The effect of polyacrylic acid and reaction conditions on nanocluster formation of precipitated calcium carbonate on microcellulose

The precipitation of micro- and nanoparticles of calcium carbonate onto lignocellulosic microfibers was investigated at different microfiber concentrations with and without polyacrylic acid (PAA), i.e. a polymer commonly used to form polymer-induced liquid precursors of CaCO₃. Concentrations of PAA, Ca(OH)₂, CO₂ and microfiber were varied in order to study the impact of reaction conditions on PCC formation in a batch reactor operated at ambient temperature. High resolution scanning electron micrographs of the samples show that both microfiber concentration and PAA dosage affected the nucleation and crystal growth of PCC filler on cellulosic fiber. Interestingly, at higher microfiber concentrations, larger amount of nano-sized spherical crystals were formed on the microfibers. A higher dosage of PAA, on the other hand, resulted in less nucleation on the microfiber, suggesting a preferential bulk nucleation mechanism. A higher concentration of PAA during the precipitation also led to the formation and stabilization of amorphous CaCO₃, which was supported by SEM images and XRD analysis (lack of characteristic crystal structure).     

Fractionation of pulp and precipitated CaCO3–pulp composites: effects on sheet properties of selective CaCO3 precipitation onto fiber size fractions

Cellulose - CaCO3-pulp composite was prepared via precipitation of calcium hydroxide in the presence of pulp. In order to investigate the precipitation selectivity and mechanism, the substrate...