Traditional indoor heating materials, such as metals and their oxides, are non-renewable and energy-intensive. Lignocellulosic fiber composites represent a sustainable alternative, yet a key challenge lies in simultaneously achieving high electrical conductivity, robust mechanical performance, and adhesive-free processing for indoor heating applications. Here, lignocellulosic binder-free composites (LBCs) with good electrothermal properties is constructed through self-bonding technology. Through mechanical refining, nanofibers were generated and exposed on the fiber surface, enabling effective anchoring of inorganic nanoparticles. The LBCs demonstrated exceptional mechanical properties with a tensile strength of 56.1 MPa. Importantly, it exhibited an electrical conductivity of 557.1 & times; 10- 3 S/m, significantly surpassing that of lignocellulosic fibers (LF) and LF/GO (3.1 & times;10- 3 S/m). This superior performance was attributed to the in-situ growth of iron oxide nanoparticles (IONPs) and the impregnation of graphene oxide (GO). They were anchored on fibrillated fibers via H-bond mediated interactions. Molecular dynamics (MD) analysis verified the enhancement of intermolecular interaction between inorganic nanoparticles and fibers. The temperature of LBCs could be rapidly increased by 9.3 degrees C in 10 min by Joule heating under low voltage. The enhanced electrothermal performance was due to the conductive pathways formed by anchoring inorganic nanoparticles. The introduction of inorganic nanoparticles also improved the thermal conductivity, which paves the way for the application of LBCs in indoor heating.

为研究木质生物炭对厌氧发酵产甲烷性能的影响,以玉米秸秆、牛粪作为发酵底物,以灌木生物炭、杨木生物炭、混合木屑生物炭作为添加剂,通过控制生物炭的种类、粒径以及灰分含量等关键因素,进行了批式厌氧发酵强化试验.结果表明:生物炭对厌氧发酵系统有重要影响,且粒径越小,产气能力越强.其中,杨木生物炭对厌氧发酵系统影响最大,不仅提升了厌氧发酵系统的甲烷累积产量(4.9％)、最大甲烷日产率(15.0％)以及水解速率(15.6％),也缩短了发酵延滞期.此外,杨木生物炭的灰分含量对厌氧发酵也有重要影响.当灰分含量为2.6 g·L-1时,对厌氧发酵系统影响最大,在提升厌氧发酵系统的缓冲能力、最大甲烷日产率(14.4％)的同时,也缩短了延滞期(11.8％),灰分含量过高或过低均不利于系统产甲烷.

采用单因素实验法和响应曲面法,以杨木碱浸渍废液的木质素去除率和B/C为评价指标,探究了漆酶与杨木碱浸渍废液在充氧条件下的最佳作用条件.单因素实验通过设置多个实验梯度确定因素最佳范围,再在最佳范围内每个因素设置3个水平进行响应曲面分析,探讨了漆酶投加量、反应温度、反应时间3个因素对处理效果的影响,从而确定出最佳作用条件.实验结果表明,最佳作用条件:漆酶投加量157 U/L,反应温度37℃,反应时间4.56 h,在此条件下,预测木质素去除率为42.66％,B/C为0.758;验证实验得到的木质素去除率为43％,B/C为0.75,与预测值偏差不超过1.06％,优化结果可信.各因素对木质素去除率和B/C影响的大小顺序为漆酶投加量>反应时间>反应温度.

采用红外光谱、紫外光谱、气相色谱-质谱联用仪(GC-MS)定性、定量分析了杨木NaOH常压浸渍废液的污染成分,以确定其污染特性和可生化性评价.结果 表明,废液中含有的有机物结构包括苯环、羟基、醚基、氨基、酚羟基、—OCOR助色基团和羰基等基团;可能含有的有机物种类有烷烃、酚或醇、芳香族化合物、糖、醚类、酚类、羧酸类物质等;相对含量较多的为酯类、烷烃类、芳香族化合物、醛酮类以及有机酸等有机化合物.木质素浓度为2539 mg/L,糖类物质浓度为4728 mg/L;废液的悬浮物浓度、可溶性固形物浓度、可溶性有机固形物浓度分别为4636、4878和860 mg/L;其CODCr、BOD5浓度分别为29216 mg/L和19400 mg/L,C∶N∶P=100.15∶4.62∶1.废液中污染物成分复杂,有机污染物浓度较高,废液具有良好的可生化性.若对废液进行厌氧处理时可能需补充N、P元素.废液中硫酸盐、硝酸盐、亚硝酸盐和氨氮等抑制厌氧处理过程的污染物含量未达到抑制浓度.

