- Email: [email protected]
ultra high molecular weight polyethylene composites
Materials Letters 134 (2014) 99–102
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Carbon fiber reinforced highly filled charcoal powder/ultra high molecular weight polyethylene composites Suiyi Li, Dagang Li n College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, China
art ic l e i nf o
a b s t r a c t
Article history: Received 27 April 2014 Accepted 12 July 2014 Available online 19 July 2014
Effects of wood charcoal powder and carbon fiber (CF) on morphologies, tensile properties and dynamic mechanical properties of ultra high molecular weight polyethylene (UHMWPE) composites prepared by the twin-screw extrusion method were studied. Scanning electron microscopy was used to investigate the surface of initial charcoal power as well as interfaces in the UHMWPE, filled with high-modulus carbon fibers. The results showed that wood charcoal could have strong interfacial interaction with UHMWPE and good dispersion of carbon fiber was achieved. The tensile strength and Young's modulus significantly increased up to 123.0 MPa and 2551.1 MPa respectively. It is obvious that while increasing charcoal and carbon fiber concentration resulted in increased storage modulus, the E' reached 25.1 GPa for the sample 30UHMWPE-70charcoal/8CF at 150 1C. Furthermore, the composites show lower tan δ values than those of the neat UHMWPE in the glass-transition temperature (Tg) and melting temperature (Tm). & 2014 Elsevier B.V. All rights reserved.
Keywords: Carbon fiber UHMWPE Wood charcoal Composite materials Scanning electron microscopy Mechanical properties
1. Introduction Recently, carbon-based materials have been widely used as biomaterials, such as carbon fiber due to their good mechanical, thermal and electrical properties. Using of carbon fiber as filler for thermoplastic matrix is one of their most prospective applications. Therefore, they are used to fabricate components with high strength to weight ratio and great fatigue life, which have extensive applications in the aerospace and automotive sectors [1,2]. Among the thermoplastic polymers, UHMWPE is a promising one which possesses many excellent properties, such as biocompatibility, good wear resistance and high mechanical properties. However, UHMWPE has not been used much for composite production because of its high melting index, which sets restrictions on the available methods of processing. Furthermore, cost is also a major factor which prohibits wider use of this material for general applications. Therefore, only some specific applications can be found. UHMWPE composites based on wood flour [3], charcoal [4,5], carbon fibers [6] and multi-walled carbon nanotubes [7] using methods of extrusion, hot-compression and mechanochemical synthesis have been studied. As far as we know, wood charcoal is a kind of cheap and abundant bioresource on earth. Carbonized wood is classified as a non-graphitizing carbon, which can withstand high temperature
n
Corresponding author. Tel.: þ 86 13912981251. E-mail address: [email protected] (D. Li).
http://dx.doi.org/10.1016/j.matlet.2014.07.081 0167-577X/& 2014 Elsevier B.V. All rights reserved.
and has a porous structure [8,9]. It possesses lots of advantages, such as supplier of negative ions, warming effect of far infrared rays, humidity regulator and oxidization prevention [10,11]. However, many researchers have studied wood charcoal as adsorbents and there is little research on the use of it to improve mechanical and thermal properties of charcoal-plastic composites. Therefore, the objective of this research is to use the dry-blending technique and extrusion method to produce high-modulus carbon fiber reinforced highly filled charcoal powder/UHMWPE composites. The effects of charcoal and fiber content on morphologies, tensile properties, dynamical mechanical properties are presented and discussed.
2. Experiment The Mitsui L5000 UHMWPE powder (Mitsui, Japan) with a molecular weight of (3 6) 106 g/mol was used as the matrix material. The charcoal was a common wood charcoal product. The reinforcers were chopped carbon fibers (Shanghai xinstar carbon Co.) with an average length of 1 mm. The content of carbon fiber in the composites was varied from 0 to 8 wt%. The samples were labeled according to the UHMWPE/charcoal percentage in the matrix and carbon fiber loading level (%). For example, 30UHMWPE-70charcoal/8CF means that the matrix was formed by 30% UHMWPE and 70% charcoal, which was reinforced by 8% short carbon fiber.
