INCREASE IN GRAIN BOUNDARY CONDUCTIVITY OF Li1+xAlxSn2-x(PO₄)₃ BY MIXING POWDERS PRETREATED AT DIFFERENT TEMPERATURES

The overall conductivity of crystalline lithium ion conductors is generally low due to the large grain boundary resistance. In order to improve the grain boundary conductivity, NASICON structured Li1+xAlxSn2-x(PO₄)₃ has been studied in this paper. Samples Li1.2Al0.2Sn1.8(PO₄)₃ with the desirable amount of Al, made of a mixture of not-treated powders and treated powders in various ratios, are prepared to investigate the mixing effect on the grain boundary conductivity. The grains morphology of samples has changed from spherical shapes to rectangular shapes upon mixing, which indicates a liquid (or glass) phase formation during sintering. The overall conductivity peaks at 20% of not-treated powders. The increase in the overall conductivity is attributed to the increase of grain boundary conductivity, not the grain conductivity. The reason accounting for the enhancement of the grain boundary conductivity is attributed to a less-resistive grain boundary as indicated by the grains morphology changes observed

Cationic Polymers with Tailored Structures for Rendering Polysaccharide-Based Materials Antimicrobial: An Overview

Antimicrobial polymers have attracted substantial interest due to high demands on improving the health of human beings via reducing the infection caused by various bacteria. The review presented herein focuses on rendering polysaccharides, mainly cellulosic-based materials and starch to some extent, antimicrobial via incorporating cationic polymers, guanidine-based types in particular. Extensive review on synthetic antimicrobial materials or plastic/textile has been given in the past. However, few review reports have been presented on antimicrobial polysaccharide, cellulosic-based materials, or paper packaging, especially. The current review fills the gap between synthetic materials and natural polysaccharides (cellulose, starch, and cyclodextrin) as substrates or functional additives for different applications. Among various antimicrobial polymers, particular attention in this review is paid to guanidine-based polymers and their derivatives, including copolymers, star polymer, and nanoparticles with core-shell structures. The review has also been extended to gemini surfactants and polymers. Cationic polymers with tailored structures can be incorporated into various products via surface grafting, wet-end addition, blending, or reactive extrusion, effectively addressing the dilemma of improving substrate properties and bacterial growth. Moreover, the pre-commercial trial conducted successfully for making antimicrobial paper packaging has also been addressed

Self-Reinforced Grease-Resistant Sheets Produced by Paper Treatment with Zinc Chloride Solution

A method for the production of paper with high strength and grease resistance was developed. Filter paper was impregnated by an aqueous solution of zinc chloride at a fixed temperature for several seconds. Swelling and partial dissolution of the cellulose fibers resulted in strong and compact paper. Various influencing factors were investigated in an attempt to improve the grease resistance of the paper. In addition, the structural properties of the zinc chloride-treated paper were investigated using a Fourier transform infrared (FT-IR) spectrometer, X-ray diffraction (XRD), and a scanning electron microscope (SEM). Paper treated in this manner was completely grease resistant, had greater stretch, and twice as high tensile strength when compared with untreated paper, while its burst strength more than doubled. Paper treated according to this method had the skeleton of un-dissolved cellulose fibers and the matrix of gelled cellulose. The cellulose of the paper was not chemically modified during this process

Starch-Based Flexible Coating for Food Packaging Paper with Exceptional Hydrophobicity and Antimicrobial Activity

Herein, we fabricated a starch-based flexible coating for food packaging papers with excellent hydrophobicity and antimicrobial properties. FTIR (Fourier transform infrared) and XRD (X-ray diffraction) spectra revealed the homogeneous dispersion of the ZnO nanoparticles (NPs) in the composite film within 5% ZnO NP dosage. SEM (scanning electron microscope) and AFM (atomic force microscope) micrographs confirmed the increased roughness on the composite film with the increased dosages of ZnO NPs. Hydrophobic characteristics showed that dramatic enhancement was obtained in the values and stabilities of DCAs (dynamic contact angles) in the resultant film and coated paper. TG (thermogravimetry) results demonstrated the increased thermal stabilities of the composite films. Significantly, a decreased water vapor transmission rate was observed in the coated paper. When 20% guanidine-based starch and 2% CMC (carboxy methyl cellulose) was added, a flexible coating with excellent antimicrobial activity towards Escherichia coli can be obtained. Furthermore, the migration of ZnO NPs into the food simulants was well below the overall migration legislative limit. The resultant starch-based flexible composite film and coated paper established an effective approach to develop a green-based material for food packaging applications

Coating PHGH-Modified Starch on Papers to Induce Antimicrobial Properties

In this work, paper was rendered antimicrobial via applying antimicrobial-modified starch as a coating material onto the paper’s surface. The antimicrobial starch was prepared by covalently bonding guanidine polymers using a coupling reaction. Two different coating layers were applied onto the paper’s surface. The first coating layer contained clay mixed with a latex binder (clay 100 g/latex 20 g). The antimicrobial starches, which possessed different grafting ratios of the antimicrobial agent (30 wt.% and 50 wt.%), were applied as the second coating layer on the paper. The results showed that the coating thickness was approximately constant at 4 μm. In the presence of 0.5 to 1.0 wt.% antimicrobial starch on cellulose fibers, the growth inhibition of bacteria was almost 100%. Additionally, the resulting coated paper exhibited high antimicrobial activities against E. coli. Furthermore, the results showed that the coated papers prevented fungal growth