Color changes in acetylated wood by the combined treatment of light and heat

This study investigated the change in color of acetylated wood by the combined treatment of light and heat. The color of acetylated wood was stable against light, however, heat treatment after light-irradiation made it change greater. Furthermore, the acetylated wood discolored greater than unacetylated one by light-irradiation after heat treatment. These results show that the acetylated wood is not stable when it is exposed under special condition.     

Thermo-hydro-mechanical behaviour of acetylated wood: swelling,compression set recovery and mouldability

Acetylated wood made from radiata pine (Pinus radiata D. Don) was densified at different temperatures in order to investigate its applicability to wood moulding. Six different densification levels ranging from 10 to 60% were carried out each at the temperature levels 80 and 110 °C. The swelling behaviour in cold (20 °C) and warm (60 °C) water and set-recovery cycles were investigated. Densified acetylated wood possesses compression set recovery especially at elevated temperature and humidity. Finally, a tubular section was moulded using a thermo-hydro-mechanical process. Such profiles are supposed to be used for structural purposes. They benefit from the strength, durability and dimension stability of acetylated wood, which in turn gains competitiveness in a material efficient structural product.     

Effect of short-term thermomechanical densification of wood veneers on the properties of birch plywood

In this study, the physical and mechanical properties of plywood panels made from pre-compressed birch (Betula verrucosa Ehrh.) veneer were evaluated. Veneer sheets underwent short-term thermo-mechanical (STTM) compression at temperatures of 150 or 180 °C and at pressures of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 or 3.5 MPa for a period of 1 min prior to adhesive being applied and pressed into panels using phenol formaldehyde adhesive at 100 g/m² spread rate; this was one-third less than the adhesive spread used for the control panels (150 g/m²). The pressing pressure was 1.0 MPa, which was almost half of the pressure used for the control panels (1.8 MPa); and pressing time was 3 min, also half of the pressing time used for the control panels (6 min). The results showed that surface roughness of compressed veneer, water absorption and thickness swelling of plywood panels made from compressed veneer were significantly improved. The shear strength values of plywood panels made from compressed birch veneer even with reduced adhesive spread were higher than those of plywood panels made from uncompressed veneer. The findings in this study indicated that compression of birch veneer could be considered as an alternative to produce more eco-friendly (owing to smaller adhesive spread) value-added material with enhanced properties.     

木材表面粗糙度测量技术

本文从国内外木材表面粗糙度研究内容、研究方向、测量方法和手段等方面综述了木材表面粗糙度研究现状与最新成果,并对木材表面粗糙度研究的未来发展方向提出了一些建议。     

某些非木浆的表面化学组成

借助于ESCA（化学分析电子能谱）研究了某些非木浆（麦草、芦苇、甘蔗渣、竹子和红麻皮）中表面木素和抽出物的覆盖情况,并与木浆做了比较。研究发现所有浆料的纤维表面都富集大量的木素和抽出物。在总木素含量相同的条件下,非木浆的表面木素覆盖率要高于针叶木浆。本文分析了这方面可能存在的原因。     

Surface finishes by mechanically induced wood surface fusion

Mechanically induced vibration wood fusion welding techniques can also be used to obtain wood surface finishes of increased surface hardness and performance in presence of polymerizing unsaturated oils such as sunflower oil, or other polymerizing finishes. Wood surface hardness values more than double than those for the untreated control timber can be obtained by this method. This result is obtained due to two effects induced by the sharp increase in temperature induced by the mechanical welding vibration (i) the polymerization to a hardened network of the unsaturated oil and (ii) the densification proven to occur in the surface layer of the timber during mechanically-induced vibration-welding. The first of these effects predominates at shorter welding times while at slightly longer welding times both effects occur with the second one progressively becoming the bigger contributor. In the latter case the some μm thin densified surface is a surface composite formed by the networked unsaturated oil permeating the wood fibre/fused lignin composite.     

