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Manufacture of Pressure-Sensitive Products
Published in István Benedek, Mikhail M. Feldstein, Technology of Pressure-Sensitive Adhesives and Products, 2008
Corona treatment requires working with high-voltage (10–25 kV), high-frequency (30–50 Hz), electrical fields. Values of 12–20 kV and frequencies of 1–3.8 MHz and 15–40 kHz were also tested. A higher frequency improves the corona treatment effect, whereas low frequency leads to blocking of the films. The so-called streamers (discharge channels during treatment) appear above a frequency of 10 kHz. For PP, treating energies of 0.15–40 J/cm2 have been used. Corona power supplies possess an output of 4–60 kW. Watt density readout equates the constant treatment-level measurement. Electrode width and watt density level are programmable and adjustable via software. There is a skip treat option, which means that there are intermittent treat and nontreat areas along the web length; that is, full-surface and partial treatment are possible. Threat areas are synchronized with line speed. A splice mode option moves electrodes from the base roll to permit the splice tail to pass. Corona treatment has a special importance for adhesiveless self-adhesive films (see also Applications of Pressure-Sensitive Products, Chapter 7).
A study on additive manufacturing build parameters as bonded joint design factors
Published in The Journal of Adhesion, 2021
L. Bergonzi, A. Pirondi, F. Moroni, M. Frascio, M. Avalle
As remarked by Packham[16] surface physics and morphology plays a key role in the adhesion mechanisms; however, only a few works are available on surface modifications for AM. Bürenhaus et al.,[5] Li et al.,[17] Fieger et al.[18] and Leicht et al.[19] investigated overlap surface modifications using industrial methods as mechanical abrasion, chemical etching, flame impingement, corona treatment and Atmospheric Pressure Plasma (APP). Even if industrial modifications, and in particular APP, led to adhesion improvements, specific equipment and post-processing are required, thus alternative approaches to embed surface modifications in AM processes were investigated. These approaches do not require any specific equipment and are based on the observations that printing setups, as parts positioning in the build volume and material deposition patterns, and printing parameters, as layer height, infill, nozzle temperature and speed, affect material physics, i.e. crystallinity,[20] and properties, i.e. Young’s modulus[21] and surface roughness.[22]
Green dyeing of weld on corona discharge treated wool fabric
Published in The Journal of The Textile Institute, 2021
Aazam Talebian, Sima Habibi, Pegah Neshat
Figure 3 illustrates the surface morphology of the untreated and corona treated wool fabrics were observed by SEM. The scales have been clearly observed on the surface of untreated wool fibers but the scales on the surface of corona treated wool fibers damaged. The amount of damaging and peeling increases by increasing the number of corona passages so that the tips of the scale are completely removed and there is not any extrusion from the surface on the treated wool fibers after 50 times corona treatment as compared to 30 times corona treated wool. Also, visible cracks have been formed on wool fibers after 50 times of corona treatment. Etching effect of corona treatment caused by the bombardment of the air plasma species on the fabric surface is the reason of scale damaging (El-Zeer & Salem, 2014; Ke et al., 2008; Wang et al., 2009).
Novel corona discharge treatment of cotton fabric with Cu and ZnO nanoparticles
Published in The Journal of The Textile Institute, 2020
Shirin Nourbakhsh, Hengameh Sepehrnia, Eela Akbari
Figure 1 shows scanning electron micrographs (SEM) of untreated (Figure 1(a)) and corona-treated cotton fabrics (Figure 1(b)). Untreated cotton showed a smooth surface and corona-treated cotton showed uneven surface with some pores and holes. These results were according to previous researches which showed the etching effect of corona discharge treatment (Nourbakhsh, Parvinzadeh, & Jafari, 2018). Zinc oxide nanoparticles were coated on cotton fabric (Figure 2(a)). The nanoparticles were distributed of the size of 53 to 94 nm on the fiber surface as shown in Figure 2(a). The ZnO nanoparticles were coated on corona-treated cotton according to the Figure 2(b) (pre-treatment), and ZnO nanoparticles-coated fabric also was treated by corona discharge (post-treatment) (Figure 2(c)). Comparing Figure 2(a,b) indicated that by corona treatment on fiber surface, the particles could penetrate into the holes and pores, whereas particles on untreated cotton were appeared on the surface. Corona treatment on nanoparticles (post-treatment) showed different surface, as some parts of the surface were smooth with some grooves and some parts showed nanoparticles (Figure 2(c)). The same treatments were carried out with copper nanoparticles, and the results are shown in Figure 3. Figure 3(a) shows Cu nanoparticles on cotton fabric, whereas corona treatment on Cu nanoparticles is shown in Figure 3(c). The copper nanoparticles were penetrated into the surface of corona discharge-treated cotton (Figure 3(b)) and corona treatment produced pores on Cu-treated cotton (Figure 3(c)).