East Asian Calligraphy Black Ink-Coated Paper as Flexible Conducting Electrode for Supercapacitor

East Asian calligraphy black ink (hereafter called simply “black ink”) is used to fabricate flexible conducting chromatography paper electrode by a simple and low-cost method. The black ink-coated paper was characterized by scanning electron microscopy, surface profiler, water contact angle measurement, electrical resistance measurement, X-ray photoelectron spectroscopy, and X-ray diffraction. The hydrophilicity slightly decreased after black ink coating but still provided good adhesion to the follow-up reduced graphene oxide/polyaniline/chitosan slurry coating for fabricating supercapacitor electrodes. A 1000-cycle repeated bending test with a bending radius of 5 mm revealed good conductance retention. Instrumental analyses indicated that the carbon black in the black ink was the main contributor to the electrical conductance. The supercapacitor with black-ink-coated paper electrodes exhibited an areal specific capacitance of up to 179.08 mF/cm² and coulomb efficiency of 80%. This confirmed that the black-ink-coated paper electrode could be feasibly applied to a supercapacitor. This black-ink-coated paper can be easily fabricated in resource-limited settings, and it provides new possibilities for the use of paper-based electrodes in flexible electronics.

Influence of Printing Substrate on Quality of Line and Text Reproduction in Flexography

This study characterizes and compares the parameters of the quality reproduction of fine elements in flexography on coated and uncoated paper as well as on OPP film (oriented polypropylene). A monochrome test form was created and printed using cyan UV ink. The analysis of results confirms the importance of interaction between the printing substrate and ink; it also indicates identical line and text deformations on the print. Quality reproduction on coated paper is higher in relation to OPP film for all the research parameters. The ink penetrates significantly more and with more irregularity into the pores and throats of the uncoated paper, which results in less homogeneous elements, and in such way that it loses its original shape. In coated paper and OPP film, the ink spreads more on the substrate area which gives it a significantly more homogeneous shape. However, due to the surface spread of the ink, the biggest changes in the size of fine elements are noticeable in the OPP film. The scientific contribution of this paper is based on the comparison of print quality parameters of fine elements, which can contribute to the optimization of the production process and quality of the final graphical product.

Sustainable coatings on paper for enhancing barrier properties based on hemicellulose

Coated paper with enhanced barrier properties was prepared via a simple layered self-assembly method using hemicellulose and starch as biobased coatings. Effect of the coating on properties of cellulose paper was investigated. Barrier properties of the paper was increasingly strengthened as the coating amount of hemicellulose rose. When the paper was coated with starch (10.7±0.3 g / m 2 \text{g}/{\text{m}^{2}} ) and hemicellulose (6.9±0.2 g / m 2 \text{g}/{\text{m}^{2}} ) successively, the oil resistance of the paper was increased from 0 to grade 7. Air permeability and water vapor transmittance was decreased by 93.8 % and 39.7 %, respectively. The water contact angle of the coated paper reached 91.7° when the amount of hemicellulose was 1.5±0.2 g / m 2 \text{g}/{\text{m}^{2}} . The hydrophobicity of the coated paper was superior to the original paper although it was negatively influenced by the increasing amount of hemicellulose. The improvement of barrier properties of the coated paper was mainly ascribed to the formation of a thin polymer network on paper surface through intermolecular interaction via hydrogen bonds as demonstrated in SEM and FTIR-ATR results. Moreover, tensile strength and rupture resistance of the coated paper was improved. The results offered an environmentally friendly and economical strategy for preparation of food packaging paper with good barrier properties using biobased coating materials.