Nano-CaCO

Ma,C.G. Mai, Y.L. Rong, M.Z. Ruan, W.H. Zhang M.Q. (2007). Phase structure and mechanical properties of ternary polypropylene/elastomer/nano-CaCOs composites. Composites Science and Technology, vol.67, No.l4, pp.2997-3005, ISSN ... 

Wang, W.Y. Wang, G.Q. Zeng, X.F. Shao, L. Chen, J.F. (2008). Preparation and properties of nano-CaCOs/ acrylonitrile-butadiene-styrene composites. Journal of Applied Polymer Science, vol.107, No.6, pp.3609-3614, ISSN 1097-4628... 

Jiang, G. Huang, H.X. (2008). Online shear viscosity and microstructure of PP/nano-CaCOs composites produced by different mixing typ>es. Journal of Materials Science, Vol. 43, No. 15, pp. (5305-5312)... 

As Table 2.1 shows, the concept of the wetting coefficient has been successfully applied in filled polymer blends containing various fillers, such as carbon black [36], silica [26,27,37], or nano-CaCOs particles [38,39]. Limitations of this criterion include strong discrepancies in interfacial tensions, due to the lack of data in the literature regarding polymer/filler interfaces and issues of extrapolation to the appropriate temperature. Also, this criterion assumes that thermodynamic equilibrium has been reached, which is not always the case experimentally due to the limited processing time. 

Alternatively, some papers have based their analysis on the values of the work of adhesion, W and the interfacial tensions rather than co [40,41] to predict the filler localization. Ma et al. [39] compared three different methods to predict the morphology of composites containing nano-CaCOs, based on interfacial tension data, estimation of the work of adhesion, and estimation of the wetting coefficient. They reported that the wetting coefficient is the most accurate tool to predict the phase structure, by comparing with the actual localization of the nano-CaCOg particles observed using SEM. 

It is observed that Slapp of nano-CaCOs is less than the commercial CaCOs filled SBR which is attributed to greater crosslinking of rubber, as the uniform dispersion of nano-CaCOs brings the chains closer and keeps them intact with nanoparticles. Swelling depends on elastomer crosslinking density and solvent used. Solvent penetration is more in commercial micron size CaCOa than the nano-CaCOs rubber composites. 

The tensile strength of nano-CaCOs filled SBR (2.58 MPa for 9 nm CaCOs) are higher than the commercial CaCOs (1.63 MPa) and the fly ash filled SBR (1.37 MPa) which means nano-CaCOs provides higher tensile strength as compared to commercial CaCOs and fly ash filled SBR which is attributed to uniform dispersion of nanofiller into the rubber matrix that intercalates the rubber matrix, and so the degree of crosslinking of rubber chain increases. 

In order to study the interfacial adhesion, the micrographs at different concentrations of nano-CaC03 and commercial CaCOa were compared with SBR as the matrix. The nano-CaCOs showed good dispersion with the SBR matrix while commercial CaC03 filled showed agglomeration thereby weakens interfacial adhesion in case commercial or microsized CaCOs-... 

In the X-ray analysis, the absence of peaks indicates that nano-CaCOs is dispersed throughout the matrix whereas commercial CaCOa filled SBR composite showed a peak at 2.82° in the X-ray diffractograms of 8 wt% SBR/ nano-CaC03 (21, 15 and 9 nm) composites which is attributed to micron size of filler and above 8 wt% of loading of filler in nano-CaC03 and commercial CaCOa presence of peaks indicate that nano- and commercial CaCOs get agglomerated. ... 

SBR filled with nano-CaCOs with linseed oil as an extender showed a significant reduction in flammability in comparison with that without an extender. The rate of flame retarding of nano-CaCOs was more than that of commercial CaCOs with linseed oil and the increase in flame retardancy with a decrease in the size was due to the uniform dispersion of the nanosized, which resulted in greater absorption of heat energy. One of the other author also investigated the SBR filled with nano-CaCOs and found that reduction in nanosize shows better improvement in flame retardancy which is attributed to nanofiller forms effective layer on the surface, which absorbs the heat of burning. 

Nano-CaCOs is one of the many emerging applications of nanotechnology that is already finding successful commercial application. Reinforcing effect of nano-CaC03 in different compounds - NR and NR/NBR blend used in sports goods (laminated sheet for inflated balls), NR based cycle tube, bromobutyl-based pharmaceutical closures and CPE/CSM blend used for coated fabric was studied with one characteristic in mind that is to improve barrier properties as all these products have requirement of one common property - air retention. 

