Nanocomposites of poly(vinyl chloride) and nanometric calcium carbonate particles: Effects of chlorinated polyethylene on mechanical properties,morphology, and rheology

Nanocomposites of poly(vinyl chloride) (PVC) and nano‐calcium carbonate (CaCO₃) particles were prepared via melt blending, and chlorinated polyethylene (CPE) as an interfacial modifier was also introduced into the nanocomposites through preparing CPE/nano‐CaCO₃ master batch. The mechanical properties, morphology, and rheology were studied. A moderate toughening effect was observed for PVC/nano‐CaCO₃ binary nanocomposites. The elongation at break and Young's modulus also increased with increasing the nano‐CaCO₃ concentration. Transmission electron microscopy (TEM) study demonstrated that the nano‐CaCO₃ particles were dispersed in a PVC matrix uniformly, and a few nanoparticles agglomeration was found. The toughening effect of the nano‐CaCO₃ particles on PVC could be attributed to the cavitation of the matrix, which consumed tremendous fracture energy. The notched Izod impact strength achieved a significant improvement by incorporating CPE into the nanocomposites, and obtained the high value of 745 J/m. Morphology investigation indicated that the nano‐CaCO₃ particles in the PVC matrix was encapsulated with a CPE layer through preparing the CPE/nano‐CaCO₃ master batch. The evaluation of rheological properties revealed that the introduction of nano‐CaCO₃ particles into PVC resulted in a remarkable increase in the melt viscosity. However, the viscosity decreased with addition of CPE, especially at high shear rates; thus, the processability of the ternary nanocomposites was improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2714–2723, 2004     

The influence of the different modifying agents on the synthesis of poly(methylmethacrylate)‐calcium carbonate nanocomposites via soapless emulsion polymerization

The synthesis of poly(methylmethacrylate)‐calcium carbonate nanocomposites via the soapless emulsion polymerization was investigated after the CaCO₃ nanoparticles were modified with different modifying agents. Such three kinds of modifying agents as sodium stearate (SS), oleic acid (OA), and PMMA were used to improve the surface property of CaCO₃ nanoparticles. What was the most important factor to improve the amount of nanoparticles in the composites is one of the general goals. As determined by Field‐emission scanning electron microscopy (FESEM), the nanocomposites size of the diluted polymer emulsion was over 250 nm, while the sample without CaCO₃ had a diameter of about 150 nm. It was worth pointing out that the surface morphology of polymer changed from slick to scraggy, when the nano‐CaCO₃ particles participated in the polymerization process. The increase of the droplet size and the change of the polymer morphology indicated that the CaCO₃ nanoparticles were present in the emulsion droplets. The X‐ray diffraction results of the nanocomposites showed the existence of typical calcite peaks. The results of the TGA, FTIR, and the contact angles indicated that the hydrophobic surface of CaCO₃ nanoparticles was crucial to improve the compatibility between the CaCO₃ and MMA monomer in emulsion system. The results of the TGA, FTIR, and the contact angles indicated that the hydrophobic surface of CaCO₃ nanoparticles was crucial to improve the compatibility between the CaCO₃ and MMA monomer in emulsion system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

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

Nonisothermal 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 Z_c 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     

The experimental results and simulation of temperature dependence of brittle‐ductile transition in PVC/CPE blends and PVC/CPE/nano‐CaCO3 composites

The effect of chlorinated polyethylene (CPE) content and test temperature on the notched Izod impact strength and brittle‐ductile transition behaviors for polyvinylchloride (PVC)/CPE blends and PVC/CPE/nano‐CaCO₃ ternary composites is studied. The CPE content and the test temperature regions are from 0–50 phr and 243–363 K, respectively. It is found that the optimum nano‐CaCO₃ content is 15 phr for PVC/CPE/nano‐CaCO₃ ternary composites. For both PVC/CPE blends and PVC/CPE/nano‐CaCO₃ ternary composites, the impact strength is improved remarkably when the CPE content or test temperature is higher than the critical value, that is, brittle‐ductile transition content (C_BD) or brittle‐ductile transition temperature (T_BD). The T_BD is closely related to the CPE content, the higher the CPE content, the lower the T_BD. The temperature dependence of impact strength for PVC/CPE blends and PVC/CPE/nano‐CaCO₃ ternary composites can be well simulated with a logistic fitting model, and the simulation results can be illustrated with the percolation model proposed by Wu and Jiang. DMA results reveal that both PVC and CPE can affect the T_BD of PVC/CPE blends and PVC/CPE/nano‐CaCO₃ composites. When the CPE content is enough (20 phr), the CPE is more important than PVC for determining the T_BD of PVC/CPE blends and PVC/CPE/nano‐CaCO₃ composites. Scanning electron microscopy (SEM) observations reveal that the impact fractured mechanism can change from brittle to ductile with increasing test temperature for these PVC systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polystyrene/calcium carbonate nanocomposites prepared by in situ polymerization in the presence of maleic anhydride

