纸浆纤维悬浮液屈服应力及其在造纸工业中的应用研究进展

纸浆纤维悬浮液是以纤维为固相的非均相混合物,属多相流体。屈服应力作为纸浆纤维悬浮液最重要的流变参数之一,在制浆造纸高效、节能、低耗的生产操作技术及装备的优化设计方面扮演着重要的角色。本文就纸浆纤维悬浮液屈服应力的产生及其影响因素、测量方法及装置进行归纳和总结;在此基础上,阐述了纸浆纤维悬浮液的屈服应力在制浆造纸生产中的应用,并对纸浆纤维悬浮液屈服应力的进一步研究及其在造纸工业相关领域的发展应用提出了思路。

Silviscan：木材及纤维性能分析测试仪

木材及其纤维的物理化学性能是决定纸的质量及生产成本的重要因素。将木材及纤维的性能与最终产品的生产性能联系起来,可以使木材获得最大程度的应用。但传统的纤维性能检测方法需要花费大量时间,Silviscan可以快速测量很多重要的木材及纤维的性能,对于林业及制浆造纸工业有重要意义。文章主要介绍了silviscan的发展历程及其测量原理,以及在林业及制浆造纸工业中的应用。实际的应用表明,silviscan是一种快速有效的木材纤维性能测试仪器,与近红外光谱相结合,还可以对大量的样品进行快速、准确的性能预测。

A Review on Surface?Functionalized Cellulosic Nanostructures as Biocompatible Antibacterial Materials

As the most abundant biopolymer on the earth,cellulose has recently gained significant attention in the development of antibacterial biomaterials.Biodegradability,renewability,strong mechanical properties,tunable aspect ratio,and low density offer tremendous possibilities for the use of cellulose in various fields.Owing to the high number of reactive groups(i.e.,hydroxyl groups)on the cellulose surface,it can be readily functionalized with various functional groups,such as aldehydes,carboxylic acids,and amines,leading to diverse properties.In addition,the ease of surface modification of cellulose expands the range of compounds which can be grafted onto its structure,such as proteins,polymers,metal nanoparticles,and antibiotics.There are many studies in which cellulose nano-/microfibrils and nanocrystals are used as a support for antibacterial agents.However,little is known about the relationship between cellulose chemical surface modification and its antibacterial activity or biocompatibility.In this study,we have summarized various techniques for surface modifications of cellulose nanostructures and its derivatives along with their antibacterial and biocompatibility behavior to develop non-leaching and durable antibacterial materials.Despite the high effectiveness of surface-modified cellulosic antibacterial materials,more studies on their mechanism of action,the relationship between their properties and their effectivity,and more in vivo studies are required.

Numerical prediction of fiber motion in a branching channel flow of fiber suspensions

Fiber orientation and dispersion in the dilute fiber suspension that flows through a T-shaped branching channel are simulated numerically based on the slender-body theory. The simulated results are consistent qualitatively with the experimental data available in the literature. The results show that the spatial distribution of fibers is dependent on the fiber aspect ratio, but has no relation with the volume fraction of fiber. The content ratio of fibers near the upper wall increases monotonically with an increasing Re number, and the situation is reverse for the region near the bottom wall. The orientation of fibers depends on Re number, however, the function of fiber volume fraction and aspect ratio is negligible. The fibers near the wall and in the central region of the channel align along the flow direction at all times, but the fibers in the other parts of the channel tend to align along the flow direction only in the downstream region.

Electro-conductive Nanocrystalline Cellulose Film Filled with TiO_2-ReducedGraphene Oxide Nanocomposite

Imparting electro-conductive properties to nanocellulose-based products may render them suitable for applications in electronics, optoelectronics, and energy storage devices. In the present work, an electro-conductive nanocrystalline cellulose （NCC） film filled with TiO2-reduced-graphene oxide （TiO2-RGO） was developed. Initially, graphene oxide （GO） was prepared using the modified Hummers method and thereafter photocatalytically reduced using TiO2 as a catalyst. Subsequently, an electro-conductive NCC film was prepared via vacuum filtration with the as-prepared TiO2-RGO nanocomposite as a functional filler. The TiO2-RGO nanocomposite and the NCC/TiO2-RGO film were systematically characterized. The results showed that the obtained TiO2-RGO nanocomposite exhibited reduced oxygen-containing group content and enhanced electro-conductivity as compared with those of GO. Moreover, the NCC flm flled with TiO2-RGO nanocomposite displayed an electro-conductivity of up to 9.3 S/m and improved mechanical properties compared with that of the control. This work could provide a route for producing electro-conductive NCC flms, which may hold signifcant potential as transparent ？exible substrates for future electronic device applications.

Fe/C micro electrolysis and Fenton oxidation process for the removal of recalcitrant colored pollutants from mid-stage pulping effluent

The pulp and paper industry produces a large amount of colored effluent in the pulping,bleaching,and papermaking processes.The wastewater from the pulp washing and bleaching stages is also known as mid-stage pulping effluent,which is difficult to treat due to its toxicity and dark dolor.This paper reports a novel Fe/C micro-electrolysis process for the treatment of the mid-stage pulping effluent.Results show that this process is effective in removing the color under optimal reaction conditions.Scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR)analyses indicate that the colored pollutants were removed from the wastewater in the Fe/C micro-electrolysis by adsorption,collection and filtration mechanisms.The Fe2+ions produced in the micro-electrolysis process functioned as Fenton’s reagents with H2O2 in the follow-up oxidation stage,which enhanced the removal of chemical oxygen demand(COD)and color.

Interfacial properties of nano TiO_(2) and cellulose paper coating

This paper examined different kinds of organic functional groups that were introduced onto the surface of nano TiO_(2) by surface modification with different types of zircoaluminate coupling agents.The modified nanoTiO_(2) products with different interfacial properties were obtained,and the impact of the interfacial properties of nanoTiO_(2) on the rheological behavior of paper coating and the properties of coated paper was systematically investigated.The steady shear rheological results showed that the paper coatings containing nano TiO_(2) exhibited a pseudoplastic fluid behavior,characterized as obvious shear thinning.Compared to the hydrophilic unmodified nano TiO_(2),modified nano TiO_(2) could contribute more to the viscosity of paper coatings.The study on the dynamic viscoelasticity revealed that,through the enhancing action among each component in paper coatings,the modified nano TiO_(2) with quaternary amine groups or carboxyl led to a higher dynamic elastic storage modulus and viscous loss modulus of paper coatings.In addition,SEM and AFM analyses indicated that adding modified nano TiO_(2) products in paper coating could improve the coating structure,thus ameliorating the optical properties and printability of coated paper.The results obtained could provide a good reference for the application of nano pigments in paper coating.

Improving the colloidal stability of Cellulose nano-crystals by surface chemical grafting with polyacrylic acid

Cellulose nano-crystals(CNC)can be tailored for various value-added applications.However,its use in aqueous systems is hampered by its limited dispersability,especially at a high CNC concentration.In this study,the improvement of CNC colloidal stability by surface chemical grafting with polyacrylic acid(PAA)was investigated,and the zeta potential and the charge density of the chemically modified CNC were analyzed.The results showed that an acrylic dosage of 1%(based on the dry weight of CNC)was sufficient to significantly enhance the colloidal stability.CNC,after chemical grafting with PAA,showed better stability against the increase in storage time or solid content of the aqueous medium,compared with the un-modified CNC.