再生纤维素／聚乙烯醇共混膜的研究

由纤维素铜氨溶液与不同体积比（１－１０％）的聚乙烯醇（ＰＶＡ）水溶液共混制备了一系列再生纤维素共混膜．扫描电镜结果表明ＰＶＡ含量大于８％时，该共混膜产生明显相分离．当ＰＶＡ低于５％时，共混膜相容性较好．膜的结晶度，抗张强度，直角撕裂强度，断裂伸长及耐热性均优于单独用钢氨液制备的再生纤维素膜．此外，用流动速率法和超滤法测定了膜的孔径，渗透性及纯水通量，结果表明共混膜的孔性没有明显变化．本文得出：再生纤维素与５％ＰＶＡ共混能改善力学性能，并且能保持其生物降解性．     

再生纤维素膜对聚苯乙烯的截留性

本文用铜氨法以及微相分离和后处理技术制备了孔径30A至1000A的一系列再生纤维素膜。采用膜渗透计按流动速率法及静态渗透压法分别测定了它们的平均孔径2rf以及膜在甲苯溶液中对聚苯乙烯标样的截留率Re。得到膜平均孔径和所截留聚苯乙烯分子最Mw及其均方根末端距〈h~2〉~(1/2)之间的关系式分别为: lg2r?=lg0.155 0.59lgM_w lg2rf=lg0.589 0.96lg〈h~2〉~(1/2)     

提高X射线荧光理论计算相对强度准确度的研究

通过与合成标样实测相对强度的比较，研究了影响ＸＲＦ中理论计算相对强度准确２度的主要因素，提出了μ＋τ计算模式的一个混合的质量吸收系数算法。     

二乙烯三胺衍生物对纤维素膜的增塑作用

用Ｎ－（２－胺基乙基）－Ｎ－正辛基－１，２－乙二胺和Ｎ－（２－胺基乙基）－Ｎ－正癸基－１，２－乙二胺增塑再生纤维素膜，并用红外光谱，差热分析以及力学性能测量研究了增塑后膜的结构与性能，实验表明，上述二种化合物对纤维素膜有良好的增塑作用，Ｎ－（２－胺基乙基）－Ｎ－正辛基－１，２－乙二胺水溶性大，和甘油增塑的情况相似，用水浸泡后，增塑效果基本丧失；而Ｎ－（２－胺基乙基）－正癸基－１，２－乙二胺用水浸包     

涂布法制备纤维素增强微孔膜

将醋酸纤维素（CA）铸膜液涂布在纤维载体上，制成增强微孔膜（RMF）。这种涂布是借助于凝胶剂的协同效应及相转换机理来实现的。此增强的表膜及载体既不分离，又不互相渗透，膜与载体中孔隙不会被堵塞，具有高强度和高水通量等优点。     

羧甲基纤维素／Eu^3＋体系的荧光性能的研究

以脱脂棉纤维为原料合成不同取代度的羧甲基纤维素，再使之与稀土离于Ｅｕ＾３＋作用，合成ＣＭＣ／Ｅｕ＾３＋荧光体系并考察其荧光性能。结果表明：无论是ＣＭＣ／Ｅｕ＾３固体状态体系，还是ＣＭＣ／Ｅｕ＾３＋水溶液体系均有较强的荧光性能，但其固体体系的荧光强度较水溶液体系的强；且固体状态体系与水溶体系的荧光发射波长有所不同。     

离子液体中的纤维素溶解、再生及材料制备研究进展

近年来,离子液体作为一类新型的环境友好介质和软功能材料受到了广泛的关注,并被广泛应用于有机合成、催化、电化学、分离分析等领域.其中,离子液体中的纤维素化学是当前离子液体研究的热点领域之一,离子液体的出现也为纤维素化学的进一步发展提供了广阔的空间.离子液体以其低熔点、高稳定性、低蒸汽压、溶解性能可调节等优异的理化性能已被证实为纤维素的有效溶剂,被广泛用于纤维素的溶解、再生及应用研究.综述了离子液体中纤维素的溶解行为,包括纤维素溶解度的影响因素、纤维素在离子液体中的溶解过程、纤维素的溶解及再生机理等,以及离子液体中基于纤维素的新型材料制备研究进展,并对离子液体中纤维素研究存在的问题和未来的发展方向进行了总结和展望.     

