Wood–plastic composites (WPCs) are facing fire hazard when they are used in construction and furniture and need to be treated with fire protection. In this work, polyurethane (PU) was applied to derive simultaneously flame‐retardancy‐improved and mechanically strengthened wood‐polyurethane composites (WPUCs). It was constructed with ammonium polyphosphate (APP) and PU by a simple way. The results showed that a decrease in smoke production in the Cone Calorimeter Test was measured. When the mass of APP is 18% of PU, limiting oxygen index can reach 31.2%. In the combustion test, the peak of heat release rate and total smoke production for WPUCs were, respectively, decreased by 42.1% and 89.7% in the presence of the above ratio of APP and PU. In addition, the results of the functional group test show that PU contains highly reactive ‐NCO which is bonded to the ‐OH and moisture in the wood fiber, resulting in improvement of physical and mechanical properties. The mechanism for the flame retardancy of WPUCs revealed that polyphosphoric acid produced by APP pyrolysis catalyzed PU into the char, and PU was arched by the resulting gases such as NH 3 to form the tiny spherical structure, which worked in blocking heat and the exchange of substances. WPUCs with APP prepared by this method are shown to have improved results, and, therefore, it is expected to provide a new strategy for the preparation of flame‐retardant WPCs.

Disposable consumer electronics become electronic waste at the end of their life, which can cause serious environmental pollution if discarded in the ground. Here, we have developed an all-wood-based flexible electronic device. The substrate is used to prepare self-densification wood-derived paper (SWP) at room temperature through the natural balsa wood (NW) self-densification process. Chemical treatment removed lignin and hemicellulose from NW, and the cell wall structure collapsed under the action of elastic capillary force generated by water evaporation. The hydrogen bonds between the cellulose fibers are further strengthened, and the arrangement of the cellulose fibers is maintained. The obtained SWP exhibits an excellent tensile strength of 229.4 ± 10.4 MPa in the fiber direction, which is 8.3–8.6 times (27.1 ± 1.7 MPa) and 4.2–4.8 times (51.2 ± 5.6 MPa) higher than NW and cellulose paper, respectively, and higher than some commercial plastics. In addition, it also exhibits excellent wetting performance and a certain degree of transparency. Finally, conductive wood carbon ink prepared from carbonized NW can be directly written on SWP using a Chinese brush to obtain customized patterns. We have demonstrated the application of an all-wood-based flexible electronic device in flexible sensors that can stably monitor finger movements. This newly developed all-wood-based composite can return to the carbon cycle of nature after its service life, providing a new way to replace traditional electronic products.

Surface modification of porous wood carbon (PWC) has been studied to improve its electrochemical perfor-mance. However, current research has not fully understood the impact of surface chemical properties of modified PWC on electrochemical performance and the mechanism of capacitive energy storage. Herein, a simple hy-drothermal method is used to obtain HNO3-treated porous wood carbon (HPWC) by surface modification of PWC using HNO3 solution. Etching PWC with HNO3 greatly increases the specific surface area and improves the pore size, which is conducive to ion/electron transport. At the same time, various oxygen-containing functional groups are introduced, improving the capacitance performance. Furthermore, the dynamic analysis of the electrode reveals that the higher rate performance of the electrode is related to the lower relaxation time constant and higher surface capacitance contribution rate. The results showed that the 6 M HNO3-treated porous wood carbon (HPWC-6) had a high area specific capacitance (747.1 mF cm-2 at 1 mA cm-2) and rate capability (38.1 % capacitance retention at 20 mF cm-2). The HPWC-6 assembled into a symmetrical supercapacitor can power an LED light, revealing its practical value. This study combines experimental and theoretical analysis to provide guidance for the preparation of high-performance wood-based supercapacitor electrodes.

