存储温度对保鲜纸中亚氯酸钠留着率的影响

目的研究不同存储温度对保鲜纸中亚氯酸钠留着率的影响。方法利用碘量法测定亚氯酸钠的留着率,用白度仪测定基材白度的变化情况,用X射线光电子能谱仪(XPS)对纤维表面的化学特性进行表征。结果不同温度下,亚氯酸钠留着率呈现出不同的下降趋势。通过白度测定结果可知,木素和亚氯酸钠反应会造成亚氯酸钠留着率降低。XPS测试结果表明,存储温度升高,木素和抽出物含量降低。结论低温环境有利于亚氯酸钠留着率的保持。     

保鲜纸涂层对其NaClO2留存率和ClO2释放规律的影响

目的研究保鲜纸涂层氧化淀粉胶对保鲜纸中NaClO_2留存率和ClO_2释放规律的影响。方法通过保鲜纸表面及横切面的SEM图片,确定保鲜纸的结构特点,采用纸基表面涂布氧化淀粉胶的方法,用碘量滴定法计算保鲜纸中NaClO_2的留存率和ClO_2的释放量。结果保鲜纸纸基表面形成的氧化淀粉胶层可以有效降低保鲜纸基结构对NaClO_2留存率和ClO_2释放量的影响,NaClO_2的留存率和ClO_2的释放量得到了提高,ClO_2的释放总量为3.4786mg,增加了70.82%。结论氧化淀粉胶涂层提高了NaClO_2的留存率和ClO_2的释放量。     

纳米TiO-2保鲜包装纸的制备及其对迷你黄瓜保鲜效果的研究

为研究纳米包装纸和保鲜膜结合对迷你黄瓜的保鲜效果,试制了不同浓度的TiO2涂膜纸,并与保鲜膜结合包装保鲜迷你黄瓜,观察了贮藏过程中迷你黄瓜的感官品质变化,并测定了迷你黄瓜的失重率、硬度、维生素C含量、叶绿素含量。实验结果表明,纳米TiO2保鲜纸结合保鲜膜包装迷你黄瓜可有效延长其货架期,15%(体积分数)的纳米涂膜纸与保鲜膜结合,可使迷你黄瓜的保质期延长到30 d以上。     

纸基摩擦材料纤维、树脂含量和孔隙率对压缩回弹性能的影响

纸基摩擦材料属多孔材料，其摩擦磨损性能与压缩回弹性能密切相关。研究了纸基摩擦材料纤维的含量及类型、树脂的含量，以及材料的孔隙率对其压缩回弹性能的影响。结果表明，材料配方及孔隙率会显著改变材料的压缩率和回弹率。纤维和树脂含量的增加都会造成纸基摩擦材料压缩率的降低和回弹率的升高。其中，树脂含量对材料压缩率的影响较大，纤维含量对材料回弹率的影响较大。加入混杂纤维的材料比较单纯采用芳纶纤维浆粕的材料具有更低的压缩率和更高的回弹率，其中混杂有纸浆纤维的材料压缩回弹性能最好。纸基材料的孔隙率越大，材料压缩率越大，回弹率越低。     

TEMPO氧化体系对废纸浆纤维的氧化改性

目的利用2,2,6,6-四甲基哌啶氧化物自由基(TEMPO)/NaClO/NaBr氧化体系改善废纸浆纤维成纸的性能。方法以废纸浆为原料,在碱性条件下采用TEMPO/NaClO/NaBr氧化体系对纤维进行选择性氧化,得到不同羧基含量的氧化废纸浆,通过纤维形态分析仪及化学分析法对纤维形态和羧基含量进行分析和测定;将氧化废纸浆、氧化废纸浆与原浆进行抄片和配抄,对手抄片的强度性能进行检测和分析;从经济效益出发,研究氧化体系中TEMPO及NaBr的循环使用次数对纸张强度性能的影响。结果随着NaClO用量的增加,废纸浆纤维的羧基含量增加;纤维长度、宽度和粗度有所降低;纸张抗张强度和环压强度增长较为明显;NaClO和NaBr循环使用2次后纸张的强度性能有所降低,但降低幅度不大。结论TEMPO氧化体系可用于废纸浆的氧化,改善废纸浆的性能。NaClO和NaBr的循环使用能够降低生产成本。     

