PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 8, Number 3, 2022
making specialty papers dedicated to food packaging, high-durability papers, and printing papers. Nanocellulose has a bright future in terms of alternatives to petroleum-based packaging and environmental issues, but intensive research and development are still needed focally on reaching the commercial stage and, safety and security issues especially when dealing with foods. PACKAGING TECHNOLOGY “Study on the barrier properties and antibacterial properties of cellulose-based multilayer coated paperboard used for fast food packaging”, Fei-jie Wanga, Li-qiang Wang, Xin-chang Zhanga, Shu-feng Ma & Zhi-cheng Zhao, Food Bioscience , 46, 101398 (April 2022). Some petroleum-based packaging materials have a series of safety issues, and as a result, people are more inclined to use biodegradable and nontoxic packaging materials for foods. However, biodegradable alternatives often need to be modified to overcome their own shortcomings. In this paper, carboxymethyl chitosan (CMCS)/carboxymethyl cellulose sodium (CMC) + polylactic acid (PLA) nano zinc oxide (ZnO) nanoparticles (CMCS/CMC + PLA/ZnO NPs) multilayer coated paperboard was prepared to explore its potential use in food package applications. The multilayer CMCS/CMC + PLA coating reduced the oxygen transmission rate by 99% and doubled the barrier properties for soybean oil penetration and water vapor compared with a single PLA coating layer in a 23°C/50 RH environment. The oil resistance time of the multilayer CMCS/CMC + PLA coating also increased 28 times, and the water vapor barrier properties increased twofold compared to a single CMCS/CMC coating layer. The water vapor barrier properties increased by a factor of 3 even at 38°C/90 RH. Compared with the CMCS/CMC + PLA coating without nanoparticles, the barrier performance of the CMCS/CMC + PLA/ZnO NPs coating was further improved. The oxygen, water vapor, and heptane vapor barrier properties all doubled, and the oil resistance time reached 235 h. While a corona treatment reduced the polar component content in the CMCS/CMC coating and led to a slight decrease in the barrier properties of the coating to heptane, it was still a good oil- repellent coating overall. The antibacterial activity (A) toward Escherichia coli and Staphylococcus aureus exceeded 2, which meant that the multilayer coating with 1.5% added ZnO NPs reduced the growth of bacteria by more than 99%. The multilayer coated paperboard created here with the blended and modified materials significantly improved the barrier and antibacterial properties, suggesting that multilayer coatings prepared from degradable materials have good commercial prospects as fast food packaging. PAPERMAKING “Wet Tensile Strength Development of PAE Wet-strengthened NBSK Handsheets by AKD Internal Sizing”, Antti Korpela, Aayush Kumar Jaiswal, Atsushi Tanaka & Jaakko Asikainen, BioResources , 17(2), 3345-3354 (2022). Polyamide-epichlorohydrin (PAE) is used in papermaking to increase the paper’s wet strength. High levels of PAE can make repulping of paper more difficult. PAE deposits can also impair paper machine performance by plugging the paper machine felts. The results of a preceding study indicated that the wet strength of paper containing a moderate amount of PAE (added amount 0.3 wt%) can be increased by utilizing internal alkylketene dimer (AKD) sizing. In the present study, the effects of an added amount of PAE and AKD on the wet strength of handsheets made from Nordic bleached softwood pulp (NBSK) were examined. The wet strength was measured after soaking the sheets in ion-exchanged water for up to 1 month. The improving effect of AKD sizing on the wet strength was long-lasting and it was apparent especially with a low and moderate added amount of PAE (0.15 and 0.45 wt%) resulting in higher wet strength than the highest added amount of PAE (1.35 wt%) alone. No clear sign of worsened repulpability was observed at low to moderate treatment levels.
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Technical Abstracts
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