Nanoprecipitated Calcium Carbonate Research Articles

Powder Loading Effects on the Physicochemical and Mechanical Properties of 3D Printed Poly Lactic Acid/Hydroxyapatite Biocomposites.

This study presents the physicochemical and mechanical behavior of incorporating hydroxyapatite (HAp) with polylactic acid (PLA) matrix in 3D printed PLA/HAp composite materials. Effects of powder loading to the composition, crystallinity, morphology, and mechanical properties were observed. HAp was synthesized from locally sourced nanoprecipitated calcium carbonate and served as the filler for the PLA matrix. The 0, 5, 10, and 15 wt. % HAp biocomposite filaments were formed using a twin-screw extruder. The resulting filaments were 3D printed in an Ultimaker S5 machine utilizing a fused deposition modeling technology. Successful incorporation of HAp and PLA was observed using infrared spectroscopy and X-ray diffraction (XRD). The mechanical properties of pure PLA had improved on the incorporation of 15% HAp; from 32.7 to 47.3 MPa in terms of tensile strength; and 2.3 to 3.5 GPa for stiffness. Moreover, the preliminary in vitro bioactivity test of the 3D printed PLA/HAp biocomposite samples in simulated body fluid (SBF) indicated varying weight gains and the presence of apatite species’ XRD peaks. The HAp particles embedded in the PLA matrix acted as nucleation sites for the deposition of salts and apatite species from the SBF solution.

Synthesis and Modification of Nano-Precipitated Calcium Carbonate (PCC) with Addition of Ethylene Glycol

ZA fertilizer waste (Ammonium sulfate) is waste generated from the industrial process of producing ZA fertilizer. The waste contains very high calcium and has the potential to be used as a raw material in the manufacture of Precipitated Calcium Carbonate (PCC). PCC with certain qualities can be developed in the field of advanced materials, with size modification into nanoparticles. One method to produce nanoparticles is using the coprecipitation method, with the help of a polymer solution. This study aims to produce Nano-PCC by finding the best conditions of CaCl2: Ethylene Glycol mole ratio and stirring speed. Nano-PCC is synthesized by reacting fertilizer waste with HCl to form a CaCl2 solution. Then, the solution is mixed with ethylene glycol to prevent particle agglomeration so that the size obtained will be smaller. The mixture is then reacted with Na2CO3 to form precipitated calcium carbonate (PCC). In this study, the variables were the mole ratio of CaCl2: ethylene glycol (1:12, 1:14, 1:18, 1:20) and stirring speed (350, 500, 650, 800, and 950 rpm). Based on PSA analysis, the Nano-PCC obtained at the smallest CaCl2: ethylene glycol ratio 1:12, stirring speed 950 rpm was 51.83 nm. Based on Scherrer’s calculations with XRD, the particle size obtained was 48.25 nm. SEM analysis showed that the crystals formed were dominated by vaterite crystals, with a size range of 55.71-607.79 nm.

Effect of nano precipitated calcium carbonate on the properties of hydrogels prepared with acrylamide, starch, and TEMPO-oxidized nanocellulose

A variety of water-retaining hydrogels possessing macroporous interiors resembling a honeycomb framework were developed by free radical polymerization of acrylamide (AM), starch, and TEMPO-oxidized nanofibrillated cellulose (TONFC) (Poly (AM-co-TONFC/Starch) (PATS) hydrogels). With the help of ultrasound, nano precipitated calcium carbonate (NPCC) was gelatinized in the preformed NPCC suspension in a monomer solution that forms a hydrogel. When NPCC was dispersed in water, its surface was positively charged, and NPCC could be used as a condensation center to form hydrogen bonds with AM, TONFC, and starch, shortening the distance between AM, TONFC, and starch, increasing the pore size, and thinning the pore wall. The uniform dispersion of NPCC in hydrogels could also promote a more uniform degree of cross-linking in hydrogels. When the hydrogels was extruded and deformed by external forces, the stress of hydrogels was more uniform, so that they could withstand more forces without collapsing. When 4% NPCC was added (relative to starch and TONFC), the pore size of PATS2 hydrogel was uniformly distributed in the range of 10 to 20 μm. The maximum tensile strength of PATS2 hydrogel reached 84.8 KPa, and the elongation at break was 399%. The water absorption reached 172.3, and 65% water content was maintained after 720 h.

