Properties Of Cellulose Materials Research Articles

The Effect of Synthetic Polymer Foams on Cellulosic Material Degradation.

Polymeric materials are widely used at present as auxiliary materials in the preservation of tangible cultural heritage in museums, galleries, or libraries. The desired properties of such materials include chemical inertness and long lifetime, which are verified by accelerated aging tests. This work has tested three color types of PE foam Plastazote® LD45 (white, grey, and black), which is recommended for use in the field of cultural heritage preservation. The volatile organic compounds released from the foams after artificial aging and their influence on lignocellulosic materials were investigated. The cellulosic materials were artificially aged in close contact with the foams. All foams released organic acids ranging from acetic acid to hexanoic acid. White foam released organic acids to an extent higher by an order of magnitude compared to the grey and black types. A great influence of white foam on the properties of cellulosic materials was observed. There were large differences in the rate of degradation between the types of foams tested, indicating the need to develop a test method in order to determine the suitability for use in the preservation of culture heritage objects.

Performance Assessment of Oil-Immersed Cellulose Insulator Materials Using Time–Domain Spectroscopy under Varying Temperature and Humidity Conditions

The measurement of polarization and depolarization currents (PDC) based on time–domain response is an effective method for state assessment of cellulose insulation material in oil-immersed electrical equipment. However, the versatility of the data obtained at different temperatures is limited because of the temperature dependence of the PDC. In this respect, the universal conversion of PDC data at different temperatures is an essential aspect to improve the accuracy of the determination of insulating properties of cellulose materials immersed in the oil. Thus, an innovative temperature conversion method based on polarization time-varying current (PTC, obtained by multiplying the polarization current and time) is proposed in this article. In the current work, the PTC data at different temperatures are obtained from the oil-immersed cellulose pressboards with different moisture. Afterwards, the functional model based on the power series theory is used to simulate the PTC data, through which the coefficients of the power series are found related to the test temperature of the PTC and the moisture content (mc%) of the oil-immersed cellulose pressboards. Furthermore, the functional relationship among moisture, test temperatures, and the feature parameter calculated by these coefficients is established. Thus, the PTC data at various temperatures can be calculated by the established function. The potential application ability of the proposed method is verified by comparing the calculated results with the measured results obtained from the various samples.

Preparation and properties of microfibrillated cellulose with different carboxyethyl content

Carboxyethyl reaction was used as a pretreatment method before grinding and homogenization to prepare microfibrillated cellulose (MFC). The effect of carboxyethylation on the properties of cellulose materials and prepared MFC samples were investigated. Results showed that cellulose materials with different carboxyethyl content were obtained by controlling the chemical dosage. This reaction increased the water retention value, decreased the degree of polymerization and crystallinity, and changed the crystalline structure of cellulose. After pretreatment, the cellulose fibers were easier to be swelled and fibrillated, which greatly reduces the frequency of grinding. In addition, the diameter of the produced MFC decreased with the increase of carboxyl content. The charge density, suspension stability and transparency of MFC increased obviously due to the presence of carboxyethyl groups. This study provides a comprehensive understanding of carboxyethyl pretreatment for the preparation of MFC, which may help to enrich and promote the preparation and application of MFC.

Effects of average molar weight, crystallinity, and hemicelluloses content on the enzymatic hydrolysis of sisal pulp, filter paper, and microcrystalline cellulose

Properties of cellulosic materials, such as average molar mass (MMvis), crystallinity index and hemicelluloses content may influence the efficiency of the enzymatic conversion of cellulose to glucose. Studies on the simultaneous influence of these parameters have been scarcely found in the literature. In the present study, the conversion of cellulose to glucose was investigated using cellulosic materials with different MMvis, crystallinity, and hemicelluloses content: microcrystalline cellulose (MCC, MMvis = 22104 g mol−1, CI = 79%, no hemicelluloses detected), sisal pulp (SP, MMvis = 94618 g mol−1, CI = 66%, hemicelluloses content = 2.6%) and filter paper (FP, MMvis = 98530 g mol−1, CI = 63%, hemicelluloses content = 19.2%). During the reactions, aliquots were withdrawn and, in addition to the liquors, the unreacted cellulosic materials were evaluated by MMvis, CI, SEM, length and thickness, which can help further understand the reaction as a whole. The liquors were characterized by high-performance liquid chromatography (HPLC) and Miller's method (or DNS). The highest yield for the conversion of cellulose to glucose was observed for SP (88%), followed by MCC (64%) and FP (52%). The results indicated that the presence of high hemicelluloses content (FP) had a more significant interference effect than high crystallinity (MCC).

