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calcium carbonate nanocomposites prepared by melt-compounding
Materials Letters 60 (2006) 1035 – 1038 www.elsevier.com/locate/matlet
Rheology enhancement of polycarbonate/calcium carbonate nanocomposites prepared by melt-compounding Zhaobo Wang ⁎, Guangwen Xie, Xin Wang, Guicun Li, Zhikun Zhang ⁎ Key Laboratory of Nanostructured Materials, Qingdao University of Science and Technology, No. 53 Zhengzhou Road, Qingdao 266042, P.R. China Received 27 April 2005; accepted 19 October 2005 Available online 10 November 2005
Abstract The focus of the letter is to investigate the influence of calcium carbonate (CaCO3) nanoparticles on the rheology enhancement of polycarbonate (PC) melt. The PC/CaCO3 nanocomposites with different compositions of CaCO3 were prepared by melt-compounding. Characterizations via energy-dispersive X-ray spectrometer (EDS) and field-emission scanning electron microscopy (FE-SEM) confirm the random dispersion of CaCO3 in the PC/CaCO3 masterbatch. The rheological experiments investigated with Rosand Presicion Rheometer show the remarkable rheology enhancement of PC melt due to the addition of CaCO3 nanoparticles. Mechanical tests show that, upon incorporation of only 1 wt.% CaCO3, the tensile modulus, the bending modulus, and the bending strength of PC are improved; however, the tensile strength and elongation at break are depressed. © 2005 Elsevier B.V. All rights reserved. Keywords: Polycarbonate; Calcium carbonate; Nanocomposites; Rheology; Mechanical properties
1. Introduction Amorphous polycarbonate (PC) is one of the most important engineering thermoplastics in a wide variety of applications, distinguished by its versatile combination of toughness, transparency, heat resistance [1]. However, the limitations of PC, such as high notch sensitivity, high melt viscosity, and poor chemical resistance, need to be improved to extend its engineering applications [2]. With the current growth in the automotive market, part molders are demanding more processable materials to meet the supply requirements. In addition, in the durable goods sector, parts are also getting thinner and would require materials that can be processed more easily. From the fabricator's point of view, easy flow is related directly to productivity. Therefore, the challenge to PC is to provide with a modest flow while maintaining toughness and heat properties. In order to improve its processability, it is generally blended with acrylonitrile–butadiene–styrene copolymer (ABS) for commercial use [3,4]. However, these PC/
⁎ Corresponding authors. Fax: +86 532 84022869. E-mail address: [email protected] (Z. Wang). 0167-577X/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2005.10.070
ABS blends have two main drawbacks. In a typical PC/ABS blend, the interfacial adhesion is not strong enough because PC blends with SAN are not miscible; this results in the limit of the application [5,6]. The other problem stems from the aging of butadiene rubber in ABS, which results in a continuous decline in the mechanical strength and color change [7]. Therefore, the improvements in the interfacial adhesion and the reduction of aging are essential for broadening the applications of PC/ABS blends. Recently, there is much interest in composites consisting of nanoparticles in organic matrices because of their interesting properties [8]. In polymer based nanocomposites, the aggregation problem of nanoparticles presents a major challenge irrespective of the method of composite preparation. In the context of industrial applications, melt-compounding is the preferred method of composite preparation. Generally, the masterbatches of polymer–nanoparticles composites are often used as the starting materials, which are diluted by the pure polymer in a subsequent melt-compounding process [9]. In this letter, we report the rheology enhancement of PC/CaCO3 nanocomposites prepared by melt-compounding, as well as the dispersion morphology of CaCO3 nanoparticles and the mechanical properties of nanocomposites.