水泥-粉煤灰-硅灰基超高性能混凝土水化过程微观结构的演变规律

超高性能混凝土(UHPC)具有卓越的力学性能和耐久性能,应用前景广阔。采用扫描电镜背散射电子图像、热重法和氮气吸附法系统研究了水泥-粉煤灰-硅灰基UHPC浆体水化过程中微观结构的演变过程。结果表明:UHPC浆体在早期水泥水化较快,但7d后水化变得较为缓慢,粉煤灰在UHPC浆体中反应较为缓慢,28d时反应程度仅为7%;UHPC浆体中Ca(OH)2含量早期上升快速,由于硅灰和粉煤灰的火山灰反应逐渐消耗,3d后含量开始下降,但28d时浆体中仍存在部分Ca(OH)2;此外,在水化过程中,UHPC浆体的比表面积不断降低,孔隙率逐渐下降,水化产物变得更为致密。     

1-MCP保鲜纸的制备及其在油桃保鲜中的应用

以吸水纸为芯纸,两侧覆上面纸,以热熔胶黏合,在芯纸上均匀打孔载入定量的1-MCP药剂,制得1-MCP保鲜纸,并采用GC-MS,对保鲜纸中1-MCP的释放规律进行研究。研究表明,实验条件下1-MCP处于气态,在第2 d保鲜纸中的1-MCP释放达到最大值,说明此时的湿度达到适合1-MCP释放的条件。以油桃为实验对象,研究保鲜纸中1-MCP用量对果实感官评价、失重率、呼吸强度及可溶性固形物含量等指标的影响。结果表明,质量浓度为4 mg/L的1-MCP保鲜纸对油桃感官评价的影响最小,对果实失重率、呼吸强度、可溶性固形物含量的抑制作用最明显,整体而言,对油桃的保鲜效果最好。     

三种散孔材植物纤维化学特征的比较

目的 以海南橡胶木为原料，对其化学全组分（灰分、综纤维素、酸不溶木素、聚戊糖、α-纤维素、NaOH(1%)抽出物、苯醇抽出物、淀粉和蛋白质）含量进行测定，观察和研究橡胶木的微观结构，并与典型阔叶材杨木和桦木进行对比分析，明确海南橡胶木的化学组分和微观结构特征。方法 采用植物显微技术结合化学组分测定的国家标准予以分析。结果 海南橡胶木的木素、综纤维素、灰分、聚戊糖、α-纤维素、抽出物与杨木和桦木存在微量差异，其淀粉和蛋白质含量远高于典型阔叶材杨木和桦木；橡胶木纤维的长度为1 176.68μm，宽度为21.35μm，长宽比约为55.11，壁腔比为0.49；橡胶木属散孔材，木射线组织呈异型Ⅰ和异型Ⅱ，木纤维具有纤维管胞和角质木纤维，轴向薄壁组织有傍管薄壁组织和离管薄壁组织2种。结论 较高的纤维素和较低的木素、苯醇抽出物含量，较大的长宽比及较小的壁腔比，使得橡胶木在制浆过程中所消耗的脱木素和漂白药剂更少，蒸煮时间更短，制浆得率更高，纤维交织能力更强，纤维分布更密，纸张结合强度更高，较为适宜作为制备力学性能优良的纸基包装材料的重要基材。     

玉米秸秆包装材料的开发研究

利用玉米秸秆的外皮为主要原料,选择适宜浓度的预处理剂,采用化学预处理与机械磨浆相结合的方法,制得了较高得率的纸浆。抄造出了超过国家标准规定的一等品质量要求的瓦楞原纸,制浆过程中产生的废液可全部循环回用。开展该研究有利于保护环境、节约资源、增加农民收入。     

陶瓷纤维含量对一种纸基摩擦材料性能的影响

纸基摩擦材料是一种采用造纸工艺生产的广泛应用于汽车、摩托车等机械传扭装置中的重要功能材料.在一种碳纤维增强纸基摩擦材料的基础上,引入了陶瓷纤维来代替芳纶纤维,制备了编号为0#-4#的5个试样.采用惯量摩擦性能测试、力学性能测试以及SEM等手段.研究了陶瓷纤维含量对纸基摩擦材料性能的影响.结果表明,随着陶瓷纤维含量的增加,材料的抗拉强度呈先减小后增大的趋势,耐热性能得到一定程度的提高.陶瓷纤维含量为2.35%的1#试样纤维分散均匀,形成了一定的材料孔隙,材料制动时间较短,制动过程较平稳,动、静摩擦系数较无陶瓷纤维的0#试样有较大提高.总体来说,当陶瓷纤维含量为2.35%时,试样具有较好的性能.     