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S. Li, D. Li / Materials Letters 134 (2014) 99–102
We dry-blended 6 g of UHMWPE powder, charcoal powder and carbon fiber with a high shear mixer (food blender) for 4 min to get a homogeneous blend. Then using a co-rotating twin-screw extruder (Haake Minilab II) melt-blended it. The UHMWPE was melt-blended with charcoal powder and carbon fiber at 190 1C for 3 min at a screw rpm of 20 in Haake Minilab II, then extruded from the mold. The structure of charcoal power and fiber-reinforced composites based on charcoal power/UHMWPE was investigated with a field emission scanning electron microscope (HITACHI S-4800, HITACHI/Japan) operating at 5 kV. XRD patterns were obtained by a Rigaku X-ray diffractometer (Ultima IV; Rigaku Corp.,Tokyo) using CuKα radiation (40 kV and 30 mA) over a range of 5–301, with a step interval of 0.021. Tensile tests were carried out with a universal testing machine (CMT4202, SANS, China). The specimens' dimensions were 60 3.8 1 mm3 for the tensile test. At least five specimens of each composition were tested, and the average values were reported. A dynamic mechanical analysis (DMA) was made in a three point bending mode at 1 Hz frequency using a DMA 242D apparatus (Netzsch, Germany). The specimens' dimensions were 40 3.8 1 mm3. The temperature scanning in the range of 150 1C to 150 1C was performed at a heating rate of 3 1C/min.
3. Results and discussion Fig. 1 shows the structure of wood charcoal. From Fig. 1a, we confirm that the most particles of wood charcoal size range from 5 to 50 μm. Furthermore, it is reasonable to expect that after wood carbonization will give rise to a solid mainly composed of carbon atoms, heteroatoms (mainly hydrogen and oxygen) and mineral matter [12,13]. Fig. 1b shows the volatile matter is lost during the wood carbonization and it is formed a carbon skeleton and pore structure. The pore structures are formed by pores in the range of narrow micropores to wide macropores and mineral matter can be observed within the holes of this sample (Fig. 1c and d). A good
deal of holes in wood charcoal might be able to stronger the interface with polymer matrix, because polymer chains could get into these holes when the polymer has good liquidity. Fig. 2 shows the tensile fracture surfaces of CF reinforced charcoal/ UHMWPE composites with different carbon fiber contents. Fig. 2a clearly demonstrates that good interface quality is produced between wood charcoal and UHMWPE without any coupling agent addition due to its large surface area, polymodal porous structure and surface chemistry. The results suggested that the countless pores in structure of wood charcoal were filled by UHMWPE, which let more UHMWPE cover the surface of wood charcoal, resulting in strong filler-matrix interface. After the addition of carbon fiber, good dispersion was achieved (Fig. 2b and c). But we can see some pull-out of carbon fibers, which implied the interface adhesion between untreated CF and UHMWPE matrix was not strong (Fig. 2d). For this reason, fibers pulled out from the matrix instead of fractured during tensile tests, which adversely affect the efficacy of the reinforcing function of carbon fiber[14]. Fig. 3 represents the XRD of neat UHMWPE and corresponding composites. The analysis of the XRD peaks reveals two major characteristic peaks at 2θ ¼22.41 and 24.81, which are assigned to the (110) and (200) diffraction planes of UHMWPE respectively. It can be seen that the polymer was partly crystalline and there was no obvious shift of diffraction peak positions with the addition of charcoal and carbon fibers. The loading of charcoal and CF affected the degree of crystallinity in the composites but had little effect on the crystallite structure. The results of mechanical tensile tests of composites are shown in Table 1. The tensile modules of composites increased with increasing content of charcoal powder and carbon fiber, which significantly increased up to 2551.1 MPa for the sample 30UHMWPE-70charcoal/ 8CF. The result was attributed that wood charcoal and carbon fibers restricted motion of polymer chains and decreased the deformation capacity of the matrix in the elastic zone. After the addition of charcoal powder and carbon fiber, the tensile strength significantly increased by 325% and 413% for the samples 30UHMWPE-70charcoal/4CF compared to neat UHMWPE respectively. This is an
a
b
c
d
Fig. 1. SEM images of wood charcoal at different magnifications: (a) 600 , (b) 3000 , (c) and (d) 50,000 .