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Z. Wang et al. / Materials Letters 60 (2006) 1035–1038
2. Experimental
3. Results and results
2.1. Materials
Fig. 1 presents the dispersion of CaCO3 in PC/CaCO3 masterbatch. Fig. 1a shows the EDS composition distribution map of Ca element on the surface of masterbatch. The white dots are the X radial signals radiated from Ca element. It is found that the dispersion of CaCO3 in PC matrix is random on the whole due to the melt-compounding process. The dispersion morphology of CaCO3 nanoparticles is shown in Fig. 1b. Most CaCO3 nanoparticles are monodipersed in the ambient PC matrix, while some CaCO3 nanoparticles are dispersed in the form of small agglomerated particles, with average diameter of 100–250 nm. These slight agglomerated particles in masterbatch will be dispersed in the latter dilution by melt-compounding. Fig. 2 shows the flow curves of neat PC and PC/CaCO3 nanocomposites with different compositions of CaCO3. Form Fig. 2a, we can understand that the flow curves of neat PC exhibit weak pseudoplastic flow behavior; the apparent viscosity only decreases slightly with increasing shear rate. Generally, PC is attributed to rigid polymer owing to the numerous aryl groups in the primary chains and this leads to the high flow activation energy of PC melt; moreover, the melt viscosity is more sensitive to the variation of temperature. Compared to the influence of increasing shear rate on rheology behavior, the increasing temperature shows a strong influence on the rheology enhancement of PC melt. Interestingly, the apparent viscosity in Fig. 2b decreases sharply with the CaCO3 loading, indicating the rheological behavior of PC melt can be regulated by the addition of CaCO3 inorganic nanoparticles. By comparing the rheology curves in Fig. 2, we can easily understand that the effect of 1 wt.% CaCO3 addition on apparent viscosity is equivalent to that of 10 °C temperature increment on apparent viscosity. The addition of CaCO3 nanoparticles certainly endows PC melt with rheology enhancement.
PC (Grade 110) used in this study was product of Chi Mei Corporation, Taiwan. CaCO3 nanoparticles with the average primary particle size 80 nm were provided by ShengDa Powder Company, China. All starting materials were used as received. 2.2. Preparation of PC/CaCO3 nanocomposites PC pellets and CaCO3 nanoparticles were dried for 8 h at 120 °C and 100 °C, respectively, before melt-compounding. A masterbatch of PC–CaCO3 containing 8 wt.% CaCO3 was prepared via a melt-compounding method using a Brabender twin-screw extruder (ZKS-25, Krupp Werner and Pfleiderer GmbH, Germany) at 250 °C with a screw speed of 80 rpm. CaCO3 nanoparticles were directly dispersed in PC matrix without any surface modification. The prepared masterbatch was diluted with different amount of PC to obtain different composition of CaCO3. The nanocomposites pellets were fabricated into standard testing bars using an injection-molding machine (model J110EL-β, Steel Works Ltd., Japan). The barrel temperature was set at 250 °C and the mold temperature at 80 °C. 2.3. Characterization The dispersion morphology of CaCO3 in nanocomposites was observed on FE-SEM (JEOL-6700F, Japan Electron Co. Ltd.). Before SEM imaging, the samples were sputtered with thin layers of gold. Calcium (Ca) element distribution on the surface of masterbatch was measured by energy-dispersive Xray microanalysis system (Oxford Instrument, U.K.). The rheological behaviors of PC and nanocomposites were measured in Rosand Precision Rheometer (Bohilin Instrument, U.K.) in the Double-bore experiment mode. The L/D ratio of the capillary in one bore was 16/1, while the orifice die in another bore was zero length capillary. Experimental results were processed by the software afforded by Bohilin Instrument, and all the rheology data obtained were Bagley and Rabinowitch calibrated. Tensile and bending tests were conducted on a H10KS-0282 universal testing machine (Hounsfield Test Equipment, England) according to ISO 527 and ISO 178, respectively. The crosshead speed in tensile and bending tests were 10 mm/min and 2 mm/min, respectively. The tests were carried out at room temperature, and the data obtained represented the average value from 5 test specimens. Glass transition temperature (Tg) was investigated with a 449C differential scanning calorimetry (DSC) instrument (Netzsch STA Instrument, Germany) under a nitrogen atmosphere. The specimens were initially heated to 200 °C at a rate of 20 °C/min. The Tg is determined by fitting straight lines to the DSC curve before, during, and after the transition and taking the points of intersection as the onset and endpoint of the transition. The Tg is then located at one-half the change in heat capacity between the onset and endpoint.