Spectral characterization of eucalyptus wood

The main difficulties in wood and pulp analyses arise principally from their numerous components with different chemical structures. Therefore, the basic problem in a specific analytical procedure may be the selective separation of the main carbohydrate-derived components from lignin due to their chemical association and structural coexistence. The processing of the wood determines some structural modification in its components depending on the type of wood and the applied procedure. Fourier transform infrared (FT-IR) spectrometry and X-ray diffraction have been applied to analyze Eucalyptus g. wood chips and unbleached and chlorite-bleached pulp. The differences between samples have been established by examination of the spectra of the fractions obtained by successive extraction (acetone extractives, acetone free extractive samples, hemicelluloses, and lignins) by evaluating the derivative spectra, band deconvolution, etc. The energy and the hydrogen bonding distance have been evaluated. The relationship between spectral characteristics and sample composition has been established, as well as the variation of the degree of crystallinity after pulping and bleaching. The integral absorption and lignin/carbohydrate ratios calculated from FT-IR spectra of the IR bands assigned to different bending or stretching in lignin groups are stronger in the spectrum of eucalyptus chips than those from brown stock (BS) pulp spectra because of the smaller total amount of lignin in the latter. FT-IR spectra clearly show that after chlorite bleaching the structure of the wood components is partially modified or removed. Along with FT-IR data, the X-ray results confirmed the low content of lignin in the pulp samples by increasing the calculated values of the crystalline parameters. It was concluded that FT-IR spectroscopy can be used as a quick method to differentiate Eucalyptus globulus samples.     

桑皮纤维的提取方法及其应用和发展

目的综述桑皮纤维组成成分、结构特征、提取工艺及其研究进展。方法化学脱胶法和生物脱胶法是研究桑皮纤维提取最常用的方法。结果桑皮与其他造纸原料相比具有高果胶含量、低木素含量的特点,果胶的质量分数最高为11.16%,木素的质量分数最低为8.74%;不同地域桑皮的果胶含量相差30%左右,木素含量相差约为50%。桑皮纤维的横截面呈现椭圆或不规则状,纤维表面粗糙、不平整。桑皮纤维提取的重点在于果胶的脱除,桑皮脱除果胶的方法主要有化学法和生物法2种。结论纺织方向上的研究近乎完善,造纸方向上的研究还刚刚起步,而开发桑皮纤维相关产品以提高其应用价值是下一阶段研究的主要方向。     

Chemical compositions of hardwood and softwood pulps employing photoacoustic Fourier transform infrared spectroscopy in combination with partial least-squares analysis

In the present study, hardwood and softwood pulps were characterized by employing Fourier transform infrared photoacoustic spectroscopy (FT-IR-PAS). The pulp samples examined originated from Swedish sulfite and kraft pulp mills, which utilize different cooking processes and modern bleaching technologies. Partial least-squares (PLS) analysis was used to correlate the spectral data obtained with the kappa (K) numbers and carbohydrate compositions of the pulp samples determined by enzymatic hydrolysis and subsequent capillary zone electrophoresis. Using four principal components, the present PLS model based on photoacoustic FT-IR spectra could explain 85% of the variance in the X matrix and 81% of the variance in the Y matrix. The FT-IR-PAS technique in combination with PLS was found to accurately predict the contents of carbohydrates, i.e., xylose, glucose, mannose, arabinose, galactose, and hexenuronic acid residues, as well as the content of lignin measured in terms of K numbers and corrected K numbers of the pulps. From these predictions, the contents of xylan, glucomannan, and cellulose can also be predicted. The content of 4-O-methylglucuronic acid residues is, however, more difficult to predict accurately, using this approach.     

