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High thermal and thermomechanical properties obtained by reinforcing a bisphenol-A based phthalonitrile resin with silicon nitride nanoparticles
Materials Letters 149 (2015) 81–84
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
High thermal and thermomechanical properties obtained by reinforcing a bisphenol-A based phthalonitrile resin with silicon nitride nanoparticles Mehdi Derradji a, Noureddine Ramdani a, Tong Zhang a, Jun Wang a,n, Zai-wen Lin b, Ming Yang a, Xiao-dong Xu a, Wen-bin Liu a,n a Polymer Materials Research Center, Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China b Institute of Composite Materials, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China
art ic l e i nf o
a b s t r a c t
Article history: Received 27 December 2014 Accepted 25 February 2015 Available online 5 March 2015
A new kind of nanocomposites based on phthalonitrile resin reinforced with silicon nitride (SiN) nanoparticles was prepared by a hot compression molding technique. For different weight ratios ranging between 0% and 15%, the effect of nano-SiN particles on the thermal and thermomechanical properties has been studied. Results from thermal analysis revealed that the starting decomposition temperature and the residual weight at 800 1C were highly improved upon adding the reinforcing phase. At the maximum nano-SiN loading, dynamic mechanical analysis showed an enhancement in both storage modulus and glass transition temperature, reaching 4 GPa and 360 1C respectively. Scanning electron microscope analysis confirmed that these improvements are essentially attributed to the good dispersion and adhesion between the particles and the resin thanks to the particles treatment with silane coupling agent. & 2015 Elsevier B.V. All rights reserved.
Keywords: Nanoparticles Polymeric composites Nanocomposites Thermal analysis Thermal properties
1. Introduction Polymer-inorganic nanocomposites as a new class of materials resulting from the incorporation of inorganic nanoparticles into a polymeric matrix attracted a great number of scientific researches. The benefits that could be obtained in terms of thermal, mechanical, electrical, fire retardancy and optical properties depends largely on the type of nanoparticles incorporated, their size and shape, as well as their dispersion and adhesion within the matrix [1]. Phthalonitrile resin firstly developed by the U.S Naval Research Laboratory and further designated as the only candidate to satisfy the flame standards of United States Navy (MIL-STD-2031) [2] shows exceptional properties superior in many ways to other high performance thermosets such as polyimide and polybenzoxazine. Over the last few decades, the use of phthalonitrile resins as matrix for composites attracted a lot of attention for example Sastri et al. studied the phthalonitrile resins filled with carbon and glass fibers [2,3], also Liu et al. investigated the polyarylene ether nitriles terminated phthalonitrile composites [4,5]. To date and
n
Corresponding authors. Tel./fax: þ86 451 82589540. E-mail addresses: [email protected] (J. Wang), [email protected] (W.-b. Liu). http://dx.doi.org/10.1016/j.matlet.2015.02.122 0167-577X/& 2015 Elsevier B.V. All rights reserved.
best to our knowledge there had been quite no reports indicating the use of silicon nitride (SiN) nanoparticles as reinforcements in phthalonitrile resins. In this work, SiN nanoparticles treated with GX-540 silane coupling agent have been used as reinforcement in a typical based bisphenol-A phthalonitrile resin. The prepared nanocomposites with different weight ratios of the nanofillers ranging from 0% to 15% with an increment of 3% were cured, in the presence of 4-aminophenoxy phthalonitrile as curing agent, by a hot compression molding technique. The thermal and thermomechanical properties of the fabricated nanocomposites were investigated in terms of their nano-SiN loading.
2. Experimental Materials: 4-Aminophenol, 2,2-bis(4-hydroxyphenyl)propane, and 4-nitrophthalonitrile were obtained from Shanghai Aladdin Reagents. N,N-Dimethyl sulfoxide and potassium carbonate were purchased from Tianjin Kermel Chemical Reagent. The silicon nitride (α-Si3N4) nanoparticles were purchased from Hefei Kaier Nanometer and Technology. These nanofillers are in the form of white powder with a crystalline structure having a density of 3.44 g/cm3 and an average diameter of particles of 50 nm. The silane coupling agent GX-540 ((CH3O)3SiC3H6NH2) was friendly
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M. Derradji et al. / Materials Letters 149 (2015) 81–84
filler) in ethanol and stirred for 3 h. The collected nanoparticles from filtration were then dried over-night under vacuum at 80 1C. Spectrum from Fig. 2a proves that the nanoparticles were successfully treated. Baph monomers and Apph curing agent were thoroughly mixed at a weight ratio of 90:10 respectively, and then the proper amount of the treated nanoparticles of SiN was added
supplied from GBXF SILICONES CO., Ltd. 4-Aminophenoxy phthalonitrile (Apph) and 2,2-bis [4-(3,4-dicyanophenoxy)phenyl] propane (Baph) monomers, illustrated in Fig. 1, were synthesized in our laboratory according to the literature [6,7]. Preparation of phthalonitrile/SiN nanocomposites: The SiN nanoparticles were mixed with GX-540 silane coupling agent (2 wt% of
CN
NH2
O
CN
4-Aminophenoxy phthalonitrile (Apph) CN
NC CH3 NC
O
C
O
CN
CH3
2, 2-bis [4-(3,4-dicyanophenoxy)phenyl] propane (Baph) Fig. 1. Chemical structrures of Baph and Apph.