Fig. 1. The dispersion of CaCO3 in the PC/CaCO3 masterbatch (CaCO3 wt.% = 8). (a) EDS composition distribution map of Ca element. (b) Dispersion morphology of CaCO3 nanoparticles.
Z. Wang et al. / Materials Letters 60 (2006) 1035–1038
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Table 1 Summary of mechanical properties of neat PC and its nanocomposite containing 1 wt.% CaCO3 nanoparticles
Elastic modulus (MPa) Tensile strength a (MPa) Tensile strength b (MPa) Elongation at break (%) Bending modulus (MPa) Bending strength (MPa) a b
Fig. 2. Flow curves of neat PC and PC/CaCO3 nanocomposites. (a) Flow curves of neat PC at various temperature. (b) The influence of CaCO3 content on the rheology.
In this research, the interaction which govern the interface region of nanocomposites is actually weak van der Waals forces due to the absence of surface modification of CaCO3. Therefore, the PC polymer chains in interface region have less restriction than the PC polymer chains in matrix. Moreover, the increasing interfacial area in nanocomposites increases the fraction of polymer chains located in interfacial region significantly. In some cases, the increased resin–filler interface in polymer based nanocomposites created extra free volume and, therefore, assisted the large-scale segmental mobility of the polymer-chain
Neat PC
PC/CaCO3 (99/1) composite
627.65 87.20 86.18 165.06 2211 81.56
728.28 91.29 72.80 63.32 2536 90.12
Strength at yield. Strength at break.
segments and led to the decrease of Tg [10–12]. The Tg values of neat PC and PC/CaCO3 nanocomposite comprising 1 wt.% CaCO3 are 150.5 °C and 144.4 °C, respectively, indicating the enhanced dynamics of PC polymer chains in nanocomposites. The enhanced dynamics of PC polymer chains will result in the obvious decrease of apparent viscosity of PC melt, which has been confirmed by the variation of rheological curves in Fig. 2. The microstructure of polymer nanocomposites in the glassy state is of fundamental importance for the macroscopic behavior of nanocomposites. Typical stress–strain curves for neat PC and PC/CaCO3 composite are shown in Fig. 3. A pronounced yield and postyield drop are observed in the curves. It can be seen that addition of CaCO3 nanoparticles slightly changes the mechanical properties of PC, as summarized in Table 1. Upon incorporation of only 1 wt.% CaCO3, the elastic modulus, the tensile strength (at yield), the bending strength and bending modulus of PC are improved by about 16%, 5%,10.5% and 15%, respectively. The slight decrease of tensile strength at break illustrates the weak interaction between CaCO3 nanoparticles and PC matrix. The elongation at break decreases remarkably, indicating that the composite becomes somewhat brittle compared with neat PC. The variation in elongation of PC/CaCO3 nanocomposites is similar to that of PA/MWNTs nanocomposites reported in literature [13]. The decrease in the toughness of PC matrix can also be seen easily as measured by the area under the stress–strain curves in Fig. 3. Shah et al. [14] reported that, when testing was performed at a temperature below the Tg of the polymer, the nanoparticles in the polymer nanocomposites were not allowed to move and, therefore, the nanoparticles could not provide an additional energy-dissipating mechanism. The restricted mobility of CaCO3 nanoparticles in PC/CaCO3 nanocomposites can initiate crack formation and ultimately lead to somewhat brittle behavior.
4. Conclusion In summary, PC/CaCO3 nanocomposites with different compositions of CaCO3 were prepared by melt-compounding. The rheological experiments show the remarkable rheology enhancement of PC melt due to the introduction of CaCO3 nanoparticles. Characterizations via EDS and FE-SEM confirm the random dispersion of CaCO3 in masterbatch. Mechanical tests show that, incorporating 1 wt.% CaCO3, most properties of PC are improved slightly while the tensile strength and elongation at break are depressed. Acknowledgement
Fig. 3. Stress–strain curves for neat PC and PC/CaCO3 nanocomposites.
