Properties of solutions of methyl cellulose blends with poly(N-methyl-N-vinylacetamide) in water and dimethylacetamide and of the related composite films

The rheological properties of dilute and moderately concentrated solutions of methyl cellulose blends with poly(N-methyl-N-vinylacetamide) in water and dimethylacetamide are studied, and the stressstrain characteristics of the composite films based on these blends are estimated. DSC, X-ray diffraction, and thermomechanical analysis are used to investigate the structural organization of composite films, to estimate the temperatures of relaxation transitions, and to determine the composition ranges in which the polymers are compatible and form mixed structures.     

Utilizing Polymer Blends to Prepare Ultrathin Films with Diverse Cellulose Textures

This paper presents an overview of the recent work on ultrathin polymer blend films containing cellulose. Three systems prepared via trimethylsilyl cellulose derivative, which is subsequently hydrolyzed to cellulose, are presented: polystyrene/cellulose, poly(methyl methacrylate)/cellulose and polystyrene-block-polyethyleneoxide/cellulose. Diverse textures emerge within the films depending on the interactions between the polymers and their interactions with the substrate as well as on different solubilities of the polymers. Furthermore, an ultrathin film containing a cellulose/xylan blend is presented. This film was deposited directly from a common solvent (dimethylacetamide/lithium chloride) and it did not exhibit distinct morphological patterns comparable to the blends with synthetic polymers.     

Anomalous reinforcing effects in cellulose gel-based polymeric nanocomposites

Cellulose-synthetic polymer nanocomposite films were prepared by immersion of cellulose gel in polymer solutions followed by dry casting. The cellulose hydrogel was prepared from aqueous alkali-urea solution. As the synthetic polymer, polystyrene (PS) and poly(methyl methacrylate) (PMMA) were used. The polymer content could be changed between 10 and 80% by changing polymer concentration of immersing solution. While the mechanical properties of the cellulose-PMMA composite films showed a nearly linear dependence on PMMA content, those of cellulose-PS composites showed an anomalous behavior; both tensile strength and Young’s modulus showed prominent maxima at 15–30 wt% PS contents. This anomaly may have resulted from the specific interaction between the aromatic ring of PS and the hydrophobic plane of the glucopyranoside. Both PMMA and PS composite films showed significant improvements in dimensional thermal stability; up to 25 wt% synthetic polymer content, the coefficient of thermal expansion (CTE) was as low as ca. 30 ppm/K, about 1/3 of the pure polymers. This indicates that the regenerated cellulose network is effective in suppressing thermal expansion of the synthetic polymers.     

Formation of gold nanoparticles in aqueous solutions of cellulose derivatives and a study of the properties of these nanoparticles

It was demonstrated that gold nanoparticles can be obtained by using cellulose ethers, methyl hydroxyethyl cellulose and carboxymethylcellulose as reducing agents and also as nanoparticle stabilizers. IR spectral studies revealed a difference between the mechanisms of reduction and nanoparticle stabilization by these cellulose derivatives. A scanning tunnel microscope was used to examine composite films formed from nanoparticle dispersions on the surface of polycrystalline gold films. It was demonstrated that, in the case of gold nanoparticles, densely packed globular structures are formed in a carboxymethyl cellulose solution. A fibril-like structure of layers is formed in the Au+(methyl hydroxyethyl cellulose) system.     

Ternary composite films of natural rubber,cellulose microfiber,and carboxymethyl cellulose for excellent mechanical properties,biodegradability and chemical resistance

Cellulose - Fast and facile preparation of composite films containing natural rubber and Eucalyptus cellulose microfiber was achieved by the addition of carboxyl methyl cellulose to yield advantage...     

纤维素/明胶复合膜的超分子结构与性能

通过一种绿色的方法在NaOH/尿素水体系中制备出纤维素和明胶组成的复合膜(C/G),并且证明这两种大分子间存在强的氢键作用,导致明胶耐水性明显改善.同时,用戊二醛作为交联剂对复合膜化学交联,进一步提高其抗水性.通过红外光谱(FTIR)、紫外光谱(UV-Vis)、13C固体核磁共振谱、扫描电镜(SEM),力学和溶胀测试对...     

