Ground Calcium Carbonate Particles Research Articles

Comparison of Particle Shape, Surface Area, and Color Properties of the Calcite Particles Ground by Stirred and Ball Mill

Since the particle size, shape, specific surface area, and purity of the ground calcium carbonate (GCC) decide its usability in the paper, paint, and plastic industries, the effect of grinding is important. However, the effect of stirred and ball mill grinding on the particle shape of GCC by dynamic image analysis (DIA) is still lacking in the literature. Therefore, the aim of this study is to compare the aspect ratio at the same fineness (d97 = 50 μm) and evaluate other properties such as color, and surface area of GCC particles by stirred and ball mill grindings. DIA results showed that particles produced by the ball mill had higher aspect ratio values than those by the stirred mill. This was attributed to the impact, and attrition breakage modes produced by the ball and stirred mill, respectively. This conclusion is supported by XRD and SEM. Finally, the results related to physical properties such as aspect ratio, surface area, and whiteness are discussed depending on the usage area of GCC.

Study on surface modification of ground calcium carbonate with novel modifier and its PVC filling performance

Ground calcium carbonate (GCC) are versatile due to low cost, low energy consumption, simple processing, and environmental protection. In this study, the novel modifier JST9001 was utilized for dry modification of GCC, and then polyvinyl chloride (PVC) based composites including modified GCC particles were fabricated to examine the mechanical properties. The performance indexes of activation index, wetting contact angle and dispersion stability showed that modified GCC obtained excellent modification effect at low modifier dosage (0.50 wt%). And the XRD, FT-TR, TGA, XPS and NMR measurements indicated that the JST9001 was coated on the surface of GCC particles successfully. The mechanical properties testing results demonstrated that 0.50 wt% JST9001 modified-GCC/PVC composites displayed better bending strength, bending modulus, tensile strength, tensile modulus, and impact strength compared with other dosage JST9001 modified-GCC/PVC composites. In addition, the filling content of modified GCC can reach 60 wt% in the premise of ensuring excellent mechanical properties with bending modulus of 3266.92 MPa, bending strength of 39.89 MPa, tensile modulus of 3092.13 MPa, tensile strength of 35.49 MPa and impact strength of 71.88 MPa, realizing the high filling of the modified GCC. Moreover, the modification of GCC remarkably improved the thermal stability of PVC based composites. Overall, novel modifier has the potential to reduce the cost and improve the performance of GCC/PVC composites. • Novel JST9001 modifier was used to modify GCC. • Optimal modification effect was gained at the low dosage (0.50 wt%). • The filling content of GCC can reach 60 wt% in the PVC-based composites. • The obtained PVC-based composites have good mechanical properties. • The study has potential to apply GCC in plastics and other industries.

Thermal treatment to improve the hydrophobicity of ground CaCO3 particles modified with sodium stearate

The surface modification of calcium carbonate (CaCO3) particles, which is used as a filler, significantly affects the properties of the composed materials. The effects of thermal treatment on ground calcium carbonate (GCC) particles subjected to hydrophobic modification using sodium stearate (RCOONa) were studied. The contact angle of the modified GCC particles increased from 24.7° to 118.9° when the amount of RCOONa added was increased from 0% to 5% and then decreased to 97.5° when the RCOONa content was further increased to 10%. When a large amount of RCOONa was added, RCOO− reacts with Ca2+ and generates (RCOO)2Ca nuclei, which are adsorbed on the surface of the GCC particles, forming a discontinuous (RCOO)2Ca modified layer. After thermal treatment under sealed conditions, the contact angle of the GCC particles modified using 1.5% RCOONa/GCC increased from 112.8° to 139.6°. The thermal stability of the (RCOO)2Ca modified layer was increased, with the temperature increase of the mass-loss peak from 358.0 to 463.0 °C. It is confirmed that the spreading of melted (RCOO)2Ca nuclei on the surface of the GCC particles during the thermal treatment increased the continuity of the modified layer, converting the physical adsorption of the (RCOO)2Ca nuclei into chemisorption. The grafting density of RCOO− on the GCC particle surface after thermal treatment approximates to 5.00/nm2, which is close to the single-molecular-layer grafting density of RCOO−, indicating that excellent modification was achieved.

