nano-CaCO3 Content Research Articles

Properties of self-consolidating concrete containing nano-CaCO3

This paper studied the effect of nano-CaCO3 on workability, strength development, and pore structures of cement paste and self-consolidating concrete. The effects of dosage and size of nano-CaCO3 were considered. For the workability, slump flow (total spread and T50 time), L-box, and V-funnel tests were conducted. The compressive strength was tested at 1, 7, and 28 days for concrete and 1 and 7 days for cement paste. The pore structure, including pore size distribution and volume, was measured using nitrogen adsorption method. The results show that the addition of nano-CaCO3 reduced the setting times. Concrete with a low content of nano-CaCO3 (≤2.5%) had satisfactory workability. No segregation was observed for all concrete specimens. The addition of nano-CaCO3 increased the compressive strength of the concrete and paste. The compressive strength decreased as the particle size increased. The addition of nano-CaCO3 reduced the average pore diameter. XRD test showed no new hydration products.

Foaming behaviour of microcellular foam short carbon fibres/polypropylene/nano-CaCO3 composites

In this paper, nano-CaCO3 was added into short carbon fibre/polypropylene composites in order to improve foamability. According to differential scanning calorimetry results, there were slight influences on the melting point and crystallinity with the addition of nano-CaCO3. The increase in melt strength with nano-CaCO3 content could be qualitatively certified by torque rheology curves. The dispersion of nano-CaCO3 was determined by scanning electron micrograph. Depressurisation foaming method was used to foam the composites using supercritical CO2. Characterisation of the cell morphology was conducted to investigate the effects of the nano-CaCO3 content and processing conditions. Concerning the effect of nano-CaCO3 content, it is found that the mean cell diameter first decreased and then increased, whereas the cell density showed the opposite trend. Moreover, increasing saturation pressure or decreasing foaming temperature made the cell size smaller and the cell density larger.

Solid-state foaming of carbon fiber/polypropylene/nano-CACO3composite using supercritical CO2

In this work, nano-CaCO3 was used to improve the foamability of carbon fiber (CF)/polypropylene (PP) composite in solid-state foaming using supercritical CO2. The CF content was maintained at 15 wt% and four concentrations of nano-CaCO3 content, 1, 3, 5 and 8phr, were used. The surface of nano-CaCO3 was firstly treated by silane coupling agent. By the way, the properties of the nano-composites with various nano-CaCO3 contents were analyzed by scanning electron microscope (SEM), differential scanning calorimeter (DSC), and torque rheometer. Before foaming, the gas absorption experiment was done using gravimetric method. Concerning on determination of the foaming conditions, it is found that 175°C and 60s were suitable as foaming temperature and time. Furthermore, we can also find that the foamed composites with 3phr nano-CaCO3 showed the smallest mean cell diameter and largest cell density compared with the other nano-CaCO3 contents under the given saturation condition. In addition, the mean cell diameter decreased while cell density increased as saturation pressure increased because of the higher gas solubility in the composites. When the saturation pressure was 25MPa, the mean cell diameter and cell density with 3phr nano-CaCO3 were 17μm and 2.20×107cells/cm3, respectively. POLYM. COMPOS., 35:1723–1735, 2014. © 2013 Society of Plastics Engineers

Effects of coating solution concentration on the interlaminar shear strength of carbon fiber/epoxy/nano-CaCO3 composites

Abstract Previously, we have shown that the effects of the coating solution concentration of coupling agent on the interlaminar shear strength of fiber/epoxy composites were best investigated with 4 wt.% nano-CaCO3 content. Here, five different types of composites were prepared: (E–0–4): composites modified by untreated nano-CaCO3, (E–1.1–4): composites modified by nano-CaCO3 with 1.1 wt.% coating solution concentration treatment. Similarly, samples E–2.3–4, E–3.5–4 and E–4.6–4 were also fabricated. The results show that nanocomposites prepared with 2.3 wt.% and 3.5 wt.% coating solution concentration treatment have the best shear properties, including interlaminar shear strength, elongation at break and fracture work. With 2.3 wt.% coating solution concentration treatment, these have values of 142.4 MPa, 1.95 mm and 1.86 J, which can increase 11%, 41% and 39% compared to the composite prepared with untreated nano-CaCO3, respectively.