Polystyrene (PS)/calcium carbonate (CaCO₃) nanocomposites were prepared by in situ polymerization in the presence of maleic anhydride (MA). The composites were characterized by Fourier transform infrared spectra, gel permeation chromatography, differential scanning calorimetry, controlled stress rheometer, scanning electron microscope (SEM), small‐angle X‐ray scattering (SAXS), and mechanical test. Results show that the copolymer of styrene (St) and MA formed during the polymerization acts as a compatibilizer between PS and nanometer calcium carbonate (nano‐CaCO₃) particles, resulting in an increase in the glass transition temperature of the composite. The complex modulus and the impact strength of the PS/nano‐CaCO₃ composite show an increase with the addition of MA on account of the enhanced interfacial adhesion and the increased molecular weight. SEM and SAXS analyses indicate that a finer dispersion of nanoparticles and an increased homogeneity of the PS/nano‐CaCO₃ composites are obtained with application of a small amount of MA. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci., 2013     

Comparative study of the mechanical and flame‐retarding properties of polybutadiene rubber filled with nanoparticles and fly ash

A comparative study was performed of fly ash and nano‐CaCO₃ as fillers in polybutadiene rubber with 0, 4, 8 and 12% fly ash and nano‐CaCO₃. Uniform sheets were prepared of well‐compounded rubber. Nano‐CaCO₃ was synthesized by in situ deposition. The CaCO₃ nanoparticles as reinforcing agents improved the tensile strength more than 50% than fly ash, and the toughness and hardness also increased significantly. Up to a 75% reduction in flammability and a 100% improvement in the tear strength were observed with nano‐CaCO₃.© 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 6–9, 2005     

Toughening and reinforcement of rigid PVC with silicone rubber/nano‐CACO3 shell‐core structured fillers

To improve the mechanical properties and structure of poly(vinyl chloride) (PVC)/nano‐CaCO₃ nano composite, a core (nano‐CaCO₃)/shell (SR) structured filler (40–60 nm) was successfully prepared by refluxing methyl vinyl silicone rubber (SR) and nano‐CaCO₃ particles (coupling agent KH550, KH560, or NDZ‐101 as interfacial modifier) in toluene with vigorous stirring, according to an encapsulation model. It is effective in rigid PVC composite's toughness and reinforcement. The interfacial modifier's structure and interaction of nanocomposites of PVC/SR/nano‐CaCO₃ were studied. The results indicate that KH560 has the optimal interfacial modificatory effect. The environmental scanning electron microscope (ESEM) study testified that PVC/SR/nano‐CaCO₃ nanocomposites had a typical rubber–plastics‐toughening mechanism. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2560–2567, 2006     

Crystallization kinetics of polypropylene composites filled with nano calcium carbonate modified with maleic anhydride

The subject of this study was the crystallization behavior and thermal properties of polypropylene (PP)/maleic anhydride (MAH) modified nano calcium carbonate (nano‐CaCO₃) composites. In this study, 5 wt % nano‐CaCO₃ modified with different contents of MAH was filled into a PP matrix. X‐ray diffraction and differential scanning calorimetry were used to characterize the crystal morphology and crystallization kinetics of a series of composites. The results demonstrate that the nano‐CaCO₃ modified with MAH had an important effect on the thermal and morphological properties of the nanocomposites. The Avrami exponent of the pure PP was an integer, but those of the composites were not integers, but the crystallization rate constant decreased as the content of MAH in the nano‐CaCO₃ filler increased in isothermal crystallization. In nonisothermal crystallization, the kinetic parameter F(T) and the degree of crystallinity of pure PP were compared with those of the PP composites filled with nano‐CaCO₃. We suggest that heterogeneous nucleation existed in the PP composites and that the transformation and retention of the β‐form crystal into the α‐form crystal took place in the composite system and the β‐form crystal had a higher nucleation rate and growth process than the α‐form crystal in the PP composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of poly(propylene carbonate)/nano calcium carbonate composites and their supercritical carbon dioxide foaming behavior