S. Li, D. Li / Materials Letters 134 (2014) 99–102
101
Fig. 2. SEM images of the broken tensile sections of carbon fiber reinforced composites, (a) 30UHMWPE-70charcoal/0CF, (b) 30UHMWPE-70charcoal/4CF, (c) 30UHMWPE70charcoal/8CF(1000 ), and (d) 30UHMWPE-70charcoal/8CF (3000 ).
Table 1 Tensile properties as a function of carbon fiber content.
Fig. 3. XRD patterns of neat UHMWPE and corresponding composites.
indication of the reinforcement effect of charcoal powder and carbon fiber on UHMWPE. However, the tensile strength and modulus of the composites were not continuously enhanced with the increasing CF content due to dispersion of CF and poor interface adhesion between them. Storage modulus for the composites with different contents as the function of temperature are demonstrated in Fig. 4a. It is obvious that while increasing charcoal and carbon fiber concentration resulted in increased storage modulus, E' reached 25.1 GPa for the sample 30UHMWPE-70charcoal/8CF at 150 1C. Furthermore, the value of E' remained higher (E' is about 5.1 GPa) for composites (30UHMWPE-70charcoal/8CF) until around 100 1C. The increase in storage modulus is mainly due to this stress transfer between the matrix and fibers. Furthermore, molecular mobility is limited and restricted. Fig. 4b shows tan δ for unfilled UHMWPE and the CF reinforced charcoal/UHMWPE composites with different fiber contents. The composites showed lower tan δ values than the
Sample
Tensile strength
Tensile modulus
Elongation at break
Neat UHMWPE 30UHMWPE-70charcoal/0CF 30UHMWPE-70charcoal/4CF 30UHMWPE-70charcoal/8CF
24.0 102.0 123.0 116.0
495.2 1860.2 2310.6 2551.1
475.5 28.4 25.8 23.4
neat UHMWPE in the glass-transition temperature (Tg); this indicates that the viscoelastic energy dissipated less in the composites than in the neat polymer in the glass-transition region and movement of polymer molecule was restricted with the incorporation of stiff fibers. The fact that a obvious difference between the neat UHMWPE and the composites is in the γ-transition region suggested that the filler is located partly in the amorphous phase. It also shows that along with the increase of charcoal powder and carbon fiber content, the α peak shifted to higher temperature; this indicates that the melting temperature (Tm) of composite materials increased.
4. Conclusions The aim of this study is to investigate the effects of charcoal and carbon fiber content on the morphological, tensile and dynamic mechanical properties of CF reinforced charcoal powder/UHMWPE composites. Charcoal powder not only can be used as a filling material, but also can act as a solid lubricant greatly improving the processing properties of UHMWPE. It is shown that wood charcoal could have strong interfacial interaction with UHMWPE and good dispersion of carbon fiber was achieved. According to tensile test results, charcoal powder and increasing CF content increases the tensile strength and Young's modulus
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S. Li, D. Li / Materials Letters 134 (2014) 99–102
Fig. 4. Variation of (a) E' and (b) tan δ with temperature for neat UHMWPE and corresponding composites.
remarkably but decreases strain at break values of composites. It demonstrates that significant changes in dynamic mechanical properties in storage modulus (E') and loss factor (tan δ) for the reason that charcoal powder and carbon fiber constrained mobility of the chains of the polymeric matrix. Acknowledgments This work is financially supported by National Natural Science Foundation of China (31170514 and 31370557), Doctorate Fellowship Foundation of Nanjing Forestry University (2011YB014), the Priority Academic Program Development of Jiangsu Higher Education Institution (PAPD), Graduate Cultivation Innovative Project of Jiangsu Province (CXZZ11-0525), and the Doctoral Program of Higher Education (20113204110011). Appendix A. Supporting information Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.matlet.2014.07.081.