Strong, conductive, and flexible materials with improving ion accessibility have attracted significant attention in electromagnetic interference (EMI) and foldable wearable electronics. However, it still remains a great challenge to realize high performance at the same time for both properties. Herein, a microscale structural design combined with nanostructures strategy to fabricate TOCNF(F)/Ti3 C2 Tx (M)@AgNW(A) composite films via a facile vacuum filtration process followed by hot pressing (TOCNF = TEMPO-oxidized cellulose nanofibrils, NW = nanowires) is described. The comparison reveals that different microscale structures can significantly influence the properties of thin films, especially their electrochemical properties. Impressively, the ultrathin MA/F/MA film with enhanced layer in the middle exhibits an excellent tensile strength of 107.9 MPa, an outstanding electrical conductivity of 8.4 × 106 S m-1 , and a high SSE/t of 26 014.52 dB cm2 g-1 . The assembled asymmetric MA/F/MA//TOCNF@CNT (carbon nanotubes) supercapacitor leads to a significantly high areal energy density of 49.08 µWh cm-2 at a power density of 777.26 µW cm-2 . This study proposes an effective strategy to circumvent the trade-off between EMI performance and electrochemical properties, providing an inspiration for the fabrication of multifunctional films for a wide variety of applications in aerospace, national defense, precision instruments, and next-generation electronics.

In this work, phase change energy storage wood (KBN-PCES@Balsa) was obtained by injecting PGMA into the porous tissue of wood by high temperature and high pressure method, and the BN grafted with KH550 and DA (KH550-DA-BN) was synthesized to improve the heat transfer rate. Studies have found that PGMA has good thermal conductivity in the cavities of woody cells. After adding KH550-DA-BN to PGMA, the KH550-DA-BN combines with PGMA in a physically dispersed manner and the crystal structure of PGMA does not change. When the filling amount of KH550-DA-BN is 6 wt%, the thermal conductivity of KBN-PCES@Balsa increases to 0.4185 W/(m.K), its melting enthalpy and solidification enthalpy are all maintained at 103.40 J/g and 100.20 J/g, respectively. The KBN-PCES@Balsa shows efficient solar-to-thermal energy conversion and a lasting heat storage capacity under simulated sunlight. After 200 cycles of cooling and heating, the melting enthalpy and solidification enthalpy of KBN-PCES@Balsa are both above 120 J/g, indicating that KBN-PCES@Balsa has good stability in use. There is no leakage of 6 % KBN-PCES@Balsa after heated at 80 degrees C for 4 h, due to the interpenetrating network structure between PGMA and wood components. The phase change heat storage wood prepared in this research increases the potential of wood for temperature regulation in fields such as building materials, furniture and aerospace.

A micro/nano-multiscale hierarchical structure strategy is used to fabricate films. A leaf-like structure with AgNWs and MXene results in a conductive 3D network. TOCNFs in the middle layer endow the films with excellent mechanical properties.

Wood is a great natural material with good energy storage and temperature adjustment for the energy crisis. In this study, wood was delignified, and the PEG-based eutectic polymer (PGMA) was impregnated into the delignified wood, and styrene (SM) grafted AlN was selected as thermal conductive filler to synthesize a stable phase change heat storage wood. The result shows that the styrene (SM) polymerized on the surface of AlN to form polystyrene (PS), and the dispersion of AlN was enhanced. The thermal stability and loss resistance of PCES-Wood are improved for the penetration of PS-AlN into the cavities, which is attributed to the PS-AlN playing a “limiting” role in the crystallization of PGMA. When the content of PS-AlN is 6%, the thermal conductivity of PCES-Wood reaches 0.5148 W/(m·K). 4% PS-AlN-PCES@Balsa has the lowest undercooling and heat loss rate, and the melting enthalpy and solidification enthalpy reach 125.60 J/g and 120.30 J/g, respectively. The phase change temperature range is between 19.59 and 33.87 °C, which is in the comfortable temperature range for humans. Under the illumination of the simulated solar light source, the surface temperature of PS-AlN-PCES@Balsa rises rapidly and shows a lasting heat storage capacity at low temperatures compared with the original wood. After 200 cold and hot cycle tests, the phase change enthalpy of PS-AlN-PCES@Balsa is still high, and there is a slight leakage phenomenon. The phase change wood prepared in this study shows that it is a potential material to store and release solar energy in practical applications.