利用AMPTS全自动甲烷潜力测试系统、First-Order水解模型、修正的Gompertz 和logistic模型,在了解生物炭各理化特性的基础上,通过对厌氧发酵的水解速率、产甲烷潜力及最大甲烷产率等进行拟合和对比分析,研究木屑生物炭对序批式湿法厌氧发酵的影响规律.结果表明:木屑生物炭对序批式厌氧发酵前期的底物水解速率、甲烷产率及累积甲烷产量均有着显著的影响,其中木屑生物炭对水解速率的影响强于果木生物炭和活性炭,较椰壳生物炭弱,且提升厌氧发酵系统的缓冲能力较椰壳生物炭和活性炭强.木屑生物炭对厌氧发酵的强化作用与生物炭粒径成负相关,当粒径＜0.5 mm 时强化效果最好,提高水解速率33.93％,提升最大产甲烷速率约19.32％,缩短延滞期约51.28％.

A novel natural fiber-metallic composite (NMC) with remarkable gradient structure is presented in this paper. Natural fibers generated from poplar wood, preformed into mat, are pre-treated through an in-situ impregnation process with Fe2+ and Fe3+ solutions. After the incorporation of ammonia, the iron oxide particles are formed inside the porous structures of fiber mat. The treated natural fiber mat with a certain moisture content, is then densified into composites through a compression molding process under a certain temperature, that a high-strength NMC is created without using binders. The resulted composites exhibited high iron oxide loading of 34.9 %, and presented a remarkable gradient structure with porous scale-like metallic surface and well-distributed uniform-sized nanoparticles for the core. The NMC also demonstrated a high flexural strength of 92.5 MPa, which was 2.2 times higher than that of poplar wood (42.6 MPa), and showed a strong magnetic response of 11.1 emu g−1 in saturation magnetization. The gradient structures of NMC can be controlled through changing the fiber mat density, impregnation process, mat moisture content, and compression molding parameters.

针对物流工程专业在实践教学过程中存在的问题,提出了基于"订单班"培养的"三融合、四模式、五持续"的实习基地建设体系,构建了校内外实践+"订单班"联合培养的多元化实践教学体系.以东北林业大学物流工程专业实践教学体系建设为例,建设了"顺丰"订单班,并建立了研究生示范实习基地.研究表明,该体系可有效提高学生的创新实践能力,为物流工程本硕实践教学体系的建设提供理论和实践指导.

A sandwich-structured natural fiber-based magnetic composite, without the use of a binder, was developed in this study. It was fabricated via in situ synthesis, densification, and magnetron sputtering processes. The chemical composition, crystal structure, microstructure, and thermal stability were characterized via X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, X-ray diffraction, scanning electron microscope, and thermogravimetric analysis. The hydrophobic, magnetic, and electromagnetic interference shielding properties were investigated by measuring the static water contact angle, the magnetic hysteresis loops, and the shielding effectiveness. The resulted composites exhibited a unique inner structure with a larger iron oxide size and content (492 nm and 26.1 wt%) on the interlayer surface in comparison to the core layer (135 nm and 18.7 wt%). The magnetic response can be controlled by the loaded iron oxide content and the copper film deposition. Sputtering copper film changed the surface free energy, and created rough micro-/nanostructures, which yielded a highly hydrophobic nature (133° in water contact angle), and approximately 99.2% of the electromagnetic energy was shielded by the 0.8 mm thick composite.