This research was supported by National 863 foundation of China under contract No. 2002AA30B613.
1038
Z. Wang et al. / Materials Letters 60 (2006) 1035–1038
References [1] H.T. Pham, C.L. Weckle, J.M. Ceraso, Adv. Mater. 12 (2000) 1881. [2] S. Balakrishnan, N.R. Neelakantan, S.N. Jaisankar, J. Appl. Polym. Sci. 74 (1999) 2102. [3] L.S. Dong, R. Greco, G. Orsello, Polymer 34 (1993) 1375. [4] D. Quentens, G. Groeninckx, M. Guest, L. Aerts, Polym. Eng. Sci. 31 (1991) 1207. [5] E.A. Kang, J.H. Kim, C.K. Kim, H.W. Rhee, S.Y. Oh, Polym. Eng. Sci. 40 (2000) 2374. [6] J.H. Kim, C.K. Kim, J. Appl. Polym. Sci. 89 (2003) 2649. [7] Y.S. Seo, J.H. Kim, C.K. Kim, R. Lee, J.K. Keum, J. Appl. Polym. Sci. 96 (2005) 2097.
[8] K.K. Koziol, K. Dolgner, N. Tsuboi, J. Kruse, V. Zaporojtchenko, S. Deki, F. Faupel, Macromolecules 37 (2004) 2182. [9] P. Potschke, T.D. Fornes, D.R. Paul, Polymer 43 (2002) 3247. [10] B.J. Ash, L.S. Schadler, R.W. Siegel, Mater. Lett. 55 (2002) 83. [11] X. Wang, Z.B. Wang, Q.Y. Wu, J. Appl. Polym. Sci. 96 (2005) 802. [12] Y.Y. Sun, Z.Q. Zhang, K.S. Moon, C.P. Wong, J. Polym. Sci., Part B, Polym. Phys. 42 (2004) 3849. [13] W.D. Zhang, L. Shen, I.Y. Phang, T.X. Liu, Macromolecules 37 (2004) 256. [14] D. Shah, P. Maiti, D. Jiang, C.A. Batt, E.P. Giannelis, Adv. Mater. 17 (2005) 525.
Rheology enhancement of polycarbonate/calcium carbonate nanocomposites prepared by melt-compounding Zhaobo Wang ⁎, Guangwen Xie, Xin Wang, Guicun Li, Zhikun Zhang ⁎ Key Laboratory of Nanostructured Materials, Qingdao University of Science and Technology, No. 53 Zhengzhou Road, Qingdao 266042, P.R. China Received 27 April 2005; accepted 19 October 2005 Available online 10 November 2005
Abstract The focus of the letter is to investigate the influence of calcium carbonate (CaCO3) nanoparticles on the rheology enhancement of polycarbonate (PC) melt. The PC/CaCO3 nanocomposites with different compositions of CaCO3 were prepared by melt-compounding. Characterizations via energy-dispersive X-ray spectrometer (EDS) and field-emission scanning electron microscopy (FE-SEM) confirm the random dispersion of CaCO3 in the PC/CaCO3 masterbatch. The rheological experiments investigated with Rosand Presicion Rheometer show the remarkable rheology enhancement of PC melt due to the addition of CaCO3 nanoparticles. Mechanical tests show that, upon incorporation of only 1 wt.% CaCO3, the tensile modulus, the bending modulus, and the bending strength of PC are improved; however, the tensile strength and elongation at break are depressed. © 2005 Elsevier B.V. All rights reserved. Keywords: Polycarbonate; Calcium carbonate; Nanocomposites; Rheology; Mechanical properties
1. Introduction Amorphous polycarbonate (PC) is one of the most important engineering thermoplastics in a wide variety of applications, distinguished by its versatile combination of toughness, transparency, heat resistance [1]. However, the limitations of PC, such as high notch sensitivity, high melt viscosity, and poor chemical resistance, need to be improved to extend its engineering applications [2]. With the current growth in the automotive market, part molders are demanding more processable materials to meet the supply requirements. In addition, in the durable goods sector, parts are also getting thinner and would require materials that can be processed more easily. From the fabricator's point of view, easy flow is related directly to productivity. Therefore, the challenge to PC is to provide with a modest flow while maintaining toughness and heat properties. In order to improve its processability, it is generally blended with acrylonitrile–butadiene–styrene copolymer (ABS) for commercial use [3,4]. However, these PC/
