Design and UV-curable behaviour of boron based reactive diluent for epoxy acrylate oligomer used for flame retardant wood coating

Difunctional boron-containing reactive flame retardant for UV-curable epoxy acrylate oligomer was synthesized from phenyl boronic acid and glycidyl methacrylate. The synthesized reactive diluent was utilized to formulate ultraviolet (UV)-curable wood coatings. The weight fractions of reactive diluent in coatings formulation was varied from 5 to 25 wt % with constant photoinitiator concentration. The molecular structure of reactive flame retardant was confirmed by Fourier-transform infrared, Nuclear magnetic resonance (NMR) and ¹¹B NMR spectral analysis. Further, the efficacy of flame retardant behaviour of coatings was evaluated using limiting oxygen index and UL-94 vertical burning test. Thermal stability of cured coatings films were estimated from thermogravimetric and differential scanning calorimetry analysis. The effects of varying concentration of reactive diluent on the viscosity of coatings formulation along with optical, mechanical and chemical resistance properties of coatings were also evaluated. The coatings gel content, water absorption behaviour, contact angle analysis and stain resistance were also studied.     

CNT基木塑复合材料的力学性能、电磁屏蔽性能

采用碳纤维(CF)和碳纳米管(CNT)通过模压工艺制备出具有电磁屏蔽功能的丙烯酸酯木塑复合材料。借助材料试验机、动态热机械分析仪、微欧计和电磁屏蔽测量仪等详细研究CNT质量分数对丙烯酸酯木塑复合材料弯曲性能、动态力学性能、电阻率和电磁屏蔽效能的影响。结果表明,添加质量分数为2%的CNT,使得复合材料的弯曲强度和弯曲弹性模量分别增加了10%和16%。复合材料的储能模量也在CNT质量分数为2%时达到最大值,之后储能模量随着CNT的增加而逐渐下降,损耗因子在CNT质量分数多于2%时也逐渐增加。复合材料的吸水率和导电性能随着CNT含量的增加而增加。同时复合材料的电磁屏蔽效能也随着CNT含量增加而递增。在30~1 500 MHz范围内,电磁屏蔽效能从27 d B增加到40 d B。结果证明,当CNT质量分数在2%时,丙烯酸酯木塑复合材料具有较佳的力学性能和较好的电磁屏蔽效能(30 d B),能满足商业要求。     

Chemical characterization of Cedrus deodara wood extracts using water and molybdenum catalysts

The effect of the presence of some molybdenum catalysts on the amount of extractives in cedar wood has been studied. Autoclave treatment of cedar wood in the presence of some molybdenum catalysts can increase the amount of extracts. While autoclave treatment of cedar wood in water gave 2.85% extractives, the same treatment in the presence of H₃PMo₁₂O₄₀ gave 7.51% extractives. In the presence of silica-supported MoO₃, the amount of extractives was 5.50%. The extractives obtained using water were partially soluble in chloroform (40.7%). Only 27.6% of the extractives obtained using H₃PMo₁₂O₄₀ was soluble in the same organic solvent. When cedar was treated with silica-supported MoO₃, 56.4% of the extractives was soluble in chloroform. The extracts can be a source of fatty acids for biodiesel production and simple carbohydrates. The analysis of the chloroform-soluble fraction showed that the autoclave treatment of cedar wood gave 49.7% of a mixture of 2-hydroxy-1-(hydroxymethyl)ethyl hexadecanoate, 2-hydroxy-1-(hydroxymethyl)ethyl octadecanoate, and 2,3-dihydroxypropyl octadecanoate. The extractives obtained in the presence of the polyoxometalate molybdenum derivative gave 95% of the same esters of fatty acids, while those obtained in the presence of silica supported MoO₃ showed the presence of 93% of the same esters. Gas chromatography–mass spectrometry (GC-MS) of water-soluble fraction showed the presence of some simple carbohydrates, mainly ribose, xylose, and arabinose.     