References [1] Servinis L, Henderson LC, Gengenbach TR, Kafi AA, Huson MG, Fox BL. Carbon 2013;54:378–88. [2] Chand S. J Mater Sci 2000;35:1303–13. [3] Mahfoudh A, Cloutier A, Rodrigue D. Polym Compos 2013;34:510–6. [4] You ZP, Li DG. Mater Lett 2014;122:121–4. [5] You ZP, Li DG. Mater Lett 2013;122:197–9. [6] Stepashkin AA, Chukov DI, Gorshenkov MV, Tcherdyntsev VV, Kaloshkin SD. J Alloys Compd 2014;586:168–72. [7] Maksimkin AV, Kaloshkin SD, Kaloshkina MS, Gorshenkov MV, Tcherdyntsev VV, Ergin KS, et al. J Alloys Compd 2012;536:538–40. [8] Huttepain M, Oberlin A. Carbon 1990;28:103–11. [9] Kyotani T. Carbon 2000;38:269–86. [10] Zhao RS, Wang X, Yuan JP, Lin JM. J Chromatogr A 2008;1183:15–20. [11] Yang FC, Wu KH, Lin WP, Hu MK. Microporous Mesoporous Mater 2009;118:467–72. [12] Pastor-Villegas J, Meneses Rodríguez JM, Pastor-Valle JF, Rouquerol J, Denoyel R, García García M. J Anal Appl Pyrolysis 2010;88:124–33. [13] Pastor-Villegas J, Pastor-Valle JF, Meneses Rodríguez JM, García García M. J Anal Appl Pyrolysis 2006;76:103–8. [14] Li J, Zhang YF. Surf Interface Anal 2009;41:610–4.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Carbon fiber reinforced highly filled charcoal powder/ultra high molecular weight polyethylene composites Suiyi Li, Dagang Li n College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, China
art ic l e i nf o
a b s t r a c t
Article history: Received 27 April 2014 Accepted 12 July 2014 Available online 19 July 2014
Effects of wood charcoal powder and carbon fiber (CF) on morphologies, tensile properties and dynamic mechanical properties of ultra high molecular weight polyethylene (UHMWPE) composites prepared by the twin-screw extrusion method were studied. Scanning electron microscopy was used to investigate the surface of initial charcoal power as well as interfaces in the UHMWPE, filled with high-modulus carbon fibers. The results showed that wood charcoal could have strong interfacial interaction with UHMWPE and good dispersion of carbon fiber was achieved. The tensile strength and Young's modulus significantly increased up to 123.0 MPa and 2551.1 MPa respectively. It is obvious that while increasing charcoal and carbon fiber concentration resulted in increased storage modulus, the E' reached 25.1 GPa for the sample 30UHMWPE-70charcoal/8CF at 150 1C. Furthermore, the composites show lower tan δ values than those of the neat UHMWPE in the glass-transition temperature (Tg) and melting temperature (Tm). & 2014 Elsevier B.V. All rights reserved.
