影响木浆粕反应性能的因素

木浆粕是生产粘胶纤维的主要原料,其反应性能对纤维素的碱化和黄化有直接影响,进而影响到纺丝粘胶的制备质量。就影响木浆粕反应性能的主要因素,从浆粕的纤维细胞结构、纤维素结构、杂质含量、纤维素聚合度四个方面进行了阐述。     

技术贸易

南方速生材制醋化木浆粕成果介绍:本项研究根据我国桉树林混种情况较多的实际出发,直接以木片厂的混合木片为原料,加入添加剂预水解,经纤维均一化处理工艺,制备出适用于二醋片生产的醋化木浆粕。     

纸浆改性溶解浆新工艺探讨

介绍以木浆粕为原料,NaOH溶液浸渍制浆工艺,制备的溶解浆达到FZT 51001-2009粘胶纤维用浆的技术要求,其中:甲种纤维素含量达到92%以上,聚合度控制在粘胶纤维生产用浆粕范围内,反应性能等其它指标达到国家标准要求,拓展粘胶纤维生产原料的多样性,有利于企业生产运营管理。     

竹、麻浆粕纺制粘胶长丝的比较试验

介绍了竹、麻浆粕性能指标,及其碱纤维素制备、粘胶制备、纺丝情况与棉、木浆粕的对比分析。竹、麻浆粕均可制备出符合粘胶长丝生产要求的纺丝胶,纺丝胶可纺性良好,纤维截面形态与棉、木浆粕纺制的粘胶长丝基本一致,纤维质量指标达到GB／T13758--1992一等品要求。     

用反应量热仪研究棉短绒纤维素的乙酰化反应

用反应量热仪(RCle)对棉短绒纤维素的乙酰化反应进行了研究。研究发现:该反应放热速率图基本由3～4个放热峰构成;初期第一或第二个放热峰的峰值较大,主要为醋酐的水解反应;往后峰值依次变小,直至缓慢放热,主要为纤维素乙酰化反应。研究中还测量了不同反应温度及水分含量对反应放热速率的影响,并与木浆粕的反应过程进行了对比。结果表明,棉短绒纤维素乙酰化过程具有非均相表面反应的特点。放热速率随温度的升高而加快。提高水分含量,使醋酐水解放热量变大,并能破坏反应区结构,提高反应速率,缩短总反应时间。与木浆粕相比,棉短绒纤维素具有结晶度高及α-纤维素含量高的特点,反应放热表现为:初期放热速率低,中后期高,总体反应时间较长。     

纤维素氨基甲酸酯溶液的制备及稳定性研究

研究了制备纤维素纤维的新型原料——纤维素氨基甲酸酯(CC)溶液的制备工艺及其稳定性。结果表明:在-5~10℃条件下,用聚合度为350~612的纤维素浆粕(棉浆粕、木浆粕)合成的氮含量(酯化度)为2.34%~3.56%的CC能很好地溶解在质量百分比浓度为8%~11%的NaOH溶液中,形成淡黄色透明溶液,该溶液稳定性良好,可用于纺丝。另外,尿素、AlCl3及ZnCl2在一定范围内对CC有助溶作用。     

石砚纸业将建10万吨醋化级木浆粕项目

正吉林石砚纸业集团确定建设10万吨醋化级木浆粕项目,总投资127000万元,其中固定资产投资107000万元。醋化级木浆粕是专用于生产醋酸纤维的高纯度溶解木浆。目前,醋酸纤维是再生纤维素纤维中仅次于粘胶纤维的第二大品种,是纤维素醋酸酯纤维的俗称。由于醋酸纤维以纤维素为基本骨架,因此具备纤维素纤维的基本特征,同时因其回潮率较低、有热塑性,而具有了合成纤维的某些特征。因此,醋酸纤维的应用非常广泛。     

