Diatomite Modified With Alkyl Ketene Dimer For Hydrophobicity of Cellulosic Paper

Multi-functionalization of papermaking chemicals is one of its main developing strategies. Fillers and internal sizing agents are often mutually restricted in practice. Therefore, it is feasible to prepare a new papermaking chemical by combining its functions. A process of diatomite modified with Alkyl ketene dimer (AKD) was developed in this study. The modified diatomite (AD) can concurrently play the role of mineral filler and sizing agent in the papermaking process. With the equal dosage of AKD, the AD had better sizing and retention performance than the commercial AKD emulsion in the case of cationic polyacrylamide (CPAM) and the CPAM/ bentonite retention system. The sizing mechanism of the AD can be interpreted as numerous hydrophobic sites and micro-surface structure of the paper sheet caused by the AD. Since the ester linkages were not detected in FT-IR spectra of the paper sheet filled by the AD, the chemical reaction may not be indispensable for its sizing performance. What’s more, an interesting “sticky” hydrophobicity phenomenon was observed when filling with AD. The approach in this study to prepare the “sticky” hydrophobic paper sheet can find its applications in some non-traditional application fields of cellulosic paper.

Analyzing the effects of thermal stress on insulator papers by solid-state 13C NMR spectroscopy

Million tons of cellulosic paper have been used for insulating coils in oil-filled electrical power transformers, thereby assuring the electricity supply for our societies. The high working temperatures in transformers constantly degrade paper insulators throughout their service life of up to 40 years. We approached the structural changes in oil-immersed cellulosic paper samples upon thermal stress in a study that compared unbleached softwood Kraft paper used as insulator paper with pure cotton cellulose paper. The model experiments used a thermal treatment in transformer oil at 170 °C for up to 14 days. The samples were characterized by means of 13C CP/MAS NMR spectroscopy, mainly based on deconvolution of the C4 resonance. An automated, fast, and reproducible C4 resonance deconvolution employing the “Peak Analyzer” tool of OriginPro 2020 (OriginLab Corporation, USA) was developed and used to exploit 13C CP/MAS NMR spectroscopy for the characterization of thermally stressed paper samples. Our results show that thermally induced structural changes depend heavily on the composition of paper, that hornification and coalescence of fibrils take place, and that the allomorph composition of cellulose crystallites is altered under the given conditions. Graphical abstract

Paper Sensors Based on Fluorescence Changes of Carbon Nanodots for Optical Detection of Nanomaterials

A paper sensor was designed in order to detect the presence of nanomaterials, such as ZnO and silica nanoparticles, as well as graphene nanoplatelets (GnP), based on fluorescence changes of carbon nanodots. Paper strips were functionalized with carbon nanodots using polyvinyl alcohol (PVA) as binder. The carbon nanodots were highly fluorescent and, hence, rendered the (cellulosic) paper stripes emissive. In the presence of silica and ZnO nanoparticles, the fluorescence emission of the carbon nanodots was quenched and the emission decay was shortened, whereas in the presence of GnP only emission quenching occurred. These different photoluminescence (PL) quenching mechanisms, which are evident from lifetime measurements, convey selectivity to the sensor. The change in fluorescence of the carbon dot-functionalized paper is also evident to the naked eye under illumination with a UV lamp, which enables easy detection of the nanomaterials. The sensor was able to detect the nanomaterials upon direct contact, either by dipping it in their aqueous dispersions, or by sweeping it over their powders. The use of the proposed optical sensor permits the detection of nanomaterials in a straightforward manner, opening new ways for the development of optical sensors for practical applications.

Application of modified phytic acid as flame retardant in cellulosic paper

A flame retardant containing phosphorus and nitrogen was synthesized using phytic acid and dicyandiamide, and it was subsequently used to prepare flame-retardant cellulosic paper via an impregnation method. Vertical flame and limiting oxygen index (LOI) were used to evaluate the flame retardancy of the paper. The paper containing modified phytic acid was characterized with Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), X-ray diffraction (XRD), and scanning electron microscopy (SEM). When the concentration of modified phytic acid was 20%, the char length of the treated paper decreased from 12.5 cm to 4.1 cm, the LOI value increased from 19.6% to 41.5%, and the tensile index was only 3.66% lower than that of the control paper. The modified phytic acid was judged to have good flame-retardant effects on the paper.

Atomic, surface morphology, structural and electrochemical properties of silver nanoparticles-polypyrrole composite film grown on cellulosic paper substrate

In this work, we describe a simple strategy for the preparation of a low-cost electrode material based on polypyrrole (PPy) film grown on an insulating cellulosic paper substrate (Pap) via in-situ oxidative polymerization technique and functionalized by silver nanoparticles (AgNPs) uniformly dispersed on its surface. The properties of the obtained AgNPs-PPy composites were characterized using FTIR-ATR spectroscopy (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscope (SEM) coupled with energy dispersive X-ray spectrometry (EDX), X-ray diffraction spectroscopy (DRX) and electrochemical impedance spectroscopy (SIE).

Effects of Hemicellulose on Recycling Performance of Paper Based on Sisal Fibers

The pulp and paper industry growingly paid attention to the recycling and maintenance of waste paper products. Each paper-making cycle would lead to a sharp drop in the mechanical properties of the cellulosic paper, which was related to the hornification effect. Here, the recycling performance of the holocellulose paper was studied, compared with that of the cellulosic paper. Holocellulose fibers from sisal were fabricated by a gentle delignification method, and the well-preserved cellulose and hemicellulose components hindered the cocrystallization and aggregation of cellulose fibril. Holocellulose paper exhibited much more favorable recycling properties, compared with cellulosic paper. After 5 runs of recycling, holocellulose paper still shown an ultimate strength as high as 25 MPa (reduced from 35 MPa), a decrease of 27.1 %. However, cellulosic paper experienced a substantial loss in ultimate strength from 35 MPa to 9 MPa, a decrease of about 74 %. This can be attributed to the core-shell structure from cellulose and hemicellulose to weaken the hornification effect.