Alkyne cellulose for Huisgen [3 + 2] cycloaddition with azido‐terminated targets

Azido‐grafted cellulose has been reported widely applied for further functionalization by click chemistry. As an alternative method, we proposed alkyne‐grafted cellulose as a prototype molecule for Huisgen [3 + 2] cycloaddition with azido‐terminated target compounds. Alkyne cellulose was synthesized by acylation with prop‐2‐ynyl 5‐chloro‐5‐oxopentanoate and, subsequently cycloaddition with 4‐aminophenylazide, ethyl 2‐azidoacetate, and (S)‐2‐(Azidomethyl)‐1‐(tert‐butoxycarbonyl)pyrrolidine (Boc‐pyrrolidine azide) to form triazole cellulose in a click manner. The reactions were confirmed qualitatively by Fourier transform infrared and NMR spectroscopy and analyzed quantitatively with elemental analysis data. The results show that a degree of substitution of up to 1.91 was obtained for esterification and, in most cases, was preferred completely in a selective way for the primary hydroxyl groups at the O‐6 position and partially at the O‐2 and O‐3 positions. Cycloaddition conversions were found as high as 0.95, 0.99, and 0.99 for aniline–triazole cellulose, acetate–triazole cellulose, and Boc‐pyrrolidine‐triazole cellulose, respectively. Both esterification and cycloaddition were undertaken under mild conditions without additional heating. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44410.     

Layer‐by‐layer self‐assembly of a lignin–poly(vinyl alcohol) based polyelectrolyte with a conductivity method

In this study, we made a new attempt to examine the relationship between the conductivity and the concentration of a polyelectrolyte solution and to prepare multilayer films with cationic lignin and polyanions through layer‐by‐layer self‐assembly. The nitrogen content of trimethyl lignin quaternary amine salt (TLQA) was 3.56%, and the carboxyl content of carboxymethylated poly (vinyl alcohol) (CMPVA) was 0.62 mmol/g. Attenuated total reflectance spectra confirmed that TLQA and CMPVA were fabricated and assembled successfully. The concentration of TLQA had a polynomial correlation with the conductivity [correlation coefficient (R²) = 0.9953], and the concentration of CMPVA was linear with the conductivity (R² = 0.9819). The electrostatic sequential adsorption process was monitored with a UV–visible spectrophotometer, and the morphology of the (TLQA/CMPVA)_n (where n is the number of double membranes) multilayer film was observed by atomic force microscopy and scanning electron microscopy. When the absorbance of the (TLQA/CMPVA)_n multilayer film increased linearly, the linear equation was y = 0.0267x + 0.07453 and R² was 0.9735. When five layers of TLQA and CMPVA were assembled, the surface root mean square roughness of TLQA and CMPVA were 21.07 and 65.28 nm, respectively. When the number of layers increased, the film surface roughness increased. The stability of the multilayer films in aqueous solution was determined by a conductivity meter. The (TLQA/CMPVA)_n multilayer film was stable in water. The results of the research demonstrate for the first time that TLQA and CMPVA could be assembled and successfully driven by electrostatic forces. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44416.     

Synthesis of an elastic β‐cyclodextrin hydrogel cage by hydroxyethyl cellulose

Current cyclodextrin (CD) hydrogels have disadvantages, including a limited CD content, long reaction time, and complicated chemical reactions. To overcome these, a one‐pot reaction was adopted, and a concept of a β‐CD hydrogel cage was proposed. Hydroxyethyl cellulose (HEC) was used as the raw material with the adjustment of the stoichiometric relationship among the crosslinking agent of epichlorohydrin, alkali environment, and β‐CD amount, and an elastic β‐CD hydrogel cage system was established. After the β‐CD was caged, the contents of active β‐CD in hydrogel products reached 74.45 and 69.14 wt % by weight measurement and photometric titration, respectively. Furthermore, compared to the pure HEC hydrogel, the hydrogel mechanical strength improved obviously after the β‐CD was caged, and we obtained a faster water swelling rate at the same time. Finally, a hydrophobic molecule of phenolphthalein (PP) was used to evaluated the activity of caged β‐CD in the hydrogel. In addition, the absorption and release of PP by an elastic β‐CD hydrogel cage at certain time intervals were also studied. The results demonstrate that the β‐CD hydrogel cage was used as a functional molecule carrier to quickly absorb and sustain the release of PP. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44388.     