Self-bonding natural fiber materials (SNFMs) were prepared at different initial moisture contents (IMCs) through a molding pressing process. The self-bonding mechanism of the SNFMs was deduced from the chemical and structural changes of lignin and their mechanical strengths. The structural transformations of milled wood lignin (MWL) in the SNFMs were investigated by two-dimensional heteronuclear single quantum coherence, quantitative 31P-nuclear magnetic resonance spectra, gelpermeation chromatography, and thermogravimetric analysis. As IMC increased from 0% to 80%, the tensile strength increased from 23.0 to 70.0 MPa and the density increased from 0.99 to 1.05 g/cm3. IMC affected the distribution and abundance of the typical lignin linkages (β-O-4', β-β, and β-5') and the S-OH/G-OH ratios of lignin. Moreover, as IMC increased, the aliphatic hydroxyl groups proportionally decreased, while the condensed phenolic and non-condensed phenolic hydroxyl groups increased, the molecular weight of MWL became larger, and the thermal stability of lignin improved. These findings indicate the simultaneous occurrence of depolymerization and condensation reactions of lignin. The condensation reaction dominated, improving the mechanical strength of the material. Our results explain (at least partly) the self-bonding mechanism of SNFMs.

A water and organic soluble N-benzyl-N,N-diethyl quaternized chitosan (NSQC) material was synthesized using chitosan, benzaldehyde, and bromoethane. Amino groups on chitosan reacted with benzaldehyde to form a Schiff base intermediate. Quaternized chitosan was obtained by reacting the Schiff base with bromoethane. The quaternized chitosan was dissolved in an organic solution with dissolved cellulose and cast to prepare quaternized chitosan/cellulose (QCC) film. The molecular structure, morphology, tensile strength, thermal stability, and antibacterial activity effects of NSQC-treated cellulose film were studied in detail. The results showed that the NSQC product exhibited superior solubility in deionized water and dimethylacetamide. The addition of NSQC as a reinforcing agent in QCC film enhanced the interlinking of fibers and slowed down the rate of cellulose pyrolysis, which improved the tensile properties and thermal stability of the cellulose film. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of NSQC showed that it had good antibacterial activity against Staphylococcus aureus and Escherichia coli. The QCC film also showed contact sterilization ability with regards to two kinds of bacteria, which suggested that QCC film has the potential for applications in food packaging and bacterial barriers.

Using N,N-dimethylacetamide (DMAc) as a reducing agent in the presence of PVP-K30, the stable silver nanoparticles (Ag-NPs) solution was prepared by a convenient method for the in situ reduction of silver nitrate. The cellulose–Ag-NPs composite film (CANF) was cast in the same container using lithium chloride (LiCl) giving the Ag-NPs-PVP/DMAc solution cellulose solubility as well as γ-mercaptopropyltrimethoxysilane (MPTS) to couple Ag-NPs and cellulose. The results showed that the Ag-NPs were uniformly dispersed in solution, and the solution had strong antibacterial activities. It was found that the one-pot synthesis allowed the growth of and cross-linking with cellulose processes of Ag-NPs conducted simultaneously. Approximately 61% of Ag-NPs was successfully loaded in CANF, and Ag-NPs were uniformly dispersed in the surface and internal of the composite film. The composite film exhibited good tensile properties (tensile strength could reach up to 86.4 MPa), transparency (light transmittance exceeds 70%), thermal stability, and remarkable antibacterial activities. The sterilization effect of CANF0.04 against Staphylococcus aureus and Escherichia coli exceed 99.9%. Due to low residual LiCl/DMAc and low diffusion of Ag-NPs, the composite film may have potential for applications in food packaging and bacterial barrier.

目的 研究温度、湿度和紫外老化对脱木素和未脱木素纸浆模塑材料性能的影响,定量地对比不同因素作用下2种材料的力学性能差异.方法 以废纸浆为原料,经打浆、脱木素、湿成型、热压等工艺制得脱木素和未脱木素等2种纸浆模塑材料;模拟不同的温湿度和紫外老化环境,测试2种纸浆模塑材料物理力学性能的变化.结果 在同等条件下,脱木素材料的拉伸强度与弯曲强度均高于未脱木素材料;2种材料的拉伸强度、弹性模量和弯曲强度随着含水率升高而大幅降低;当温度为20℃、含水率为0～40％时,脱木素材料的拉伸强度下降了45 MPa,未脱木素材料的拉伸强度下降了35 MPa.当温度为0℃、含水率为0～40％时,脱木素材料的弯曲强度下降了70 MPa,未脱木素材料的弯曲强度降低了62MPa;当含水率低于20％时,脱木素材料的拉伸性能和弯曲性能更易受到温度影响;虽然2种材料的拉伸性能和弯曲性能均随着紫外老化时间的延长而不断降低,但其影响程度远小于温湿度.结论 湿度对材料的力学性能影响最大,其次是温度和紫外老化;脱去木素有利于提高纸浆模塑材料的力学性能和抗紫外老化性能.