Printability and Warpage Evaluation of Polypropylene/Nano Precipitated Calcium Carbonate Composite Prepared by Extrusion-Based 3D Printing

Polypropylene (PP) is a promising material for extrusion-based additive manufacturing due to its low cost, chemical resistance, good mechanical properties, versatile, and can be applied in various industrial applications. Recent research has focused on addressing the warpage issue in 3D printing of PP filaments. The effect of environmental conditions and loading of nanoprecipitated calcium carbonate (NPCC) in the pristine polypropylene to decrease warpage using the Fused Deposition Modelling (FDM) printing technology was studied. PP-NPCC composite filaments containing 5, 10, and 15 NPCC (wt%) were prepared using the twin-screw extruder. The printability, physicochemical, and mechanical properties of the PP-NPCC blends were determined. Based on the results, the incorporation of NPCC has contributed to the improvement of 3D printability and warpage in the PP-NPCC composite. At controlled environmental conditions, the filament was printable and the warpage was decreased by 44% at 10% NPCC loading. At the same concentration, there was a 30% increase in compressive strength and 43% increase in elastic modulus of the 3D printed parts.

Synthesis and Modification of Nano-Precipitated Calcium Carbonate (PCC) with Addition of Ethylene Glycol

ZA fertilizer waste (Ammonium sulfate) is waste generated from the industrial process of producing ZA fertilizer. The waste contains very high calcium and has the potential to be used as a raw material in the manufacture of Precipitated Calcium Carbonate (PCC). PCC with certain qualities can be developed in the field of advanced materials, with size modification into nanoparticles. One method to produce nanoparticles is using the coprecipitation method, with the help of a polymer solution. This study aims to produce Nano-PCC by finding the best conditions of CaCl2: Ethylene Glycol mole ratio and stirring speed. Nano-PCC is synthesized by reacting fertilizer waste with HCl to form a CaCl2 solution. Then, the solution is mixed with ethylene glycol to prevent particle agglomeration so that the size obtained will be smaller. The mixture is then reacted with Na2CO3 to form precipitated calcium carbonate (PCC). In this study, the variables were the mole ratio of CaCl2: ethylene glycol (1:12, 1:14, 1:18, 1:20) and stirring speed (350, 500, 650, 800, and 950 rpm). Based on PSA analysis, the Nano-PCC obtained at the smallest CaCl2: ethylene glycol ratio 1:12, stirring speed 950 rpm was 51.83 nm. Based on Scherrer’s calculations with XRD, the particle size obtained was 48.25 nm. SEM analysis showed that the crystals formed were dominated by vaterite crystals, with a size range of 55.71-607.79 nm.

Bio-based thermoplastic natural rubber based on poly(lactic acid)/thermoplastic starch/calcium carbonate nanocomposites

Bio-based thermoplastic natural rubber (TPNR) has recently received much attention due to its sustainability. TPNR based on natural rubber (NR), poly(lactic acid) (PLA), thermoplastic starch (TPS), and nano-precipitated calcium carbonate (NPCC) was fabricated using a twin-screw extruder with two different mixing sequences: MI (NPCC was first compounded with PLA) and MII (NPCC was initially compounded with TPS), and then converted to a sheet through cast sheet extrusion. A constant weight ratio of NR:PLA:TPS at 30:40:30 and varying concentrations of NPCC at 0.5, 1, 3, and 5 wt% were employed. The effects of NPCC and mixing sequence on the properties of NR/PLA/TPS/NPCC nanocomposites were investigated. The NR and TPS phases were dispersed in the PLA matrix. The nanocomposites loaded with a small amount of NPCC (0.5 and 1 wt%) showed increased tensile strength and Young's modulus. NPCC enhanced melt flowability, slightly improved the water vapor barrier property of the NR/PLA/TPS blend and caused decreased Tg, Tcc, and Tm of PLA in the nanocomposites. The PLA phase of the MI nanocomposites contained a higher amount of NPCC, consequently having greater PLA chain scission and poorer tensile properties than that of the MII nanocomposites.

