阴极电泳漆槽液MEQ值的容量法检测

介绍了乙醇法测阴极电泳漆槽液MEQ值的方法。用乙醇对阴极电泳漆槽液进行溶解,通过人工滴定法记录氢氧化钠标准溶液的用量,得到槽液p H与氢氧化钠消耗量的函数。利用相关软件绘图并进行数据处理,再根据公式便可计算出槽液MEQ值。此外还对四氢呋喃法和乙醇法测MEQ值的准确性和难易程度等进行了比较。     

木材中的纳米分形木质纤维及碳素纤维材料的制备

利用分形理论构建了木材细胞壁中的分形木质纤维,并计算了分形木质纤维S1层和S2层的扭曲分形维数,指出木材中具有纳米尺度的纤维结构;同时,以木材液化和纳米纺丝技术为基础,提出了木材苯酚液化产物制备碳素纤维材料的构思和技术路线,为解决木材纳米、微米材料的制备提出了新思路。     

聚丙烯保温材料连续比热容的测定

介绍差示扫描量热法(DSC)测定材料连续比热容的原理和实验过程,用DSC法测定了标准样品苯甲酸及3种聚丙烯保温材料样品在310￣370K的连续比热容。苯甲酸测定结果与文献值之差不大于0.02J/(K.g),3种聚丙烯保温材料样品平行测定结果之差不大于0.03J/(K.g)。     

Micro Analytical Methods for Determination of Compression Wood Content in Loblolly Pine

Abstract

All loblolly pine trees, especially the juvenile portion, contain various amounts of compression wood. The morphological, chemical, and papermaking properties of compression wood are distinctively different from those of normal juvenile wood and mature wood. Compression wood has higher lignin and galactan, but lower cellulose and mannan content, shorter average fiber length, lower fiber width but thicker cell wall, higher fiber coarseness and higher microfibril angles as compared with the corresponding normal wood. Micro analytical methods have been developed to quantitatively determine the percentage of compression wood in an incremental core so as to eliminate the effects of compression wood on the aforementioned properties. This enables accurate quantitative genetic analyses of these properties for tree breeding programs.     

Properties of Acetylated Wood Prepared at Low Temperature in the Presence of Catalysts

Abstract

In the presence of catalysts such as sodium acetate, zinc chloride, magnesium perchlorate, and magnesium chloride hexahydrate, acetylation of wood at 75°C was investigated. The results showed that it was possible to endow wood with high dimensional stability at low temperature by a catalyzed acetylation method. In particular, the magnesium chloride–catalyzed acetylation of wood showed very little or no effect on the color change or mechanical property of wood, as contrasted to those of the zinc chloride or magnesium perchlorate–catalyzed treatment, which showed a great effect. In addition, the concentrations of catalysts proved to have an effect on weight percent gain.     

电位滴定法测定工业用三壬基苯亚磷酸酯(TNPP)的酸值

自动电位滴定法代替容量法测定TNPP的酸值,具有更快捷、准确、安全,重现性好等特点,适用于酸值不小于0．02mg KOH·mg-1的TNPP酸值的测定。     

库仑滴定法测定生物乙醇制备原料的还原糖含量

利用库仑滴定法测定生物乙醇原料蔗糖的还原糖含量.样品经5 mL 10％盐酸于65-70 ℃水解15 min后,以铂电极为电解电极和指示电极,1.0 mol/L硫酸亚铁(pH 2.0)为电解质溶液,恒电流电解生成Fe3+,与预处理样品后生成的氧化亚铜定量发生氧化还原反应,记录电解至滴定终点时间,通过法拉第电解定律,计算样...     

A Comparison of the Drying Simulation Codes Transpore and Wood2D which are used for the Modelling of Two-Dimensional Wood Drying Processes

ABSTRACT

This study is devoted to investigating the heat and mass transfer phenomena that occur during the convective drying of wood at high temperatures. A comparison will be made between an existing two-dimensional computer code known as Transpore. which was developed by Perre in France, and another two-dimensional code which was developed independently by Turner in Australia. Both numerical codes use a comprehensive set of macroscopic equations to describe the drying process, and most importantly treat the anisotropic behaviour of the wood. The porous medium is defined by three state variables: temperature, moisture content and gaseous pressure and the numerical simulation codes allow the evolution of the distributions of these state variables to be analysed throughout the drying process. The numerical investigation presented in this research work will compare the results obtained from both simulation codes and comments will be made on their consistencies. The influence that the drying air characteristics (moist air and super-heated stream) have on the overall drying kinetics, together with the effect that varying the mesh structure or changing the relative permeability curves have on the results will be throughly scrutinised.     