Keywords: Carbon fiber UHMWPE Wood charcoal Composite materials Scanning electron microscopy Mechanical properties
1. Introduction Recently, carbon-based materials have been widely used as biomaterials, such as carbon fiber due to their good mechanical, thermal and electrical properties. Using of carbon fiber as filler for thermoplastic matrix is one of their most prospective applications. Therefore, they are used to fabricate components with high strength to weight ratio and great fatigue life, which have extensive applications in the aerospace and automotive sectors [1,2]. Among the thermoplastic polymers, UHMWPE is a promising one which possesses many excellent properties, such as biocompatibility, good wear resistance and high mechanical properties. However, UHMWPE has not been used much for composite production because of its high melting index, which sets restrictions on the available methods of processing. Furthermore, cost is also a major factor which prohibits wider use of this material for general applications. Therefore, only some specific applications can be found. UHMWPE composites based on wood flour [3], charcoal [4,5], carbon fibers [6] and multi-walled carbon nanotubes [7] using methods of extrusion, hot-compression and mechanochemical synthesis have been studied. As far as we know, wood charcoal is a kind of cheap and abundant bioresource on earth. Carbonized wood is classified as a non-graphitizing carbon, which can withstand high temperature
n
Corresponding author. Tel.: þ 86 13912981251. E-mail address: [email protected] (D. Li).
http://dx.doi.org/10.1016/j.matlet.2014.07.081 0167-577X/& 2014 Elsevier B.V. All rights reserved.
and has a porous structure [8,9]. It possesses lots of advantages, such as supplier of negative ions, warming effect of far infrared rays, humidity regulator and oxidization prevention [10,11]. However, many researchers have studied wood charcoal as adsorbents and there is little research on the use of it to improve mechanical and thermal properties of charcoal-plastic composites. Therefore, the objective of this research is to use the dry-blending technique and extrusion method to produce high-modulus carbon fiber reinforced highly filled charcoal powder/UHMWPE composites. The effects of charcoal and fiber content on morphologies, tensile properties, dynamical mechanical properties are presented and discussed.
2. Experiment The Mitsui L5000 UHMWPE powder (Mitsui, Japan) with a molecular weight of (3 6) 106 g/mol was used as the matrix material. The charcoal was a common wood charcoal product. The reinforcers were chopped carbon fibers (Shanghai xinstar carbon Co.) with an average length of 1 mm. The content of carbon fiber in the composites was varied from 0 to 8 wt%. The samples were labeled according to the UHMWPE/charcoal percentage in the matrix and carbon fiber loading level (%). For example, 30UHMWPE-70charcoal/8CF means that the matrix was formed by 30% UHMWPE and 70% charcoal, which was reinforced by 8% short carbon fiber.
100
S. Li, D. Li / Materials Letters 134 (2014) 99–102
We dry-blended 6 g of UHMWPE powder, charcoal powder and carbon fiber with a high shear mixer (food blender) for 4 min to get a homogeneous blend. Then using a co-rotating twin-screw extruder (Haake Minilab II) melt-blended it. The UHMWPE was melt-blended with charcoal powder and carbon fiber at 190 1C for 3 min at a screw rpm of 20 in Haake Minilab II, then extruded from the mold. The structure of charcoal power and fiber-reinforced composites based on charcoal power/UHMWPE was investigated with a field emission scanning electron microscope (HITACHI S-4800, HITACHI/Japan) operating at 5 kV. XRD patterns were obtained by a Rigaku X-ray diffractometer (Ultima IV; Rigaku Corp.,Tokyo) using CuKα radiation (40 kV and 30 mA) over a range of 5–301, with a step interval of 0.021. Tensile tests were carried out with a universal testing machine (CMT4202, SANS, China). The specimens' dimensions were 60 3.8 1 mm3 for the tensile test. At least five specimens of each composition were tested, and the average values were reported. A dynamic mechanical analysis (DMA) was made in a three point bending mode at 1 Hz frequency using a DMA 242D apparatus (Netzsch, Germany). The specimens' dimensions were 40 3.8 1 mm3. The temperature scanning in the range of 150 1C to 150 1C was performed at a heating rate of 3 1C/min.