Safety assessment of the substance fatty acid-coated nano precipitated calcium carbonate for use in plastic food contact materials.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the substance identified by the applicant as ‘fatty acid‐coated nano precipitated calcium carbonate’. It is intended to be used as a filler in all plastics at up to 5% for contact with acidic food and at up to 40% for contact with all other types of food. Articles made with the substance are intended for long‐term storage over 6 months at room temperature and below. No information was provided on the mechanism of coating as to whether there is chemical modification of the surface and/or physical adsorption. The substance was not properly characterised, either as pristine material or when incorporated into plastic. Contrary to the non‐coated material, data show that the coated material does not dissolve fully and quickly under pH conditions simulating gastrointestinal tract. Surface analysis with electron microscopy of low‐density polyethylene (LDPE) samples before and after migration experiments showed major differences that indicate release of the substance from the surface after the tests with 3% acetic acid and to a lesser extent with 10% ethanol. This is consistent with measurable migrations that were up to 39 mg CaCO3/kg when using an LDPE sample made with 5% of the substance in contact with acetic acid for 64 days at 40°C. The required data on the release of nanoparticles and on the potential toxicity of the substance in nanoform were not provided. Therefore, the Panel could not conclude on the safe use of the substance.

Safety assessment of the substance nano precipitated calcium carbonate for use in plastic food contact materials.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the substance ‘nano precipitated calcium carbonate’, FCM substance No. 1087, the particles size of which is in the range of ■■■■■, with a median of ■■■■■. The substance is intended to be used as a filler in all plastics at up to 5% w/w for contact with acidic food and at up to 40% w/w for contact with all other types of food. Articles made with the substance are intended for long‐term storage at room temperature or below. The particulate form of the calcium carbonate dissolved rapidly under simulated gastric conditions and, therefore, in accordance with the EFSA Guidance on Particle – Technical Requirements (2021), an assessment of the particles in nanoform is not required and a conventional risk assessment is sufficient. Calcium carbonate, not in nanoform, is authorised for use in plastic FCM without specific migration limit (FCM No. 21) and for use as a food additive (E 170). Migration, from low‐density polyethylene (LDPE) containing 40% of the substance, was below 0.03 mg/kg in isooctane and 95% ethanol, and 5.4 mg/kg in 10% ethanol. For LDPE containing 5% of the substance, corresponding to the maximum intended amount for contact with acidic foods, the migration was 17 mg/kg. Therefore, the CEP Panel concluded that the substance nano precipitated calcium carbonate is not of safety concern for consumers when used as a filler in all types of polymer for all types of food, except for infant food formulae. The Panel noted, however, that for acidic foods, the overall migration limit may be exceeded.

Effects of Cellulose Nanocrystal and Inorganic Nanofillers on the Morphological and Mechanical Properties of Digital Light Processing (DLP) 3D-Printed Photopolymer Composites

Photopolymer composites filled with cellulose nanocrystal (CNC) and/or inorganic nanofillers were fabricated by using digital light processing (DLP) 3D printing. To investigate the effects of different CNC lyophilization concentrations and behaviors of CNC particles in the photopolymer composites, morphological and mechanical properties were analyzed. CNC loading levels affected the morphological and mechanical properties of the filled composites. Better CNC dispersion was seen at a lower lyophilization concentration, and the highest mechanical strength was observed in the 0.25 wt% CNC-filled composite. Furthermore, nano-precipitated calcium carbonate (nano-PCC) and nanoclay were added to photocurable resins, and then the effect of inorganic nanofillers on the morphological and mechanical properties of the composites were evaluated. By analyzing the morphological properties, the stress transfer mechanism of nano-PCC and nanoclay in the photopolymer composites was identified and related models were presented. These supported the improved mechanical strength of the composites filled with CNC, nano-PCC, and nanoclay. This study suggested a new approach using wood-derived cellulose nanomaterials and inorganic nanofillers as effective fillers for DLP 3D printing.

