Optimisation of the DCSBD roll-to-roll treatment of LLDPE/PA tubular foil using rollers of different electrical resistance
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| Year of publication | 2021 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | This study aimed to optimise the diffuse coplanar surface barrier discharge (DCSBD) roll-to-roll (R2R) treatment of multi-layer tubular foil using several types of rollers differing in material resistance. Multi-layer tubular foils are used as casings in the meat industry. The effect of ambient air plasma generated by coplanar and volume dielectric barrier discharge on the surface characteristics of tubular foil formed from outside by polyamide had already been studied previously [1]. Subsequently, the influence of R2R plasma treatment on the surface properties of tubular foil's inner layer formed with linear low-density polyethylene (LLDPE) was studied. During the roll-to-roll treatment, the plasma acts from outside of the tubular foil, whereas the inside surface of the tubular foil is affected by plasma as well in dependence on the material of the roller. The utility model “Device for plasma treatment of tubular foils” was registered based on this finding [2]. It has been experimentally verified that a non-conductive roller constructed from plastic does not allow the surface discharge to be superimposed by microfilaments generated perpendicular to the film surface. This finding clarified the different effects of plasma treatment achieved using plastic and metal-rubber roller on the surface properties of LLDPE foil. Applied exposure times of DCSBD treatment were in the range of 0.5–2 seconds. Evident wettability improvement of LLDPE foil surface after the plasma treatment was observed with the naked eye, while the pristine LLDPE foil surface repelled water solution of methylene blue (Fig. 1). The increase in peel resistance in the case of 0.5 s exposure time when comparing plastic and metal-rubber roller was three times higher for the second one. Peel resistance of untreated LLDPE foil was so low that it was unmeasurable. Best results were obtained for 2 s plasma exposure, where the peel resistance achieved using the metal-rubber roller was 31 % higher than for the plastic roller. The specific electrical resistance of a standard metal roller covered with rubber on the surface corresponds to 238.5 G?cm2, whilst the value for an optimised metal-rubber roller is 7.5 M?cm2. Significantly better film-to-meat adhesion was observed for the DCSBD plasma unit using a metal-rubber roller with the specific resistance of 7.5 M?cm2 than for the metal-rubber roller with the resistance of 238.5 G?cm2. This result could be attributed to the low specific resistance of the roller, which means higher conductivity when the surface discharge is superimposed by microfilaments generated perpendicular to the film surface. |
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