Optimal Method for Production of Amorphous Cellulose with Increased Enzymatic Digestibility

In this paper, a simple and cheap method for producing of amorphous cellulose was studied by treating the initial cellulosic material (MCC and waste paper) with a cold solvent, such as aqueous solution of 7% NaOH/12% Urea, at the various ratios of the solvent to cellulose (v/w) (R). If was found that after treatment of cellulose materials with the solvent at R ≥5, a completely amorphous cellulose (AC) is formed. Due to high digestibility, the AC with concentration of 50 g/L is converted to glucose almost completely for 48 h under the action of cellulolytic enzyme CTec-3 with a dose of 30 mg/g solid sample. Such sample can be used as an amorphous standard in the study of crystallinity degree and enzymatic hydrolysis of various types of cellulose and lignocellulose. It was found that enzymatic saccharification is most advantageous to carry out at elevated concentrations of AC, 150 g /L. Due to high cost of MCC, it is preferable to use a cheap cellulose raw material, such as mixed waste paper (MWP), for the commercial production of AC and glucose. The resulting glucose can find application in biotechnology as a promising nutrient for various microorganisms

Study of Structural Characteristics of Cellulose Esters with Different Degrees of Substitution

In this article, structural characteristics of amorphous mono-, di-, andtri-substituted esters of cellulose have been studied. These esters weresynthesized under homogenous conditions using anhydrides of variousaliphatic acids. The specific gravity of the highly substituted samples wasmeasured by a pycnometric method in the aqueous medium. To calculatethe molar, Van der Waals, and free volumes, as well as the packingcoefficient of amorphous esters the method of additive contributions ofpartial volumes of atoms and atom groups in the volumes of polymerswas used. Based on the molar volume, also specific gravity of celluloseesters was calculated. The coincidence of calculated and experimentalcharacteristics was shown. In addition, the relationship between glasstransition temperature and free volume was found for the esters. Thetheoretical equations were derived, which provide predicting the structuralcharacteristics of cellulose esters with different degrees of substitution

Study of Hydrophilic Properties of Polysaccharides

In this research, the structural characteristics, specific surface area, sorption of water vapor, and wetting enthalpy of various polysaccharides (cellulose, hemicelluloses, starch, pectin, chitin, and chitosan) have been studied. It was confirmed that crystallites are inaccessible for water, and therefore water molecules can interact only with polar groups in noncrystalline (amorphous) domains of biopolymers. The isotherms of water vapor sorption for various polysaccharides had sigmoid shapes, which can be explained by the absorption of water molecules in heterogeneous amorphous domains having clusters with different packing densities. The method of contributions of polar groups to sorption of water molecules was used, which allowed to derivate a simple calculating equation to describe the shape of sorption isotherms. The wetting of biopolymers with water was accompanied by a high exothermic thermal effect, in direct proportion to the amorphicity degree. The sorption values and wetting enthalpies of amorphous domains of biopolymers were calculated, which allowed to find the hydrophilicity index and compare the hydrophilicity of the various polysaccharides

Green Biocomposites for Thermoelectric Wearable Applications

The materials commonly used to fabricate thermoelectric devices are tellurium, lead, and germanium. These materials ensure the best thermoelectric performance, but exhibit drawbacks in terms of availability, sustainability, cost, and manufacturing complexity. Moreover, they do not guarantee a safe and cheap implementation in wearable thermoelectric applications. Here, p-Type and n-type flexible thermoelectric textiles are produced with sustainable and low-cost materials through green and scalable processes. Cotton is functionalized with inks made with biopolyester and carbon nanomaterials. Depending on the nanofiller, i.e., graphene nanoplatelets, carbon nanotubes, or carbon nanofibers, positive or negative Seebeck coefficient values are obtained, resulting in a remarkable electrical conductivity value of 55 S cm−1 using carbon nanotubes. The best bending and washing stability are registered for the carbon nanofiber-based biocomposites, which increase their electrical resistance by 5 times after repeated bending cycles and only by 30% after washing. Finally, in-plane flexible thermoelectric generators coupling the best p- and n-type materials are fabricated and analysed, resulting in an output voltage of ≈1.65 mV and a maximum output power of ≈1.0 nW by connecting only 2 p/n thermocouples at a temperature difference of 70 °C.Peer reviewe

Plasma deposition of polymer composite films incorporating nanocellulose whiskers

International audienceIn a trend for sustainable engineering and functionalization of surfaces, we explore the possibilities of gas phase processes to deposit nanocomposite films. From an analysis of pulsed plasma polymerization of maleic anhydride in the presence of nanocellulose whiskers, it seems that thin nanocomposite films can be deposited with various patterns. By specifically modifying plasma parameters such as total power, duty cycle, and monomer gas pressure, the nanocellulose whiskers are either incorporated into a buckled polymer film or single nanocellulose whiskers are deposited on top of a polymeric film. The density of the latter can be controlled by modifying the exact positioning of the substrate in the reactor. The resulting morphologies are evaluated by optical microscopy, AFM, contact angle measurements and ellipsometry