Effect of Fly Ash and nanoCaCO<sub>3</sub> on the Setting Time of Cement Paste

This paper presents an experimental study to evaluate the effects of fly ash and nanoCaCO3 on setting time of cement paste. The test group included the contents of fly ash was 30%, 40%, 50%, 60% and content of nanoCaCO3 was 2.5%, 5%, 10%, 20%. Results indicate that setting time was increased with the incorporation of fly ash, shortened with the incorporation of nanoCaCO3. The incorporation of 5% nanoCaCO3 by mass of cementitious materials reduced initial and final setting times by 60 and 70 min, respectively. In comparison to the referenced paste with 40% fly ash. The best fly ash content appear to be 40% when nanoCaCO3 was added.

Heat distortion temperature of PPS/PC blend, PPS/PC nanocomposite and PPS/PC/GF hybrid nanocomposite

Abstract The polyphenylene sulfide (PPS) blended with polycarbonate (PC), reinforced glass fiber (GF) and nanometer calcium carbonate (nano-CaCO3) filled PPS ternary composite, as well as the PPS/PC/GF/nano-CaCO3 hybrid composite, were prepared by means of a twin-screw extruder, and the heat distortion temperature (Td) of these materials was measured to identify the influence of the PC and nano-CaCO3 content on the heatproof properties. The Td values for the PPS/PC blend were lower than that of the neat PPS, when the PC weight fraction (φPC) was less than 20%, and increased with increase in φPC. The Td values for the PPS/GF/nano-CaCO3 ternary composite, on which the particle surface was treated with a titanate coupler, were higher than that of the composite with the particle surface treated with a stearate coupler. When the nano-CaCO3 weight fraction (φf) was less than 6%, the Td values for the PPS/PC/GF/nano-CaCO3 hybrid composites increased with increasing φf; at greater than the maximum of 6%, Td decreased. There was a certain synergistic effect of the GF and nano-CaCO3 on the heatproof properties in the PPS/PC composite.

An investigation of the machinability of PA 6/nano-CaCO3 composite

Nowadays, polymer nanocomposites have attracted manufacturers’ attention because of their good mechanical, thermal, and physical properties. Over the past decade, the requirement of the direct machining of polymer nanocomposites has increased due to the production of most polymer nanocomposites using the extrusion method in simple cross-section and the increased demand for personalized products. In this paper, the effect of milling parameters (spindle speed and feed per tooth) and nano-CaCO3 content on the machinability properties of PA 6/nano-CaCO3 composites was studied by analyzing variance. Harmony search-based neural network (HSNN) was then utilized to create predictive models of surface roughness and total cutting forces from the experimental data. The results revealed that the nano-CaCO3 content on PA 6 decreased the cutting forces significantly, but did not have a significant effect on surface roughness. Moreover, the results for modeling total cutting forces and surface roughness showed that HSNN is effective, reliable, and authoritative in modeling the surface roughness formation and total cutting force mechanism for end-milling of PA 6/nano-CaCO3 composites.

Effect of nano-calcium carbonate content on the properties of poly(urethane methacrylate) nanocomposites

Nanocomposites containing nano-calcium carbonate (nano-CaCO3) in the range of 0.25–1.5% (w/w) were prepared via in situ polymerization of urethane methacrylate pre-polymer derived from poly(ethylene glycol) (PEG 400), polymeric diphenylmethane diisocyanate and 2-hydroxyethyl methacrylate. Incorporation of nano-CaCO3 into poly (urethane methacrylate) matrix was confirmed by Fourier transform infrared spectroscopy and wide-angle x-ray diffraction studies. Density studies indicated that nanocomposites containing 0.75 wt% nano-CaCO3 had more condensed microstructure. Tensile strength, abrasion resistance, heat deflection temperature and shore hardness of nanocomposites were found to be higher than that of pristine polymer. Impact strength decreased with an increase in the nano-CaCO3 content. Thermal studies indicated single-step degradation under a nitrogen atmosphere. Scanning electron microscopy studies confirmed the uniform distribution of nano-CaCO3 at lower loading of nano-CaCO3 and microcracking occurred during wearing.