Biodegradable polymer foams are attracting extensive attention in both academic and industrial fields. In this study, an emerging biodegradable polymer, poly(propylene carbonate) (PPC), was compounded with nano calcium carbonate (nano‐CaCO₃) and foamed via supercritical carbon dioxide for the first time. Four concentrations of nano‐CaCO₃, 1, 3, 5, and 10 wt %, were used and the thermal properties of PPC/nano‐CaCO₃ composites were investigated. The glass‐transition temperature and thermal decomposition temperature of the PPC/nano‐CaCO₃ composites increased with the addition of nano‐CaCO₃. The morphologies of the PPC/nano‐CaCO₃ composites and the rheological results showed that homogeneous dispersions of nano‐CaCO₃ and percolated nano‐CaCO₃ networks were achieved at a nano‐CaCO₃ content of 3 wt %. Therefore, the finest cell diameter (3.13 μm) and highest cell density (6.02 × 10⁹ cells/cm³) were obtained at the same nano‐CaCO₃ content. The cell structure dependences of PPC and PPC with a nano‐CaCO₃ content of 3 wt % (PPC‐3) foams on the foaming pressure and temperature were investigated as well. The results suggested that the cell structure of PPC‐3 was more stable at different foaming conditions due to the networks of nano‐CaCO₃. Moreover, the change in pressure was more influential on the cell structure than the temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42248.     

Morphology and properties of PP/EPDM binary blends and PP/EPDM/nano‐CaCO3 ternary blends

In this article, the morphology, crystallization, and rheological behaviors of polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) binary blend and PP/EPDM/calcium carbonate nanoparticles (nano‐CaCO₃) ternary blend were investigated. Two processing methods, i.e., direct extrusion and two‐step extrusion, were employed to prepare the PP/EPDM/CaCO₃ blend. The influence of EPDM and nano‐CaCO₃ respectively on phase morphology and properties of PP/EPDM blend and PP/EPDM/CaCO₃ blend were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and dynamic rheometer. The crystallinity and crystallization temperature of PP/EPDM blend were improved in comparison to pure PP due to addition of EPDM, but kept invariable with the increased EPDM loading. As the EPDM content was increased, the mobility of PP molecular chains was weakened. Compared with direct extruded blend, less and finer nano‐CaCO₃ was dispersed in matrix of two‐step extruded blend. Accordingly, the increased nano‐CaCO₃ in matrix gave rise to a weaker increment in crystallinity and crystallization temperature of two‐step extruded blend, and a later platform of tanδ curve. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of surface modifiers and surface modification methods on properties of acrylonitrile–butadiene–styrene/poly(methyl methacrylate)/nano‐calcium carbonate composites

Nano‐calcium carbonate (nano‐CaCO₃) was used in this article to fill acrylonitrile–butadiene–styrene (ABS)/poly(methyl methacrylate) (PMMA), which is often used in rapid heat cycle molding process (RHCM). To achieve better adhesion between nano‐CaCO₃ and ABS/PMMA, nano‐CaCO₃ particles were modified by using titanate coupling agent, aluminum–titanium compound coupling agent, and stearic acid. Dry and solution methods were both utilized in the surface modification process. ABS/PMMA/nano‐CaCO₃ composites were prepared in a corotating twin screw extruder. Influence of surface modifiers and surface modification methods on mechanical and flow properties of composites was analyzed. The results showed that collaborative use of aluminum–titanium compound coupling agent and stearic acid for nano‐CaCO₃ surface modification is optimal in ABS/PMMA/nano‐CaCO₃ composites. Coupling agent can increase the melt flow index (MFI) and tensile yield strength of ABS/PMMA/nano‐CaCO₃ composites. The Izod impact strength of composites increases with the addition of titanate coupling agent up to 1 wt %, thereafter the Izod impact strength shows a decrease. The interfacial adhesion between nano‐CaCO₃ and ABS/PMMA is stronger by using solution method. But the dispersion uniformity of nano‐CaCO₃ modified by solution method is worse. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The preparation of core‐shell CaCO3 particles and its effect on mechanical property of PVC composites