In this study, poplar chemi-mechanical pulp was used as a raw material to investigate the effect of enzymatic hydrolysis lignin (EHL) content on the tensile strength and hydrophobicity of molded fiber materials (MFMs). The tensile strength and hydrophobic properties of the fabricated MFMs with different EHL contents were evaluated, and changes in their microstructure, chemical structure, and thermal stability were characterized via scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis, respectively. Results show that under the experimental conditions used herein, the addition of EHL could increase the tensile strength and surface water contact angle of MFMs up to 20.3 MPa and 95.0 degrees, respectively. The SEM observations indicate that the addition of EHL expanded the contact area between the EHL and fibers, thereby reducing the holes between fibers. The FTIR and TG analyses indicated that hot-pressing degraded EHL to form small molecular substances and improved the reaction with aldehydes produced via carbohydrate degradation, improving both the inter-fiber bonding strength and hydrophobicity of the MFM surface.

Self-bonded natural fiber material (SNFM) is a promising alternative for plastic and wood owing to its abundant raw material resources and low environmental impact. In this study, a high-performance SNFM was developed by the comprehensive treatments for the plasticity and structure of fiber cell walls. The cell wall structure was treated by a progressive chemical etching process for selectively removing surface lignin, internal lignin and hemicelluloses, respectively. The cell wall plasticity was tuned by controlling the fiber moisture content during compression molding process. The results showed that the increase in fiber plasticity improved the tensile strength from 38.0 to 83.5 MPa and the flexural strength from 31.2 to 73.3 MPa. The selective removal of surface lignin increased the flexural strength from 101.3 to 122.1 MPa. The functional relationships among mechanical strength, lignin content, hemicellulose content and moisture content were established. The self-bonded mechanism for natural fiber materials was also discussed. The SNFM products showed excellent mechanical performance (tensile strength: 21.5-83.5 MPa; flexural strength: 31.2-127.3 MPa), which was superior to that of natural wood (46.5-55.6 MPa; 70.7-92.4 MPa) and plastic (15.9-51.0 MPa; 21.7-73.0MPa) (e.g., HDPE, PP, PVC, and ABS). (c) 2019 The Authors. Published by Elsevier Ltd.

To obtain the natural fiber products with high electromagnetic interference (EMI) shielding effectiveness (SE), magnetron sputtering Cu film was firstly applied to the surface of an eco-friendly self-bonded natural fiber product (SNFP) (0.8 mm in thickness). For a better combination of Cu film onto the SNFP surface, the chemical etching using sodium chlorite was newly used to treat the SNFP for obtaining an improved surface roughness. The surface morphology and chemical compositions were studied by the scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). A rougher fiber surface was successfully obtained due to the shedding of surface lignin with decreased lignin content from 62% to 52% after the etching treatment. When sputtering Cu film for 1 h, 2 h, 3 h, and 4 h, the EMI SE values were increased to be 22 dB, 22.7 dB, 24.6 dB, and 25.5 dB, respectively, which all indicated that more than 99.4% incident signals were blocked. SEM observations revealed that an increased surface roughness could be achieved with the sputtering time increased from 1 h to 3 h. The water contact angle increased from 76.4 degrees to 105.9 degrees for 1 h sputtering, indicating that the sputtering Cu film could obviously improve the hydrophobic property of SNFP. When the sputtering time increased to be 3 h, this product exhibited the best hydrophobic performance with a maximum water contact angle of 131.5 degrees.

