竹原纤维增强石膏板性能研究

研究采用润湿处理、NaOH处理和硅烷偶联剂KH550(γ-氨丙基三乙基氧基硅烷)处理等方式改性竹原纤维(长度为20 mm),并将竹原纤维用于增强石膏板。对竹原纤维/石膏复合材的静曲强度、弯曲模量、吸水厚度膨胀率及内结合强度进行测试,采用傅里叶红外光谱、扫描电子显微镜和X射线扫描分析手段探究增强原理。竹原纤维经处理后制备的复合材脆性减小、结晶度增大、力学性能都有提高,脆性得到改善。NaOH处理去除了纤维表面的蜡质等,使表面粗糙;偶联剂处理降低了纤维表面的极性,这些都有利于改善纤维与石膏的界面结合,提高石膏板的力学性能。当竹原纤维质量分数为3%时,复合材的静曲强度比纯石膏提高了77.8%,弯曲模量提高了9.4%,内结合强度提高了229.6%,24 h吸水厚度膨胀率未发生明显变化。     

漂白竹浆碱抽提制备溶解浆的研究

以漂白竹浆为原料,通过碱抽提技术制备竹溶解浆,并用X射线衍射仪研究竹浆中纤维素晶型结构的变化,用场发射扫描电镜(FE-SEM)观察纤维表面形貌的变化,采用凝胶渗透色谱(GPC)分析碱抽提后竹浆相对分子质量分布(MWD)。经碱抽提后,采用盐酸进行酸处理,以调控溶解浆的聚合度、灰分和白度。研究结果表明:在浆质量分数10%条件下,Na OH质量分数10%,温度30℃,时间60 min,半纤维素脱除率可达66.71%;FE-SEM观察到半纤维素的去除减少了纤维表面原纤化现象,增大纤维横向宽度,增加了纤维柔软性及卷曲性;GPC分析表明多分散系数(PDI)随半纤维素的去除逐渐下降,由7.71降至4.43,竹浆相对分子质量增加,提高了相对分子质量分布的均一性。酸处理过程使残余半纤维素质量分数降至7.02%,竹溶解浆纤维素纯度高达94.25%。     

椰子树树干微结构对其抗风能力的影响

为了给出海南省省树椰子树(Cocos nucifera L.)树干的理论抗风相关数据,通过对椰子树树干的外观及其微结构进行抽象模型化分析后,利用国家标准《建筑结荷载范》(GB 50009-2012)中柱状物体的经验公式,计算了生长在低海拔的海岛海岸地区,高度分别为5、10、20 m的椰子树在风强度为台风等级时的所受风压、风力以及根部所产生的弯矩。结合华南地区多个树种抗风能力的对比调查分析结果,根据椰子树树干中纤维束管结构的物理特性,解释了热带植物椰子树在受到台风侵袭时其树干不易被折断的原因。这些计算过程和结果可以给在台风中搭建建筑物等提供实际重要的参考;同时说明了热带植物椰子树所特有的簇状纤维束物理结构有很强的抗弯折强度,这一结构特性可广泛应用于生产生活中。     

葛根纤维化学脱胶工艺研究

采用化学脱胶处理的方法,从葛根废渣中制备生态友好型的天然葛根纤维.通过变量控制法分析了氢氧化钠的质量浓度、煮练时间的长短对葛根纤维的细度、拉伸断裂强力的影响.实验结果表明,葛根纤维的细度与拉伸断裂强力随NaOH质量浓度或碱煮时间的增加都有减少趋势,通过对比试验,确定了葛根脱胶的最优工艺:葛根纤维的残胶率在氢氧化钠质量浓...     

稻草原料表面特性FTIR和XPS分析

运用红外光谱(IR)和X射线光电子能谱分析(XPS)法，考察了热磨处理对稻草表面特性的影响。结果表明：稻草秸秆内表面的活性基团数量和氧碳元素百分比都明显高于外表面；经热磨处理，稻草纤维表面的羟基、甲基、亚甲基等官能团含量显著增加，氧碳元素百分比相对秸秆表面有大幅度提高，证明热磨处理能增强稻草表面活性，为脲醛树脂稻草中纤板制造的技术可行性提供了依据。     

蔗渣膳食纤维

该项目是以糖厂榨糖后剩下的甘蔗渣为原料,经压力蒸煮软化纤维,采用稀碱处理,去除蛋白质、部份木质素和脂肪,并脱除异味,然后经漂白脱色、干燥、粉碎制得蔗渣膳食纤维。主要技术指标     

