Optimization study on wet electrostatic powder coating process to manufacture UHMWPE/LDPE towpregs

In the present study, an attempt has been made to coat the non-conductive Ultra-high Molecular Weight Polyethylene (UHMWPE) fibers with Low-Density Polyethylene (LDPE) powder. In order to enable the deposition of electrostatically charged LDPE powder onto the fiber surface, UHMWPE fibers are dipped into a surface modification bath to impart momentary conductivity. Further, Box Behnken’s experimental design is used to optimize the processing parameters for Fiber Volume Fraction (Vf) for this wet electrostatic spray coating process. An experimental multi-parametric equation is acquired through response surface methodology to ascertain the association amid the process parameters such as processing temperature (A), conveying air pressure (B), and gun nozzle angle (C) on the output response of Vf. The process parametric values for A, B, and C are varied from 225°C to 245°C, 0.2 bar to 0.4 bar, and 0° to 120° respectively. The Vf obtained is in the range of 37.02%–56.28% depending on the combination of process parametric values. Powder pick-up increases with an increase in the gun nozzle angle. An increase in conveying air pressure and temperature of the hot air oven leads to an increase in powder deposition. The values predicted from the model are observed to be in close proximity (94.59%) to the experimental results. Gun nozzle angle is the principal parameter affecting the matrix deposition on the fiber surface in comparison to other process parameters.

Preparation of TiO2 Coatings on Carbon Fibers

Carbon fibers have been TiO2 coated. Previously, the carbon fiber surface has been heat-treated to remove the sizing. The TiO2 layer has been formed on the fiber surface using the sol-gel technique by immersion in a solution. After coating, the samples have been dried at room temperature and annealed at 500 °C in air for 30 minutes. The phase composition of the coating obtained has been studied using X-ray diffraction. X-ray diffraction analysis of the coating and sol has shown that the rutile phase and the average size of TiO2 crystallites grow with an increase in the annealing temperature. The results of studying TiO2 coating antioxidative properties within 500-800 °C are given. Studying the morphology of the TiO2 coating on the fiber surface and the burnout rate (weight change) have shown that the coating exhibits good oxidation resistance up to 600 °C.

Electroless plating process for the manufacture of radiation protection suits for pregnant woman: Effect of bending on its electromagnetic shielding performance

Multi-ion fabrics (especially silver ion fabrics) have special advantages as electromagnetic radiation, but the use of noble metals enhances its cost. Electroless nickel plating (EP-Ni) has great potential application in fabricating low-cost metallized material. Here, EP-Ni on pure cotton surface to fabricate radiation protection suits for pregnant woman was established to replace traditional protection suits with silver film. The active groups on the cotton/polyester blend fiber surface could absorb tin and palladium ions, acting as catalytic centers, which can catalyze the reduction of Ni2+ in the plating solution. Ni particle with (111) crystal plane preferential oriented crystal structure deposited on cotton surface with a coarse microstructure. The Ni deposited amount is about 19%. The fabricated material exhibited a shielding effectiveness of 29.5 dB. Studies also shown that bending has no negative effect on crystallinity and electrical property. But more bending times could lead to crack, which would decline electromagnetic shielding performance by 24%.

How Fiber Surface Topography Affects Interactions between Cells and Electrospun Scaffolds: A Systematic Review

Electrospun scaffolds have a 3D fibrous structure that attempts to imitate the extracellular matrix in order to be able to host cells. It has been reported in the literature that controlling fiber surface topography produces varying results regarding cell–scaffold interactions. This review analyzes the relevant literature concerning in vitro studies to provide a better understanding of the effect that controlling fiber surface topography has on cell–scaffold interactions. A systematic approach following PRISMA, GRADE, PICO, and other standard methodological frameworks for systematic reviews was used. Different topographic interventions and their effects on cell–scaffold interactions were analyzed. Results indicate that nanopores and roughness on fiber surfaces seem to improve proliferation and adhesion of cells. The quality of the evidence is different for each studied cell–scaffold interaction, and for each studied morphological attribute. The evidence points to improvements in cell–scaffold interactions on most morphologically complex fiber surfaces. The discussion includes an in-depth evaluation of the indirectness of the evidence, as well as the potentially involved publication bias. Insights and suggestions about dose-dependency relationship, as well as the effect on particular cell and polymer types, are presented. It is concluded that topographical alterations to the fiber surface should be further studied, since results so far are promising.