水溶性PVA纤维对包装纸增强作用的研究

在高强度包装纸抄造过程中,使用水溶性PVA纤维做增强剂,研究了水溶性PVA纤维的添加量、加入方式、磨浆条件对增强效果的影响.结果表明,添加水溶性PVA纤维后,纸张抗张强度显著提高,裂断长提高幅度为18.8%～45.8%,撕裂指数、耐破指数也有不同程度的改善.研究确定了水溶性PVA纤维的最佳使用条件为:PVA60用量为6%,两段磨浆,程序升温干燥,此时抄片各项强度指标有不同程度的提高,裂断长提高45.8%,撕裂指数提高32.9%,耐破指数提高17.3%.研究表明水溶性PVA纤维是一种有效的纸张增强剂,制备的高强度纸包装材料生物降解性能好,是真正的绿色包装材料.     

季铵型瓜尔胶的制备及在纸质文献加固中的应用

纸质文献是人类文明的瑰宝,大量的脆弱纸质文献亟待加固保护,因此急需探究一种与纸张纤维相容性好、操作简便、加固效果显著的材料。本研究对天然高分子瓜尔胶进行季铵化改性,制得取代度为0.137的季铵型瓜尔胶,改性产物具有更好的溶解性及稳定性,并将其应用于纸质文献加固。结果表明,相比未处理厚纸,加固处理后纸张的抗张强度从2.64 kN/m提升至3.16 kN/m、耐折度从7次提升至13次、撕裂度从161.5 mN提升至193.5 mN、零距抗张强度从65.0 kN/m提升至72.8 kN/m,分别提升了19.7%、85.7%、19.8%、12.0%。老化后色差变化为1.31,且不会对纸张及字迹颜色产生负面影响,证明季铵型瓜尔胶在纸质文献的加固中具有一定的应用前景。     

一种新型阳离子复合表面施胶剂的研制及应用

研制了一种新型阳离子复合(AKD-石蜡)表面施胶剂,考察了该施胶剂对瓦楞原纸的施胶效果。结果表明,自制新型阳离子复合表面施胶剂制备工艺简单;相同施胶量下与阳离子SAE施胶剂相比,新型阳离子复合表面施胶剂施胶纸的纵向环压指数、耐破指数和耐折度分别提高14%、8%和25%;当施胶量为2 kg/t纸时,与阳离子SAE施胶剂相比,表面施胶成本降低4元/t纸。     

液体直接染料纸张染色效果的影响因素

探讨了硫酸铝及其用量、液体直接染料的种类和用量、浆料种类和打浆度等因素对液体直接染料纸张染色效果的影响。结果表明,加入适量的硫酸铝可以改善染色效果,硫酸铝对阴离子直接染料比对阳离子直接染料染色效果的改善更大;黄色染料可显著提高纸张的b*值,而L*值、a*值会有不同程度的减小;红色染料可显著提高纸张的a*值,而L*值、b*值会有不同程度的减小;红色染料对L*值的减小程度比黄色染料大;棕色染料可增加纸张的a*值、b*值,但同时L*值会有所降低;黑色染料可大幅度降低纸张的L*值,但同时a*值、b*值均会有一定程度的减小;直接染料对漂白化学浆的染色比未漂浆的染色效果更好;打浆度高的浆料有利于染色。     

速生桉木硫酸盐浆氧脱木素工艺的优化

对卡伯值为17．1的速生桉木硫酸盐浆进行了氧脱木素各影响因素的研究。结果表明，用碱量、温度、氧压和时间对氧脱木素后纸浆的性质均有明显的影响。从氧脱木素后纸浆的脱木素程度和黏度的变化考虑，该速生桉木硫酸盐浆较适宜的氧脱木素工艺条件为：浆浓10％，用碱量2％，MgSO4用量0．2％，反应温度100℃，反应时间60min，氧压0．5MPa。     

纤维素酶酶解苇浆纤维微观结构和结晶结构的变化

采用红外光谱(IR)、X射线衍射分析和扫描电镜对在纤维素酶解进程中苇浆纤维素大分子的结构及纤维形态的变化进行了研究.研究结果表明,纤维素酶酶解进程中,纤维素大分子的晶型没有改变,但结晶度呈现周期性变化,微晶尺寸略有降低.在酶解初期,纤维素酶不仅作用于纤维素无定形区,也开始作用在纤维素结晶区表面;在酶解中、后期,纤维素酶对纤维素结晶区和无定形区的作用呈现周期性变化.纤维素酶解过程中纤维表面呈现周期性"剥皮"现象,并且在纤维表面出现孔洞和沟槽,在孔洞处纤维易断裂,导致纤维长度和粗度的降低.     