Phase change materials (PCMs) in the thermal storage of construction can reduce energy waste by shrinking the diurnal daily temperature changes inside. The thermal energy storage (TES) wood-plastic composites (WPC) are manufactured by employing expanded perlite (EP) stabilized PEG as PCM and wood powder/high-density polyethylene (WF/HDPE) as a matrix. The novel type of shell-core PCM (E-shell PCM) was prepared through cation exchange and layer upon layer self-assembly built organic network structure, which was featured by the very thin shell and ultra-high content of active core materials. The unique protective shell gave the PCM high latent heat potential (136.40 J/g), good structural stability, and broad prospects for sustainable energy appliocation. The TES WPC has excellent morphological stability, high phase transition heat and significant thermal stability, heat storage performance, and good mechanical strength. With the gradual increase of E-Shell PCM, the latent heat of TES WPC phase transition increases gradually, and the melting enthalpy and crystallization enthalpy reach 76.06 J/g and 74.61 J/g, respectively. Simultaneously, the introduction of EP promoted the composite heat and smoke suppression ability, suggested as a building material used for temperature control. Latent heat WPC may be utilized as biological building materials with high latent heat and strong mechanical properties to cut down on energy use and enhance interior comfort.

The possibility of agricultural-forestry waste (rice husks) and biodegradable plastics (poly(lactic acid)) being used to produce ecologically friendly foam composite was discussed in this work. The effects of different material parameters (the dosage of PLA-g-MAH, type and content of chemical foaming agent) on the microstructure and physical properties of composite were investigated. PLA-g-MAH promoted the chemical grafting between cellulose and PLA, and made the structure denser, thus improving the interface compatibility of the two phases and resulting in good thermal stability, high tensile strength (6.99 MPa) and bending strength (28.85 MPa) of composites. Furthermore, the properties of rice husk/PLA foam composite prepared by two kinds of foaming agents (endothermic and exothermic) were characterized. The addition of fiber limited the growth of pores, which provided better dimensional stability and narrower pore size distribution, made the interface of the composite bond tightly. And the bubble can prevent crack propagation and improve the mechanical properties of the composite. The bending strength and tensile strength of composite were 37.36 MPa and 25.32 MPa, which increased by 28.35 % and 23.27 %, respectively. Therefore, the composite prepared by using agricultural-forestry wastes and poly(lactic acid) possess acceptable mechanical properties, thermal stability and water resistance, expanding the scope of application.

To improve the flammability of foamed polyurethane/wood-flour composites (FWPC), ammonium polyphosphate (APP) was used as a flame retardant to modified FWPC. The effects of different flame treatment processes on flame performance, smoke suppression, thermal property, and surface micrographs of flame retardant FWPC were investigated. The results showed that FWPC with the addition or impregnation process both improved the combustion behaviors. Compared with the addition process, FWPC-impregnation (FWPC-I) had a lower total heat release (THR), lower peak heat release rate (PHRR), prolonged time to ignition (TTI), more residues, and better combustion safety. FWPC-I had the highest residual carbon rate reaching 39.98%. A flameretardant layer containing the P-O group was formed in the residual carbon of FWPC-I. Although APP had negative effects on the physical properties of FWPC, it was an effective flame-retardant ability for foamed polyurethane/wood-flour composites.

