Formation of Physical Thermally Reversible Gels in Solutions of Methyl Cellulose in Water and Dimethylacetamide and Properties of Films Thereof

Gelation conditions in solutions of methyl cellulose in water and dimethylacetamide were studied. The gelation mechanisms were studied by X-ray diffraction and photocolorimetry, and their differences in the two systems were revealed. The physicomechanical properties of methyl cellulose films prepared from solutions with preliminary gelation were determined.     

Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies

We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.     

Properties of Aqueous Solutions of Mixtures of Methyl Cellulose and Hydroxypropyl Cellulose

Rheological properties of dilute and moderately concentrated aqueous solutions of mixtures of methyl cellulose and hydroxypropyl cellulose and gelation in these solutions were studied. Using the solvent vapor sorption, the compatibility of the polymer pair was examined and the composition range in which the thermodynamic compatibility is realized was determined.     

纤维素/壳聚糖共混透明膜的制备及阻隔抗菌性能研究

利用壳聚糖溶液包覆法制备了具有高气体阻隔性及抗菌性的透明纤维素膜,其扫描电镜照片证明壳聚糖厚度在1.31 ～4.07 μm之间.通过红外光谱、紫外光谱、热重分析仪、电子万能试验机和接触角测试仪对纤维素/壳聚糖共混膜的结构和性能进行了详细研究,结果表明由于壳聚糖和纤维素之间具有一定的氢键相互作用,使得纤维素/壳聚糖共混膜较好地保持了纯纤维素膜的机械强度,其拉伸强度都大于110 MPa.此外,壳聚糖的包覆对纤维素膜的透明性没有影响,它在600 ～ 800 nm处的透光率仍维持在80％左右,并且提高了纤维素膜的疏水性,其水接触角从纤维素膜的70°提高到了100°.利用气体渗透仪进一步研究了纤维素/壳聚糖共混膜的氧气阻隔性,结果表明该膜具有很好的氧气阻隔性,其氧气渗透系数甚至低于市场上理想的氧气阻隔材料乙烯-乙烯醇共聚物(EVA).金黄色葡萄球菌抗菌测试表明,通过壳聚糖包覆法改性纤维素能够明显提高纤维素膜的抗菌性.     

Sorption Properties of Gel Films of Bacterial Cellulose

The structure and sorption properties of gel films of bacterial cellulose were studied in its interaction with polyvinylpyrrolidone and silver nanoparticles stabilized by this compound.     

Properties and Bioapplications of Blended Cellulose and Corn Protein Films

A series of blend films have been prepared from cellulose and corn protein in a NaOH/urea solution by a simple, low cost, and ‘green’ pathway. Their structure and properties are characterized by amino acid analysis, X‐ray diffraction, scanning electron microscopy, thermogravimetry, and tensile testing. The results reveal that a certain miscibility exists between cellulose and corn protein and their thermal stability and mechanical properties are improved significantly, compared with the protein materials, when the protein content is less than 18 wt.‐%. The protein, which contains tyrosine and histidine, could remain in the blend films after being washed for ten days, which indicates the strong hydrogen bonding between the hydroxy groups of cellulose and the hydroxyphenyl of tyrosine and imidazolyl of histidine in the protein. Furthermore, they exhibit good biocompatibility capable of supporting cell adhesion and proliferation.

     

Structure and Transport Properties of Films of Mixed Cellulose Esters

Cellulose acetomyristates of varied composition were studied. The sample volume abnormally increases in high-temperature stretching and after swelling in benzene. Cellulose acetomyristates can be used as membranes for separating aromatic and aliphatic hydrocarbons.     

Properties of Solutions of Cellulose and Chitin with Montmorillonite Nanoparticles in Aqueous Alkali with Urea and Thiourea Additions and of Composite Films Prepared from These Solutions

Russian Journal of Applied Chemistry - Rheological properties of cellulose and chitin solutions with additions of montmorillonite nanoparticles in NaOH/urea/thiourea aqueous-alkaline solutions were...     

环氧树脂/反应性聚碳酸酯/叔胺体系的表面结构与性能

环氧树脂/反应性聚碳酸酯/叔胺体系的表面结构与性能;环氧树脂; 胺化聚碳酸酯; 形态结构     

纤维素/全硫化弹性纳米粒子复合膜的制备与性能

利用碱脲溶剂低温溶解纤维素,在该体系中掺杂一定比例的全硫化羧基丁苯弹性纳米粒子,制备了纤维素/全硫化弹性纳米粒子复合膜.通过透射电镜、扫描电镜、WAXD、固体核磁共振、热分析和力学性能测试等对该复合膜的结构和性能进行了表征.结果表明,全硫化羧基丁苯弹性纳米粒子(CSB ENP)均匀的分散在具有微纳孔洞结构的纤维素基体中.CSB ENP的引入对纤维素再生过程中的结晶性影响不大.纤维素/全硫化弹性纳米粒子复合膜具有良好的透光性,并且热稳定性也有所提高.加入少量的CSB ENP可以增韧纤维素膜,且能保持良好的力学性能.当CSB ENP的含量为5 wt%时复合膜的断裂拉伸强度和断裂伸长率同时得到了提高.     