Toughness evaluation of poly(butylene terephthalate) nanocomposites

This research investigates the toughness of poly(butylene terephthalate) (PBT) nanocomposites, based on mechanical characterizations and subsequent microstructural observations. Montmorillonite (MMT) and nano-precipitated calcium carbonate (NPCC) were selected as nano-reinforcing phases. Notched Izod impact test, tensile test as a quasi-static loading, and mode-I fracture toughness test, were conducted to evaluate the toughness. The corresponding fracture surfaces were analyzed using scanning electron microscopy (SEM). Tensile test results were linked with the morphologies of corresponding tensile-fractured surfaces. The results indicated that massive fibrillation in PBT/MMT nanocomposites dissipated lower energy relative to the large plastic deformation that was induced in the fracture surface of pure PBT. For PBT/NPCC samples, however, surface roughening mechanism was observed to increase the toughness in the tensile test, as compared to plain PBT. The fracture morphology of compact tension (CT) specimens exhibited a low extent of plastic deformation for pure PBT. However, the crack initiation zone of both nanocomposites showed a fibrillated morphology, leading to the increase of stress intensity factor up to 57% and 45% with the application of MMT and NPCC, respectively, as compared to pure PBT. The crack propagation region was, however, associated with shallow fibrils for MMT and local polymer yielding for NPCC.

A combined differential scanning calorimetry‐dynamic mechanical thermal analysis approach for the estimation of constrained phases in thermoplastic polymer nanocomposites

AbstractPoly(butylene terephthalate) (PBT) nanocomposites reinforced with different weight fractions of montmorillonite (MMT), and nanoprecipitated calcium carbonate (NPCC) were prepared by a two‐step melt compounding method. X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses were employed to explore the effect of nanofiller inclusion on the crystalline structure of PBT nanocomposites. The mobile amorphous fraction (MAF) and the rigid amorphous fraction (RAF) were first measured using the specific heat capacity (Cp) and melting enthalpy data. However, the contributors to total RAF, including interfacial RAF (RAFint) and crystalline RAF (RAFc), could not be discerned using only DSC. A novel and simple method was hence developed by employing a combined DSC‐dynamic mechanical thermal analysis (DMTA) approach (CDDA) to disentangle the RAF components and determine the fractions of constrained volume constituents. To validate the results, the MAF calculated by CDDA were compared to those of DSC. The values obtained using CDDA were relatively higher, owing to the more significant sensitivity of this approach to polymer chain mobility.

Thermomechanical properties of woven abaca fiber‐reinforced nanocomposites

AbstractIn this study, natural fiber‐reinforced polymer nanocomposites were prepared from high‐density polyethylene (HDPE), abaca fiber, and nanoprecipitated calcium carbonate (NPCC) using the hot press technique. The study investigated the influence of untreated and alkali‐treated woven abaca fabric and NPCC hybrid reinforcement on the thermomechanical behavior of the natural fiber composites. The HDPE with different amounts of NPCC was melt‐blended in a twin‐screw extruder followed by hot press to produce sheets. A lamination of composites containing alternating layers of HDPE sheets with different amounts of NPCC and layers of untreated and alkali‐treated woven abaca fabric was produced using a hot press machine. The resulting material was composed of 20% weight ratio of woven abaca fibers. The tensile strength showed that the nanocomposite exhibited a high tensile value of 60.1 MPa with alkali‐treated abaca and 1% NPCC. However, a further increase in the NPCC concentration beyond 1% reduced the mechanical strength of the nanocomposite. The thermal stability of the abaca fiber‐reinforced nanocomposite improved with addition of NPCC. Scanning electron microscopic analysis demonstrated that alkali‐treated abaca and 1% NPCC improved the adhesion and compatibility between the fiber and polymer matrix. The potential applications of this natural fiber‐reinforced composite are for automotive and construction materials.