甘油单醚类化合物对纤维素膜的增塑作用

报道甘油单丁醚、单己醚、单庚醚和单辛醚４种化合物的合成，并用作再生纤维素膜的增塑剂．实验结果表明这４种甘油单醚类化合物对纤维素膜具有较好的增塑作用，随增塑剂单醚碳原子数的增加，增塑效果降低，但增塑剂与纤维素分子间相互作用增强．经甘油单己醚、单庚醚和单辛醚增塑的再生纤维素膜其耐水洗性明显高于甘油增塑的膜．     

溶液预凝胶化对再生纤维素水凝胶膜性能的影响

研究了溶液预凝胶化对纤维素/NaOH/尿素水溶液体系以浸没沉淀相转化法制备的再生纤维素水凝胶膜的影响.通过静态拉伸、扫描电子显微镜研究了预凝胶化温度、凝固浴温度、凝固浴组成对再生纤维素水凝胶膜结构和性能的影响.结果表明,与常规的浸没沉淀相转化法相比,使溶液预凝胶化可以提高所制备的水凝胶膜的机械性能.经60℃预凝胶30 min后制备的水凝胶膜,拉伸强度比未经预凝胶处理的水凝胶膜提高85%.凝固浴温度的升高和凝固浴中硫酸浓度的增大均会导致形成具有较大孔结构的纤维素水凝胶膜,机械性能也随之下降.     

邻苯二亚胺纤维素水溶液的荧光行为

目前，用于制造光致发光材料的基材均为合成高分子材料，如聚氯乙烯（ＰＶＣ）等热塑性材料以及不饱和聚酯等热固性材料［１］．天然高分子材料发光性能的研究并不多见．而与合成高分子相比，纤维素的结构特征决定了它易参与化学反应，可用以制备各种用途的功能材料，如高...     

三维结构和氧化度对C6位氧化再生纤维素止血材料性能影响

C6位氧化再生纤维素作为可吸收止血材料,其止血性能受材料理化性质的影响。通过比较氧化再生纤维素的吸水率、凝胶化速率、溶解速率、降解速率、抗老化性能和止血效果,研究三维结构和氧化度对氧化再生纤维素性能影响。结果发现,氧化度增高,氧化再生纤维素吸水率增强,凝胶化速率加快,溶解速率和降解速率变快,抗老化性能变差,产品有效期变短。纤丝松散网状多孔结构比纱布致密结构更有利于提高吸水率,加快凝胶化速率和溶解速率;同时降低氧化剂用量,提高抗老化性能。同一氧化度条件下,纤丝止血速率优于纱布,止血效果更好。     

Synthesis and Alignment of Iron Oxide Nanoparticles in a Regenerated Cellulose Film

Summary: A polymer‐iron oxide nanocomposite film has been successfully synthesized by using a microporous regenerated cellulose film as template and aqueous ferrous chloride as precursor. The nanocomposite film was investigated with XRD, XPS, SEM, TEM, and VSM. The nanoparticles synthesized in situ were disk‐shaped with a mean diameter of ≈24 and thicknesses of 2.5–3.5 nm. For the first time, the nanodisks were well aligned in the cellulose matrix to form an ordered multibilayer structure by the shrinkage of the hybrid film while drying. The nanocomposite film displayed anisotropic magnetic properties as a result of the alignment of magnetic nanodisks. This work provides a novel and facile method for template synthesis of nanoparticles and aligned nanocomposites.

TEM image of the air‐dried nanocomposite film; slice perpendicular to the film plane.     

Effect of Butyl Methacrylate on Properties of Regenerated Cellulose Coconut Shell Biocomposite Films

In this study, butyl methacrylate acid (BMA) is used as chemical modifier of regenerated cellulose (RC) coconut shell (CS) biocomposite films. The effect of CS content and BMA on tensile properties and crystallinity index (CrI) of RCCSbiocomposite films were investigated. It is found that the increasing of CS content up to 3 wt% increased the tensile strength and modulus of elasticity but decreased at higher content of CS. Elongation at break decreased with increasing of CS content and increased at 4 wt% of CS. Cystallinity index (CrI) of biocomposite films also increased with increasing CS up to 3 wt% content. At similar CS content, treated RC CS biocomposite films with BMA were found to have higher tensile properties and crystallinity index (CrI) than the untreated biocomposite films. The modification by BMA improved interfacial interaction and dispersion of CS in RC biocomposite films.     

Tensile Properties and Morphology of Oil Palm Empty Fruit Bunch Regenerated Cellulose Biocomposite Films

The regenerated cellulose (RC)biocomposite films were prepared using casting method where oil palm empty fruit bunch (OPEFB) and microcrystalline cellulose (MCC) were dissolved in N-dimethylacetamide/lithium chloride (DMAc/LiCl)solution. The increasing of OPEFB contents up to 2 wt% increased the tensile strength and modulus of elasticity of RC biocomposite films while the elongation at break decreased. However, at 3 and 4 wt% of OPEFB content, the tensile strength and modulus of elasticity decreased with increases OPEFB content, but elongation at break increased. The increment of tensile strength and modulus of elasticity at 2 wt% is due to the OPEFB fiber that partially dissolved and dispersed with the OPEFB matrix. The morphology studies illustrate that at 2 wt% of OPEFB content of biocomposite films surface consists less voids and agglomerations than at 4 wt%. This can be considered the RC filler was partially dispersed with the RC matrix in the biocomposite films.     