Fabrication of Microcrystalline and Powdered Cellulose from Short Flax Fiber and Flax Straw

Conditions of manufacture of microcrystalline cellulose from variously treated short flax fibers and of powdered cellulose from flax straw were examined. The effect of fats, waxes, and pectins contained in the fibers on the kinetics of hydrolysis of the polysaccharide was studied.     

Influence of Thermal Aging Conditions on the Molecular Characteristics of Cellulose and Mechanical Properties of Paper Thereof

Molecular characteristics of cellulose during accelerated aging were studied over wide temperature and time ranges. Also studied were mechanical properties of model samples of paper made of cotton, sulfate, and sulfite cellulose. Interrelation of the molecular characteristics of cellulose and strength properties of paper was investigated.     

Flow Properties of Moderately Concentrated Solutions of Cellulose Acetate Polymer

Calculations [1] of rheological properties of polymeric solutions have usually been restricted to very dilute o r to very concentrated solutions. In either case, one starts with a model for the micro- structure. Between these two conceptual extremes lies the broad class of moderately concentrated solutions. To cover this region theoretically, two approaches have been used; 1) network theories focusing attention on entanglement junctions, and 2) single-molecule theories focusing attention on single molecules but including inter- molecular interactions. Williams, Wang, and Zimm introduced a double model; one for a particular macromolecule and another for solutions containing like molecules in which the chosen macro- molecule is suspended. This approach has turned out to be quite successful because spheres immersed in a suspension of like spheres behave as i f suspended in a Newtonian fluid, and the resulting ex- pression for viscosity is quite simple in form and qualitatively correct for moderate concentrations.     

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。     

Rheological Properties of Aqueous H-Carboxymethyl Cellulose Solutions with Various Additives

Rheological properties of moderately concentrated aqueous solutions of carboxymethyl cellulose in the H form with various additives were studied.     

Properties of Mixed Aqueous Solutions of Polyethylene Oxide and Carboxymethyl Cellulose with Different Degrees of Ionization and of Composite Films Prepared from Them

Russian Journal of Applied Chemistry - Rheological properties of mixtures of dilute and moderately concentrated aqueous solutions of carboxymethyl cellulose with various degrees of ionization and...     

聚丁二烯丙烯酸酯液态光学透明胶的合成及其UV固化膜的性能

针对丙烯酸酯大单体在合成过程中常带有颜色,以及由其制备的液态光学透明胶的UV固化膜易黄变的问题,本文报道了一条新的大单体合成路线:首先以端羟基聚丁二烯(HTPB)、萘钾、丙烯酰氯(AC)为原料,通过一锅法合成了一种无色透明的聚丁二烯丙烯酸酯大单体(PBAM);然后将PBAM与丙烯酸酯活性稀释单体、光引发剂混合,制备了液态光学透明胶;最后通过UV固化制备了一系列无色透明的薄膜。利用GPC、1H-NMR、FTIR等手段对PBAM进行了表征;进一步研究了液态光学透明胶UV固化膜的光学性能、耐黄变性能、耐低温性能等。结果表明:基于新路线合成的PBAM呈现无色透明,液态光学透明胶的UV固化膜展现出优良的光学性能和耐黄变性能,固化膜透光率高达98%;经紫外线加速老化264h后,色差(ΔE)≤1.5;此外,该固化膜还具有优良的耐低温性能,玻璃化转变温度为-30℃。     

Water Sorption Properties and Antimicrobial Action of Zinc Oxide Nanoparticles-Loaded Cellulose Acetate Films

In this work, ZnO nanoparticles loaded cellulose acetate (ZOLCA) films have been prepared and characterized by XRD, SPR and SEM analysis. The moisture permeation properties of the films have been investigated. The GAB isotherm model has been found to fit well on the moisture uptake data obtained at different temperatures. The monolayer sorption capacity χ_m was found to decrease from 0.059 to 0.0079 g water/g dry film with increase in temperature from 20 to 37°C. The isosteric heat of sorption, when studied in the lower water activity range of 0.04 to 0.10, was evaluated to be 46.55 to 87.29 kJ/mol. The water vapor permeability across the ZOLCA films was found to increase with temperature and activation energy of moisture sorption process was found to be 48.57 kJ/mol. These films have shown excellent antibacterial action against model bacteria E-Coli when investigated by qualitative and quantitative methods. Films exhibit great potential to be used as edible films to protect food stuff against microbial infections.     

Structural Changes Induced in Flax Cellulose by Alkaline Treatment

Treatment of flax cellulose with NaOH was studied.