Fig. 2. (a) FTIR spectrum of native SiN and treated SiN, (b) DSC thermograms of Baph/SiN nanocomposites at the heating rate of 20 1C/min, (c) FTIR spectrum of neat resin before and after the curing, and (d) thermal stability of P(Baph)/SiN nanocomposites.
M. Derradji et al. / Materials Letters 149 (2015) 81–84
ranging from 3 to 15 wt% at increments of 3 wt%. The mixtures were melted, vigorously stirred and then quenched to room temperature. Owing to obtain a void free thermosets, the mixtures were first dried in a vacuum oven at 120 1C for 5 h, then transferred to an appropriate steel mold according to the DMA shapes requirements. The samples were finally cured by the hot compression molding technique by the curing procedure of 240 1C for 2 h, 260 1C for 3 h, 280 1C for 6 h, and 300 1C for 6 h. Hereafter, the cured nanocomposites were noted as P(Baph)/SiN. Characterization techniques: The FTIR spectra were recorded by a Perkin-Elmer Spectrum 100 spectrometer. DSC analysis was performed on a TA Q200 calorimeter. Thermogravimetric (TG) tests were performed on a TA Instruments Q50 at a heating rate of 20 1C/min from 50 to 820 1C under nitrogen atmosphere at a flow rate of 50 mL/min. The DMA test was carried out with a TA Q800 dynamic mechanical analyzer. The fracture surface morphology of the P(Baph)/SiN nanocomposites was explored using SEM microscope (JOEL, model JSM-5800LV) at 15 kV with gold coating on the samples.
3. Results and discussion The curing processes of the Baph/SiN systems were recorded by DSC, and the obtained results are shown in Fig. 2b. All the compositions exhibit an exothermic peak at about 235 1C which indicates that the nanoparticles do not participate or enhance the curing of the nanocomposites. Furthermore, spectrum from Fig. 2c proves that the Apph has effectively cured the Baph monomers and triazine structure has been formed [8]. The thermal stability of the pure resin and its related nanocomposites at different amounts of nano-SiN was performed to determine the degradation temperatures at 5% weight loss (T5%) and 10% weight loss (T10%) as well as the percentage of the Table 1 Thermal and thermomechanical properties of the P(Baph)/SiN nanocomposites. Specimen code
G’ at 501C (GPa)
Tg (1C)
T5%(1C)
T10%(1C)
Yc (%,8001C)
P(Baph) P(Baph)/SiN03 P(Baph)/SiN06 P(Baph)/SiN09 P(Baph)/SiN12 P(Baph)/SiN15
1.7 2.3 2.8 3.1 3.4 4.0
300 318 338 341 349 360
459.8 467.0 474.1 480.2 488.7 496.8
488.7 508.1 513.6 519.4 539.7 547.2
69.7 76.6 77.7 79.5 82.0 83.5
83
residual weight at 800 1C (char yield Yc). The TGA curves of all samples are shown in Fig. 2d. Table 1 resumes all the properties discussed above. T5% and T10% of the unfilled resin were 459.8 and 488.7 1C respectively, and the char yield was 69.7%. These parameters were all increased with the increase of the amount of the nanoparticles reaching their highest values at 15 wt% of nano-SiN content. In fact T5% and T10% increased by approximatively 37 and 58 1C respectively and the char yield at 800 1C reached a value of 83.5%. These considerable enhancements in T5% and T10% are related to the shielding effect of the nano-SiN particles that act as a barrier reducing the motion and insulating the materials from the heat source [9]. Moreover, these enhancements can be related to the good dispersion and the ameliorated adhesion between the nanofillers and the polymeric matrix thanks to the treatments of the particles with GX540 silane coupling agent. Dynamic mechanical analysis was performed in order to get an insight about the variations of the storage modulus (G0 ) along with the glass transition temperature (Tg) of the P(Baph)/SiN nanocomposites. The storage modulus which gives information about the stiffness of the materials is presented in Fig. 3a, and the glass transition temperature which defines the frontier between the glassy state and the rubbery state is plotted in Fig. 3b. Table 1 resumes the thermomechanical parameters of the neat resin and its subsequent nanocomposites. As seen from the Fig. 3a, the storage modulus at 50 1C for the unfilled resin is 1.7 GPa and this