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A cellulose nanocrystal based oxidation system is developed for oxidizing starch in the presence of NaClO, and provides an alternative and green method to improve the oxidizing degree of oxidized starch. The underlying mechanism for the oxidation was studied with confocal laser scanning microscopy. It was found that cellulose nanocrystal would penetrate into the starch microparticles and contribute to oxidation. The function of cellulose nanocrystal on the physicochemical properties of oxidized starch was investigated. With the incorporation of the oxidized starch into starch/polyvinyl alcohol/glyceryl composite films, the mechanical property and transparency of the films improved substantially. The highest oxidation level of starch was attained at 0.5 wt% cellulose nanocrystal dosage and the carboxylate content was 1.10%, the composite film showed the maximum transparency of 0.66 and highest contact angle of 102.0°. Meanwhile, the best film was obtained with oxidized starch containing 1.0 wt% cellulose nanocrystal. Compared to native starch and TEMPO-oxidated starch, the cellulose nanocrystal-based oxidized starch improved the hydrophobicity of film more substanially. In conclusion, cellulose nanocrystal acts as prooxidant and reforcing agent in this starch-based composite film, which makes them promising materials in the preparation of novel composite materials.

In this study, a novel type of high-strength regenerated cellulose composite fiber reinforced with cellulose nanofibrils (CNFs) and nanosilica (nano-SiO2) was prepared. Adding 1% CNF and 1% nano-SiO2 to pulp/AMIMCl improved the tensile strength of the composite cellulose by 47.46%. The surface of the regenerated fiber exhibited a scaly structure with pores, which could be reduced by adding CNF and nano-SiO2, resulting in the enhancement of physical strength of regenerated fibers. The cellulose/AMIMCl mixture with or without the addition of nanomaterials performed as shear thinning fluids, also known as “pseudoplastic” fluids. Increasing the temperature lowered the viscosity. The yield stress and viscosity sequences were as follows: RCF-CNF2 &gt, RCF-CNF2-SiO22 &gt, RCF-SiO22 &gt, RCF &gt, RCF-CNF1-SiO21. Under the same oscillation frequency, G’ and G” decreased with the increase of temperature, which indicated a reduction in viscoelasticity. A preferred cellulose/AMIMCl mixture was obtained with the addition of 1% CNF and 1% nano-SiO2, by which the viscosity and shear stress of the adhesive were significantly reduced at 80 °C.

Lumpy corn stalk is conventionally used as interlayer filling material in plywood, while high temperature and humidity in tropical and subtropical areas are easy to cause bacteria growth on plywood. Silver nanoparticles (AgNPs) are one of efficient antibacterial metal nanoparticles due to their excellent broad-spectrum antibacterial properties. But most of these AgNPs are normally in solution and easy to aggregate, which limits their utilization. Besides, the synthesis of AgNPs always needs chemical reducing agents, which can cause environmental and cost problems. In this study, lumpy corn stalk with honeycomb-like structure acted as green reducing agent and stabilizer to in situ synthesize AgNPs, the obtained antibacterial lumpy corn stalk (CS@AgNPs) could be used as interlayer filling material to protect plywood from bacteria erosion. Durable antibacterial study showed that the bacteriostatic properties of lumpy CS@AgNPs against E. coli and S. aureus were stronger and more durable than commercial Ag+ spray and hydrogel. The antibacterial mechanism may be that the controlled-released AgNPs destroyed the morphological structure of bacteria by penetrating into the bacterial cell membrane, following by leaking cellular content. Notably, the final release amount of AgNPs from lumpy CS@AgNPs after 12 days in buffer solution was only 0.011 mg/L, which was 9 times lower than the domestic drinking water limit presented by United States Environmental Protection Agency (USEPA). The plywood with lump CS@AgNPs as interlayer filling material could keep efficient and durable bacteria killing activity in 21 days, which could be used safely in food packaging, furniture and flooring fields.

Cellulose and starch are main chemical components of plant biomass, and can be used to produce value-added materials. Herein, cellulose nanocrystals (CNC) was used along with NaClO to prepare oxidized corn starch. Subsequently, the oxidized starch was blended with PVA/glycerol to prepare oxidized starch-based blends for film formation and coating paper. The properties of oxidized starch and film formability were modified by addition of CNC and PVA/glycerol. The oxidized starch showed the highest oxidizing degree at 1.10% with 0.5 wt% CNC and 8.0 wt% NaClO. Oxidized starch-based blends had lower viscosity and better uniformity than that of corn starch. The oxidized starch-based composite film showed the optimal water resistance, surface free energy and air permeability. Blending with 30 wt% PVA, the oxidized starch-based composite film showed the best tensile strength, and a simple structural model was simulated. The three-dimensional structure of coated paper was visualized using computed tomography scan (CT-Scan), and verified the good penetration of starch-based blends. The coated paper showed a more dense structure compared to the control paper, and had better waterproof performance and physical strength properties with oxidized starch with the highest oxidizing degree.

Octadecenyl succinic anhydride (ODSA) is an oily paper sizing agent that is generally introduced into the paper-manufacturing system as an ODSA-in-water emulsion. In this paper, magnetic ODSA-in-water emulsions are prepared by homogenizing the mixture of ODSA and aqueous dispersion of Fe3O4 nanoparticle. The emulsion droplets are covered with magnetic nanoparticles and easily deform at the present of magnetic field. Recoverable structure and time hysteresis effect have been observed in the as-prepared emulsions with viscoelasticity. The shear moduli G′ and G′′ increase logarithmically with the increasing angular frequency; it is noted that G′ remained higher than G′′ throughout the entire experiment, which is characteristic for elastic system, illustrating the evolution of particles and the particulate network in the system. Raman spectroscopy reflects the good hydrolysis stability of as-prepared ODSA emulsions. Paper coated by as-prepared ODSA Pickering emulsion containing Fe3O4 nanoparticles shows good hydrophobicity and magnetic induction.

Octadecenylsuccinic anhydride (ODSA) is an internal sizing agent used to hydrophobize paper and paper board in the process of papermaking. To prepare stable ODSA Pickering emulsions, montmorillonite clay-particles modified by γ-methacryloxy propyl trimethoxysilane (γ-MPTMS) were used as particulate emulsifiers of ODSA and water at room temperature. The effects of pH value, oil-to-water ratio, and particle concentration on the stability of the Pickering emulsions were investigated. The stability of ODSA emulsions in the presence of grafted-MMT first increased and then decreased as the pH value of the aqueous phase decreased. The critical pH for the phase separation of the ODSA emulsions was ∼7. Addition of ODSA oil induced phase inversion from an O/W emulsion to a W/O emulsion when the ratio of oil-to-water passed a specific threshold of 3:1 ( C p ∼ 1.5 wt%). The particle concentration was linked to the formation of particle films at oil–water interface and of clay particle networks in water phase. The ODSA emulsions stabilized by grafted-MMT could have good sizing performance and lifespan. This study on ODSA Pickering emulsions based on MPTMS-grafted MMT particles opens up a new route to the preparation of a variety of paper sizing agents in the papermaking industry.