Ag@AgCl embedded on cellulose film: a stable,highly efficient and easily recyclable photocatalyst

In this work, cellulose–Ag@AgCl composite films have been fabricated directly through a one-step coagulation of a cellulose/1-butyl-3-methylimidazolium chloride (BmimCl) solution with AgNO₃ and PVP. The AgCl was formed upon the addition of AgNO₃ to a cellulose/BmimCl solution, and underwent further reaction with excess Cl^?, leading to the complete dissolution of AgCl. The AgCl crystals were regenerated on the cellulose matrix during the coagulation process. The AgCl was partial decomposed to Ag⁰ and formed Ag@AgCl under visible light irradiation. The morphology of Ag@AgCl in the cellulose matrix was controlled by varying the concentration of PVP. The addition of PVP enabled the formation of stable cellulose films embedded with Ag@AgCl. The composite film demonstrated efficient photodegradation of methyl orange, which was retained upon recycling. This work thus provides a simple pathway for the preparation of Ag@AgCl embedded on a polymer support via one-step coagulation.     

Formation of a composite based on selenium nanoparticles stabilized with poly-<Emphasis Type="Italic">N,N,N,N</Emphasis>-trimethylmethacryloyloxyethylammonium methyl sulfate and on Acetobacter xylinum cellulose gel films

Formation of a composite based on selenium nanoparticles stabilized with poly-N,N,N,N-trimethylmethacryloyloxyethylammonium methyl sulfate and on Acetobacter xylinum cellulose gel films was studied. Optimal sorption parameters at which the amorphous form of selenium is preserved in the composite film were suggested.     

Properties of Some Chitosan-containing Blends and Films Therefrom

Mixed solutions of chitosan and polymers with different chain rigidities (polyvinyl alcohol and methyl cellulose) in 2% acetic acid, at various component ratios, were studied viscometrically. The compatibility of the components in solutions and in the solid phase was assessed, and the mechanical characteristics of films prepared from these blends were determined.     

Transcrystallization of polypropylene at cellulose nanocrystal surfaces

There is a resurgence of interest in composite materials incorporating cellulose as fibrous reinforcement in semicrystalline melt-processed polymers. Potential natural cellulose sources range from flax and ramie fibres down to whiskers and nanocrystals isolated from bacteria. It has long been known that the crystallization of matrix polymers such as polypropylene may be preferentially nucleated by Cellulose I surfaces, leading to a “transcrystalline” layer around the fiber. In this note, a transcrystalline layer at the edge of films cast from cellulose nanocrystal suspensions is demonstrated, and preferential nucleation of polypropylene on nanocrystals deposited on a glass surface is also observed.     

Structure and characteristics of film composites based on methyl cellulose,poviargol, and montmorillonite

The structure of film composites based on methyl cellulose and fillers, such as montmorillonite and silver nanoparticles stabilized by poly(vinylpyrrolidone) (Poviargol), is studied by X-ray diffraction. In the composite, montmorillonite nanoparticles exist in the exfoliated state; when the content of the nanoparticles is below 7 wt %, the crystallinity of methyl cellulose increases. Owing to the presence of the filler and structural ordering of the matrix, elastic characteristics improve and the degradation temperature of the composites increases. The X-ray structural data show that the Ag particles in the methyl cellulose-Poviargol composite are 30 nm in size. The introduction of up to 20 wt % Poviargol assists the crystallization of methyl cellulose. The strength and strain characteristics of the film composites based on methyl cellulose and Poviargol make it possible to use these composites in medicine and agriculture.     

