to the formation of sediments possibly due to the good water solubility of Sal-B itself. The prepared scaffolds had good blood compatibility and cytocompatibility, and a small additional amount of Sal-B could significantly promote cell proliferation and alkaline phosphatase activity. Their sustained release performance indicated that the biomimetic scaffolds had controlled the release of Sal-B. The kinetic model showed that the PLA/GO/Sal-B drug-loaded biomimetic scaffolds followed the diffusion mechanism.

Unsaturated Polyester Resin as a Nonformaldehyde Adhesive Used in Bamboo Particle Boards.

Unsaturated polyester resin (UPR) with good chemical resistance, excellent mechanical properties, and formaldehyde-free shows great potentials in the wood industry. In this study, the mechanical strength, thermostability, dynamic thermomechanical property, and interfacial bonding of bamboo particle boards (BPBs) made from UPR adhesives with toluene diisocyanate (TDI) as the coupling agent were explored. The results showed that covalent bonds were formed among TDI, bamboo particles, and UPR, which could significantly enhance the mechanical strength. The internal bonding strength, modulus of elasticity, and modulus of rupture of treated BPBs were 1.36, 3010, and 19.6 MPa with the increment of 1250, 514, and 833%, respectively, compared to the control samples. Also, the thickness swelling rate of the BPB was 4.6%, much lower than that of the control, with a decrease of 92%. The thermostability of the treated BPB was also improved. As a result, the BPB using UPR as the adhesive and TDI as the coupling agent shows better usability, higher efficiency, and excellent mechanical strength.

Eco-benign PVA/aluminum phosphate as an alternative to formaldehyde-based adhesives in wood-based panels.

Aluminum phosphate (AP) shows great potential to replace formaldehyde-based adhesives in the wood industry, except for its weak hygroscopic resistance and low wet bonding strength. This study chose PVA as an AP modifier to prepare a PVA-AP organic-inorganic hybrid adhesive (PAP). The preparation, bonding mechanism and heat resistant property of PAP were studied by using X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The result showed that covalent bonds between PVA and AP were built. The mechanical properties of PAP improved remarkably; the dry and wet bonding strength are 2.28 and 0.79 MPa with 15.2% and 690% increment, respectively, compared to the control samples. The thermostabilities of PAP and plywood samples were improved. In conclusion, PVA could effectively improve the hygroscopic resistance and low wet bonding strength of AP adhesives.

Highly Anisotropic Corncob as an Efficient Solar Steam-Generation Device with Heat Localization and Rapid Water Transportation.

Solar steam generation is receiving considerable interest because of its potential application in wastewater treatment and desalination. Many devices with various photothermal materials and structures have been demonstrated to be solar steam evaporators by improving their light absorption, heat loss, water transportation, and vapor escape. However, developing a biomass-based evaporator with heat localization and rapid water transportation is highly desired yet still challenging. Here, corncobs, a kind of agricultural waste with vascular bundle and "vesiculose" structures, are used to fabricate solar steam-generation devices. After high-temperature treatment, the carbonized corncobs maintain the highly anisotropic porous framework and favorable hydrophilicity and thereby have excellent thermal management and water transportation. With efficient solar absorption, heat localization, and rapid water transportation, the lightweight carbonized corncobs can float on water and generate water vapor with a high steam generation efficiency of 86.7% under 1 sun.

Hierarchical Porous Aluminophosphate-Treated Wood for High-Efficiency Solar Steam Generation.

Solar steam generation as a promising solar energy conversion technology has attracted considerable interest in achieving seawater desalination and water purification. Although wood with fast water transportation and excellent heat localization has drawn particular interest in regard to its application for solar steam generation, challenges still remain in terms of its complicated processing techniques and relatively low efficiency. Here, we propose a facile, cost-efficient, and scalable brushing method to prepare an aluminophosphate-treated wood (Wood@AlP) solar steam generation device. The aluminophosphate compound deposited on the wood surface can not only be considered as the Lewis acid catalyst capable of accelerating the formation of the carbon layer but also provide an aluminophosphate layer with a hierarchical porous structure, which is beneficial for broad solar absorption and vapor escape. On the other hand, benefiting from the natural hydrophilicity, low thermal conductivity, and excellent water transportation of wood, the obtained Wood@AlP device can float on seawater and exhibit a high solar thermal efficiency of 90.8% with a net evaporation rate of 1.423 kg m-2 h-1 under 1 sun illumination.

Machinability investigation in turning of high density fiberboard.

A series of experiments were conducted to assess the machinability of high density fiberboard using cemented carbide cutting tools. The objective of this work was to investigate the influence of two cutting parameters, spindle speed and feed per turn, on cutting forces, chip formation and cutting quality. The results are as follows: cutting forces and chip-breaking length decrease with increasing spindle speed and decreasing feed per turn. In contrast, surface roughness increases with decrease of spindle speed and increase in feed per turn. Chips were divided into four categories based on their shape: dust, particle, splinter, and semicontinuous chips. Chip-breaking length had a similar tendency to the variance of cutting forces with respect to average roughness and mean peak-to-valley height: an increase in the variance of cutting forces resulted in increased average roughness and mean peak-to-valley height. Thus, high cutting speed and low feed rate are parameters suitable for high-quality HDF processing and will improve not only machining quality, but production efficiency.