浒苔纤维聚丙烯酸吸水树脂的制备及性能分析

在浒苔纤维上接枝丙烯酸,通过改变浒苔纤维的预处理方法,探讨浒苔纤维在聚丙烯酸类吸水树脂中应用的可行性。以未预处理、1%NaOH预处理和漂白预处理浒苔纤维为原料,在固定的碱用量、交联剂和引发剂用量条件下制备浒苔纤维聚丙烯酸吸水树脂,考察了预处理方法、丙烯酸中和度、浒苔纤维用量和尺寸对吸水树脂性能的影响;比较了吸水树脂对去离子水、生理盐水、人工尿液3种液体的吸液倍率。研究结果表明:合成吸水树脂过程中浒苔纤维用量为1.00 g、丙烯酸中和度为65%、筛分尺寸为250～380μm的未预处理浒苔纤维合成的吸水树脂吸液性能最好,其对去离子水、生理盐水和人工尿液的吸液倍率分别为1 643、244和201 g/g。通过扫描电子显微镜(SEM)观察发现,未预处理浒苔纤维与丙烯酸接枝效果最好,合成的树脂吸水饱和后纤维形态饱满、孔隙少。X射线衍射(XRD)结果也显示,浒苔纤维经过预处理后其非结晶区大量流失,结晶度升高,纤维素结晶区不利于与丙烯酸单体的接枝,从而阻碍了碱预处理和漂白预处理浒苔纤维与丙烯酸的接枝反应。     

木纤维增强石膏板性能研究

利用木纤维及其表面改性手段提高石膏板的强度,并探讨纤维形态和尺寸对石膏板性能的影响。在木纤维不同粒径(0.38~1.70 mm、212~380μm、160~212μm和未筛分)、不同使用比例(1%,3%,6%和10%),以及添加硅烷偶联剂表面处理因素条件下制备木纤维增强石膏板,研究上述因素水平对石膏板力学性能、密度及吸水厚度膨胀率的影响,并利用红外光谱、扫描电子显微镜和X射线衍射仪对性能改进的原因进行了分析。试验结果表明,粒径为0.38~1.70 mm的木纤维增强效果最好,当添加量为3%时,板材的弹性模量、静曲强度和内结合强度最高,与纯石膏板相比分别提高了14.24%,35.73%和57.41%。经硅烷偶联剂处理改性后,木纤维表面极性减弱,与石膏界面的结合得到改善,并提高了石膏结晶度。添加量为3%改性木纤维增强石膏板的弹性模量、静曲强度和内结合强度分别达到7 501.43,6.67和1.08 MPa,与纯石膏板相比,分别提高了25.75%,92.22%和100.67%。此外,适当添加木纤维还能减小石膏板的脆性。研究证明,对木纤维进行筛分有利于提高石膏板的增强效果,硅烷偶联剂KH550的加入可改善木纤维和石膏间的结合,提高石膏板的力学性能。     

短纤维增强型聚丙烯基复合材料的性能研究

利用短纤维代替粉状材料作为增强材料制备纤维增强型聚丙烯基复合材料,研究不同的木纤维/聚丙烯配比、密度以及不同浓度的碱处理对木纤维/聚丙烯复合材料物理力学性能的影响。结果表明,目标密度仅为0.55g/cm3时,且当木纤维与聚丙烯的配比为30︰70时,木纤维/聚丙烯复合材料表现出最佳的物理力学性能,但仍达不到标准要求。因此,综合产品成本和物理力学性能,选取了50︰50的原料配比,研究密度对该产品物理力学性能的影响。进一步研究表明,随着密度的增加,复合材料的力学强度得到不断提高,当密度为0.70g/cm3时,板材的力学性能就可以满足国标要求但吸水厚度膨胀率不能满足国标要求。当密度为0.83 g/cm3时,板材的力学性能满足国标要求,吸水厚度膨胀率有减小的趋势。为了进一步提高该复合材料的物理力学性能,利用浓度分别为1%,3%和5%的氢氧化钠溶液对木材纤维和工业大麻杆纤维进行处理,结果表明,经过碱处理后复合材料的吸水厚度膨胀率减小了,静曲强度和弹性模量仍可满足标准要求。     

响应面分析法优化烟梗氧碱制浆工艺

为优化烟梗氧碱制浆工艺条件,在单因素试验基础上,通过Box-behnken响应面分析优化碱用量、保温温度和保温时间对细浆得率的影响。结果表明:碱用量及碱用量和温度之间的交互作用对烟梗细浆得率影响极显著,在较优的工艺条件(碱用量15.5%、保温温度75℃、保温时间45 min)下细浆得率为29.35%,与预测值29.48%接近。通过分析对比烟梗机械浆与烟梗氧碱浆纤维的显微结构发现,烟梗经过氧碱制浆后,纤维的分丝帚化程度较好,纤维表面也比较光滑,纤维既细且长,两端尖削,且烟梗中非纤维细胞较多。     