Preparation of ground calcium carbonate-based TiO2 pigment by a two-step coating method

A two-step coating method for preparing ground calcium carbonate-based TiO2 pigment (GCTD) was proposed and studied in this paper. The tetraethoxysilane (TEOS, C8H20O4Si) was selected as Si source. Aqueous ammonia was used as precipitant in the first coating step while titanyl sulfate (TiOSO4·2H2O) was used as Ti source in the second step. The Energy dispersive spectrometer (EDS) and X-ray fluorescence (XRF) results prove that SiO2 is coated on the surface of ground calcium carbonate (GCC) particles successfully. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) results demonstrate that the coated SiO2 is in the form of amorphous. The EDS, XRD, TEM and Scanning electron microscope (SEM) results show that TiO2 is coated on the surface of SiO2 coated GCC (SiO2@GCC) and TiO2 particles are composed of mixed crystal of anatase and rutile. The hiding power of obtained GCTD is significantly improved compared with ordinary composite TiO2 pigment (CTD) and close to that of anatase TiO2 (ATD). The whiteness and lightness of this GCTD are just slightly decreased compared to that of CTD and ATD. Nevertheless, its oil absorption value is some higher than that of ATD but lower than that of CTD.

The effects of surface modification of ground calcium carbonate powdery fillers on the properties of PVC

The effects of surface modification of ground calcium carbonate (GCC) particles on the thermal and mechanical properties of poly(vinyl chloride) (PVC) based composites were investigated. Aminopropyltrimethoxysilane (APS) was used as a modifier for GCC particles. The experimental results indicated that the pre-treatment of GCC particles with NaOH promoted the formation of OH− on the surface of GCC particles, which improved the graft of APS on GCC surface and enhanced the interfacial interaction between GCC particles and PVC matrix. The SEM micrographs of the PVC filled with different GCC particles showed that the dispersion of fillers in the PVC matrix was improved by surface modification. The results of TG showed that the thermal properties of PVC filled with NaOH/APS modified GCC particles (PVC/GCC–OH–APS) outweighed those of PVC filled with APS modified GCC particles (PVC/GCC–APS) or raw GCC particles (PVC/GCC). Compared with the use of raw GCC, the use of the surface modified GCC particles, especially the GCC–OH–APS, led to the increase of the tensile strength and impact strength of the composites.

Effect of particle size distribution on stress development and microstructure of particulate coatings

The role of pigment particle size distribution on stress and microstructure development was studied for coatings prepared from aqueous suspensions of ground calcium carbonate (GCC) and latex binder. Stress development was monitored using a modified beam deflection technique under controlled environment. Microstructure was characterized by scanning electron microscopy (SEM) and cryogenic SEM. For coatings containing only GCC particles and no latex, a wide particle size distribution resulted in a significant particle size gradient in the cross-sectional microstructure and irregular stress development. With latex addition, uniform microstructures were observed in coatings with either wide or narrow GCC particle size distribution. GCC/latex coatings prepared using GCC with a wide particle size distribution developed a higher stress than those prepared using GCC with a similar average particle size but a narrow particle size distribution. The higher stress is related to the particle packing that results in smaller pore sizes and larger capillary pressures that drive compaction. In coatings prepared with the same GCC particles but different latex binders, the stress and cracking behavior of the coating depends on the latex properties.