In this study, a novel mechanochemical route to prepare core‐shell structured particles was introduced. XPS, TEM, and dissolving experimental results indicate the formation of [(inorganic particle)/(elastomer)] core‐shell structured particles, and several kinds of calcium carbonate (nano‐CaCO₃) particles with various interfaces were obtained. The mechanical properties and morphological results indicate that the surface treatment of nano‐CaCO₃ particles and the existence of outer elastic layer will strengthen the interfacial interaction between nano‐CaCO₃ particles and PVC matrix, which results in improvement of mechanical properties of PVC/CaCO₃ composites. The theoretical calculations of the interfacial interaction and DMA results confirm these especially when the surface of nano‐CaCO₃ particles was treated by MMA and coated in succession by ACR through vibro‐milling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1084–1091, 2006     

Preparation of epoxy resin/CaCO3 nanocomposites and performance of resultant powder coatings

Epoxy resin/CaCO₃ nanocomposites were prepared by the methods of extruding, solution blending, and in situ and inclusion polymerization, respectively. The contents of nanoparticles in the nanocomposites were varied from 5 wt % to 15 wt %. Powder coatings with different content of nanoparticles were made from the nanocomposites. The results showed that the cupping property and impact resistance decreased with the increase of coating film thickness. The dispersion of nanoparticles in epoxy matrix affected the impact resistance and cupping property of the obtained coating films greatly. The coating films made from the nanocomposite prepared by in situ and inclusion polymerization showed that the best impact resistance and the maximum cupping property was achieved when nano‐CaCO₃ content was 5 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2656–2660, 2006     

A novel highly efficient β‐nucleating agent for polypropylene using nano‐CaCO3 as a support

In order to increase the isotactic content of β‐nucleated polypropylene (β‐iPP) and decrease the cost of its production, the investigation and development of novel highly efficient β‐nucleators are important issues. Nano‐CaCO₃ was used as a support to prepare a supported β‐nucleator, nano‐CaCO₃‐supported calcium pimelate. Fourier transform infrared spectral analysis shows that an in situ chemical reaction takes place between nano‐CaCO₃ and pimelic acid. Differential scanning calorimetry results indicate that the crystallization and melting temperatures of β‐phase in supported β‐nucleator‐nucleated iPP are higher than those of calcium pimelate‐nucleated iPP. The β‐nucleating ability of the supported β‐nucleator is little influenced by the cooling rate and crystallization temperature over a wide range. The decreased content of pimelic acid in the supported β‐nucleator slightly decreases the crystallization temperature of iPP but it has no influence on the content of β‐phase in nucleated iPP. A novel supported β‐nucleator has been successfully synthesized via pimelic acid supported on the surface of CaCO₃. The crystallization temperature of iPP and melting temperature of β‐phase in iPP nucleated using the supported β‐nucleator are higher than those of iPP nucleated using calcium pimelate. The concept of a supported nucleator will provide a new way to increase the efficiency of polymer additives and to decrease the amounts of them that need to be used by using nanoparticles as supports. Copyright © 2010 Society of Chemical Industry     

Production of nano‐calcium carbonate from shells of the freshwater channeled applesnail,Pomacea canaliculata,by hydrothermal treatment and its application with polyvinyl chloride

The use of naturally renewable shells of the freshwater channeled applesnail, Pomacea canaliculata, as a filler to replace commercial calcium carbonate (CaCO₃) was investigated in this study. Ground P. canaliculata shell particles were converted to nano‐CaCO₃ particles by the displacement reaction of calcium chloride in sodium carbonate solution followed by hydrothermal treatment at 100°C for 1 h to synthesize nano‐CaCO₃ with particle sizes of 30–100 nm in diameter. The mechanical properties, in terms of the tensile strength, elongation at brake and impact strength, of polyvinyl chloride (PVC) were greatly improved by mixing with nano‐CaCO₃ at 5–10 parts per hundred of resin. Additionally, the presence of nano‐CaCO₃ at the same levels increased the flame resistance and thermal stability of the PVC composite materials. POLYM. COMPOS., 36:1620–1628, 2015. © 2014 Society of Plastics Engineers     

Kinetics of thermal degradation of nanometer calcium carbonate/linear low‐density polyethylene nanocomposites

To improve the thermal properties of linear low‐density polyethylene (LLDPE), the CaCO₃/LLDPE nanocomposites were prepared from nanometer calcium carbonate (nano‐CaCO₃) and LLDPE by melt‐blending method. A series of testing methods such as thermogravimetry analysis (TGA), differential thermogravimetry analysis, Kim‐Park method, and Flynn‐Wall‐Ozawa method were used to characterize the thermal property of CaCO₃/LLDPE nanocomposites. The results showed that the CaCO₃/LLDPE nanocomposites have only one‐stage thermal degradation process. The initial thermal degradation temperature T₀ increasing with nano‐CaDO₃ content, and stability of LLDPE change better. The thermal degradation activation energy (E_a) is different for different nano‐CaCO₃ content. When the mass fraction of nano‐CaCO₃ in nanocomposites is up to 10 wt %, the nanocomposite has the highest thermal degradation E_a, which is higher (28 kJ/mol) than pure LLDPE. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Impact‐toughening mechanisms of calcium carbonate‐reinforced polypropylene nanocomposite