Surface characterization of esterified cellulosic fibers by XPS and FTIR Spectroscopy

 X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy techniques were used to study the surface chemical compositions of cellulosic fibers before and after treatments. The fibers were treated with phthalic anhydride and maleated polypropylene for surface modifications. Both XPS and FTIR spectroscopy analysis indicated that chemical bonds between hydroxyl groups of cellulosic fibers and anhydride moieties of phthalic anhydride and maleated polypropylene have occurred through esterification reaction. These chemical reagents have been added to the surface of cellulosic fibers in the form of monoester, i.e., the formation of esterified cellulosic fibers bearing a pendent carboxylic group. Received 20 July 1997     

Mechanical and physical characterization of sodium hydroxide treated Borassus fruit fibers

In order to improve the properties by chemical modification and to optimize the alkali concentration,we treated Borassus fruit fine fibers with aqueous sodium hydroxide solutions of different concentrations.In each case,the tensile properties of the fibers were determined.The morphology of the untreated and alkali treated fibers was observed using scanning electron microscope.The surface of the fibers became rough on alkali treatment.The tensile properties of the fibers improved on alkali treatment.The fibers attained maximum tensile properties when treated with 15% aqueous sodium hydroxide solution and decreased thereafter.The crystallinity index of the fibers showed a similar trend.The thermal stability of the alkali treated fibers was found to be higher than that of untreated fibers.Further,the char content was maximum for fibers treated with alkali having concentration of 15% and above.The chemical composition indicated that the percentageof α-cellulose was maximum when the fibers were treated with 15% aqueous sodium hydroxide solution and then decreased thereafter thus indicating the beginning of degradation of the fibers at higher concentrations.Thus,the optimum concentration of NaOH was established as 15% for alkali treatment of the Borassus fibers.     

球磨-酶解法制备纳米竹纤维的结构表征

采用机械球磨对竹纤维进行预处理,再经纤维素酶水解制备纳米竹纤维。通过光学显微镜(OM)、透射电子显微镜(TEM)、傅立叶红外光谱仪(FTIR)和X射线衍射仪(XRD)对竹纤维的形貌、组成、光谱学性能以及晶体特性进行了表征。实验结果表明:球磨法和酶解法在一定程度上都可以细化竹纤维;球磨预处理有助于竹纤维的酶解过程,且球磨-酶解法制备的纳米竹纤维粒径在100 nm左右;所制备的纳米竹纤维仍然保持竹纤维的基本化学结构,但球磨处理破坏了纤维素的结晶结构,其结晶度由64.15%降低到了38.55%。     

Effect of alkali treatment on wettability and thermal stability of individual bamboo fibers

The aim of this study is to examine the wettability and thermal properties of individual bamboo fibers after alkali treatment. The individual bamboo fibers were treated by sodium hydroxide (NaOH) solution with varying concentrations (6, 8, 10, 15 and 25%) followed by freeze-drying treatment. The surface analysis of alkali-treated individual bamboo fibers was characterized by atomic force microscope. Water droplet on the individual fiber surface was observed with drop shaper analyzer and the contact angles on fiber surface were also measured. Thermal properties were further studied by thermogravimetric analysis. The results indicated that alkali treatment resulted in the increase in surface roughness of individual bamboo fibers. Alkali treatment with low NaOH concentration could enhance the wettability of treated individual bamboo fibers, and while the wettability was reduced with alkali treatment at high concentration (25%). Thermal analysis revealed that the onset of decomposition and the maximum decomposition were moved to higher temperature after alkali treatment at low NaOH concentrations (6, 8, and 10%), suggesting the improvement in the thermal stability of treated individual bamboo fibers, while the thermal stability was compromised after alkali treatment at higher concentrations (15 and 25%).     