阳离子化纳米纤维素晶体增强壳聚糖复合膜的制备及性能

利用水相连续法实现了纳米纤维素晶体(NCC)的高碘酸钠氧化及阳离子化,然后将阳离子化纳米纤维素晶体(CDAC)悬浮液与壳聚糖(CTS)醋酸溶液混合,并采用流延法制得壳聚糖-纳米纤维素(CTS-CDAC)复合膜。采用红外光谱(FT-IR)、透射电镜(TEM)、X射线衍射(XRD)、Zeta电位及粒径分析表征了改性前后NCC的结构与性能,并研究了制得的CDAC悬浮液与CTS醋酸溶液混合时的相容性及CTS-CDAC复合膜中CDAC质量分数对复合膜力学性能、水溶胀性的影响。结果表明:CDAC悬浮液与CTS醋酸溶液混合时相容性良好,CDAC在CTS基质中分散均匀,CTS-CDAC复合膜的力学性能较纯CTS膜明显提高。当复合膜中CDAC的质量分数为12%时,拉伸强度达到最高。另外,CTS-CDAC复合膜在水中的溶胀度较纯CTS膜明显降低,稳定性变好。     

Dissolution of Cellulose in Aqueous NaOH Solutions

Dissolution of a number of cellulose samples in aqueous NaOH was investigated with respect to the influence of molecular weight, crystalline form and the degree of crystallinity of the source samples. A procedure for dissolving microcrystalline cellulose was developed and optimized, and then applied to other cellulose samples of different crystalline forms, crystallinity indices and molecular weights. The optimum conditions involved swelling cellulose in 8–9 wt % NaOH and then freezing it into a solid mass by holding it at –20°C. This was followed by thawing the frozen mass at room temperature and diluting with water to 5% NaOH. All samples prepared from microcrystalline cellulose were completely dissolved in the NaOH solution by this procedure. All regenerated celluloses having either cellulose II or an amorphous structure prepared from linter cellulose and kraft pulps were also essentially dissolved in the aqueous NaOH by this process. The original linter cellulose, its mercerized form and cellulose III samples prepared from it had limited solubility values of only 26–37%, when the same procedure was applied. The differences in the solubility of the celluloses investigated have been interpreted in terms of the degrees to which some long-range orders present in solid cellulose samples have been disrupted in the course of pre- treatments.     

Tensile Testing of Single Regenerated Cellulose Fibres

Summary: A tensile testing set-up was developed for the determination of the elastic modulus, tensile strength, and failure strain of single regenerated cellulose fibres. Since the accuracy of strain measurement is crucial for the measured elastic modulus and failure strain, strain measurements were performed mechanically and with a non-contacting optical method in parallel. The optical validation of mechanical strain measurement showed an agreement of measured strain >99%, confirming the accuracy and usefulness of the set-up and sample geometry developed for the test series.     

Mechanical Properties of Regenerated Cellulose Fibres for Composites

Summary: A broad variety of regenerated cellulose fibres was subjected to single fibre tensile tests in order to determine the modulus of elasticity, tensile strength, and failure strain. The results were compared to glass fibres and flax fibres, which are considered the most important technical and natural fibres, respectively. With regard to their modulus of elasticity and tensile strength, regenerated cellulose fibres showed clearly lower values than glass fibres, even when their low density was taken into account. The average modulus of elasticity and tensile strength of regenerated cellulose fibres was also lower than the values measured for flax fibres, but when variability was considered, both fibres performed similarly. In terms of interfacial shear strength with polypropylene, lyocell fibres performed significantly less well than sized glass fibre and ramie fibre. The most important difference between regenerated cellulose fibres and both glass and flax fibres is their high failure strain and thus high work to fracture. The high work to fracture of regenerated cellulose fibres makes them particularly useful for composite applications where high fracture toughness is required.     

Conversion of Cellulose and Lignin Residues into Transparent UV-Blocking Composite Films

The valorization of cellulose and lignin residues in an integrated biorefinery is of great significance to improve the overall economics but has been challenged by their structural recalcitrance, especially for lignin residue. In this work, a facile chemical conversion route to fabricating functional UV-blocking cellulose/lignin composite films through a facile dissolution–regeneration process using these biomass residues was proposed. Three representative lignin residues, i.e., aspen and poplar wood lignin, and corn stover (CS) lignin were assessed for their feasibility for the film fabrication. The UV-blocking performance of the composite films were comparatively investigated. Results showed that all these three lignin residues could enhance the UV-blocking property of the composite films, corresponding to the reduction in the optical energy band gap from 4.31 to 3.72 eV, while poplar lignin had a considerable content of chromophores and showed the best UV-blocking enhancement among these three assessing lignins. The enhancement of UV-blocking property was achieved without compromising the visible-light transparency, mechanical strength and thermal stability of the composite films even at 4% lignin loading. This work showed the high promise of integrating biomass residue conversion into lignocellulose biorefinery for a multi-production purpose.