Nano Calcium Carbonate Production Utilizing Solvay-Process Industrial Wastewater and Carbon Dioxide

nanoparticles are catching more attention due to their implementation as a filling material in a variety of fields. Nowadays, calcium carbonate nanoparticles have a large number of industrial applications replacing more expensive binders. Global warming and climate change, which are mainly caused by the increased concentration of carbon dioxide gas (CO2), turned to be a significant problem for our society. This research aims to develop an economic mineral carbonation process for the manufacture of nanoprecipitated calcium carbonate (NPCC), which can be considered also as an efficient way for the sequestration of CO2. The proposed research was divided into two stages, during the first stage a pure calcium chloride solution was carbonated, and the effect of different parameters (CO2 flow rate, ammonia amount, presence of additives, stirring rate, and ultrasonic waves) on the yield and the particle size of the produced particles was discussed. Then a synthetic Solvay wastewater sample was prepared and carbonated to study the effect of the presence of impurities on the particle size. The experimental results showed that increasing the amount of ammonia or the gas flow rate can affect the yield of the product while, increasing the stirring rate, the ammonia amount, or a suitable additive like glycerol have the effect to decrease the particle size. In the second stage, a process for ammonia recovery was modeled using Aspen Plus software v8.8 in order to make our process more economic.

Characterization of Limestone in Pamekasan Madura Island as Raw Material for Producing Nano Precipitated Calcium Carbonate (NPCC)

Characterization of limestone in Pamekasan Madura island was investigated. So far, limestone at Madura island has low economic value as additional building material. Limestone was taken from three mining locations. The chemical composition of limestone was characterized by X-Ray Fluorescence (XRF), the crystalline phase was characterized by X-ray diffraction (XRD) and morphological investigation was analyzed by Scanning Electron Microscope (SEM). The results XRF tests are obtained limestone with very high purity from Blumbungan, Pamekasan, East Java with Ca content 99,25 wt%. Characterization by using XRD and SEM are showed 100% calcite phase with rhombohedral-cubic shape and a particle size of CaCO3 ranges between 1.594 – 2.503 μm. In conclusion, limestones from Blumbungan are able to material for producing nano precipitated calcium carbonate (NPCC). Furthermore, economic value of limestone in Madura Island are able to advance.

Isothermal and non-isothermal crystallization kinetics of poly(butylene succinate) with nanoprecipitated calcium carbonate as nucleating agent

Poly(butylene succinate) (PBS) nanocomposites filled with nanoprecipitated calcium carbonate (NPCC) were prepared via melt blending. The hybrid materials were crystallized under isothermal and non-isothermal conditions in order to understand the influence of NPCC on the crystallization behavior of PBS matrix. For both of these conditions, the nucleating effect induced by the addition of NPCC was clearly shown by differential scanning calorimetry (DSC) additionally to an increase of crystallinity. The analysis of isothermal crystallization by Avrami theory allowed to notice a variation of the crystallization mechanism in the presence of the filler and the apparition of secondary stage crystallization. The nanocomposites exhibited higher nucleation activity than the neat PBS and a faster crystallization process as indicated by the values of the half-time of crystallization. Ozawa and Mo theory applied on DSC data highlighted the variations of PBS crystallization behavior in the presence of NPCC. Finally, the crystallization ability of each material was evaluated via the theories of Takhor and Augis–Bennett. The crystallization activation energy showed a promotion of polymer chain diffusion that was correlated with the simultaneous apparition of secondary crystallization stage.