XPS、AFM和ToF-SIMS的工作原理及在植物纤维表面分析中的应用

介绍了先进的表面分析仪器化学分析电子能谱(XPS)、原子力显微镜(AFM)、含飞行时间分析器的二次离子质谱仪(ToF-SIMS)的工作原理,回顾了近年来它们在植物纤维表面分析中的成功应用,综合利用XPS、AFM及ToF-SIMS方法,可分析和解决制浆造纸过程中的现象和问题。     

Promoted cell proliferation and mechanical relaxation of nanocomposite hydrogels prepared in cell culture medium

Nanocomposite hydrogels (NC gels) were synthesized through in situ polymerization of N-isopropylacrylamide (NIPAm) in the hectorite clay suspension made from cell culture medium Dulbecco’s modified Eagle medium (DMEM). Cell cultured on these NC gels (D-NC gels) surface proliferated faster compared with that on the NC gels synthesized in water due to the nutrients in the D-NC gels. Cells attached and proliferated faster on the D-NC gels with higher modulus. In addition, cell sheets with good viability spontaneously detached from the gel surface by lowering temperature. Their tensile elongation at break was higher than 7 and the true strength σ_true was up to 800 kPa. The stress–strain curves of the D-NC gels were described quantitatively with the Mooney–Rivlin equation. A stretched exponential stress equation was adopted to express the stress relaxation of the D-NC gels with an average relaxation time τ (～10² s) estimated from data fitting, showing a broad distribution (polydispersity k ～ 0.4). The τ value, which was used in simulation for the tensile creep compliance of the D-NC gels, became shorter with increasing clay concentration due to the decrease in the network chain length. The relaxation process was similar to the natural articular cartilage. This work provides a facile way to produce hydrogels with improved cell compatibility and satisfactory mechanical properties for biomedical applications.     

Compositional analysis and projected biofuel potentials from common West African agricultural residues

In recent years the focus on sustainable biofuel production from agricultural residues has increased considerably. However, the scientific work within this field has predominantly been concentrated upon bioresources from industrialised and newly industrialised countries, while analyses of the residues from most developing countries remain sparse. In this study the theoretical bioenergy potentials (bioethanol and biogas) of a spectrum of West African agricultural residues were estimated based on their compositions. We analysed 13 of the most common residues: yam peelings, cassava peelings, cassava stalks, plantain peelings, plantain trunks, plantain leaves, cocoa husks, cocoa pods, maize cobs, maize stalks, rice straw, groundnut straw and oil palm empty fruit bunches. The yam peelings showed the highest methane and bioethanol potentials, with 439 L methane (kg Total Solids)⁻¹ and 0.61 L bioethanol (kg TS)⁻¹ based on starch and cellulose alone due to their high starch content and low content of un-biodegradable lignin and ash. A complete biomass balance was done for each of the 13 residues, providing a basis for further research into the production of biofuels or biorefining from West African agricultural residues.     

Effects of periodically alternating temperatures on performance of single-chamber microbial fuel cells

Practical applications of microbial fuel cells (MFCs) for wastewater treatment are usually operated over a wide range of temperature, especially day–night temperature difference. Here, MFCs at alternating temperatures were compared with those at constant temperatures. MFCs at 6/18 °C reached a steady-state voltage of 0.41 ± 0.05 V at 6 °C and 0.36 ± 0.04 V at 18 °C, which were lower than that of MFCs at 18/30 °C (0.42 ± 0.01 V at 18 °C and 0.47 ± 0.02 V at 30 °C). MFCs at 18/30 °C produced the highest power density of 2169 ± 82 mW m⁻² at 30 °C, even higher than that of MFCs at constant temperature 30 °C. Moreover, MFCs at 6/18 °C and 18/30 °C obtained a comparable coulombic efficiencies (94.6 ± 5.2%, 83.2 ± 4.1%, respectively) compared with MFCs at constant temperatures (86.3 ± 7.3% at 18 °C and 84.1 ± 5.5% at 30 °C). These results demonstrate that MFCs could be successfully adapted for use under day–night temperature difference conditions.