Compressive properties of nano-calcium carbonate/epoxy and its fibre composites

Compressive properties of fibre reinforced polymer composites are always weak parts in structural applications, and improvement of such properties can lead to the usage in the wider fields. Matrix modification is an effective way to improve this property. In this paper, a silane coupling agent (KH550) as an interfacial modifier was introduced into nanocomposites through manufacturing KH-550/nano-calcium carbonate (nano-CaCO3) master batch. The effect of different modified nano-CaCO3 content on the compressive properties of epoxy resin cast and its carbon fibre composites was evaluated. Compression test revealed a remarkable improvement of 13.5%, 6.1%, 42.5% and 106.3% in compressive strength, elastic modulus, displacement and the total fracture work of epoxy resin cast filled with 4wt.% nano-CaCO3 contrasted to neat epoxy casts. It showed that the modified nano-CaCO3 particles had a strengthening and toughening effect. Accordingly, the compressive properties of nano-CaCO3/epoxy/carbon fibre composites based on the modified epoxy matrix are also improved. The influence of the nanoparticles on the failure modes of the fibre composites was also studied.

Atomic Force Microscopy, thermal, viscoelastic and mechanical properties of HDPE/CaCO3 nanocomposites

High Density Polyethylene (HDPE) and calcium carbonate (CaCO3) nanocomposites were prepared from masterbatch by melt blending in twin screw extruder (TSE). The physical properties of HDPE/CaCO3 nanocomposites samples (0, 10 and 20 wt% CaCO3 masterbatch) were investigated. The morphology, thermal, rheological/viscoelastic and mechanical properties of the nanocomposites were characterized by Atomic Force microscopy (AFM), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analyzer (DMA) as well as tensile test. The AFM images showed homogeneous dispersion and distribution of nano-CaCO3 in the HDPE matrix. The DSC analysis showed a decrease in crystallinity of HDPE/CaCO3 nanocomposites with the increase of CaCO3 loading. This was due to the presence of nanofiller which could restrict the movement of the polymer chain segments and reduced the free volume/spaces available to be occupied by the macromolecules, thus, hindered the crystal growth. However, there was an increase in crystallization temperature about 1–2 °C with the addition of CaCO3. It was suggested that the CaCO3 nanoparticles acted as nucleating agent. In melt rheology study, the complex viscosities of HDPE/CaCO3 nanocomposites were higher than the HDPE matrix and increased with the increasing of CaCO3 masterbatch loading. The DMA results showed that the storage modulus increased with the increasing of nano-CaCO3 contents. The improvement was more than 40 %, as compared to that of neat HDPE. Additionally, the tensile test results showed that with the addition of CaCO3 masterbatch, modulus elasticity of nanocomposites sample increased while yield stress decreased.

Effect of Nano-CaCO3 on Properties of Cement Paste

In this paper, effect of nano-CaCO3 (NC) on properties of cement paste was studied. Experimental results showed that NC had no effect on water requirement of normal consistency of cement. However, with the increase of NC content, the flowability decreased and the setting time of fresh cement paste was shortened. The early hydration of cement was activated by NC. The strength and the early age shrinkage of cement paste were also studied. Mechanical experiments indicated that the flexural and compressive strength of hardened cement paste increased with the addition of NC at the age of 7d and 28d, and the optimal content of NC was 1%. The early age (12h) shrinkage of cement paste containing 1% NC was the most prominent which could decrease the shrinkage strain obviously.

Study on the Performance of Nano-CaCO<sub>3</sub> and LLDPE Based Artificial Turf Fibers

In this paper, a new type of LLDPE/nano CaCO3 composite based artificial turf yarns with good tensile property and UV resistance is introduced. The effect of nano CaCO3content on tensile properties shows that the tensile force reached the maximum value when the CaCO3 content is about 7wt%, and the elongation at break gets to the highest point at 10wt%. After 3000h UV accelerated aging, the nano-CaCO3 and LLDPE based artificial turf fiber yarns has tensile strength retention about 87%, and the elongation at break is higher than LLDPE. DSC results shows that with the increase of nano-CaCO3 content, the crystallization temperature gradually increased, and the crystallinity degree declined. SEM images of cross sections of monofilament fibers show that nano CaCO3 had a good dispersion in monofilament fiber matrix. These reasons give rise to the improved mechanical properties of turf yarns.