Fiber charge characteristics of pulp suspension containing aluminum sulfate

Fiber charge characteristics of pulp suspensions containing aluminum sulfate were investigated with relation to adsorption behavior of aluminum components on the pulp fibers by streaming potential measurement using a particle charge detector, X-ray photoelectron spectroscopy, and X-ray fluorescence analysis. When aluminum sulfate was added to a pulp suspension prepared using deionized water, a streaming potential of the suspension went from negative to slightly negative according to the adsorption of aluminum components on the pulp fibers. Subsequent addition of a dilute NaOH solution to the suspension drastically cationized the fibers in the pH range of around 5 by predominant and homogeneous adsorption of cationic aluminum complexes on the fiber surfaces. However, the aluminum flocs that formed heterogeneously on the fiber surfaces at higher pH by further alkali addition made nearly no contribution to cationization of the fibers, although the abundant aluminum components were retained in the pulp sheets. Therefore, only aluminum cations adsorbed uniformly on the fiber surfaces perform well to control the charge properties of the pulp fibers at the wet end; and the preferential aluminum adsorption behavior on the fiber surfaces, by utilizing the required amounts of hydroxyl ions, probably accounts for the effective cationization of the fibers under acidic to neutral papermaking conditions.This research was presented in part at the presymposium of the International Symposium on Wood and Pulping Chemistry, Seoul, June 1999; at the International Symposium on Environmentally Friendly and Emerging Technologies for a Sustainable Pulp and Paper Industry, Taipei, April 2000; and at the 2000 annual meeting of the Society of Fiber Science and Technology, Japan, Kyoto, June 2000     

麦草低温氧碱蒸煮黑液降黏技术

麦草经碱法蒸煮后,所得浆料不经洗涤,直接通入氧气进行处理。以黑液黏度,浆料卡伯值为考核指标,设置4因素3水平正交试验,对试验结果作极差分析发现,在用碱量0～2%、氧压0.2～0.6 MPa、温度70～100℃和时间30～90 min内得到较适宜的工艺条件为:用碱量1%,氧压0.6 MPa,温度85℃,时间60 min。氧碱蒸煮结果为:黑液黏度3.4 mPa.s,浆料卡伯值17.9。与第一段碱法蒸煮相比,黑液黏度降低33.3%,浆料卡伯值降低11.8%。     

蒸煮处理对竹纤维化学组成的影响及机理

采用热机械-蒸煮方法制备慈竹纤维,并运用FTIR、x-射线衍射分析技术对蒸煮处理前后慈竹纤维的化学组成、结晶结构进行了研究,此外,还研究了处理前后慈竹化学成分的变化,结果表明:不同蒸煮工艺处理后竹纤维的纤维素较未处理竹材有所上升,而木质素含量有所下降,其中,第2组蒸煮工艺所得纤维素含量提高了19.27%,木质素含量下降了38.85%,运用x-射线衍射测得的纤维素结晶度均有所上升。     

The ambient aging of wood fiber and its effect on mechanical properties of MDF panels

Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to study ambient-aged wood fibers and their effects on the mechanical properties of medium-density fiberboard (MDF). It was found that MDF made with ambient-aged fibers had poorer mechanical properties than MDF made with fresh fibers; this difference resulted from the alterations of surface characteristics of wood fibers after ambient aging, which led to poor wettability of the urea–formaldehyde (UF) resin applied to the aged wood fibers. After 6 months of ambient aging, the concentration of carbonyl groups in the fibers increased by 144%, while the pH value of wood fiber decreased from 5.2 to 4.7. SEM showed that much more UF resin agglomerated on the surface of ambient-aged fibers and the breakage of MDF made with aged fiber frequently occurred at the resin-fiber interfaces, indicated the poorer wettability of UF resin to fibers due to the decrease in surface energy after aging.     

不同预处理对竹纤维束提取及其结构的影响

采用3种不同的预处理工艺提取获得竹纤维束,利用光学显微镜和X射线衍射法分别比较3种工艺下竹纤维束的微观形态和结晶结构。研究结果表明,低碱处理可分离提取竹纤维束,提取的竹纤维束为黄褐色丝状,直径为100～200μm。微观形态下,竹纤维束横截面呈蜂窝状,纵面呈多根柱形紧密排列状。3种工艺中,10%碱常温处理分离竹纤维最易,分离效果最好,残留基质黏附最少。由竹材经3种工艺提取的竹纤维束,结晶结构未改变,但相对结晶度均较原竹材有所提高。     

Morphological changes of ramie fiber during mercerization

Morphological changes of ramie fibers due to swelling in alkali solution were investigated. The observed twisting and changes in the cross-sectional shape of the fibers could be explained as a geometrical alteration caused by lateral expansion of coiling fibrils, as the unmercerized ramie fiber showed an S-helix structure. The fibril angle of ramie fibers was estimated to be 3°. Although the swollen fiber untwisted to some extent on washing with water, the shape of the twisted ribbons as observed by scanning electron microscopy was retained even after drying. Concentrated 8N NaOH produced only a moderate change in morphology, whereas swelling with 3.5N NaOH at 0°C expanded the cross sections about 30 times over the initial ones accompanied by a drastic change in the shape of the fiber.Part of this paper was presented at the annual meeting of the Wood Research Society of Japan in Kumamoto, April 1996