Effects of delignification in the production of plant-based cellulose nanofibers for optically transparent nanocomposites

The pulp-making procedures prior to nanofibrillation require considerable chemical treatments to leach the matrix substances. In particular, the sodium chlorite (NaClO₂) solution treatment is cyclically applied to remove lignin. In this study, we clarified the effects of delignification in the production of cellulose nanofibers and nanocomposites through a comparison of plants with lignin (2 year old lignified mature bamboo culms) and without lignin (immature bamboo shoot culms). We concluded that the NaClO₂ treatment might have degraded the cellulose nanofibers, as we found that the morphology and properties of the cellulose nanofibers extracted from mature bamboo had no advantages over the nanofibers from immature bamboo. In addition, the light transmittance of the cellulose nanocomposites from immature bamboo was higher even at lower wavelengths.     

阻燃改性纤维素浆粕和阻燃纸的制备及表征

将降纤维素浆粕在不同温度下进行碱化、醚化,得到不同Na+含量的阻燃改性纤维素浆粕。利用红外光谱、极限氧指数、锥形量热和扫描电镜等测试方法,对改性纤维素浆粕的燃烧和阻燃性能进行了研究。结果表明,改性纤维素浆粕的最大氧指数达到34.0,远远高于纤维素的氧指数19.0,并且改性纤维素浆粕的总热释放量最小值为6.74 MJ/m2,远远低于纤维素的总热释放量20.44 MJ/m2。同时通过造纸工艺制备了海藻酸钙纤维-改性纤维素浆粕复合阻燃纸张,并利用极限氧指数、锥形量热和扫描电镜等测试方法,对复合纸的燃烧和阻燃性能进行了研究。     

温湿度和紫外老化对纸浆模塑材料性能的影响

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62 MPa;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。     

芳纶浆粕和纳米钛酸钠晶须在汽车摩擦材料中的协同效应

以包括酚醛树脂、芳纶浆粕、纳米钛酸钠晶须、氧化铝、重晶石和二硫化钼的简化配方为基础制备一种摩擦材料,研究芳纶浆粕和纳米钛酸钠晶须的含量对摩擦材料的物理力学性能和摩擦磨损性能的影响。结果表明：随着芳纶浆粕含量的提高摩擦材料试样的布氏硬度呈现提高的趋势;当芳纶浆粕与钛酸钠晶须的比例为3:1时,材料的冲击强度达到最大值0.392 J/cm²,两种增强纤维的均匀混合为摩擦过程中产生高内聚强度的摩擦膜提供了基础,且这个比例产生最佳的协同效应,摩擦系数稳定在0.38~0.45,磨损率为5%。     

天然纤维表面化学处理性能研究

针对天然纤维强化复合材料中纤维与基体相容性差和纤维的高吸湿性导致复合材料吸水率高的问题,以大麻、苎麻和黄麻3种麻为原料,采用苯甲酰氯、亚氯酸钠、氢氧化钠和丙烯酸对麻进行表面处理,来考察不同麻种类和不同化学处理方式对麻纤维拉伸强度和吸湿度的影响。研究表明,处理方式和麻种类均对纤维拉伸强度和吸湿度有显著的影响,其中丙烯酸处理的大麻纤维影响最显著;纤维经处理后表面变粗糙,表面积增大。     

Influence of commercial and residual sorbents and silicates as additives on the stabilisation/solidification of organic and inorganic industrial waste

An environmental problem of the foundry activities is the management of industrial waste generated in different processes. The foundry sludge from gas wet cleaning treatment that contains organic and inorganic compounds and a high content of water is an interesting example. Due to their characteristics, they can be managed using different stabilisation/solidification (S/S) technologies prior to land disposal. The purpose of this work is to study S/S formulations in order to improve the control of the mobility of the pollutants and the ecotoxicity of the samples. Different mixtures of cement or lime as binders and additives (foundry sand, silica fume, sodium silicate, silicic acid, activated carbon and black carbon) have been used in order to reduce the mobility of the chemical and ecotoxicological regulated parameters and to compare the results for commercial and residual additives. The best results have been obtained with sorbents (activated carbon and black carbon) or sodium silicate. The results of the foundry sand ash as additive can conclude that it can be used as replacement in the cement products. However, silica fume in the samples with lime and siliceous resin sand as additives gives products that do not fulfil the regulated limits. Finally, some linear expressions between the chemical parameters and the quantity of material used in the samples have been obtained.