目的 为了提高我国农林剩余物资源的利用率,解决我国绿色包装材料的市场需求,研究外包装箱板材料的制备工艺与组分参数.方法 以稻壳和木质刨花为主要原料,以酚醛树脂和异氰酸酯为胶粘剂,采用热压方法制备外包装箱用复合板;采取WCAMA六循环老化方法对试件进行处理,并对老化处理后的复合板进行内结合强度、静曲强度和弹性模量等力学性能的宏观分析和材料组分变化的微观分析.结果 当表层施胶量质量分数为8％、芯层施胶量质量分数为11％、密度为0.9 g/cm3和防水剂含量为0.6％时,复合板的内结合强度、静曲强度和弹性模量保留率在50％以上,具有良好的耐老化性能.结论 基于老化性能得出的制备工艺及组分参数可对绿色环保、经济性好、可持续发展的稻壳-木刨花外包装箱板材料的开发提供理论与实践支撑.

The hemicellulose content of cellulosic material from poplar chemi-thermomechanical pulp (CTMP) was controlled by a microwave-assisted formic acid (MFA) extraction process. The environmentally friendly, self-bonded, and cellulose-rich fiber sheets (around 0.3 mm thick and 280 g/m2 grammage) were fabricated via a molding and compression process. The results showed that the MFA treatment effectively controlled the hemicellulose content in the range from 6.8% to 20.4%. Mechanical testing results showed a good linear relationship between the tensile strength and the hemicellulose content, where a higher hemicellulose content obtained a stronger tensile strength. Meanwhile, as hemicellulose content decreased, the onset temperature, representing the thermal stability, increased from 318.1 °C to 335.7 °C and the elastic modulus, representing the mechanical stiffness, increased from 0.047 MPa to 0.068 MPa. Additionally, as the hemicellulose content decreased, the water-resistance of the cellulose-rich fiber sheets improved. During the hemicellulose removal process, the strength of single fibers was found to have a dominant role in the mechanical strength of the cellulose-rich fiber sheets, rather than the inter-fiber bonding strength. This was contrary to research on the delignification process, where the inter-fiber bonding strength was found to be more important than the strength of single fibers in deciding the material strength.

为研究不同老化条件对稻壳-木刨花外包装箱板内结合强度和热稳定性的影响,分别采用WCAMA六循环老化法和紫外老化法,对两种老化后试件的内结合强度进行测试和热重分析.结果 表明:经历WCAMA六循环老化,稻壳-木刨花外包装箱板内结合强度保留率仅剩45.9％,老化使得木刨花中纤维素、半纤维素和木质素被大量分解,失重率为63.04％,酚醛树脂全部水解,异氰酸酯部分水解;而经历1 500 h紫外老化,稻壳-木刨花外包装箱板的内结合强度保留率为87.46％,木刨花中的纤维素、半纤维素和木质素部分分解,失重率为49.19％,只有小部分酚醛树脂发生光化降解,异氰酸酯几乎未受到影响.从而得到,不同的老化处理方式对稻壳-木刨花外包装箱板内结合强度和热稳定性都有影响,但WCAMA六循环老化法影响更大.

对专业学位研究生实习基地建设需求与融合点进行了分析,从学校、企业和学生3个角度分析了各自的需求,得出人才和技术是3方的主动需求点,具有较高的融合度,并可拉动与被动需求的融合.以该校物流工程研究生实习基地建设为案例,介绍了"顺丰班"订单式培养实践教学模式和"顺丰"研究生示范性实习基地建设取得的成效.

The effective separation of hemicelluloses and cellulose is the prerequisite for creating high-value products using wood wastes. In this study, a novel process including mechanical pre-beating, microwave-assisted formic acid (MAFA) extraction, and bleaching treatment was developed for producing high-purity cellulose from the pulp fibers of hardwood waste. Most hemicelluloses and lignin were simultaneously removed (i.e., hemicelluloses were separated from cellulose) due to the MAFA treatment. The pulp fibers were pre-beaten for a loose fiber structure for the formic acid impregnation. The results showed that the introduction of microwave could significantly enhance hemicellulose removal and separation from pulp fibers. The MAFA treatment was performed under atmospheric pressure and mild condition (≤ 100 °C), which led to the significant increase in the lignin yield, cellulose content, crystallinity index, and crystallite homogeneity. After the beating pretreatment and MAFA process (88% formic acid, 100 °C, 4 + 4 h), the hemicellulose removal rate reached 75.5%, and the cellulose purity was as high as 93.2% along with a maximal cellulose crystallinity index (77.5%) and minimum crystallite cross-sectional area (12.40 nm2).