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This study examined the use of Plantago psyllium seed husk flour as paper additive with the aim of improving the properties of cellulose sheet. The husk flour was added in 5 wt%, 10 wt%, 20 wt% and 30 wt% to the cellulose suspensions and its effect on the handsheet properties was studied. The results showed that the direct addition of husk flour highly improves the mechanical properties of the handsheets like tensile index (with up to 400 %), burst index (with up to 600 %) and tear index (with up to 1200 %). Cobb and contact angle tests with distilled water showed that the handsheets containing husk flour are more hydrophobic compared to the unmodified handsheets. The Cobb-Unger and contact angle tests with oil revealed that the additive reduces the oil absorbency of the handsheets as well, at the highest by 86 %. Additionally, the water vapor and especially the air barrier properties were improved. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant capacity test showed that the modified handsheets had free radical scavenging properties. The direct addition of Plantago psyllium seed husk flour can be a promising, easy and green method to improve the mechanical and barrier properties, oil and water resistance of cellulose sheets.

Throughout our research we have made potassium-humate from brown coal of Dudar. With potassiumhumate and copper(II)-sulfate we made test sheets of linter cellulose fibers. The surface energy, surface wettability, CIE Lab color-coordinates changing, bending resistance and tensile strength of the produced test sheets has been examined. There was no big difference in the different samples during surface energy and wettability testing. Examination of mechanical properties suggests that potassium-humate content increases bending resistance of the test sheets. The bending resistance of samples increased by 32%, 100% and 336% compared to the control test sheets while adding potassium-humate.

During our research, cellulose‐based test sheets containing copper and potassium humate were prepared and tested against several bacterial and fungal strains. The energy dispersive X‐ray spectrometry and attenuated total reflectance (ATR) Fourier‐transform infrared spectroscopy revealed that humate contributed to increase the copper content of the test sheets. The antimicrobial impact of test sheets on various fungi (Penicillium expansum, Wallemia sebi, and Aspergillus brasiliensis) and bacteria (genera Micrococcus, Enterococcus, Bacillus, Salmonella, Staphylococcus, Listeria genera) was tested using a modified agar diffusion‐based assay. On the basis of the disc diffusion results, the sheets effectively inhibited all the tested fungi and Gram‐positive bacteria. The highest antimicrobial effect was exhibited by the copper‐containing test sheet with 1:0.1 and 1:0.25 cellulose:humate weight ratio. Deterioration test with blackberries demonstrated the shelf life extending effect of the sheets.