Recent developments of cellulose materials for lithium-ion battery separators

This paper reviews the recent developments of cellulose materials for lithium-ion battery separators. The contents are organized according to the preparation methods such as coating, casting, electrospinning, phase inversion and papermaking. The focus is on the properties of cellulose materials, research approaches, and the outlook of the applications of cellulose materials for lithium-ion batteries.

Technology of Deep Dehydration of Excess Active Sludge Based on the Use of the Effect of Elastic Vibrations

Methodological approaches to the development of technology of deep dehydration of wastewater precipitates and excess active sludge are presented. It is established that the effect of ultrasound positively affects the physical properties of cellulose materials, and the moisture percentage in the initial material is reduced. The ultrasonic effect is also widely used in adjacent branches of science and technology to intensify the separation of emulsion solutions. Main regularities of the influence of the degree of dehydration and neutralization of waste from municipal treatment facilities on time and intensity of the effect of elastic vibrations emitted by means of ultrasonic dispenser are investigated. The technology of deep dehydration of the mixture of wastewater precipitate and excess active sludge, which is implemented by means of modernizing the standard dehydration scheme of waste existing at the most of enterprises of the municipal complex, is proposed.

Influence of the Structure of Glycidyl Methacrylate Copolymers on the Hydrophobic Properties of Cellulose Materials

The modification of the surface of cellulose-containing materials by copolymers of polyglycidyl methacrylate (PGMA) obtained by means of two ways: acylation of PGMA by stearic acid and copolymerization of glycidyl methacrylate and lauryl methacrylate is proposed. It is demonstrated, that the use of obtained copolymers allows to get the superhydrophobic coatings on the surface of cellulose-containing materials with reaching of contact angles up to 161°. Such modified materials can be used as filters for the separation of the water-oil emulsions.

Effect of fiber orientation in dynamic FTIR study on native cellulose

The properties of cellulose materials are highly dependent on the interactions between and within the cellulose chains mainly related to inter- and intramolecular hydrogen bonds. To investigate the deformation behavior of cellulose and its relation to molecular straining, cellulose sheets with different fiber orientations were studied by dynamic FTIR spectroscopy. The sheets were stretched sinusoidally at low strains while being irradiated with polarized infrared light. It is shown that the polarization direction determines the dynamic IR response to a higher extent than the fiber direction in the sample sheets. Different polarization modes give different dynamic signals, allowing conclusions to be drawn on the structural orientation of submolecular groups in the cellulose molecules. The bands in the spectra mainly affected by the deformation of the sheets were derived from skeletal vibrations that include the COC bridge connecting adjacent rings and from the hydrogen bonds. The conclusion that these groups are the ones that are mainly deformed under load has thereby experimentally demonstrated the theoretical calculations from Tashiro and Kobayashi [Tashiro, K.; Kobayashi, M. Polymer 1991, 32, 1516–1526].

Effect of ionizing radiation on the properties of cellulosic materials

-- It has been shown by x-ray diffraction and sorption methods that the radiolysis of cellulose does not cause changes in its ordered regions. -- The change in viscosity mean degree of polymerization of celluloses under the action of γ-quanta does not depend on the degree of crystallinity of the starting celluloses. -- Intensity of change in DP under the action of γ-radiation depends on the DP of the starting unirradiated cellulose; the higher the DP of the unirradiated cellulose, the more intensive is the degradation at the same absorbed dose.

Hygroscopic properties of cellulose materials for electrical insulation

Results are shown of an experimental study concerning the hygroscopic properties of cellulose materials for electrical insulation under low water vapor pressure.

Modification of the surface properties of cellulose materials by grafting fluoroalkyl(meth) acrylates

Modification of the surface properties of cellulose materials by grafting fluoroalkyl(meth) acrylates