⁎ Corresponding authors. Fax: +86 532 84022869. E-mail address: [email protected] (Z. Wang). 0167-577X/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2005.10.070
ABS blends have two main drawbacks. In a typical PC/ABS blend, the interfacial adhesion is not strong enough because PC blends with SAN are not miscible; this results in the limit of the application [5,6]. The other problem stems from the aging of butadiene rubber in ABS, which results in a continuous decline in the mechanical strength and color change [7]. Therefore, the improvements in the interfacial adhesion and the reduction of aging are essential for broadening the applications of PC/ABS blends. Recently, there is much interest in composites consisting of nanoparticles in organic matrices because of their interesting properties [8]. In polymer based nanocomposites, the aggregation problem of nanoparticles presents a major challenge irrespective of the method of composite preparation. In the context of industrial applications, melt-compounding is the preferred method of composite preparation. Generally, the masterbatches of polymer–nanoparticles composites are often used as the starting materials, which are diluted by the pure polymer in a subsequent melt-compounding process [9]. In this letter, we report the rheology enhancement of PC/CaCO3 nanocomposites prepared by melt-compounding, as well as the dispersion morphology of CaCO3 nanoparticles and the mechanical properties of nanocomposites.
1036
Z. Wang et al. / Materials Letters 60 (2006) 1035–1038
2. Experimental
3. Results and results
2.1. Materials
Fig. 1 presents the dispersion of CaCO3 in PC/CaCO3 masterbatch. Fig. 1a shows the EDS composition distribution map of Ca element on the surface of masterbatch. The white dots are the X radial signals radiated from Ca element. It is found that the dispersion of CaCO3 in PC matrix is random on the whole due to the melt-compounding process. The dispersion morphology of CaCO3 nanoparticles is shown in Fig. 1b. Most CaCO3 nanoparticles are monodipersed in the ambient PC matrix, while some CaCO3 nanoparticles are dispersed in the form of small agglomerated particles, with average diameter of 100–250 nm. These slight agglomerated particles in masterbatch will be dispersed in the latter dilution by melt-compounding. Fig. 2 shows the flow curves of neat PC and PC/CaCO3 nanocomposites with different compositions of CaCO3. Form Fig. 2a, we can understand that the flow curves of neat PC exhibit weak pseudoplastic flow behavior; the apparent viscosity only decreases slightly with increasing shear rate. Generally, PC is attributed to rigid polymer owing to the numerous aryl groups in the primary chains and this leads to the high flow activation energy of PC melt; moreover, the melt viscosity is more sensitive to the variation of temperature. Compared to the influence of increasing shear rate on rheology behavior, the increasing temperature shows a strong influence on the rheology enhancement of PC melt. Interestingly, the apparent viscosity in Fig. 2b decreases sharply with the CaCO3 loading, indicating the rheological behavior of PC melt can be regulated by the addition of CaCO3 inorganic nanoparticles. By comparing the rheology curves in Fig. 2, we can easily understand that the effect of 1 wt.% CaCO3 addition on apparent viscosity is equivalent to that of 10 °C temperature increment on apparent viscosity. The addition of CaCO3 nanoparticles certainly endows PC melt with rheology enhancement.