Surface characteristics and overlaying properties of flat-pressed wood plastic composites

This study evaluated surface characteristics and overlaying properties of wood plastic composite (WPC) panels made from dry-blended rubber wood fiber-polypropylene (PP) powder formulations using a conventional flat-press process under laboratory conditions. Three levels of rubberwood fibers (Hevea brasiliensis), 40%, 50%, and 60%, based on the composition by weight, were mixed with the PP powder without and with 3% (based on weight) maleic anhydride grafted PP (MAPP) as a coupling agent. Contact angle measurements on the WPC samples were performed using a goniometer connected with a digital camera which collected one image per second. Roughness measurements, average roughness (R _a), mean peak-to-valley height (R _z), and maximum roughness (R _y), were taken from the sanded samples along and across the sandmarks using a fine stylus tracing technique. With increasing polymer content, surface roughness of the WPC panels improved while their wettability and adhesive bonding strength decreased. The formulations without MAPP were found to have higher surface roughness but they also had better wettability. Wettability and surface roughness of the WPC panels can provide good information on their ability to bond.     

Lipase-catalyzed synthesis of acetylated EGCG and antioxidant properties of the acetylated derivatives

(−)-Epigallocatechin-3-O-gallate (EGCG) acetylated derivatives were prepared by lipase catalyzed acylation of EGCG with vinyl acetate to improve its lipophilicity and expand its application in lipophilic media. The immobilized lipase, Lipozyme RM IM, was found to be the optimum catalyst. The optimized conditions were as follows, 1:1 of the molar ratio of EGCG to vinyl acetate, 2.0% (w/w of both substrates) of enzyme amount, and 84.5% conversion was obtained after 8 h reaction at 40 °C in acetonitrile. The presence of mono-, di- and tri-acetylated derivatives in acetylated EGCG were confirmed by LC–MS–MS and the tri-acetylated EGCG was identified as 5′,3″,5″-3-O-acetyl-EGCG by NMR. Their enhanced lipophilicity was confirmed by octanol–water partition coefficient. The antioxidant activity of the acetylated EGCG derivatives were superior to butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ) and EGCG as determined by peroxide values (POVs) in sunflower oil as well as by the p-anisidine method. Acetylated EGCG exhibited the highest 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀ of 0.09 mg/mL) compared to EGCG, BHT and TBHQ. Acetylated EGCG might be used as a potent antioxidant for controlling oxidation of sunflower oil.     

乙酰乙酰化纤维素材料的合成及在降低卷烟主流烟气中醛类化合物的应用

为选择性降低卷烟主流烟气中醛类化合物的释放量,以微晶纤维素作为底物合成了乙酰乙酰化纤维素材料,根据材料的降醛效果优化合成条件,并将材料添加于卷烟滤嘴中考察降低醛类化合物的性能。结果表明:(1)乙酰乙酰化纤维素的最佳合成条件为:纤维素离子溶液质量百分比浓度为5%,衍生化试剂摩尔比为双乙烯酮纤维素=21,反应时间3h,反应温度110℃,催化剂为DMAP;(2)将乙酰乙酰化纤维素材料以30 mg/cig添加量制备成二元复合滤棒应用于卷烟后,卷烟主流烟气中醛类化合物释放量降低了21.6%,而烟气常规及感官质量变化较小,表明所制备的材料对卷烟主流烟气中的醛类化合物有良好的选择吸附性能。     

Properties of acetylated potato protein preparations

The purpose of the present study was to determine the influence of protein isolation from potato juice and acetylation on the chemical composition and chosen functional properties of obtained preparations. Potato protein preparations used for the experiment were obtained by thermal coagulation and membrane technology. Preparations containing thermal coagulated (PPI) and native (PPC) protein, respectively, were subjected to the chemical modification by acetylation with the use of different doses of acetic anhydride. Changes in chemical composition (total and coagulable protein content, ash content and amino acid composition), functional properties (water holding capacity, oil holding capacity, protein solubility index, emulsification properties as well as foam capacity and stability) and extent of chemical modification were determined. The chemical composition and functional properties of obtained preparations were significantly different (p < 0.05).     

乙酰化香蕉淀粉的特性

通过与玉米淀粉比较,乙酰化香蕉淀粉的灰分、蛋白质、脂肪含量均比乙酰化玉米淀粉高.乙酰化香蕉淀粉糊的透明率在低温下出现较小的退化趋势,但常温下淀粉糊的透明率较高且有较好的稳定性.在较高温度下,乙酰化香蕉淀粉的持水能力比原淀粉高.乙酰化作用增加淀粉的溶解度和膨胀率.乙酰化作用也增加了香蕉淀粉糊的粘度值.     

