There has been increasing concern regarding environmental problems arising from the widespread use of petroleum-based plastic materials for packaging. Many efforts have been made to develop sustainable and biodegradable packaging materials to replace plastic products. The current review summarizes recent research progress in developing cellulose packaging materials to replace plastics used for cushioning and barrier packaging functions based on pulp fibers, cellulose nanofibers, and regenerated cellulose films to benefit from their renewability, sustainability and biodegradability. The cushioning packaging materials include molded pulp products and bio-based foams. Advanced cellulose films and paper can be good barriers for oxygen and carbon dioxide gases, as well as for water vapor. Several cellulose fiber-based packaging products have been commercialized in areas that used to be occupied solely by plastic products.
Lignocellulosic
recyclable packaging material is in high demand,
because of the emergence of e-commerce. Old corrugated container (OCC)
pulp is the main raw material in China for manufacturing packaging
boxes/bags, but its strength needs improvement. In this project, waste
cellulose in the form of used printing paper was oxidized using 2,2,6,6-tetramethylpiperidine-1-oxyl
radical (TEMPO) concept so that more carboxyl groups were introduced.
The TEMPO-oxidized waste cellulose (TOWC) having a carboxyl content
of 1.451 mmol/g was then used as reinforcement for the OCC fiber networks.
The TOWC addition to the OCC fiber networks at different mass ratios
of 5%, 10%, and 15% on its strength properties was studied. The results
showed that the addition of TOWC remarkably improved the tensile and
other strength properties, which can be explained by the improved
hydrogen bonding and interpenetrating capacity of fiber networks,
thanks to the increased carboxyl groups and fibrillation after the
TEMPO oxidation.
Brightness is an important quality parameter for pulp products, and it is important to have reliable measurement of pulp brightness in a timely manner for process control and/or quality control purposes. In these circumstances, a quick testing method for pulp brightness is highly desirable.
A rapid handsheet brightness testing method for lignin-rich mechanical pulp has been developed, which is based on the use of tap water to make handsheets and microwave ovens to rapidly dry the handsheet. Microwave oven fast drying decreased the handsheet brightness of mechanical pulp by 5–6 points due to the lignin-originated discoloration reactions. The spray of ascorbic acid and ethylenediaminetetraacetic acid (EDTA) solutions to the handsheet can effectively inhibit these lignin discoloration reactions.
With 0.2% ascorbic acid and 0.2% EDTA spraying on the wet pulp handsheet, the brightness of the handsheet from a peroxide-bleached stone groundwood pulp after the microwave oven fast drying method was similar to that obtained from the same pulp but following TAPPI Standard Test Method T 272 sp-12 “Forming handsheets for reflectance testing of pulp (sheet machine procedure)”. The effect of handsheet dryness on the handsheet brightness was also studied, and the results showed that the brightness reading was almost constant in the dry-ness range of 70% to 90%. The method developed is a reliable, fast brightness testing method for lignin-rich pulp that is of practical interest in industrial operations.
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