It is of great value to create new bio based green energy-saving and temperature regulating materials under the background of carbon peak and carbon neutralization. In this study, balsa wood was prepared by delignification as encapsulation materials to combine with polyethylene glycol based phase change materials (PCMs) to make phase change energy storage wood (PCES-Wood). In order to improve the thermal conductivity of PCES-Wood, the carbon black grafted with octadecyl isocyanate(aCB)was impregnated into the wood to obtain a thermally enhanced phase change energy storage wood (aCB-PCES@Balsa). The results show that aCB exhibited superior dispersibility and formed thermal conduction pathways in the wood. When the aCB content is 4%, the degree of supercooling of aCB-PCES@Balsa is the smallest, and the melting enthalpy and solidification enthalpy reach 100.34 J/g and 91.10 J/g, respectively. The 4% aCB-PCES@Balsa also exhibits strong hydrophobicity and full-optical-segment absorption. Under the irradiation of a simulated solar light source, the surface temperature of 4% aCB-PCES@Balsa rises rapidly to 28 degrees C and exhibits long-lasting heat storage capacity at low temperatures. After 200 cycles of cooling and heating, the phase change energy storage wood still maintains a high phase change enthalpy value, indicating that the aCB-PCES@Balsa has a good durability. This study provides a new approach for green heat storage in biomass composites.

AbstractWood-plastic composites (WPCs), which are widely used in construction and furniture, need to be treated with fire protection. In this work, polyurethane (PU) was applied to derive simultaneously flame-retardancy-improved and mechanically strengthened wood-polyurethane composites (WPUCs). It was constructed with ammonium polyphosphate (APP) and PU by an eco-friendly way of pressing at ambient temperature. The combination of APP and PU improves the flame retardancy and smoke suppression of WPCs. The results indicated that the flame retardancy of WPUCs is the best when the mass of APP is 18% of PU, making LOI reach 31.2%. In the combustion test, the peak of heat release rate and total smoke production for WPUCs were respectively decreased by 42.1% and 89.7% in the presence of the above ratio of APP and PU. In addition, the results of the functional group test show that PU contains highly reactive -NCO which is bonded to the -OH and moisture in the wood fiber, resulting in improvement of physical and mechanical properties. The mechanism for the excellent flame retardancy of WPUCs revealed that polyphosphoric acid produced by APP pyrolysis catalyzed PU into the char, and PU was arched by the resulting gases such as NH3to form the tiny spherical structure. Meanwhile, the spherical structure increased the height and density of the carbon layer, which worked in blocking heat and the exchange of substances. This work provides a simple and economic strategy for the preparation of flame-retardant WPCs.

A novel thermal energy storage (TES) composites system consisting of the microPCMs based on n-octadecane nucleus and SiO2 /honeycomb-structure BN layer-by-layer shell as energy storage materials, and wood powder/PBAT as the matrix, was created with the goal of improving the heat transmission and photothermal responsiveness of building materials. The microPCMs were made via mini-emulsion interfacial polycondensation and electrostatic self-assembly to anchor BN on the surface of the SiO2 shell. The two kinds of microPCMs we designed had regular spherical morphology, BN was successfully anchored outside the SiO2 shell, showing a honeycomb structure and good heat storage performance (140.4J/g and 140.6J/g). The TES WPCs had considerable energy storage capacity and temperature regulation ability. The TES WPCs with the unique honeycomb structure of BN-MicroPCMs had better heat transfer performance and photothermal conversion efficiency (69.54%), and the thermal conductivity, specific heat capacity and energy storage efficiency of which were increased by 75.06%, 87.06% and 200% respectively. Meanwhile, the unique honeycomb structure strengthened the interfacial bond strength of TES WPCs and brought satisfactory mechanical strength, and the tensile strength, elongation at break, bending strength and bending modulus of BN-WPC are increased by 51.16%, 97.01%, 81.28% and 742.74%, respectively compared with the S-WPC. These results indicated that this research by designing the BN honeycomb structure layer on the traditional microPCMs surface, obtained the rapid thermal response of high-performance TES WPCs in residential construction, thermal energy storage, solar energy collection system and thermal regulation has broad application prospects.