The impact of a designed lactic acid-based crosslinker in the thermochemical properties of unsaturated polyester resins/nanoprecipitated calcium carbonate composites

Unsaturated polyester composites (UPCs) were prepared from biobased unsaturated polyester resins (UPRs) and nanoprecipitated calcium carbonate (NPCC). The UPRs were obtained from the crosslinking reaction of an unsaturated polyester (UP) made from renewable monomers and styrene (St) or a mixture of St with a designed lactic acid-based crosslinker (BPPC). The UPCs were obtained by adding the NPCC to the formulations. Aspects of the composition of the UPs and of the BPPC were confirmed by FTIR and 1H NMR spectroscopies. Different UPCs were prepared and the influences of the addition of NPCC and of the amount of BPPC on their thermomechanical properties were evaluated. The BPPC has a major influence on the properties of the UPCs, namely a significant improvement of mechanical properties and of the thermal stability of UPCs. Both results suggest that the BPPC may be acting as a compatibilizer between the polymer matrix and the filler.

Nucleated polylactide blend films with nanoprecipitated calcium carbonate and talc

Nucleated polylactide (PLA) blend films with various types and contents of nucleating agent were prepared in a twin-screw extruder. The influences of type and level of nucleating agent on the tensile, thermal, and morphological properties of the blend films were investigated. Furthermore, effects of different cooling rates (1–10 °C min−1) on non-isothermal processes and various crystallization temperatures (Tc) (100–125 °C) on isothermal conditions were used to evaluate the crystallization behaviors and kinetics of these films by differential scanning calorimeter (DSC) and polarized light microscope. Nanoprecipitated calcium carbonate (NPCC) and talc were used as a nucleating agent at different concentrations from 0 to 2 phr. The results showed that the tensile properties, thermal stability, spherulitic morphology, and crystallization behaviors of the nucleated PLA blends significantly depended upon the addition of nucleating agent. Tensile properties of the blends were improved with increasing of nucleating agent contents; in contrast, its thermal stability decreased. These behaviors were similarly observed in both nucleated PLA blends with NPCC and talc. Furthermore, DSC curves revealed that NPCC and talc could be a proficient nucleating agent for PLA, resulting in the increments of Tc, crystallization rate, degree of crystallinity (χc), and spherulitic density of nucleated PLA films.

Mechanical, Thermal and Morphological Properties of Injection Molded Poly(lactic acid)/Calcium Carbonate Nanocomposites

In this work, mechanical and thermal properties of maleated ethylene-propylene rubber (EPR-g-MAH) toughened poly(lactic acid) (PLA)/nano-precipitated calcium carbonate (NPCC) nanocomposites were investigated. It was found that elongation at break of PLA/NPCC was increased with increasing EPR-g-MAH content up to 15 phr (parts per hundred resin). The investigations on the crystallization behaviours demonstrated that the NPCC acted as nucleating agent for the PLA. However, the degree of crystallinity of PLA was reduced by the addition of EPR-g-MAH which appears to be due to encapsulation of NPCC by the maleated rubber. Dispersion of NPCC was observed using transmission electron microscopy (TEM), and it was revealed that both nano-dispersed and agglomerates NPCC exist in the PLA matrix. Moreover, encapsulation of NPCC was favored in the presence of EPR-g-MAH.

Synthesis of nano precipitated calcium carbonate by using a carbonation process through a closed loop reactor

Nano calcium carbonate particles have a wide range of industrial applications due to their beneficial properties such as high porosity and high surface area to volume ratio and due to their strengthening the mechanical properties of plastics and paper. Consequently, significant research has been done to deliver a new approach for the synthesis of precipitated nano calcium carbonate by using a carbonation process through a closed loop reactor. Both the experimental and the instrumental parameters, i.e. the CO2 flow rate, the concentration of the starting materials (Ca(OH)2 and CaO), the pH, the orifice diameter, etc., were investigated. The carbonation efficiency was increased due to the diffusion process involved in the loop reactor. The particle size was affected by the CO2 flow rate, reaction time, and orifice diameter. Finally, precipitated nano calcite calcium carbonate (50 to 100 nm) was synthesized by optimizing all the experimental and the instrumental parameters. The synthesized precipitated nano calcium carbonate was characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. This study has proved that the carbonation efficiency can be enhanced for a short time by using a loop reactor and that the carbonation process was more energy efficient and cost effective than other conventional methods.

Seeded Growth Route to Noble Calcium Carbonate Nanocrystal.

A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33–41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed.