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

Abstract CaCO 3 -pulp composite was prepared via precipitation of calcium hydroxide in the presence pulp. In order to investigate selectivity and mechanism, substrate pulps obtained composites were fractionated (R30, R100, R200, R400 a sedimented fraction that passed 400 mesh wire) using Bauer-McNett unit. The main fractionation criterion therefore fiber length. pulp used CTMP (chemithermomechanical pulp), yielding precipitated carbonate-chemithermomechanical (PCC-CTMP) with targeted PCC-to-CTMP ratio 1:1. PCC consisted primarily nano-sized primary particles which formed aggregates clusters on fibers. When morphology, zeta potential surface charge density fractions determined, correlation found between ash content corresponding PCC-CTMP fractions. This supports hypothesis is driven by interparticle interaction. use refined furnishes demonstrates preferably fixed fines fibrils since it appears at higher Fiber activation split, removal wall defibrillation enhanced affinity for fibrils. laboratory handsheets from material demonstrated importance controlling properties mineral-fiber composite, e.g. refining, as differences refining levels lead both optical bonding. Graphic abstract