Mechanically enhanced electrically conductive films from polymerization of 3,4‐ethylenedioxythiophene with wood microfibers

This study was aimed at enhancing the mechanical properties of poly(3,4‐ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) using wood microfibers. Ultra fine friction grinding was conducted on wood particles to reduce their size to the micron scale and to induce fibrillation. Oxidative polymerization was performed on 3,4‐ethylenedioxythiophene (EDOT) monomer at seven dosages based on the content of microfibers in the formulation. The presence of PEDOT:PSS in the prepared films was verified by infrared spectroscopy and scanning electron microscopy. The composite films became stronger and stiffer as the fiber content increased. An EDOT:microfibers ratio of 33 wt % was considered the best among the seven tested levels, judging from their low sheet resistivity (340 Ω/sq.) and favorable tensile properties (38 MPa strength and 4.8 GPa stiffness). The selected films were also tested for their resistance to solvents to obtain information about their potential use in different environments. Among the tested solvents, sodium hydroxide greatly decreased the film conductivity. It also had the harshest effect on reducing the weight of the film. Findings from this study demonstrate the successful use of wood microfibers alternative to synthetic substrates and cellulose nanofiber as a supportive and reinforcing material for electrically conductive polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45127.     

Comparison of the performance of copper oxide and yttrium oxide nanoparticle based hydroxylethyl cellulose electrolytes for supercapacitors

Biodegradable solid polymer electrolyte (SPE) systems composed of hydroxylethyl cellulose blended with copper(II) oxide (CuO) and yttrium(III) oxide (Y₂O₃) nanoparticles as fillers, magnesium trifluoromethane sulfonate salt, and 1‐ethyl‐3‐methylimidazolium trifluoromethane sulfonate ionic liquid were prepared, and the effects of the incorporation of CuO and Y₂O₃ nanoparticles on the performance of the SPEs for electric double‐layer capacitors (EDLCs) were compared. The X‐ray diffraction results reveal that the crystallinity of the SPE complex decreased upon inclusion of the Y₂O₃ nanoparticles compared to CuO nanoparticles; this led to a higher ionic conductivity of the Y₂O₃‐based SPE [(3.08 ± 0.01) × 10^?4 S/cm] as compared to CuO [(2.03 ± 0.01) × 10^?4 S/cm]. The EDLC performances demonstrated that the cell based on CuO nanoparticles had superior performance in terms of the specific capacitance, energy, and power density compared to the Y₂O₃‐nanoparticle‐based cell. However, Y₂O₃‐nanoparticle‐based cell displayed a high cyclic retention (91.32%) compared to the CuO‐nanoparticle‐based cell (80.46%) after 3000 charge–discharge cycles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44636.     

负载型中孔碳气凝胶脱硫剂的制备及其性能评价

通过溶胶-凝胶法制备了碳气凝胶,用浸渍法合成锰基高温脱硫剂.利用N2吸附/脱附(BET)、扫描电镜(FESEM)的分析手段对脱硫剂进行物相和微观结构的表征,并在固定床反应器中考察了硫化温度、载体、气体组分对其脱硫性能的影响.结果表明,最佳硫化反应温度为850℃;脱硫剂在H2条件下硫容大大降低,在CO条件下脱硫剂硫容无明显变化.     

上海沈义生住宅的检测鉴定与加固

沈宅建于19世纪60年代,是旧上海董家渡地区码头贸易的见证,是具有保存价值的优秀历史建筑。该建筑为砖木结构,文章介绍了加固前结构检测方法和结果,并用M ADIS软件对该建筑进行验算,提出了修缮加固的处理方案,以期对砖木结构古建筑的检测鉴定与加固工作有所帮助。