The structure and spontaneous orientational order in surface layers of water-soluble methyl- and hydroxypropylmethyl cellulose films

The structure of the surface layers of thin films cast from water-soluble derivatives of cellulose—methyl cellulose and hydroxypropyl methylcellulose—has been studied by the methods of an oblique polarized beam and molecular hydrodynamics. It has been demonstrated that the molecular chains of the polymers under study are characterized by a high degree of order in surface film layers. The orientational order of molecular chains demonstrates a strong molecular mass dependence. This effect is associated with the concentration of terminal segments whose orientational order parameter relative to the film surface differs from the corresponding value of internal segments composing the molecular chain. The quantitative estimates of the orientational order parameter of terminal and internal segments have been performed.     

The Effect of UV-Irradiation on Poly(vinyl alcohol) Composites with Bacterial Cellulose

The development of biodegradable packaging materials, especially from renewable resources is a constant preoccupation of nowadays, because of the environmental problems caused by synthetic polymers. The combination of cellulose with other polymeric materials could be an ecologic alternative and a way to use renewable resources for food packaging. Bacterial cellulose which is produced by microbial fermentation is also a promising material which can be used not only in biomedical application, but also as food packaging material. In this research different composite films between poly(vinyl alcohol)-bacterial cellulose (PVA-BC) were obtained by casting method. The obtained films were UV irradiated for different periods of times from 1 to 10 hours, using a mercury lamp, Philips TUV-30, emitting light mainly at 254 nm. Changes in FT-IR spectra before and after UV irradiation and the modification of transparency and of the swelling characteristics of the films were observed. As it was expected the composites materials are sensitive at UV exposure.     

Properties of blends of methyl cellulose and carboxymethyl cellulose with different degrees of ionization in solutions and solids

The rheological properties of dilute and moderately concentrated aqueous solutions of methyl cellulose with carboxymethyl cellulose having different degrees of ionization, were examined. The solvent vapor sorption method was applied to examine the compatibility of the polymers in the solid state and elucidate how the amount of nonionized carboxy groups in carboxymethyl cellulose affects its compatibility with methyl cellulose.     

Preparation and Properties of Cellulose/Waste Leather Buff Biocomposites

The aim of the present work was to utilize waste leather buff (WLB) as filler in cellulose and make biocomposites for packaging applications such as wrappers. Cellulose was dissolved in the environmentally friendly ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl). To this solution, WLB was added in amounts of 5 to 25 wt.% of cellulose. The cellulose and cellulose/WLB composite films were prepared by regenerating the corresponding cast solutions in a water coagulation bath followed by washing and drying. These films were tested for their tensile properties, thermal stability, and morphology. The tensile modulus and strength of the composite films were lower than those of the matrix. The lowering of the tensile modulus and strength with increasing WLB loading was attributed to the random orientation of the leather fibers of WLB in the composites. However, the % elongation at break of the composite films was found to be higher than that of the matrix and increased with increasing WLB content. The possible interaction between the matrix and WLB filler was probed using FT-IR analysis. The thermal stability of the composite films was higher than that of the matrix. The increase in thermal stability of the composite films was attributed to cross-linked collagen protein leather fibers in WLB. The fractographs of the composite films indicated good interfacial bonding between cellulose and leather fibers of WLB. These composite films may be considered for packaging and wrapping applications.     

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.     

Cellulose as matrix component of conducting films

Conjugated polymers gain growing importance as conductive materials in industrial applications in various fields of electronic devices. Cellulose with its extraordinary supramolecular structure and material properties can help to awake the possibilities for conducting polymers in interplay of the two materials. The ability of additional derivatization, the stiff and oriented molecular structure and the inherent strength, stability and film-forming properties give cellulose a complementary role to the brittle conjugated polymers, cellulose imparting the features of a stable and robust carrier component. To go forward this way, making a composite out of cellulose and conducting polymers is a prerequisite. Different strategies to form composite materials of non-derivatized cellulose and conductive organic polymers were tested. Significant differences between various mixing strategies as well as between the conducting polymers polyaniline (PAni), polypyrrole (PPy), and polythiophen (PTh) were observed. In situ synthesis of the conducting polymers in cellulose solutions and microcellulose dispersions as well as blending of pre-synthesized conducting polymers in these cellulose systems were tested. Unexpectedly, not homogenous mixtures showed best results in respect to film formation and conductivity, but composites formed by heterogeneous mixtures of the conducting polymers within a cellulose gel. Best results were obtained with finely dispersed PAni. The results support development studies towards circuitry and photo-current systems based on cellulose carriers.     