PC (Grade 110) used in this study was product of Chi Mei Corporation, Taiwan. CaCO3 nanoparticles with the average primary particle size 80 nm were provided by ShengDa Powder Company, China. All starting materials were used as received. 2.2. Preparation of PC/CaCO3 nanocomposites PC pellets and CaCO3 nanoparticles were dried for 8 h at 120 °C and 100 °C, respectively, before melt-compounding. A masterbatch of PC–CaCO3 containing 8 wt.% CaCO3 was prepared via a melt-compounding method using a Brabender twin-screw extruder (ZKS-25, Krupp Werner and Pfleiderer GmbH, Germany) at 250 °C with a screw speed of 80 rpm. CaCO3 nanoparticles were directly dispersed in PC matrix without any surface modification. The prepared masterbatch was diluted with different amount of PC to obtain different composition of CaCO3. The nanocomposites pellets were fabricated into standard testing bars using an injection-molding machine (model J110EL-β, Steel Works Ltd., Japan). The barrel temperature was set at 250 °C and the mold temperature at 80 °C. 2.3. Characterization The dispersion morphology of CaCO3 in nanocomposites was observed on FE-SEM (JEOL-6700F, Japan Electron Co. Ltd.). Before SEM imaging, the samples were sputtered with thin layers of gold. Calcium (Ca) element distribution on the surface of masterbatch was measured by energy-dispersive Xray microanalysis system (Oxford Instrument, U.K.). The rheological behaviors of PC and nanocomposites were measured in Rosand Precision Rheometer (Bohilin Instrument, U.K.) in the Double-bore experiment mode. The L/D ratio of the capillary in one bore was 16/1, while the orifice die in another bore was zero length capillary. Experimental results were processed by the software afforded by Bohilin Instrument, and all the rheology data obtained were Bagley and Rabinowitch calibrated. Tensile and bending tests were conducted on a H10KS-0282 universal testing machine (Hounsfield Test Equipment, England) according to ISO 527 and ISO 178, respectively. The crosshead speed in tensile and bending tests were 10 mm/min and 2 mm/min, respectively. The tests were carried out at room temperature, and the data obtained represented the average value from 5 test specimens. Glass transition temperature (Tg) was investigated with a 449C differential scanning calorimetry (DSC) instrument (Netzsch STA Instrument, Germany) under a nitrogen atmosphere. The specimens were initially heated to 200 °C at a rate of 20 °C/min. The Tg is determined by fitting straight lines to the DSC curve before, during, and after the transition and taking the points of intersection as the onset and endpoint of the transition. The Tg is then located at one-half the change in heat capacity between the onset and endpoint.
Fig. 1. The dispersion of CaCO3 in the PC/CaCO3 masterbatch (CaCO3 wt.% = 8). (a) EDS composition distribution map of Ca element. (b) Dispersion morphology of CaCO3 nanoparticles.
Z. Wang et al. / Materials Letters 60 (2006) 1035–1038
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Table 1 Summary of mechanical properties of neat PC and its nanocomposite containing 1 wt.% CaCO3 nanoparticles
Elastic modulus (MPa) Tensile strength a (MPa) Tensile strength b (MPa) Elongation at break (%) Bending modulus (MPa) Bending strength (MPa) a b
Fig. 2. Flow curves of neat PC and PC/CaCO3 nanocomposites. (a) Flow curves of neat PC at various temperature. (b) The influence of CaCO3 content on the rheology.
In this research, the interaction which govern the interface region of nanocomposites is actually weak van der Waals forces due to the absence of surface modification of CaCO3. Therefore, the PC polymer chains in interface region have less restriction than the PC polymer chains in matrix. Moreover, the increasing interfacial area in nanocomposites increases the fraction of polymer chains located in interfacial region significantly. In some cases, the increased resin–filler interface in polymer based nanocomposites created extra free volume and, therefore, assisted the large-scale segmental mobility of the polymer-chain
Neat PC
PC/CaCO3 (99/1) composite
627.65 87.20 86.18 165.06 2211 81.56
728.28 91.29 72.80 63.32 2536 90.12
Strength at yield. Strength at break.