Lignocellulosic biomass for the preparation of cellulose‐based hydrogel and its use for optimizing water resources in agriculture

Recently, efforts have been devoted to find ways in utilizing biomass as feedstocks for the production of organic chemicals. This is because of its abundance, renewability and worldwide distribution. Lignocellulosic agricultural waste materials are regarded as abundant, inexpensive, and readily available natural resources for both chemical and paper industries. Hydrogels are polymeric materials that vary in their origin and composition and can absorb large amount of water without dissolving. In our study, cellulose‐based acrylic acid hydrogel was synthesized starting from rice straw as a source for the lignocellulosic material, where cellulose was first isolated after alkaline‐acid pulping treatment followed by bleaching step with sodium hypochlorite resulting of 90.8% holocellulose. The cellulose‐based acrylic acid hydrogel was synthesized applying heterogeneous reaction and shows a swelling ratio more than 3000%. The resulting hydrogel was further characterized with FT‐IR and SEM. On the other hand, comparison between the rice straw‐based hydrogel and the commercially available acrylamide hydrogel was studied for improving maize production in salt affected soil as well as in the growth promoters of maize under water stress. The experimental results demonstrated that the yield parameters were increased with increasing irrigation rates. Both types of hydrogels introduce positive and significant effect compared to the one without adding hydrogels. Also, acrylamide hydrogel was effective for improving almost yield parameters more than applying rice straw‐based hydrogel. Generally, the addition of hydrogel increases the nutrient concentration, uptake, and both of water and nutrients use efficiency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42652.     

活性染料在木材染色中上染率的研究

选用三只活性染料对速生杨木进行染色。上染率最佳的染色条件：温度：70℃～80℃；染色时间：3小时：无机盐用量：40g／l；纯碱用量：20g／l。在染色条件中，当温度由40℃上升至80℃时，上染率由33．74％上升至56．31％：染色时闻由1小时延长至3小时，上染率由34．74％上升至54．92％继续延长时间，上染率变化不大；当无机盐由0变为50g/l时上染率达到55．61％，碱的用量在20g／l时上染率达到最高为55．15％。     

一种新兴的绿色胶粘剂-浅谈改性植物蛋白基木材胶粘剂

用植物蛋白制作的木材胶粘剂具有可再生、价廉、原料来源广、环保等优点，本文就植物蛋白改性作木材胶粘剂的研究及发展状况进行了较详尽的阐述。     

间歇过滤机最大生产能力的确定

研究了间歇过滤机最大生产能力的计算方法，并根据最大生产能力确定在一个操作周期中各个阶段应采用的最佳时间，对这于工业生产中提高过滤机的生产具有重要意义。另外，计算结果过滤机型号及操作压力的选择具有参考价值。     

中性镀镍溶液柠檬酸钠的测定

柠檬酸钠含量的准确检测对中性镀镍溶液的维护是非常重要的。有些中性镀镍溶液还含有氯化物、光亮剂和润湿剂,这些物质对常见的分析方法有干扰,因此分析柠檬酸钠含量时必须针对镀液的成分选择适当的方法。列举了几种分析方法供从事镀液监控分析工作的同行参考。     

三元正极材料中镍钴锰含量的化学分析测定

三元正极材料中镍钴锰的含量直接影响着电极材料的电化学性能,准确测量镍、钴、锰的含量对三元正极材料的研究具有重要的意义。介绍了一种快速、简便的分析方法。首先采用EDTA滴定镍钴锰的总量;其次用硫酸亚铁铵滴定溶液中的锰含量;然后在氨水环境中,使用过硫酸铵将Co~(2+)氧化为Co~(3+),并将二价锰氧化成沉淀物除去,对滤液进行EDTA滴定得到Ni的含量;最后用差减法推出Co含量。该方法操作快速、简便、准确度高。     

Spectrophotometric Determination of Phenolic Antioxidants in the Presence of Thiols and Proteins