The thermal stability of calcium carbonate (CaC03) nanoparticles on polybutadiene rubber (PBR) were studied by Shimpi and Mishra [105]. They observed that the incorporation of nano CaCOs in PBR shows better thermal stability. At 12 wt% of nano CaCOs (21, 15, and 9 nm) filled in PBR shows decomposition temperature at 491, 483, and 472 °C, respectively. At 4 wt% loading of filler, decomposition temperature is observed to be 488,480,450 °C for nano CaCOs (21, 15, and 9 nm), respectively. This enhancement in thermal stability is due to uniform dispersion of nano CaCOs throughout the matrix that keeps the rubber chains intact on cross-linking, which prevent out diffusion of the volatile decomposition product [106]. The presence of nanoinorganic particles in between the mbber chains is responsible for preventing the diffusion of the volatile decomposition products firom the mbber nanocomposites at same time. It is clear that nanoinorganic filler provides better thermal stability as compared with commercial micron size filler. 

The cement used in this study was commercially available ordinary Portland cement (PC) Type I confirming to the ASTM C150 standard (2012). The FA used was sourced from the Colie Power Station of Western Australia and was classified as class F FA in accordance with ASTM C618 (2012). Commercially available dry nano-CaCOs (NC) powder with a size of approximately 40—50 nm and 97.8% calcite (CaCOs) content was used (see Figure 11.1). The NC was bought from Reade Advanced Materials (United States). Figure 11.2 shows the XRD analysis of PC, FA, and NC. The chemical composition and physical properties of cement, class F FA, and NC are presented in Table 11.1. 

Sato, T., Diallo, F., 2010. Seeding effect of nano-CaCOs on the hydration of tricalcium silicate. 

Supit, S., Shaikh, F.U.A., 2014b. Effect of nano-CaCOs on compressive strength development of high volume fly ash mortars and concretes. Journal of Advanced Concrete Technology. 12, 178-186. 

Kumar, P., Ramya, C, Jayakumar, R., Lakshmanan, V.-K. Drug delivery and tissue engineering apphcations of biocompatible pectin-chitin/nano CaCOs composite scaffolds. Colloids Surf. B Biointerfaces 106,109—116 (2013)... 

Surface treatment of CaCOj can change its nucleating activity in iPP. In Reference [134] iPP composites with nano-CaCOs were modified with iPP grafted with acrylic acid (PP-g-AA). of iPP in the composites increased with increasing nano-CaCOs content, and it was further increased by the addition of PP-g-AA. Recently, composites of iPP with 1 wt% and 3 wt% of nanosized calcium carbonate, both calcite and aragonite, coated either with PP-g-MA or fatty acids were... 

This chapter provides a snapshot of the current status of the rapidly developing science and technology in the field of polymer/CaCOs nanocomposites, which includes preparation and modification of nano-CaCOs,... 

Particle size distributions of nano-CaCOs prepared by different methods (a) by HGRPand (b) by conventional precipitation. Reprinted with permission from ref. 10 (Figure 9). Copyright (2000) American Chemical Society. 

It is worth noting that this cost-effective HGRP technology has been commercialized in China and Singapore recently, which led to massive production of nano-CaCOs with narrow size distribution at relatively low cost and spurred more intensive research on polymer/CaCOs nanocomposites. 

In the second case, Lorenzo et al. prepared poly(ethylene terephthalate) (PET)/ CaCOs nanocomposites via in-situ polymerization, and the effects of surface treatment on the dispersion morphology and thermal behavior of the nanocomposites were studied. For untreated nano-CaCOs, a large number of very small discrete particles were observed. For the nanocomposites with stearic acid treated nano-CaCOs the discrete particles were still evident, but they were better welded to the PET matrix, suggesting that the stearic acid coating improves adhesion between the nano-CaCOs and the PET matrix. The improved compatibility between the phases is probably due to the hydrophobic characteristics of the treated nano-CaCOs imparted by the stearic acid coating. 

To obtain the required homogeneous dispersion of the nanoparticles, the PMMA polymerization process has been modified and performed in two steps as follows. The acrylic monomer, in which the organic peroxide was previously dissolved, and the nano-CaCOs particles were added to a cylindrical reactor. The reaction was carried out under vigorous stirring at 100°C until viscosity of the mixture reaches a critical value. In this step, pre-polymerization of the acrylic monomer in the presence of the nanoparticles occurred. It was observed that the time to the point of critical viscosity of the solution depended on the amount of nanoparticles. In the second step, the mixture was put into a mold and kept in an oven at 100°C for 24 h to complete the polymerization process. As a result, the nanoparticles were fairly homogeneously dispersed in the PMMA matrix, even at relatively high contents of nanoparticles, with size of 40-70 nm. 

Chen et al. prepared PVC/nano-CaCOs and PVC/acrylonitrile-butadiene-styrene terpolymer (ABSj/nano-CaCOs composites by melt-mixing different concentrations of stearic acid modified nano-CaCOs with the matrices in a highspeed two-roll mixer at different processing temperatures. TEM study revealed that the nano-CaCOs particles with size of 30-45 nm were dispersed uniformly at nanometer-scale in both PVC and the PVC/ABS blend. In particular a monodispersion of nano-CaCOs in the PVC matrix was observed at filler content of lOphr. This is a rare example where nano-CaCOs can achieve truly mono-... 

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