segments and led to the decrease of Tg [10–12]. The Tg values of neat PC and PC/CaCO3 nanocomposite comprising 1 wt.% CaCO3 are 150.5 °C and 144.4 °C, respectively, indicating the enhanced dynamics of PC polymer chains in nanocomposites. The enhanced dynamics of PC polymer chains will result in the obvious decrease of apparent viscosity of PC melt, which has been confirmed by the variation of rheological curves in Fig. 2. The microstructure of polymer nanocomposites in the glassy state is of fundamental importance for the macroscopic behavior of nanocomposites. Typical stress–strain curves for neat PC and PC/CaCO3 composite are shown in Fig. 3. A pronounced yield and postyield drop are observed in the curves. It can be seen that addition of CaCO3 nanoparticles slightly changes the mechanical properties of PC, as summarized in Table 1. Upon incorporation of only 1 wt.% CaCO3, the elastic modulus, the tensile strength (at yield), the bending strength and bending modulus of PC are improved by about 16%, 5%,10.5% and 15%, respectively. The slight decrease of tensile strength at break illustrates the weak interaction between CaCO3 nanoparticles and PC matrix. The elongation at break decreases remarkably, indicating that the composite becomes somewhat brittle compared with neat PC. The variation in elongation of PC/CaCO3 nanocomposites is similar to that of PA/MWNTs nanocomposites reported in literature [13]. The decrease in the toughness of PC matrix can also be seen easily as measured by the area under the stress–strain curves in Fig. 3. Shah et al. [14] reported that, when testing was performed at a temperature below the Tg of the polymer, the nanoparticles in the polymer nanocomposites were not allowed to move and, therefore, the nanoparticles could not provide an additional energy-dissipating mechanism. The restricted mobility of CaCO3 nanoparticles in PC/CaCO3 nanocomposites can initiate crack formation and ultimately lead to somewhat brittle behavior.
4. Conclusion In summary, PC/CaCO3 nanocomposites with different compositions of CaCO3 were prepared by melt-compounding. The rheological experiments show the remarkable rheology enhancement of PC melt due to the introduction of CaCO3 nanoparticles. Characterizations via EDS and FE-SEM confirm the random dispersion of CaCO3 in masterbatch. Mechanical tests show that, incorporating 1 wt.% CaCO3, most properties of PC are improved slightly while the tensile strength and elongation at break are depressed. Acknowledgement
Fig. 3. Stress–strain curves for neat PC and PC/CaCO3 nanocomposites.
This research was supported by National 863 foundation of China under contract No. 2002AA30B613.
1038
Z. Wang et al. / Materials Letters 60 (2006) 1035–1038
References [1] H.T. Pham, C.L. Weckle, J.M. Ceraso, Adv. Mater. 12 (2000) 1881. [2] S. Balakrishnan, N.R. Neelakantan, S.N. Jaisankar, J. Appl. Polym. Sci. 74 (1999) 2102. [3] L.S. Dong, R. Greco, G. Orsello, Polymer 34 (1993) 1375. [4] D. Quentens, G. Groeninckx, M. Guest, L. Aerts, Polym. Eng. Sci. 31 (1991) 1207. [5] E.A. Kang, J.H. Kim, C.K. Kim, H.W. Rhee, S.Y. Oh, Polym. Eng. Sci. 40 (2000) 2374. [6] J.H. Kim, C.K. Kim, J. Appl. Polym. Sci. 89 (2003) 2649. [7] Y.S. Seo, J.H. Kim, C.K. Kim, R. Lee, J.K. Keum, J. Appl. Polym. Sci. 96 (2005) 2097.
[8] K.K. Koziol, K. Dolgner, N. Tsuboi, J. Kruse, V. Zaporojtchenko, S. Deki, F. Faupel, Macromolecules 37 (2004) 2182. [9] P. Potschke, T.D. Fornes, D.R. Paul, Polymer 43 (2002) 3247. [10] B.J. Ash, L.S. Schadler, R.W. Siegel, Mater. Lett. 55 (2002) 83. [11] X. Wang, Z.B. Wang, Q.Y. Wu, J. Appl. Polym. Sci. 96 (2005) 802. [12] Y.Y. Sun, Z.Q. Zhang, K.S. Moon, C.P. Wong, J. Polym. Sci., Part B, Polym. Phys. 42 (2004) 3849. [13] W.D. Zhang, L. Shen, I.Y. Phang, T.X. Liu, Macromolecules 37 (2004) 256. [14] D. Shah, P. Maiti, D. Jiang, C.A. Batt, E.P. Giannelis, Adv. Mater. 17 (2005) 525.