Thermal stability and impact and flexural properties of epoxy resins/epoxidized castor oil/nano-CaCO3 ternary systems

Epoxy ternary systems were prepared from the diglycidylether of bisphenol-A (DGEBA), epoxidized castor oil (ECO), and nano-CaCO3 using a thermally latent initiator. The effects of ECO and the nano-CaCO3 contents on the thermal stability and mechanical interfacial properties of the prepared DGEBA/ECO/nano-CaCO3 ternary systems were examined by thermogravimetric analysis (TGA), Izod impact tests, and mechanical tests. The morphology of the ternary systems was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The statistic heat-resistant index temperature (Ts) of the ternary systems was approximately constant up to 30 wt% ECO, and thereafter decreased with increasing ECO content. The impact strength of the ternary systems was improved by the addition of ECO and nano-CaCO3. The flexural strength of the ternary systems exhibited a maximum value at 20 wt% ECO. SEM showed that shear deformation occurred, which prevented the propagation of cracks in the DGEBA/ECO/nano-CaCO3 ternary systems.

Effects of Nano-CaCO3 Content and Surface Treatment on Tensile Properties of PPS/GF Ternary Composites

Nanometer calcium carbonate (nano-CaCO3) filled polyphenylene sulfide (PPS/GF) ternary composites reinforced with glass fiber were fabricated in this paper, and the Young's modulus, tensile strength and tensile elongation at break were measured at room temperature, to identify the influence of the content and surface treatment of the nano-CaCO3 particles on the tensile mechanical properties of these ternary composites. It was found that the Young's modulus, tensile strength and tensile fracture strength of the composites increased slightly with an addition of the weight fraction (φ f ) of the nano-CaCO3 particles, and the maximum increase of them was more than 7.5% at φ f = 2%. When φ f was less than 4%, the tensile elongation at break of the composites increased obviously and then increased gently with an increase of φ f , and the maximum increase of it was more than 21% at φ f = 4%. Relatively, the tensile properties of the PPS/GF/nano-CaCO3 composite systems for the particle surface treated with titanate coupler were somewhat better than those of the systems for the particle surface treated with stearic acid at the same nano-CaCO3 content.

Mechanical Properties of PPS/PC/GF/Nano-CaCO3 Hybrid Composites

A kind of nanometer calcium carbonate (nano-CaCO3) filled glass fibre-reinforced polyphenylene sulfide/polycarbonate (PPS/PC/GF) hybrid composites were fabricated with a twin-screw extruder in this paper, and the surface of the nanometer particles was pretreated with stearic acid in a high speed mixer before melt blending. The Young's modulus, tensile strength, tensile elongation at break, flexural modulus and strength of these hybrid composites were measured at room temperature by using a universal materials testing machine, to identify the influence of the nano-CaCO3 content on the mechanical properties of these hybrid composites. It was found that there were relatively evident reinforcing and toughening effects of the nano-CaCO3 on the PPS/PC/GF hybrid composites. The Young's modulus, tensile strength, flexural strengt and elongation at break of these composites increased nonlinearly with an addition of the nano-CaCO3 weigh fraction (φ f ) when φ f was less than 6%, and they reached the maximum at φ f of 6%, and then decreased; while the flexural modulus increased as φ f was less than 4%, and then decreased.

Impact Toughness and Flexural Properties of PPS/GF/Nano-CaCO3 Ternary Composites

To identify the influence of the content and surface treatment of nano-CaCO3 on the mechanical properties of nanometer calcium carbonate (nano-CaCO3)-filled glass fiber (GF)-reinforced polyphenylene sulfide ternary composites, the impact strength, flexural modulus, and strength were measured at room temperature. It was found that the notched impact strength and flexural strength of these composites increased with an increase of the nano-CaCO3 weight fraction (φ f ) when φ f was less than 2% and then they decreased, and the unnotched impact strength of these composites roughly nonlinearly increased with an addition of φ f , whereas the effect of φ f on the flexural modulus was insignificant. The impact strength and flexural strength for these filled systems with the particle surface pretreated with titanate coupler were greater than those of the filled systems with the particle surface pretreated with sttaric aicd.