Formulation and characterization of in situ generated copper nanoparticles reinforced cellulose composite films for potential antimicrobial applications

Cellulose was dissolved in aq.(LiOH + urea) solution pre-cooled to –12.5°C and the wet films were prepared using ethyl alcohol coagulation bath. The gel cellulose films were dipped in 10 wt.% Cassia alata leaf extract solution and allowed the extract to diffuse into them. The leaf extract infused wet cellulose films were dipped in different concentrated aq. copper sulphate solutions and allowed for in situ generation of copper nanoparticles (CuNPs) inside the matrix. The morphological, structural, antibacterial, thermal, and tensile properties of dried cellulose/CuNP composite films were carried out. The presence of CuNPs was established by EDX spectra and X-ray diffraction. The composite films displayed higher thermal stability than the matrix due to the presence of CuNPs. Cellulose/CuNP composite films possessed better tensile strength than the matrix. The composite films showed good antibacterial activity against E.coli bacteria. We conclude that good antibacterial activity and better tensile properties of the cellulose/CuNP composite films make them suitable for antibacterial wrapping and medical purposes.     

Supramolecular architectures of cellulose derivatives

Several cellulose derivatives belong to a special class of polymers called hairy-rod macromolecules which are used to generate well-defined supramolecular architectures by the Langmuir-Blodgett (LB) technique. In particular trimethylsilyl cellulose (TMSC) forms monomolecular films on the Langmuir-trough and is transferred onto hydrophobic substrates with a constant transfer ratio, as it does not undergo chemical changes in the film-building process. Silylated celluloses was regenerated which represents a convenient method for the generation of homogeneous ultrathin films with hydrophilic surfaces. The adsorption of polymers and dyes as well as biomolecules onto regenerated and modified cellulose LB films have been studied. In addition, chemical reactions, such as cycloaddition, desilylation and crosslinking reactions within single monolayers have been performed.     

X-ray and neutron reflectometry investigation of Langmuir-Blodgett films of cellulose ethers

Langmuir-Blodgett films of a series of cellulose ethers are investigated by X-ray and neutron reflectometry. Two types of samples are considered: simple alkyl ethers of cellulose and derivatives obtained by the alkylation of (2-hydroxypropyl)cellulose (HPC). All of the cellulose ethers form stable monolayers at the air-water interface. Significant differences are, however, found in the surface pressure-area compression isotherms. Ethers prepared from HPC typically exhibit larger limiting molecular areas and higher surface pressures than the corresponding simple cellulose ethers. The ease of monolayer transfer to hydrophobic silicon substrates differs greatly from one type of molecule to another. Successful transfer conditions are found only for ethers that form stable monolayers at sufficiently high surface pressures. Surprisingly, deuterated HPC ethers, prepared for neutron reflectivity measurements, exhibit monolayer properties significantly different from those of their hydrogenated analogues. Although essentially identical limiting molecular areas are found, the surface pressure corresponding to a characteristic plateau transition in the compression isotherm is found to decrease by about 8-10 mN m(-1) upon side chain deuteration. X-ray reflectivity results show a linear increase of film thickness with the number of deposited layers, indicating a regular and reproducible transfer. Observed average layer spacings are, however, significantly smaller than the calculated length of fully extended side chains. Neutron reflectivity curves recorded for composite LB films composed of both deuterated and hydrogenated polymers exhibit regular Keissig fringes, but no Bragg peak. This result indicates that these LB films do not possess an internal periodic structure and the initial layer-by-layer organization is lost by large interlayer diffusion.