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In this work, phosphorylated cellulosic fibers were functionalized with an aminosilane ((3-aminopropyl)triethoxysilane, APTES) using a simple and economical method. Several characterization were performed to determine the types of bonds between phosphorylated fibers and grafted APTES. The thermal behavior, hydrophobicity and surface charge variation as a function of pH of the multifunctional cellulose fibers were determined. Results demonstrate that APTES should proceed through Si-O-C, and possibly Si-O-P, covalent bonds with cellulose although the dimerization of silane through Si-O-Si bonds has also been observed. The terminal amino groups are expected to be partially involved in hydrogen bonds with phosphate hydroxyl groups found at phosphorylated cellulose fiber surface, causing a pulling in the configuration of the grafted APTES. The two chemical modifications proposed in this work do not significantly modify the morphology of cellulose fibers. XRD analysis also shows that the crystal structure of the phosphorylated fibers did not change after functionalization with APTES. The silylated phosphorylated fibers show potential flame-retardant properties with improved hydrophobicity. Furthermore, the functionalization of phosphorylated fibers with APTES changes the pH of zero charge point from 3.2 to 9.4 and providing a zwitterionic structure suitable for the simultaneous adsorption of both cationic and anionic species. [Display omitted] [ABSTRACT FROM AUTHOR]

Zeolites are framework aluminosilicates that have been proposed as a replacement for bentonite in microparticle retention systems. It has been claimed in many patents that zeolite can improve sheet formation in fine paper manufacturing. However, this improvement was not observed in mechanical grades. These experimental results, and also theoretical evidence, suggest that papermaking pH plays an important role in zeolite efficiency. In consequence, the effect of pH and temperature on the chemical properties of zeolite and bentonite microparticles was determined. Streaming potential, conductivity, and pH were measured while microparticle solutions were gradually acidified to pH 5. Samples were also taken at specific pH values to measure the cationic demand. Results showed that a gradual reduction of pH caused several modifications to zeolites. The first step was the neutralization of free hydroxyl ions in solution. The second step was an irreversible exchange of the charge-compensating sodium ions by hydrogen ions on the inner and outer surface of microparticles. Finally, dealumination of the zeolites occurred. It was determined that neutralization must be completed before ion-exchange can begin. However, ion-exchange and dealumination occurred simultaneously. Between pH 7.5 and 9, zeolites had more anionic sites than bentonite (around 0.8 meq/g vs. 0.5 meq/g). The higher surface charge of zeolites might partly explain their efficiency in microparticle systems. On the other hand, under pH 7.5, the anionic charge of zeolite samples rapidly decreased while that of bentonite was stable. The effect of temperature was also studied in the 25 to 55 °C range. Generally, a temperature rise promoted a greater dissociation of the surface hydroxyl groups and an acceleration of ion-exchange and dealumination processes. [Copyright &y& Elsevier]

• A novel electrospun Chitosan/Phosphorylated Nanocellulose biosorbent was prepared. • Phosphorylated Nanocellulose was added to improve the Cd2+ adsorption. • Phosphate groups (PO 4 2 -) were formed on the surface of electrospun nanofibers. • Langmuir isotherm best described equilibrium for Cd2+ removal. • Thermodynamic study showed the spontaneity endothermic reaction for adsorption. The removal of Cd(II) ions from aqueous solution was carried out using a new nanofibrous electrospun nonwoven sorbent made from Chitosan (CS) and Phosphorylated Nanocellulose (PNC). The sorbent material was characterized using SEM, EDX, AFM and FTIR. The sorption capacity reached 62.3 mg/g at pH 5.5 and 25 °C. The Cd(II) adsorption occurred rapidly and achieved equilibrium within 120 min. The pseudo-second order kinetic model best fitted experimental data. The sorption isotherm was also best described by the Langmuir model. The maximum adsorption capacity of Langmuir was 232.55 mg/g at 25 °C, and increased with temperature, which can be explained by the high affinity of amine and phosphate groups with cadmium on the surface of the nanofibrous mats. The thermodynamic study showed that the adsorption is a spontaneous endothermic reaction. This work confirmed that an electrospun nanofibrous mats based on CS and PNC can be used as an alternative material for the removal of cadmium ions, contributing to water sustainability. [ABSTRACT FROM AUTHOR]

Highlights: [•] We present a new synthesis pathway to produce phosphorylated cellulosic fibers. [•] The main phosphorylating reagent is a phosphate ester. [•] Phosphorylated fibers show negligible degradation compared to previous phosphorylation processes. [•] The phosphorus distribution (bulk vs. surface) is presented. [•] The type of phosphate structures found on modified fibers is discussed. [ABSTRACT FROM AUTHOR]

This paper presents the effect of compaction parameters on the permeability to resin, tensile and flexural performances of unidirectional (UD) composites made of UD flax-mat reinforcements. In these reinforcements the UD fiber yarns are held together by a thin mat layer of short flax fibers. Reinforcements were compacted in dry or wet conditions at ambient or high temperature prior to permeability testing and composites molding with the resin transfer molding (RTM) process. A micrographic analysis of the morphology and structure of the laminates prior to and after tensile testing was also performed. It is found that hot and wet compaction do not change the permeability. Moreover, after molding with compacted reinforcements, the tensile strength increases while the tensile modulus is not affected. It also leads to a substantial increase in the flexural properties (strength and modulus). This means the chosen compaction parameters are appropriate for preforming this type of reinforcement. [ABSTRACT FROM AUTHOR]