Phase change materials (PCMs) with high heat recovery and high energy density were introduced to the wood-plastic composites (WPCs) to regulate the indoor temperature, achieving the purpose of reducing building energy consumption. However, the interface compatibility between PCMs and WPCs seriously restricts its applications. To improve the utilization efficiency and expand the application fields, novel thermal storage wood-plastic composites (WPCs) were synthesized based on poly (ethylene glycol) (PEG) encapsulated by organic montmorillonite (OMMT) and WPC matrix. The leakage of PEG in PCMs were effectively solved. WPCs were successfully prepared since the peaks of the C–O bond and Si–O bond in WPC-3 are significantly more intense than WPC-0. The phase change temperature range of WPCs (17–26 °C) was similar to PCM3 (17–23 °C), which was caused by the restriction on crystal arrangement and orientation of PEG molecular chains in the wood-plastic matrix. The value of latent heat for PCM3 was 108.97 J/g, while the enthalpy value of WPCs reached 47.53 J/g when the loading percentage of PCM3 was 40%. Based on the good thermal properties, both PCMs and WPCs could effectively regulate the indoor temperature. The results of TG show that the fabrication of the organic network enhanced the thermal stability of PCMs, and the high-temperature resistance of the MMT reduced the degradation rate of WPCs. The thermal storage WPCs possess excellent thermal reliability and stability, good interface interaction and combustion performance, which are potential in the application of building energy-saving and indoor air-conditioning systems.

Wood is widely used in the field of building materials as a green and renewable natural porous material. With the continuous increase of global carbon dioxide emissions and increasingly serious environmental problems, improving the energy storage performance of wood is conducive to reduce carbon dioxide and regulate the temperature of the living environment. In this work, a composite phase change material is prepared by introducing stable polyethylene glycol-based energy storage polymer (PGMA) into the porous structure of delignified wood by high temperature immersion method. The wood structure has a greater influence on the crystallinity of PGMA and the modifier is widely distributed inside the lumen and also the cell wall, with crystallinity of 90% PGMA-Wood up to 8.97% and it exhibits good dimensional stability at high temperature. The thermal conductivity of 90% PGMA-Wood is increased to 0.32W/m center dot K, which reaches 190% higher than that of original wood for the lattice heat transfer replaces phonon heat transfer. The phase change temperature of 90% PGMA-Wood meets the comfortable indoor temperature for human with the melting enthalpy and solidification enthalpy are 25.12 J/g and 31.59 J/g, respectively. The simulated sunlight experiment shows that under the same lighting conditions, the indoor temper-ature of the house model made by 90% PGMA-Wood is 3 degrees C higher than that of the house made of original wood, which also has stronger thermal insulation performance at low temperature. All above indicates that PGMA-Wood have great potential applications in the field of solar-thermal energy conversion and storage as building insulation board and agricultural greenhouses. (c) 2022 Elsevier Ltd. All rights reserved.

Next‐generation flexible electronics must achieve multifunctionality, environmental friendliness and antibacterial activity. Accordingly, organisms in nature are interconnected. Inspired by the honeycomb multilayer porous structure, a wood‐nanotechnology‐derived flexible membrane circuit is created to meet the abovementioned requirements. The flexible wood (FW) matrix is made of natural balsa wood that underwent a simple top‐down chemical treatment. The multiwalled carbon nanotube (MWCNT) acts as a “bridge” between the FW matrix with a porous array structure and the active material (silver nanoparticles (Ag NPs) and poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS). Due to the three‐dimensional porous microstructure and highly conductive surface inherited by the wood‐nanotechnology‐derived flexible membrane (FW/MWCNT/Ag/PEDOT:PSS), it shows a high area capacitance (266.7 mF cm −2 at 20 mV s −1 ) and a good long‐term cycling stability 84.3% capacitance retention after 5000 cycles at 5 mA cm −2 when used as a supercapacitor electrode. In addition, it shows an excellent specific electromagnetic shielding efficiency (up to 970 dB cm 2 g −1 ), proving its application potential in the field of electromagnetic shielding. Because of the biocidal property of Ag NPs, the FW/MWCNT/Ag/PEDOT:PSS shows a remarkable antibacterial effect on Escherichia coli and Staphylococcus aureus . This strategy provides a new opportunity for researchers to design biomass‐based integrated electronic materials.

