马蔺纤维性能测试及应用研究

从马蔺叶中提取纤维素纤维,观察了马蔺纤维的外观形态,测试了马蔺束纤维的长度、细度、回潮率、强伸性能、摩擦因数等性能,并阐述了其应用。探索了一种新型纺织原料,改变传统纺织天然纤维紧缺的现况,以期对企业有所帮助。     

天然纤维的分形结构和分形结构纤维的开发

根据分形理论对天然纤维进行了解析 ,天然纤维内在的分形自然扭曲是其特有的一种分形结构。今后开发仿、超天然纤维应从研究多层次分形结构纤维开始 ,并提出开发具有区域结构的 PET纤维 ,即 SFY纤维。     

各种纤维卷曲机理、形态及其特性

为了提高合成纤维织物的加工性和服用性,可以通过改变合成纤维的形态结构来实现该目的。本文从天然纤维的结构形态出发,总结了各种纤维卷曲的形态及机理。     

静电纺丝制备具有扭曲螺旋结构的微/纳米纤维

天然纤维大多具有一种自扭曲螺旋结构,这种结构使得天然纤维具有较强的柔韧性和很高的孔隙度。主要介绍了两种可以用来制备扭曲螺旋结构微/纳米纤维的静电纺丝装置,并分别阐述了用这两种装置制备具有自扭曲螺旋结构微/纳米纤维的聚合物体系,最后指出了其发展现状和前景。     

企鹅绒毛状的人造纤维

正天然纤维(如蜘蛛丝、动物毛羽等)因其自身结构的独特性而在纺织领域备受欢迎,而且其某些结构是化学合成纤维难以模仿的。例如:企鹅的羽毛是具有独立分支的纤维形态,在其抵御寒冷时发挥了重要作用,但目前在合成纤维体系尚未见此种结构纤维的报道且其性能未知。     

特殊功能纤维的由来与发展

第二代纤维 所谓“第二代纤维”,是指在50年代的末期开始对纤维的性质、化学组成及结构及分子形态的改进。不像前述传统式的人造纤维一样,第二代纤维不再想求仿造天然纤维的化学结构或组成,而是修改人造纤维的构造使得它们有近天然纤维的性质。主要的也是在尼龙、聚酯、聚丙烯腈及聚烯烃四类作化学上及物理上的修改。这时所谓蚕丝状的、麻状的、光滑的、改质的、起皱的、变色的、透湿防水的、保温的及耐热的等。     

国外动态

天然纤维增长迅速据美国Ｋｌｉｎｅ＆Ｃｏ估计,北美市场对天然纤维尤其在热塑性和热固性树脂共混物中的需求量已超过180000ｔ。随着北美市场在木材和农业纤维量的增长,天然纤维成为增长速度最快的聚合物添加剂,该纤维在汽车领域其年增长率达到15%～20%,而在一些建筑市场,其年增长率达到50%或更多,其中木材纤维约占75%,其它为农业纤维如剑麻纤维、黄麻纤维、大麻纤维、亚麻纤维。长天然纤维包括亚麻纤维、大麻纤维。主要用于汽车制件领域,由于天然纤维的成本比玻璃纤维低30%,且纤维的质量仅为玻璃纤维的一半,天然纤维复合材料更易回收再用,因…     

碱脲体系对稻草化机浆制浆性能的影响

利用氢氧化钠-硫脲-尿素水溶液处理稻草草片以求改善其化机浆制浆性能,通过单因素试验探究用碱量、浸渍时间和冷冻时间等因素对稻草化机浆制浆性能的影响情况,并利用FT-IR、XRD和SEM等方式表征原料或浆料微观性能的变化情况。结果表明:在用碱量6%、浸渍时间15 min和处理时间60 min、处理温度-5℃的条件下,制得稻草漂白化机浆的性能最佳,和自制稻草BCTMP相比,经氢氧化钠-硫脲-尿素水溶液预处理后制得化机浆的磨浆能耗降低18.6%、细浆得率提高3.8%、白度提高4.4%、抗张指数提高12.8%、耐破指数提高15.7%、松厚度降低2.9%,此外对两种漂白化机浆而言,其官能团结构、结晶区结构、预处理后原料纤维的整体形态均没有明显变化,但经氢氧化钠-硫脲-尿素水溶液预处理后稻草单根纤维表面的破损程度略高。     

爆破法制浆的研究与应用

概述了国内爆破法制浆的研究现状及发展方向,包括爆破法制浆的工艺、爆破机理、影响因素、纤维化学组分和形态结构变化,并简要介绍了其应用前景。     

纸浆回用对纤维形态及强度性能的影响

探讨了纸浆回用对纤维形态结构和主要物理强度性能的影响。扫描电子显微镜的观察结果显示 ,第一次回用对化学浆纤维形态的影响较大 ,而化学热磨机械浆纤维在回用过程中变化较小。循环回用中浆张的表观密度均有下降 ,化学热磨机械浆的下降幅度较小。漂白化学木浆的抗张强度、耐破强度和耐折度均随着回用次数的增加而下降 ,前两次回用对强度性质的影响最大 ,而化学热磨机械浆的抗张强度、耐破强度随着回用次数的增加略有上升 ,耐折度的变化则不明显     

