Lauric Arginate/Cellulose Nanocrystal Nanorods-Stabilized Alkenyl Succinic Anhydride Pickering Emulsion: Enhancement of Stabilization and Paper Sizing Performance

Biodegradable colloidal particle materials are becoming attractive candidates as eco-friendly chemical additives in the low-carbon economy era. However, developing cheap, stable, and efficient paper-sizing agents is still a challenging issue both for paper making academic community and industry. Here, an easy-fabricating, stable, and high-performance alkenyl succinic anhydride (ASA) paper-sizing emulsion is developed, which is stabilized by lauric arginate (LAE)/cellulose nanocrystal (CNC) nanorods. Furthermore, the chemical crosslinking between ASA and LAE/CNC nanorods can adjust the wettability and interfacial adsorption of LAE/CNC, resulting in improved stability of ASA-sizing emulsion. This novel paper-sizing emulsion shows a small droplet size (0.8 μm), high hydrolysis resistance, and a high paper-sizing degree (300 s) along with a remarkable hydrophobicity contact angle of 110° for long-term storage. This work opens a door for realizing an interfacial self-assembled Pickering-stabilizer, which leads to an environmentally friendly, pervasive and cost-effective emulsification technique for the next-generation paper-sizing additives.

Pre-Fibrillation of Pulps to Manufacture Cellulose Nanofiber Reinforced High-Density Polyethylene using the Dry-Pulp Direct Kneading Method

The dry-pulp direct-kneading method is an industrially viable, low-energy process to manufacture cellulose nanofiber (CNF) reinforced polymer composites, where chemically modified pulps can be nanofibrillated and dispersed uniformly in the polymer matrix during melt-compounding. In this study, cellulose fibers with different sizes, ranging from surface-fibrillated pulps with 20 µm in width to fine CNFs with 20 nm in width were prepared from softwood bleached kraft pulps (NBKPs) using a refiner and high-pressure homogenizer (HPH). These cellulose fibers were modified with alkenyl succinic anhydride (ASA), and then dried. The dried ASA-treated cellulose fibers were used as a feed material for melt-compounding in the dry-pulp direct kneading method to fabricate CNF reinforced high-density polyethylene (HDPE). When surface-fibrillated pulps were employed as a feed material, the pulps were nanofibrillated and dispersed uniformly in the HDPE matrix during the melt-compounding, and the composites had much better properties (i.e., much higher tensile modulus and strength and much lower coefficient of thermal expansion) than the composites produced using the pulps without pre-fibrillation. However, when CNFs were used as a feed material, the CNFs were shortened and agglomerated during the melt-compounding, thus deteriorating the properties of the composites. The study concludes that the pre-fibrillation of pulps had a significant impact on the morphology and properties of the composites. Unexpectedly, the surface-fibrillated pulp, which can be produced cost-effectively using a refiner at an industry scale, was a more suitable form than the CNF as a feed material for melt-compounding in the dry-pulp direct kneading method.

Hydrophobic Modification of Cashew Gum with Alkenyl Succinic Anhydride

Cashew gum (CG) shows promise of being useful as an agro-based raw material for the production of eco-friendly and biodegradable polymers. In this work, we modified this water-soluble polymer with alkenyl succinic anhydride in order to attach a hydrophobic group to it. The modification used two reagents: octenyl succinic anhydride and tetrapropenyl succinic anhydride. Reactions were conducted at 120 °C using dimethyl sulfoxide as a solvent, with conversions better than 88%. Samples with degrees of substitution (DS) between 0.02 and 0.20 were made. The resulting polymers were characterized using 1H NMR, 13C NMR, FTIR, TGA, and GPC. The addition of the hydrophobe decreased the affinity of cashew gum for water absorption. Hydrophobically modified polysaccharides are often used as polymeric emulsifiers, thickeners, and compatibilizers; we anticipate that these new hydrophobically modified CGs may be used for the same applications.