Crystallization behavior and melting characteristics of PP nucleated by a novel supported β-nucleating agent

The β-nucleated PP with high β-PP content was prepared by a novel supported β-nucleating agent, which was prepared with pimelic acid supported on nano-CaCO3 as support. The influences of the content of the support and supported β-nucleating agent, pre-melting temperature (Tmelt) and scan rates on crystallization behavior and melting characteristics, and the β-PP content of β-nucleated PP were determined by Differential Scanning Calorimeter (DSC) and Wide-Angle X-ray Diffraction (WAXD). The results indicated that the addition of supported β-nucleating agent markedly increased the crystallization temperature (Tc) of PP. Increasing the content of supported β-nucleating agent slightly increased the Tc, but had no influence on the melting temperatures (Tm) of β-nucleated PP. The Tc and Tm of β-nucleated PP decreased slightly with increasing the content of the support nano-CaCO3. The effects of scan rates and multiple scans with different Tmelt on the crystallization and melting behavior of PP nucleated by supported β-nucleating agent are similar to that of PP nucleated by calcium pimelate (CaHA). The β-PP content above 90 percent was obtained in PP nucleated by supported β-nucleating agent and was not influenced by the content of nano-CaCO3. The supported β-nucleating agent prepared by supporting pimelic acid on nano-CaCO3 is a β-nucleating agent with high efficiency and selectivity, and low cost.

Nonisothermal crystallization behavior and crystals morphology of poly(trimethylene terephthalate)/nano‐calcium carbonate composites

AbstractNonisothermal crystallization behavior and crystal morphology of poly(trimethylene terephthalate) (PTT) composites filled with modified nano‐calcium carbonate (CaCO3) had been investigated by using differential scanning calorimetry and polarized optical microscopy. The modified Avrami equation and Ozawa theory were used to investigate the nonisothermal crystallization, respectively. The particles of nano‐CaCO3, acting as a nucleation agent in composites, accelerated the crystallization rate by decreasing the half‐time of crystallization or increasing the parameters of Zc and K(T). Moreover, the nano‐composite with 2 wt% nano‐CaCO3 exhibited the highest crystallization rate. The Avrami and the Ozawa exponents, n and m of the nano‐composites, were higher than those of neat PTT, suggesting more complicated interaction between molecular chains and the nanoparticles that cause the changes of the nucleation mode and the crystal growth dimension. The effective activation energy calculated from the Friedman formula was reduced as nano‐CaCO3 content increased, suggesting that the nano‐CaCO3 made the molecular chains of PTT easier to crystallize during the nonisothermal crystallization process. The optical micrographs showed that much smaller or less perfect crystals were formed in composites because of the presence of the nano‐CaCO3 particles. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

Online shear viscosity and microstructure of PP/nano-CaCO3 composites produced by different mixing types

In this work, the online melt shear viscosity of polypropylene/nano-calcium carbonate composites was measured during the compounding to investigate the relationship between their rheological behavior and microstructure. Effects of dispersive mixing, distributive mixing, and chaotic mixing on online shear viscosity and microstructure of nanocomposites were analyzed. The results showed that the online shear viscosity of nanocomposites is lower than that of pure PP, when the nano-CaCO3 content is lower than 5, 10, and 15 wt%, compounded by high dispersive mixing, dispersive/distributive mixing, and dispersive/distributive/chaotic mixing, respectively. This is greatly related with the dispersion of nanoparticles in PP matrix. It is deduced that there exists a critical percentage (Φcr) of the nano-CaCO3 with size lower than 100 nm and a critical mean diameter (dcr). The shear viscosity is lower than that of pure PP when the percentage is higher than the critical percentage and the mean diameter is lower than the critical diameter. In this work, the critical percentage is 80% and critical mean diameter is 60 nm.

Effect of Silica Sol-Modified Nano-Calcium Carbonate on Polyurethane(Urea) Dispersions and their Films

A series of novel aqueous polyurethane(urea) (PUU)/silica sol-modified nano-calcium carbonate (CaCO3) hybrid dispersions were prepared using an in situ dispersion technique. Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) examinations indicated that the modified nano-CaCO3 particles were mostly covered or partially inlaid on the surface of PUU particles or in the PUU matrix. PUU/modified nano-CaCO3 hybrid dispersions with lower modified nano-CaCO3 content (≤15%) exhibited low viscosity, small particle size and excellent stability. The rheological features revealed that this hybrid PUU dispersion belonged to pseudoplastic fluids. In addition, the incorporation of modified nano-CaCO3 could also enhance the mechanical properties of PUUs dramatically through the reinforcing effect of inorganic CaCO3. The better water resistance of PUU/modified nano-CaCO3 hybrid films proved that modified nano-CaCO3 could be used as effective modifiers for PUUs, and this method provided an efficient way to incorporate silica sol-modified nano-CaCO3 in the PUU matrix.