Development of easy, practical, and low-cost spectrophotometric methods is required for the selective determination of phenolic antioxidants in the presence of other similar substances. As electron transfer (ET)-based total antioxidant capacity (TAC) assays generally measure the reducing ability of antioxidant compounds, thiols and phenols cannot be differentiated since they are both responsive to the probe reagent. In this study, three of the most common TAC determination methods, namely cupric ion reducing antioxidant capacity (CUPRAC), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt/trolox equivalent antioxidant capacity (ABTS/TEAC), and ferric reducing antioxidant power (FRAP), were tested for the assay of phenolics in the presence of selected thiol and protein compounds. Although the FRAP method is almost non-responsive to thiol compounds individually, surprising overoxidations with large positive deviations from additivity were observed when using this method for (phenols + thiols) mixtures. Among the tested TAC methods, CUPRAC gave the most additive results for all studied (phenol + thiol) and (phenol + protein) mixtures with minimal relative error. As ABTS/TEAC and FRAP methods gave small and large deviations, respectively, from additivity of absorbances arising from these components in mixtures, mercury(II) compounds were added to stabilize the thiol components in the form of Hg(II)-thiol complexes so as to enable selective spectrophotometric determination of phenolic components. This error compensation was most efficient for the FRAP method in testing (thiols + phenols) mixtures.     

确定地基承载力的公式计算法

就现行地基基础设计规范中用公式计算确定的地基承载力与用载荷试验测定的地基承载力进行详细的比较,并对公式计算法存在的问题进行讨论。     

水性聚氨酯木器漆胶膜物性的研究

以甲苯二异氰酸酯（TDI）、聚己二酸己二醇酯二醇（PHA）、二羟甲基丙酸（DMPA）等为原料,采用内乳化法制备了水性聚氨酯,研究了NCO与OH摩尔比、PHA相对分子质量及交联剂三羟甲基丙烷用量对水性聚氨酯成膜物性能的影响。结果表明：通过提高硬段含量和交联度等方法可改善聚氨酯膜的力学性能和耐介质性,制得的水性聚氨酯成膜物拉伸强度20．58MPa、邵A硬度90、吸水率2．0％,在70％酒精中浸泡24h增重率12．4％,性能达到国外同类产品的技术指标。这种水性聚氨酯可用于木器漆。     

柴油酸含量试验方法的选择

为解决柴油外加生物质燃料组分、抗磨剂后生产、使用过程中酸含量测定标准的规范、有效问题,通过对GB/T264-1983、GB/T258-1988、GB/T4945-2002、GB/T7304-2000、GB/T5530-2005、GB/T9104-2008等国家标准测定方法的分析,认定矿物柴油、生物类柴油调合组分及柴油添加剂、生物柴油分别采用GB/T258、GB/T5530-2005中冷溶剂法、GB/T264-1983可方便指导生产,满足柴油产品质量中关于酸度的测定要求。     

Influence of Polar Monomers on the Performance of Wood Fiber Reinforced Polystyrene Composites. I. Evaluation of Critical Conditions

Abstract

Wood fibers and nonpolar thermoplastics, e.g. polystyrene, are not the ideal partner for the preparation of composites because of a wide difference in their polarity. In the present study, polarity of the polystyrene was modified by the introduction of a—COOH group, through the reaction with maleic anhydride (MA) in the presence of an initiator (benzoyl peroxide: BPO) in a roll mill at the elevated temperatures. Optimum conditions for the preparation of polar polystyrene have been investigated. The temperature of the roll mill, i.e., the reaction temperature, and reaction time varied between 160–175°C and 10–15 min., respectively. The concentrations of the monomer, (MA) as well as the initiator (BPO), also varied: 0–10% and 0–2% (by weight of polymer), respectively. The mechanical properties of chemithermomechanical pulp (CTMP)-filled modified polystyrenes were evaluated. The effect of 3% coupling agent [e.g. poly(methylene (polyphenyl isocyanate))] (PMPPIC) on the mechanical properties of the same composites was also determined.

Generally, mechanical properties of the composite materials were enhanced when modified polymers were used as base polymers. Moreover, the extent of the improvement in mechanical properties depends on the reaction temperature and time, as well as on the concentrations of the monomer (maleic anhydride) and initiator. Maximum improvements in mechanical properties occur when the temperature was maintained at 175°C for 15 min. In addition, preferred concentrations of both the monomer and initiator were found to be 5% and 1% (by polymer weight), respectively. Once again, properties were further accelarated when coupling agent (e.g. PMPPIC) was used in addition to the modified polystyrene. The improvements in mechanical properties (over those of the original polymer and those of composites containing unmodified polymers) indicate that the compatibility between hydrophilic cellulosic fiber and hydrophobic polymer has increased.     

含-NCO双组分水性木器漆的应用研究

介绍了以-NCO交联的双组分水性木器漆常用的树脂、固化剂类型，对其在木器涂装过程中的施工时限、泡沫控制等影响生产应用的因素进行了分析研究，并提出了一些解决方案。