Study On Emusification And Application Of Pickering-type ASA Emulsions Stabilized By Particles

Preraration and application of novel and functional nanoparticle materials and Pickeringemulsions have attracted extensive attention because of the particular performances andapplications in wide fields. As an inorganic solid mineral material, clay mineral particle is richin resources, low-cost and environment-friendly. However, the potential value of the clays inthe particulate emulsification and demulsification technology has not been effectivelyexploited, especially in the papermaking industry. Effective and high-value utilization of claysin the emulsification of paper chemicals is one of the most important and challenging researchareas in the cleaner and non-pollution production.To the best of our knowledge, few studieshave been conducted on the application of particulate emulsifiers in the papermaking industry.For the purpose of efficiently emusification dispersion systems and promoting the researchand application of Pickering-type emulsions of papermaking additives, the current workfocused on emulsification performance, stability mechanism and sizing performance of ASAemulsions stabilized by layered clay nanoparticles. This study on Pickering-type ASAemulsions not only provied the basic research, but also opens up a new route to thepreparation of a variety of paper sizing agents in the papermaking industry.1. Pickering-type ASA emulsions stabilized by anionic layered clay particle. Particleconcentration of MMT had greatly effects on both the enrichment of these particles at theoil–water interface and the formation of the three-dimensional network built-up by the MMTlamellae. Stable ASA emulsions containing1wt%MMT particles could be obtained and morestable emulsion with smaller doplet diameter could be prepared at C_p¹.5wt%. The initialoil fraction obviously influenced on the type and stability of ASA emulion. Catastrophic phaseinversion occured when the value of Фowas0.8. Adjusting the pH value of MMT aqueousdispersion changed the wettability and electrostatic interactions of particle-particle andparticle-interface, promoting the stability of emulsion. Stable ASA emulsion withoutseparated phase was prepared at pH⁷. The addition of sults weakened the electrostaticinteractions of charged MMT particles, which enhancing the envelope of particles. Theemulsification and stability was obviously influenced when the alkanes with different chainscooperated with ASA oil. The synergic effect of dodecane was more obvious than other alkenes. The CLSM analysis indicated the enrichment of these particles at the oil–waterinterface of Pickering emulsions and the envelope of particles creates a barrier which impededthe droplets from coalescence.2. ASA Pickering emulsions stabilized by cationic layered clay particles solely andco-stabilized with anionic layered clay particles. Sults boosted the stability of LDHs stabilizedASA emulison. Increasing the content of NaCl could improve the adsorption of particle at theoil/water interface and the creation of compact particulate envelope, reducing the droplet size.The stability of ASA emulsion to separation depended on the viscosity and oil volumefraction. For the MMT/LDHs co-stabilizer system, homogeneous and stable ASA emulsionscould be prepared when the mass ratio of MMT/LDHs was0.11or9. The house-cardstructure of clay particles that formed through the electrostatic attraction between positive andnegative platelet-edages would evolve into hexagonal structure, which could be the basicstructure unit of the clay-particle3D-network. We also found that co-stabilization system wasbetter than the solo stabilization system on the ASA emulsion. At low strain amplitude, thehiger the particle concentration was, the greater the storage modulus was, indicating astronger interparticle interaction and the three-dimensional network and a solidlikeviscoelastic behavior of the emulsion. This rheological behavior can be explained by theformation of the reversible particulate network in the emulsion. However, the rebuilding ofthree-dimensional network exhibited hysteresis, especially in the co-stabilizer system.MMT/LDHs stabilized ASA emulsion had good sizing performance within150min storagetime. AFM analysis indicated the change of fiber morphology and arrangement and theadsorption of layered particles.3. ODSA emulsion stabilized by γ-Methacryloxy propyl trimethoxysilane grafted MMT. Toprepare stable ODSA Pickering emulsions, montmorillonite clay-particles modified byγ-Methacryloxy propyl trimethoxysilane （γ-MPTMS） were used as particulate emulsifiers ofODSA and water at room temperature. The effects of pH value, oil-to-water ratio, and particleconcentration on the stability of the Pickering emulsions were investigated. The stability ofODSA emulsions in the presence of grafted-MMT first increased and then decreased as thepH value of the aqueous phase decreased. The critical pH for the phase separation of theODSA emulsions was⁷. 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 of3:1（C_p¹.5wt%）. The particle concentration was linked to the formation of particle films atoil–water interface and of clay particle networks in water phase. The ODSA emulsionsstabilized by grafted-MMT could have good sizing performance and lifespan. This study onODSA Pickering emulsions based on MPTMS-grafted MMT particles opens up a new route tothe preparation of a variety of paper sizing agents in the papermaking industry.4. Stablization and mechanism of ASALP emulsion prepared by grafted-MMT particles.Based on this study, it was found that MPTMS-grafted-MMT particles could be used forpreparing stable oil-in-water Pickering emulsions of ASA by emulsification in combinationwith30⁶0vol.%paraffin oil. The ASALP Pickering emulsions exhibited some kind of asolidlike viscoelastic behavior, which may be resulted from the particulate network formed bygrafted-MMT particles at oil/water interface and influence of the organic coemulsifier on theparticle–particle interactions. LP oil added not only improveed the stability of ASA Pickeringemulsions stabilized by particulate emulsifier, but also significantly promoted the stability andinternal paper sizing performance of ASA. Lotus-leaf-like paper surface structure would formthrough the ASALP internal sizing, which would facilitate the design of composite sizingagents.5. ASA emulsions stabilized by Magnetic Fe₃O₄nanoparticles. Magnetic Fe₃O₄nanoparticles were used as the stabilizer to prepare Pickering-type ASA emulsions. Particleconcentration, oil/water volume ratio, oil polarity, pH value of aqueous phase had significanteffects on the type, stability, and morphology of ASA emulsion. With the increase of Fe₃O₄particle concentration, the stability of emulsion to creaming and coalescence initiallyincreased and then decrease, and0.1⁰.3wt%particles performed good stabilizationperformance. Increasing the volume fraction of ASA oil phase lead to phase conversation butincreased the stability of emulsion to separeation. Stable O/W type ASA emulsion wasprepared when the value of Φowas0.5⁰.66. Adjusting the pH value of aqueous couldinprove the stability of emulsions to coalescence and separation. Homogeneous ASAemulsions with small droplet size were prepared at pH7⁸. Fe₃O₄particles stabilized ASAemulsions presented well sizing performance in about1h storage time. However, there was asignificant reduction of sizing degree in prolonged storage time.