Effect of Shear Condition on Washless Polyelectrolytes Multilayering Treatment on GCC

To find a practical application approach of polyelectrolyte multilayering (PEM) on inorganic filler, we introduced PEM process without washing step and investigated the effect of shear condition on the washless PEM treatment of ground calcium carbonate (GCC). Washless multilayering on GCC was conducted under various shear conditions such as stirring, homogenization, and ultrasonication. Highly charged polyelectrolytes combination of polydiallyldimethylammonium chloride (PDADMAC) and poly sodium 4-styrene sulfonate (PSS) and low charged polyelectrolytes combination with cationic starch and anionic polyacrylamide (PAM) were compared. In the case of highly charged polyelectrolytes combination, shear conditions did not affect the zeta potential and the particle size of treated GCC. However, the modified GCC particles with low charged polyelectrolytes were more dispersed under higher shear condition while maintaining the zeta potential. In addition, GCC was successfully modified through laboratory inline washless polyelectrolyte multilayering system which consists of homogenizers and pumps.

Deposition Behavior of LbL Multilayered GCC Particles on Pulp Fibers

The effects of ground calcium carbonate (GCC) modification through the polyelectrolyte multilayering technique on deposition kinetics were investigated. The surface charge of GCC particles was changed from negative to positive through Layer-by-Layer (LbL) multilayering with polyelectrolytes on GCC particles. The LbL multilayered GCC particles could deposit onto negatively charged cellulose fibers due to electrostatic attraction. Deposition kinetics followed modified Langmuir kinetics, which describe the dynamic equilibrium of deposition and detachment of the particles. The multilayer that had more affinity to the fibers had the higher deposition rate constant. The multilayer with a branched polyelectrolyte showed a low detachment rate constant compared to the linear polyelectrolyte, which led to a high equilibrium deposition amount for the particle. Application of high shear had adverse effects on deposition. However, LbL multilayered GCC particles showed reversible deposition characteristics after lowering the stirring speed.

Modification of GCC with Poly-DADMAC and PSS with Different Molecular Weights and its Effect on the Paper Properties

In this study, we modified the surface of ground calcium carbonate (GCC) with polyelectrolytes with different molecular weight using Layer-by-Layer (LbL) multilayering technique and investigated its effect on the paper properties. Polydiallydimethylammonium chloride (poly-DADMAC) and poly sodium 4-styrene sulfonate (PSS) which have different molecular weights were used for LbL multilayering. Zeta potential and particle size of the LbL modified GCC were measured. After preparation of handsheets, their structural and mechanical properties were evaluated. The zeta potential and average particle size of the modified GCC were affected by the molecular weight of anionic polyelectrolyte (PSS). The zeta potential was higher and the particle size was smaller when GCC was treated by PSS with high molecular weight compared to the case with low molecular weight of PSS. The tensile and internal bond strength of the handsheets was increased with an increase in the number of layers on GCC particles, but the molecular weight of polyelectrolyte did not significantly affect the paper strength.

The development of hydrophobised ground calcium carbonate particles for the effective adsorption of dissolved and colloidal substances (DCS) from thermo mechanical pulp (TMP) filtrates

Abstract Talc is often used to control unwanted deposition of resins and wood processing derivatives in the wet end circuit of a paper mill. It was the aim of this study to develop a calcium carbonate based mineral particle with improved pitch adsorption properties, and to compare these properties with those of talc. Partially treating the surface of the calcium carbonate with stearic acid led to improved adsorption of wood resin constituents and useful wetting properties. It was shown that the partially hydrophobised calcium carbonate had a higher capacity for the adsorption of the colloidal fraction of TMP than did the corresponding untreated calcium carbonate. Both calcium carbonates preferentially adsorb colloidal substances together with a minor amount of dissolved carbohydrates. In contrast, talc preferably adsorbs colloidal substances when the colloidal concentration is high but starts to adsorb substantial amounts of dissolved carbohydrates at lower concentration of colloidal wood resin droplets.