Phase change materials (PCMs) is one of the most efficient and reliable methods to store latent heat and reduce energy consumption. This work focused on heat-storage bio-based building materials for energy-saving using encapsulate poly (ethylene glycol) (PEG)/organic diatomite (O-Dt) as the latent heat storage agents, and wood fiber (WF)/high-density polyethylene (HDPE) as the matrix. PEG was encapsulated into the porous structure of Dt, and the obtained form-stable PCM has desired great interface action, high latent heat (105.35 J/g), good packaging capability, and excellent thermal stability. The heat-storage WPCs incorporated with form-stable PCM possessed considerable thermal storage capacity (60.42 J/g) and temperature-regulating ability (12 C-15 C). The thermal conductivity of WPC-20% was increased by 26.7% than WPC-0%. The mechanical strength and hydrophobicity of WPCs were increased when the loading percentage of PCM was 5%. Thermal cycling test results demonstrated that the heat storage WPCs had considerable heat storage reliability and chemical stability. The satisfying latent heat capacity and acceptable mechanical strength indicated the heat-storage WPCs could be potentially utilized as building materials for low carbon and energy conservation.

Controllable fabrication of lightweight, highly conductive, and flexible films is important to simultaneously achieve excellent electromagnetic interference (EMI) shielding and high-rate energy storage. Herein, ultrathin, flexible, and conductive (up to 365,000 +/- 5000 S m(-1)) TOCNFs/CNT/Ti3C2Tx hybrid films were fabricated by a facile vacuum-filtration. The obtained films with 60 wt% Ti3C2Tx content exhibited a high specific EMI SE of 9316.4 +/- 205.32 dB cm(2) g(-1), which was comparable to most of the other carbon-and MXene-based materials synthesized by complex steps. Additionally, the porous structure contributed to exposing more active sites and providing efficient transport of electrolyte ions. Consequently, the hybrid films showed a high areal capacitance and high specific capacitance of 537 mF cm(-2) and 279.7 F g(-1) at 0.3 mA cm(-2), respectively, together with impressive stability of 93.1% after 8000 cycles. This work provides an effective strategy to synthesize high-performance conductive films for applications in wearable or portable electronic devices.

A novel thermal energy storage (TES) composites system consisting of the microPCMs based on n-octadecane nucleus and SiO2/honeycomb-structure BN layer-by-layer shell as energy storage materials, and wood powder/ Poly (butyleneadipate-co-terephthalate) (PBAT) as the matrix, was created with the goal of improving the heat transmission and photothermal responsiveness of building materials. The microPCMs were made via miniemulsion interfacial polycondensation and electrostatic self-assembly to anchor BN on the surface of the SiO2 shell. The two kinds of microPCMs we designed had regular spherical morphology, BN was successfully anchored outside the SiO2 shell, showing a honeycomb structure and good heat storage performance (140.4 J/g and 140.6 J/g). The thermal energy storage wood plastic composites (TES WPCs) had considerable energy storage capacity and temperature regulation ability. The TES WPCs with the unique honeycomb structure of BN-MicroPCMs (BNWPC) had better heat transfer performance and photothermal conversion efficiency (69.54%), and the thermal conductivity, specific heat capacity and energy storage efficiency of which were increased by 75.06%, 87.06% and 200% respectively. Meanwhile, the unique honeycomb structure strengthened the interfacial bond strength of TES WPCs and brought satisfactory mechanical strength, and the tensile strength, elongation at break, bending strength and bending modulus of BN-WPC are increased by 51.16%, 97.01%, 81.28% and 742.74%, respectively compared with the WPC added with S-MicroPCMs (S-WPC). These results indicated that this research by designing the BN honeycomb structure layer on the traditional microPCMs surface, obtained the rapid thermal response of high-performance TES WPCs in residential construction, thermal energy storage, solar energy collection system and thermal regulation has broad application prospects.

A cellulose carbonaceous aerogel/MnO2 ultrathick electrode with a unique low curvature, porous carbon thin-walled tube array structure was obtained from natural wood using a simple top-down approach.