Cold alkali refining of cellulosic pulps derived from Egyptian cotton and bagasse

A cotton linter pulp, a bagasse dissolving pulp and a bagasse paper pulp were subjected to cold sodium hydroxide refining and the resulting changes in their chemical, physical and submicroscopic characteristics were investigated. In the case of cotton linters the main change took place in the physical and submicroscopic properties and the refining resulted in better reactivity towards xanthation. The α-cellulose content of the paper and viscose pulps increased with alkali concentration until it reached a constant value which depends on the type of pulp and the concentration of alkali. The refining of the paper and viscose pulps impaired their reactivity towards xanthation. The presence of the more hydrophilic hemicellulose increased the swelling ability of the fibres and made them more reactive towards xanthation. The undesirable effects of drying after refining with high alkali concentration could be overcome if the DP is sufficiently lowered. In this case the resulting shorter chain macromolecules dissolve more readily during xanthation.     

Acetylation behaviour of cotton and bagasse celluloses. II. Effect of hot alkali refining

The alkali pretreatments of cotton linters, bagasse dissolving pulp, and bagasse kraft pulp increased the accessibility of the cellulose hydroxy groups to acetylating molecules. The pretreatment with hot alkali resulted in a higher degree of esterification than with cold alkali. The filterabilities of cellulose acetates obtained from alkali pretreated samples of cotton linters, dissolving pulp, and kraft pulp were better than in case of the untreated samples. Hot refining resulted in better filterability than cold refining, but resulted in stronger degradation and lower thermal stability than cold refining. The presence of hemicelluloses in the untreated pulp lowered the reactivity towards acetylation but favoured the reactivity towards xanthation. In case of cotton linters both reactivities were improved by the alkaline pretreatments. The increase in reactivity resulting from the depolymerization of the cellulose overcame the increase in inaccessibility resulting from drying after the alkaline treatment. The removal of hemicelluloses from the dissolving and kraft pulps by alkaline extraction deteriorated the reactivities towards xanthation, but had a favourable effect on the reactivity towards acetylation.     

Properties of cellulose xanthate solutions prepared in an organic solvent

Conclusions 1. To compare the properties of cellulose xanthates made by xanthation of alkali cellulose in an organic solvent medium, in a quasi-liquid state and in carbon disulphide vapour, the change in the properties of xanthate solutions with time was studied.2. Solutions of quasi-liquid xanthate differ by increased viscosity and decreased ripeness, which involves increased structure-formation in the solution, because of the higher degree of polymerisation of the cellulose and the lower degree of esterification of the cellulose xanthate.3. The decomposition rate of quasi-liquid xanthate in the initial ripening period of the viscose is higher than the decomposition rate of standard xanthate because of the increased degree of esterification of the secondary hydroxyl groups of the cellulose macromolecules, and the complication of secondary esterification of cellulose xanthate in solution.All-Union Scientific Research Institute for Man-Made Fibres. Translated from Khimicheskie Volokna, No. 2, pp. 33–35, March–April, 1969.     

从不同纤维素原料制得的粘胶在熟成过程中的行为

<正>在制造粘胶人造丝过程中需要将自碱纤维素黄酸化而得的纤维素黄酸盐溶于稀碱液中成为粘胶,然后在恒温下放置若干时间以进行熟成,达到一定程度后始可纺丝。在这熟成过程中,粘胶发生一系列的化学变化和胶体化学变化。 Klauditz曾指出在粘胶熟成过程中纤维素黄酸盐分子逐步分解,其酯化度逐渐降低,他认为这是由于纤维素黄酸盐的皂化作用:     

Effect of carbon disulfide consumption on the basic properties of viscose prepared from radiation-modified cellulose

Conclusions -- The process of preparing viscose from radiation-modified cellulose using carbon disulfide in the range of 6–32% of the weight of -cellulose in the xanthation has been investigated.-- Equations have been given which describe the dependence of the degree of esterification of the cellulose xanthate, the ripeness index, the byproduct content, the viscosity, and the filterability of the viscoses on CS₂ consumption in xanthation within the range 6–32% by wt.-- It has been found that a decrease in consumption of CS₂ primarily affects the viscosity of the viscoses obtained, and then it affects figures which characterize the content of byproducts, degree of esterification of the cellulose xanthate, ripeness, and the filterability of the spinning solutions.Translated from Khimicheskie Volokna, No. 5, pp. 51–53, September–October, 1991.     