Film formation from pigmented latex systems: Mechanical and surface properties of ground calcium carbonate/functionalized poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) latex blend films

AbstractThe mechanical and surface properties of films prepared from model latex/pigment blends were studied using tensile tests, surface gloss measurements, and atomic force microscopy. Functionalized poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) [P(BMA/BA)] and ground calcium carbonate (GCC) were used as latex and extender pigment particles, respectively. The critical pigment volume concentration of this pigment/latex blend system was found to be between 50 and 60 vol % as determined by surface gloss measurement and tensile testing of the blend films. As the pigment volume concentration increased in the blends, the Young's modulus of the films increased. Nielsen's equations were found to fit the experimental data very well. When the surface coverage of carboxyl groups on the latex particles was increased, the yield strength and Young's modulus of the films both increased, indicating better adhesion at the interfaces between the GCC and latex particles. When the carboxyl groups were neutralized during the film formation process, regions with reduced chain mobility were formed. These regions acted as a filler to improve the modulus of the copolymer matrix and the modulus of the resulting films. The carboxyl groups on the latex particle surfaces increased the surface smoothness of the films as determined by surface gloss measurement. When the initial stabilizer coverage of the latex particles was increased, the mechanical strength of the resulting films increased. At the same time, rougher film surfaces also were observed because of the migration of the stabilizer to the surface during film formation. With smaller‐sized latex particles, the pigment/latex blends had higher yield strength and Young's modulus. Higher film formation temperatures strengthen the resulting films and also influence their surface morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4550–4560, 2006

Surface treatment and characterization of functionalized latex particles and inorganic pigment particles used in the study of film formation from pigmented latex systems

AbstractThe adsorption of sodium polyacrylate [NaPA] on noncarboxylated and carboxylated poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) [P(BMA/BA)] latexes and ground calcium carbonate (GCC) was studied. The adsorption isotherms of NaPA on P(BMA/BA) latex surfaces showed that NaPA tended to adsorb to a greater extent onto the latex particle surfaces when the carboxyl group surface coverage of latex polymer particles is low, which indicates a repulsive interaction between the dissociated carboxyl groups and NaPA macroions. The electrophoretic mobility of cleaned model P(BMA/BA) latexes decreased with the increasing carboxyl group surface coverage at pH 10 due to the alkali‐swelling characteristics of carboxylated latexes. For GCC, used as extender pigment particles in the pigmented latex blend systems, the size of the GCC pigment particles stabilized with NaPA decreased during a sonification process and their ζ‐potential became increasingly negative with the addition of NaPA to the GCC pigment slurry. Particle size and ζ‐potential measurements showed that NaPA can stabilize GCC particles effectively, and the optimum concentration of NaPA to stabilize GCC is around 1 wt % based on solid GCC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 398–404, 2006

Surface Analysis of Ground Calcium Carbonate Filler Treated with Dissolution Inhibitor

This work demonstrates that the solubility of ground calcium carbonate (GCC) decreased when GCC was treated with phosphate-containing chemical inhibitors. The extent of inhibition of the dissolution process was found to increase with inhibitor dosage until a saturation point was reached, beyond which further addition of inhibitor did not have any further effect. The mechanism of the inhibition was investigated by conducting surface analysis of the treated GCC. X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray analysis were employed to confirm the presence of phosphate on the surface of the treated GCC. Scanning electron microscopic pictures revealed that the treated GCC particles had a different surface morphological pattern than the untreated GCC particles. It is proposed that the inhibition was brought about by the precipitation of calcium phosphate phases such as hydroxyapatite on the GCC surface.

Tensile test of poly(vinyl chloride) filled with ground calcium carbonate particles

The fracture behavior of poly(vinyl chloride) filled with ground calcium carbonate particles during a tensile test was studied. The particles were prepared by crushing natural raw crystalline limestone. For this purpose, 10–50 parts of the particles having two different mean sizes (2 and 8 μm) without further surface treatment were mixed with 100 parts of poly(vinyl chloride) and 3 parts of lead stearate as a stabilizer using a mixing roll. A tensile test was carried out using a dumbbell specimen. As a result, the yield stress decreased with increase in the particle content; however, there was no significant influence of particle size. From scanning electron microscopic observations of the specimen's surfaces during the tensile test, it was found that the particle/matrix interfaces were delaminated and formed voids around the particles when the applied stress approached the yield stress, that is, the particles acted as voids and the matrix around the voids was plastically deformed effectively. These observations appear to be the reason for the decrease of yield stress by the incorporation of the particles. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 311–316, 1998