3. Results and discussion Fig. 1 shows the structure of wood charcoal. From Fig. 1a, we confirm that the most particles of wood charcoal size range from 5 to 50 μm. Furthermore, it is reasonable to expect that after wood carbonization will give rise to a solid mainly composed of carbon atoms, heteroatoms (mainly hydrogen and oxygen) and mineral matter [12,13]. Fig. 1b shows the volatile matter is lost during the wood carbonization and it is formed a carbon skeleton and pore structure. The pore structures are formed by pores in the range of narrow micropores to wide macropores and mineral matter can be observed within the holes of this sample (Fig. 1c and d). A good
deal of holes in wood charcoal might be able to stronger the interface with polymer matrix, because polymer chains could get into these holes when the polymer has good liquidity. Fig. 2 shows the tensile fracture surfaces of CF reinforced charcoal/ UHMWPE composites with different carbon fiber contents. Fig. 2a clearly demonstrates that good interface quality is produced between wood charcoal and UHMWPE without any coupling agent addition due to its large surface area, polymodal porous structure and surface chemistry. The results suggested that the countless pores in structure of wood charcoal were filled by UHMWPE, which let more UHMWPE cover the surface of wood charcoal, resulting in strong filler-matrix interface. After the addition of carbon fiber, good dispersion was achieved (Fig. 2b and c). But we can see some pull-out of carbon fibers, which implied the interface adhesion between untreated CF and UHMWPE matrix was not strong (Fig. 2d). For this reason, fibers pulled out from the matrix instead of fractured during tensile tests, which adversely affect the efficacy of the reinforcing function of carbon fiber[14]. Fig. 3 represents the XRD of neat UHMWPE and corresponding composites. The analysis of the XRD peaks reveals two major characteristic peaks at 2θ ¼22.41 and 24.81, which are assigned to the (110) and (200) diffraction planes of UHMWPE respectively. It can be seen that the polymer was partly crystalline and there was no obvious shift of diffraction peak positions with the addition of charcoal and carbon fibers. The loading of charcoal and CF affected the degree of crystallinity in the composites but had little effect on the crystallite structure. The results of mechanical tensile tests of composites are shown in Table 1. The tensile modules of composites increased with increasing content of charcoal powder and carbon fiber, which significantly increased up to 2551.1 MPa for the sample 30UHMWPE-70charcoal/ 8CF. The result was attributed that wood charcoal and carbon fibers restricted motion of polymer chains and decreased the deformation capacity of the matrix in the elastic zone. After the addition of charcoal powder and carbon fiber, the tensile strength significantly increased by 325% and 413% for the samples 30UHMWPE-70charcoal/4CF compared to neat UHMWPE respectively. This is an
a
b
c
d
Fig. 1. SEM images of wood charcoal at different magnifications: (a) 600 , (b) 3000 , (c) and (d) 50,000 .
S. Li, D. Li / Materials Letters 134 (2014) 99–102
101
Fig. 2. SEM images of the broken tensile sections of carbon fiber reinforced composites, (a) 30UHMWPE-70charcoal/0CF, (b) 30UHMWPE-70charcoal/4CF, (c) 30UHMWPE70charcoal/8CF(1000 ), and (d) 30UHMWPE-70charcoal/8CF (3000 ).
Table 1 Tensile properties as a function of carbon fiber content.
Fig. 3. XRD patterns of neat UHMWPE and corresponding composites.
indication of the reinforcement effect of charcoal powder and carbon fiber on UHMWPE. However, the tensile strength and modulus of the composites were not continuously enhanced with the increasing CF content due to dispersion of CF and poor interface adhesion between them. Storage modulus for the composites with different contents as the function of temperature are demonstrated in Fig. 4a. It is obvious that while increasing charcoal and carbon fiber concentration resulted in increased storage modulus, E' reached 25.1 GPa for the sample 30UHMWPE-70charcoal/8CF at 150 1C. Furthermore, the value of E' remained higher (E' is about 5.1 GPa) for composites (30UHMWPE-70charcoal/8CF) until around 100 1C. The increase in storage modulus is mainly due to this stress transfer between the matrix and fibers. Furthermore, molecular mobility is limited and restricted. Fig. 4b shows tan δ for unfilled UHMWPE and the CF reinforced charcoal/UHMWPE composites with different fiber contents. The composites showed lower tan δ values than the
Sample
Tensile strength
Tensile modulus
Elongation at break
Neat UHMWPE 30UHMWPE-70charcoal/0CF 30UHMWPE-70charcoal/4CF 30UHMWPE-70charcoal/8CF
24.0 102.0 123.0 116.0
495.2 1860.2 2310.6 2551.1
475.5 28.4 25.8 23.4
neat UHMWPE in the glass-transition temperature (Tg); this indicates that the viscoelastic energy dissipated less in the composites than in the neat polymer in the glass-transition region and movement of polymer molecule was restricted with the incorporation of stiff fibers. The fact that a obvious difference between the neat UHMWPE and the composites is in the γ-transition region suggested that the filler is located partly in the amorphous phase. It also shows that along with the increase of charcoal powder and carbon fiber content, the α peak shifted to higher temperature; this indicates that the melting temperature (Tm) of composite materials increased.
