Carbon dioxide-mediated thermochemical conversion of banner waste using cobalt oxide catalyst as a strategy for plastic waste treatment

In this study, the effects of CO₂ thermochemical agent and a metal oxide catalyst (Co₃O₄) on thermochemical banner waste conversion were explored. The results revealed that compared to the non-catalytic conversion of banner waste under N₂ environment, the conversion under CO₂ yielded more non-condensable gases owing to an enhanced thermal cracking of volatiles. In addition, the CO and CH₄ yields at >700 °C in CO₂ increased considerably owing to the reverse water-gas shift reaction and CO₂ methanation. The CO₂ agent reduced the yields of condensables (e.g., benzoic acids, phthalic acids, esters, biphenyls, fluorenes) and decomposition residue (e.g., char and wax), which could be attributed to the enhancement of the thermal cracking of volatiles evolved during the banner waste conversion by CO₂ and the C-H and O-H bonds present in the feedstock. In addition, the Co₃O₄ catalyst promoted the decarboxylation reaction under N₂ environment, whereas it promoted the methanation and reverse water-gas shift reaction under CO₂. This indicates that compared to the non-catalytic CO₂-assisted banner waste conversion, the use of CO₂ for the conversion of banner waste in the presence of Co₃O₄ significantly increased the yields of CH₄ and CO. Furthermore, Co₃O₄ promoted the thermal cracking of polyester bond, thus decreasing the yields of long-chain chemical compounds. In addition, the simultaneous use of Co₃O₄ catalyst and CO₂ agent minimized the formation of char and wax. For all cases (N₂ versus CO₂, non-catalytic versus catalytic), an increase in temperature enhanced the total permanent gas yield and decreased the yields of condensables, char, and wax. The findings of this study revealed the importance of the synergistic use of Co₃O₄ catalyst and CO₂ agent for the plastic waste upcycling, such as banner waste.

Preparation and Characterisation of Polyurethane Acrylate-Based Titanium Dioxide Pigment for Blue Light-Curable Ink

Herein, a polyurethane acrylate-based TiO2 (PU-TiO2) was fabricated using a two-step method. First, a polyurethane prepolymer was prepared. Second, PU-TiO2 was prepared using amino-modified TiO2 (A-TiO2). The best synthesis process of the polyurethane prepolymer was when the reaction temperature was 80 °C, the reaction time was 3 h and the R-value of the polyurethane acrylate was 2. Next, the influence of the A-TiO2 content on the structure and performance of PU-TiO2 was examined. The analysis of the rheological properties of the PU-TiO2 ink indicated that its viscosity gradually increased as the A-TiO2 content increased. The tensile performance of film improved because of the presence of A-TiO2. The photo-polymerisation and photo-rheological performance indicated that the PU-TiO2 structure changed from a hyperbranched structure with TiO2 as the core to a segmented structure, as the A-TiO2 content was 3%.

Photopolymerization of Macroscale Black 3D Objects Using Near-Infrared Photochemistry

The efficiency of the photopolymerization technology significantly decreases when the color of materials blackens, which is contributed by the limitations of light penetration. Herein, we demonstrate rapid generation of black 3D objects up to the centimeter level in size based on melanin using near-infrared (NIR) photochemistry. Melanin, of a low absorption coefficient in the NIR range, allows thorough penetration of the 980 nm light to induce emission from upconversion nanoparticles (UCNPs) for initiating UCNP-assisted photopolymerization (UCAP). A model that describes light-attenuation gradients and dose-dependent kinetics in UCAP-guided NIR photochemistry is developed. Notably, the established model for the UCAP concept provides sufficient vertical light penetration to form scale-predictable black materials and instructs 3D printing applications. The critical control parameters were evaluated, and it was shown that complex macroscale black objects can be processed within dozens of minutes. The modeling methodologies integrated with rich functional fillers will further extend the versatility of UCAP technology in device design and manufacturing.

High-Quality Images Inkjetted on Different Woven Cotton Fabrics Cationized with P(St-BA-VBT) Copolymer Nanospheres

The porosity, roughness, and thickness of woven fabrics limit inkjet printing quality, which is extremely important for obtaining high-quality inkjet printing images on fabrics. This study reveals the application of poly[styrene-butyl acrylate-(P-vinylbenzyl trimethyl ammonium chloride)] nanospheres prepared via a soap-free emulsion polymerization approach as a novel kind of the cationization modifier for the inkjet printing of different woven cotton fabrics by the pad-cure process. It was found that the nanospheres exhibited an average diameter of 65.5 nm, a zeta potential of +57.8 mV, and a glass transition temperature of 94.7 °C. The nanospheres deposited on three cotton fabrics through the dip-rolling process, resulting in the increase of zeta potential, hydrophobicity and thickness of the fabric, and the decrease of porosity and roughness. The high-quality inkjet printing images can be obtained on fabrics with different structures owing to the differences in zeta potential, hydrophobicity, porosity, roughness, and thickness of fabrics. The plain, twill, and honeycomb weave fabrics obtained high-quality inkjet printing images for portraits, oil paintings, and landscape paintings, respectively. The nanospheres could strongly adsorb on the fiber by electrostatic attraction. The reactive dye molecules in the inks could react with the cationized fibers by electrostatic attractive force, resulting in the increase of the color strength, fixation rates, and outline sharpness. The nanosphere cationization of different woven fabrics offers a new potential method for obtaining high-quality patterns without significantly affecting the fabric handle.

Efficient Inkjet Printing of Graphene-Based Elements: Influence of Dispersing Agent on Ink Viscosity

Inkjet printing is an excellent printing technique and an attractive alternative to conventional technologies for the production of flexible, low-cost microelectronic devices. Among many parameters that have a significant impact on the correctness of the printing process, the most important is ink viscosity. During the printing process, the ink is influenced by different strains and forces, which significantly change the printing results. The authors present a model and calculations referring to the shear rate of ink in an inkjet printer nozzle. Supporting experiments were conducted, proving the model assumptions for two different ink formulations: initial ink and with the addition of a dispersing agent. The most important findings are summarized by the process window regime of parameters, which is much broader for the inks with a dispersing agent. Such inks exhibit preferable viscosity, better print-ability, and higher path quality with lower resistivity. Presented results allow stating that proper, stable graphene inks adjusted for inkjet technique rheology must contain modifiers such as dispersing agents to be effectively printed.