The impact fracture mechanisms of polypropylene (PP), containing 9.2 vol % of calcium carbonate (CaCO₃) nanoparticles, were investigated using optical microscopy and transmission electron microscopy. The incorporation of CaCO₃ nanoparticles reduces the size of spherulites and induces the formation of β‐phase crystallites, which leads to a more ductile PP matrix. Double‐notch four‐point bending (DN‐4PB) Charpy impact specimens and notched Izod impact specimens were utilized to study the fracture mechanism(s) responsible for the observed toughening effect. A detailed investigation reveals that the CaCO₃ nanoparticles act as stress concentrators to initiate massive crazes, followed by shear banding in PP matrix. These toughening mechanisms are responsible for the observed, improved impact strength. A comparison of the fracture mechanisms observed between DN‐4PB Charpy and Izod impact tests is also made to show the effectiveness of DN‐4PB for investigation of impact fracture mechanisms of polymeric systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3070–3076, 2006     

Preparation and characterization of injection‐homo‐polypropylene filled with nano‐CaCO3

Nano‐CaCO₃/homo‐PP composites were prepared by melt‐blending using twin‐screw extruder. The results show that not only the impact property but also the bending modulus of the system have been evidently increased by adding nano‐CaCO₃. The nano‐CaCO₃ particles have been dispersed in the matrix in the nanometer scale which was investigated by means of transmission electron microscopy (TEM). The toughening mechanism of nano‐CaCO₃, investigated by means of dynamical mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM), lies on that the nano‐CaCO₃ particles take an action of initiating and terminating crazing (silver streak), which can absorb more impact energy than the neat PP. At the same time, the nano‐CaCO₃ particles, as the nuclear, decrease the crystal size of PP, the results of which were investigated by means of polarized optical microscope (POM). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synergistic reinforcement of NBR by hybrid filler system including organoclay and nano‐CaCO3

Rubber nanocomposites containing one type of nanofiller are common and are widely established in the research field. In this study, nitrile rubber (NBR) based ternary nanocomposites containing modified silicate (Cloisite 30B) and also nano‐calcium carbonate (nano‐CaCO₃) were prepared using a laboratory internal mixer (simple melt mixing). Effects of the hybrid filler system (filler phase have two kind of fillers) on the cure rheometry, morphology, swelling, and mechanical and dynamic–mechanical properties of the NBR were investigated. Concentration of nano‐CaCO₃ [0, 5, 10, and 15 parts per one hundred parts of rubber by weight (phr)] and organoclay (0, 3, and 6 phr) in NBR was varied. The microstructure and homogeneity of the compounds were confirmed by studying the dispersion of nanoparticles in NBR via X‐ray diffraction and field emission scanning electron microscopy. Based on the results of morphology and mechanical properties, the dual‐filler phase nanocomposites (hybrid nanocomposite) have higher performance in comparison with single‐filler phase nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42744.     

Synthesis of CaCO3–P(MMA–BA) nanocomposite and its application in water based alkyd emulsion coating

As part of broader effort to synthesize a new class of water-based composite, hybrid emulsion polymerization was carried out with acrylic monomers [methyl methacrylate (MMA), n-butyl acrylate (BA)]. Nanocomposite of P(MMA–BA)/nano CaCO₃ was synthesized by in situ emulsion polymerization. Water-based alkyd coating with various proportions nano CaCO₃, P(MMA–BA) and its nanocomposite was formulated. Extent of polymerization with and without nano CaCO₃ was measured using gravimetric method. Thermal properties of neat polymer, nanocomposite and coating films were evaluated by TGA and DSC, DTA analysis. Uniform dispersion of nano CaCO₃ in polymer matrix was ensured from SEM/TEM images. Incorporation of nanoparticles to hybrid polymer and nanocomposite to alkyd emulsion showed significant enhancement in mechanical and thermal properties. Dual role of nanocomposite in coating; as a partial binder and a filler to improve property profile of neat coating has been reported.