4. Conclusions The aim of this study is to investigate the effects of charcoal and carbon fiber content on the morphological, tensile and dynamic mechanical properties of CF reinforced charcoal powder/UHMWPE composites. Charcoal powder not only can be used as a filling material, but also can act as a solid lubricant greatly improving the processing properties of UHMWPE. It is shown that wood charcoal could have strong interfacial interaction with UHMWPE and good dispersion of carbon fiber was achieved. According to tensile test results, charcoal powder and increasing CF content increases the tensile strength and Young's modulus
102
S. Li, D. Li / Materials Letters 134 (2014) 99–102
Fig. 4. Variation of (a) E' and (b) tan δ with temperature for neat UHMWPE and corresponding composites.
remarkably but decreases strain at break values of composites. It demonstrates that significant changes in dynamic mechanical properties in storage modulus (E') and loss factor (tan δ) for the reason that charcoal powder and carbon fiber constrained mobility of the chains of the polymeric matrix. Acknowledgments This work is financially supported by National Natural Science Foundation of China (31170514 and 31370557), Doctorate Fellowship Foundation of Nanjing Forestry University (2011YB014), the Priority Academic Program Development of Jiangsu Higher Education Institution (PAPD), Graduate Cultivation Innovative Project of Jiangsu Province (CXZZ11-0525), and the Doctoral Program of Higher Education (20113204110011). Appendix A. Supporting information Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.matlet.2014.07.081.
References [1] Servinis L, Henderson LC, Gengenbach TR, Kafi AA, Huson MG, Fox BL. Carbon 2013;54:378–88. [2] Chand S. J Mater Sci 2000;35:1303–13. [3] Mahfoudh A, Cloutier A, Rodrigue D. Polym Compos 2013;34:510–6. [4] You ZP, Li DG. Mater Lett 2014;122:121–4. [5] You ZP, Li DG. Mater Lett 2013;122:197–9. [6] Stepashkin AA, Chukov DI, Gorshenkov MV, Tcherdyntsev VV, Kaloshkin SD. J Alloys Compd 2014;586:168–72. [7] Maksimkin AV, Kaloshkin SD, Kaloshkina MS, Gorshenkov MV, Tcherdyntsev VV, Ergin KS, et al. J Alloys Compd 2012;536:538–40. [8] Huttepain M, Oberlin A. Carbon 1990;28:103–11. [9] Kyotani T. Carbon 2000;38:269–86. [10] Zhao RS, Wang X, Yuan JP, Lin JM. J Chromatogr A 2008;1183:15–20. [11] Yang FC, Wu KH, Lin WP, Hu MK. Microporous Mesoporous Mater 2009;118:467–72. [12] Pastor-Villegas J, Meneses Rodríguez JM, Pastor-Valle JF, Rouquerol J, Denoyel R, García García M. J Anal Appl Pyrolysis 2010;88:124–33. [13] Pastor-Villegas J, Pastor-Valle JF, Meneses Rodríguez JM, García García M. J Anal Appl Pyrolysis 2006;76:103–8. [14] Li J, Zhang YF. Surf Interface Anal 2009;41:610–4.