Oil sorption behavior of acetylated nettle fiber

Abstract

In this work, acetylation of raw nettle fibers was performed to improve the oil sorption capacity. Raw nettle fibers were acetylated with acetic anhydride using N-Bromosuccinimide (NBS) as a catalyst. Box–Behnken experimental design was used to study the effect of some selected parameters such as reaction time, reaction temperature and catalyst concentration (%) on weight percent gain (WPG) and oil sorption behavior. Highest WPG and oil sorption were achieved at 90?min reaction time, 120?°C and 2% catalyst. The oil sorption of acetylated nettle was 23.21?g/g and 18.75?g/g against diesel engine oil and crude oil, respectively. Nettle fibers were also characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis and Scanning electron microscopy. Oil sorption capacity of acetylated nettle were higher than that of commercial polypropylene sorbent. Hence, these acetylated nettle fibers can be used in the place of synthetic sorbents for oil spill cleanup applications.     

Toxicological evaluation of acetylated faba bean globulin

Acetylated faba bean globulin (acVFG, acetylation degree 97%) was evaluated toxicologically in a subchronic feeding study and a female fertility test. Groups of male and female rats received acVFG in their diet at levels of 20, 40 and 80 g kg⁻¹ for 3 months. Additional groups were fed a commercial diet or given food containing 38 or 75 g kg⁻¹ casein. The subchronic toxicity study revealed growth retardation in both sexes at the 80 g kg⁻¹ acVFG level. The food consumption was reduced in males at 40 and 80 g kg⁻¹ acVFG and in females at 80 g kg⁻¹ acVFG. Histopathological alterations in the ovaries were observed at dietary levels of 40 and 80 g kg⁻¹ acVFG. Histopathological changes and decreases in the absolute and relative weight of the uterus were found in all groups fed acVFG. Therefore a no‐observed‐effect level (NOEL) was not derivable. Feeding females 80 g kg⁻¹ acVFG resulted in diminished pre‐implantation losses but increased post‐implantation losses in the fertility study. © 2000 Society of Chemical Industry     

乙酰化二淀粉磷酸酯研究进展

综述了乙酰化二淀粉磷酸酯(ADSP)的制备及应用技术,阐述了国内外研究进展,展望ADSP研究方向,为其进一步研究奠定基础。     

Synthesis and characterization of highly acetylated sago starch

This study was carried out to understand and establish the changes in physicochemical parameters of sago starch after acetylation. Highly substituted starch acetate was prepared by reaction with native sago starch and acetic anhydride in organic solvent. Their formation was confirmed by the titrimetric analysis and FT‐IR. The presence of absorption band in FT‐IR at 1748 cm⁻¹ confirmed the carbonyl group attachment. The thermal behavior of native and acetyl substituted sago starch was investigated using thermo gravimetric analysis (TGA) and DSC. The results reveal that highly substituted starch acetate was more thermally stable as compared to native form. The XRD patterns showed loss of crystalline nature and its transformation into amorphous form. The SEM study suggested that the smooth surfaces of starch granules were changed into fibrous form after acetylation.     

Photo-scanning colorimetry of wood and transparent wood coatings

Although conventional spectrophotometers are well-known to give very accurate and reproducible measuring results of the wood surface colour, the areal resolution of this method is limited due to the fixed aperture size. In this study, the applicability of a colour calibrated flatbed scanner for areal-resolved colorimetry was investigated. For this purpose, the colorimetric values of several wood species calculated from images of a colour calibrated photo-scanner were correlated with those obtained by a conventional spectrophotometer. Further, this method was used to evaluate the discoloration of earlywood and latewood of Siberian larch (Larix sibirica) during Xenon arc exposure as a demonstration of the potential application of this method. In addition, an investigation concerning the possibility of image analysis for the evaluation of the colour change as a consequence of the application of transparent coatings was done. Good correlation among the measured methods could be found by applying relative colour values ΔL* Δa*, Δb* and ΔE*, whereas absolute colour values L*, a* and b* obtained rather weak correlations. The investigation of the relative discoloration of earlywood and latewood of Siberian larch showed a higher amount of discoloration in the earlywood. The investigation concerning the colour change induced by the application of transparent coatings showed that it is possible to evaluate the discoloration by the coating for earlywood and latewood separately. This could be the basis for a more quantitative comparison of quality parameters of coatings like the visual contrast enhancement effect, known as wet-look or “Anfeuerung” of transparent coatings. It was concluded that when evaluating colour changes on wood the use of a calibrated photo-scanner is a valuable addition to conventional spectrophotometry.