提高马尾松木纤维用浆粕中甲纤含量的研究

木材通过化学方法可制得用于生产木粘胶纤维用的浆粕，但制得的浆粕中甲纤含量较低，难以满足后续纺丝的要求。为了提高木浆粕中的甲纤含量，用漆酶对木浆粕进行处理，取得了一定的效果，木浆粕的甲纤台量由原来的83．2％提高到89．2％。     

国产木浆合成烟用醋酸纤维素的研究

采用国产醋化级木浆进行合成烟用醋酸纤维素的小试试验研究,系统分析了醋化值、粘度、堵塞值等重要性能指标,并以进口的国外同等级木浆为参照基准,探索推广国产醋化级木浆的可行性。     

竹浆酸处理工艺及其对竹浆粕纤维素性能的影响

探讨了pH值、温度、时间、浆浓以及螯合剂对酸处理工艺的影响效果,优化酸处理工艺条件,并应用于竹浆粕制备过程,分析了竹浆粕酸处理前后的纤维素性能变化。结果表明,通过对漂白竹浆灰分及黏度下降率变化规律的分析,获得酸处理最优的工艺为:pH值3.0、温度50℃、时间30min、浆浓5%、DTPA用量0.5%;通过酸处理前后绿竹浆粕性能的对比,表明酸处理可进一步提高浆粕α-纤维素纯度,显著降低灰分含量,调整浆粕聚合度范围,提高并稳定浆粕白度,从而改善浆粕质量。     

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.     

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.     

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:     

棉浆和木浆掺混纺醋酸纤维素纤维结构与性能的分析

对棉浆和木浆三种掺混纺比例(棉浆与木浆的掺混纺比例为0∶100,50∶50,100∶0)的醋酸纤维素纤维的结构与性能进行了测试分析。采用光学显微镜观察、纤维图形分析软件计算、X射线衍射和强伸性能测试,对比分析了三种掺混纺比例纤维的截面形态、结晶度、取向度、断裂伸长率、断裂强度以及初始模量,为棉浆与木浆掺混纺醋酸纤维素纤维的广泛应用提供了理论依据。实验结果表明:三种掺混纺比例纤维的截面形态指标无显著差异,内部晶体基本结构相同,随着棉浆与木浆掺混纺比例的增加,结晶度、取向度以及强伸性能呈现出略微增大的趋势。     

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.     

硫酸水解对再生纤维素纤维葡萄糖转化率的影响

用浓硫酸水解竹浆、棉浆、木浆三种再生纤维素纤维,通过改变反应温度和时间,找出再生纤维素纤维水解葡萄糖得率最优的反应条件,并对不同种类的纤维素纤维水解液进行高效液相色谱分析。结果表明:当反应温度为50℃、反应时间为120 min时,竹浆再生纤维素纤维的葡萄糖转化率可达75%;在高效液相色谱中,竹浆再生纤维素纤维在7 min的位置有较明显的出峰,在12.5～14.5 min的位置有一个双峰,有别于木浆、棉浆再生纤维素纤维。     

竹材用于生产溶解浆的试验研究

将竹材与木材原料相对比,分析了竹原料的特性,直观地说明了竹材用于溶解浆生产的可行性.结合工厂的现有工艺流程,以造纸竹浆为原料,优化了其蒸煮、漂白等工艺条件,制取了溶解浆.结果表明:所得浆粕甲种纤维素含量高、白度高、反应性能较好,适用于黏胶纤维用浆粕的生产.     

Cellulose membranes for reverse osmosis part II. Improving RO membranes prepared from non-woody cellulose

Experiments were carried out to minimize the stages of preparing reverse osmosis (RO) desalination membranes at economical cost and to improve the transport properties of RO membranes prepared from non-wood fibrous materials (cotton linters and bagasse pulp) to approach those prepared from imported viscose pulp and purchased cellulose acetate (see Part I). Further study was carried out on examining the effects of long-term testing and subsequent washing of membranes by a special mixture. Finally the quality of the product water reverse osmosis was examined by comparing its water analysis with standard specification for drinking and domestic water.