Grafting of acrylonitrile onto different cellulose forms by the xanthate method

Wood pulp and regenerated cellulose (viscose fibres) were grafted by the xanthate method. In some cases, the regenerated cellulose was more accessible towards grafting than wood pulp. Grafting of incompletely regenerated viscose fibres which were obtained by changing the spinning conditions in order to spare the step of partial xanthation caused more orientation of the filaments. The mechanical properties of these filaments were in general poor.     

Light scattering studies on the ripening of viscose solution

Investigations were made on cellulose xanthate molecular weights by light scattering during the ripening of the solutions of (a) viscose-containing colored thio salts and (b) pure cellulose xanthate separated from viscose. Though an apparent reduction in molecular weight was recorded with time of ripening for the viscose solution, no such fall was observed with pure cellulose xanthate. The apparent fall of molecular weight in the case of viscose has been shown to be due to the increasing absorption of the incident beam and to the change in the value of dn/dc with progressive color formation. Reproducible results can be obtained for cellulose xanthate solutions freed from color. Intrinsic viscosity of the viscoses and the degree of polymerization (D.P.) of the regenerated cellulose from viscoses during ripening were also measured and found to be constant. The results indicate that no degradation of alkali cellulose molecule takes place during the ripening process, irrespective of the state of degradation of alkali cellulose from which the viscose is made.     

Hot Alkali Refining of Cellulosic Pulps in the Presence of Sodium Sulfide

Cotton linter pulp and paper pulp were subjected to hot refining with potassium and sodium hydroxide in the presence of sodium sulfide at concentrations of 5% and 20%. The resulting changes in their chemical, physical, and submicroscopic properties as well as their mercerization depth were studied. The addition of sodium sulfide during hot sodium or potassium hydroxide refining of the pulps resulted in a small increase in α-cellulose content of the cotton linters. Remarkable increase was observed in the case of the paper pulp as well as in the resulting decrystallization, and it increased the heterogeneity of the macromolecular structure of both pulps. This led to an increase in the swelling ability of the fibers as revealed from the results of water retention value (WRV), liquor retention value (LRV), and sodium hydroxide retention value (NaOH RV). The addition of sodium sulfide to sodium or potassium hydroxide during hot refining of the cotton linters or to sodium hydroxide during refining of the paper pulp led to the reduction in the degree of polymerization and to improvement in the reactivity towards xanthation. This was in contrast to the results of the alkali refining of the paper pulp with a mixture of potassium hydroxide-sodium sulfide in which the degree of polymerization was increased and the reactivity towards xanthation was decreased. The mercerization depth of the hot refined pulps was also investigated using FUR 1650 spectrophotometer absorption method. The cotton linters refined with a mixture of 5% sodium hydroxide-sodium sulfide possessed a higher degree of chemical purity and a good open and accessible fine structure and at the same time were characterized with a higher degree of polymerization suitable for use as a starting refined pulp for the manufacture of paper documents.     

The water retention values of never-dried alkali-treated celluloses

The extent of swelling of refined and unrefined cotton linter, viscose pulp and paper pulp treated with various concentrations of NaOH from 4 to 20% at 20°C, then washed with water and never dried was measured in terms of the water retention values (WRV). The treatment of unrefined fibers with alkali resulted in increase in WRV; the only exception was viscose pulp treated with 12 and 14% NaOH. Cotton pulp refined with 5% NaOH showed an increase in the swelling ability in water which increased with the concentration of alkali treatment, whereas for viscose and paper pulps the amount of water retained increased with alkali concentration up to 12% and 14% NaOH, respectively, then decreased with further increase in alkali concentration. For cotton and viscose pulps refined with 20% NaOH, the alkali treatment increased the affinity of fibers to water up to alkali concentrations of 16% and 12% NaOH, respectively,′ then the WRV became more or less stable after treatment with higher concentrations of NaOH. On the other hand, the paper pulp refined with 20% NaOH then treated with alkali concentrations from 10 to 20% showed decreased WRV.     

Acetylation behaviour of cotton and bagasse celluloses. III. Upgrading pulps by extraction with sodium hydroxide-borax solutions

The presence of borax during alkali refining of pulps increased the solubility of the short-chain celluloses and hemicelluloses and thus improved their chemical characteristics. Small improvements in the chemical characteristics of cotton linters took place. A stronger effect was observed in case of the dissolving pulp and a more pronounced effect took place in case of the kraft pulp. Cold 20% NaOH refining was more effective than hot 5% NaOH refining. The physical and sub-microscopic characteristics of linters were mainly affected. Refining lowered the D.P., increased the affinities towards water and alkali, decreased the crystallinity, and improved the reactivity towards xanthation. The presence of borax resulted in a more open and accessible fine structure and better reactivity. Cold refining of the dissolving and kraft pulps resulted in lower reactivity than hot refining and the presence of borax improved the reactivity. It also increased the yield of cellulose acetate. The increase in the solubility of the short-chain celluloses and hemicelluloses resulting from the presence of borax resulted in better homogenisation of the pulp. This was reflected in better chemical and physical characteristics of the acetate.