value sharply increased when adding the nano-SiN reaching 4 GPa at the maximum fillers loading. The Tg of the samples was obtained from the maximum of Tan Delta peaks, the unfilled resin cured with Apph exhibited a Tg of 300 1C. When analyzing data from Fig. 3b, it is easy to notice that in contrast with the neat resin, the SiN based nanocomposites showed a much more ameliorated Tg values. In fact, a value of 360 1C has been recorded when the amount of the nanoparticles reached 15 wt%. Moreover, a decrease in the height of Tan Delta has been noticed upon adding the nanofillers, this is due to the dilution phenomena caused by the addition of the nanoparticles. Also the Tan Delta peak became more broadened and its height lowered when the amount of the fillers increased, indicating that the relaxation process occurred due to the interactions between the polymeric matrix and the reinforcing phase [10]. These improvements in the thermomechanical properties are mainly attributed to the good dispersion and adhesion of the nanoparticles in the resin, owing to the particles treatment with the GX-540 silane coupling agent. These variations in the storage modulus and the Tg values also reflect changes in the
Fig. 3. Evolution of storage modulus (a) and Tan delta (b) of the cured P(Baph)/SiN nanocomposites.
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M. Derradji et al. / Materials Letters 149 (2015) 81–84
Fig. 4. SEM micrographs of fracture surface of the P(Baph)/SiN nanocomposites at various SiN contents: (a) 0%, (b) 6%, (c) 9%, and (d) 15%.
materials rigidity because the nano-SiN restrict the segmental motion inside the matrix. SEM analysis was performed to get clear images about both the dispersion and adhesion of the nano-SiN nanoparticles inside the polymeric matrix. Fig. 4 shows images of the unfilled resin and its related nanocomposites at 6, 9 and 15 wt% nanofillers. As seen from Fig. 4 the neat resin presents smooth and featureless fracture surface morphology confirming the brittle character of this kind of thermosets. In the other hand, SEM images for the nanocomposites have highlighted the fact that as far as the particles are treated with the GX-540 silane coupling agent, the nano-SiN particles are not only well dispersed in the matrix but also their adhesion with the resin is highly improved. Moreover, through SEM micrographs, it was possible to observe that no voids or air gaps were detected. These results could be attributed to the good characteristics of the phthalonitrile resin which even unfilled can be polymerized into voids free thermosets. 4. Conclusions Silicon nitride nanoparticles were successfully treated with GX540 silane coupling agent and used to prepare a new kind of nanocomposites based on a typical phthalonitrile resin. The prepared nanocomposites exhibited improvements in stiffness and glass transition temperatures as seen from the DMA test. An excellent thermal stability was achieved through the addition of the nano-SiN fillers. SEM results revealed that the improvements in the thermal and thermomechanical properties are not only due
to the good dispersion of these nanoparticles in the resin but also to the ameliorated adhesion achieved among the treatment of the particles by the GX-540 coupling agent.
References [1] Kango S, Kalia S, Celli A, Njuguna J, Habibi Y, Kumar R. Surface modification of inorganic nanoparticles for development of organic–inorganic nanocomposites—a review. Prog Polym Sci 2013;38:1232–61. [2] Sastri SB, Armistead JP, Keller TM. Phthalonitrile–carbon fiber composites. Polym Compos 1996;17:816–22. [3] Sastri SB, Armistead JP, Keller TM. Phthalonitrile–glass fabric composites. Polym Compos 1997;18:48–54. [4] Liu M, Xu M, Tong L, Huang X, Yang X, Liu X. Nitrile functionalized Al2O3 reinforced polyarylene ether nitriles terminated with phthalonitrile composites. J Polym Res 2014;21:414–21. [5] Tong L, Pu Z, Chen Z, Huang X, Liu X. Effect of nanosilica on the thermal, mechanical, and dielectric properties of polyarylene ether nitriles terminated with phthalonitrile. Polym Compos 2014;35:344–50. [6] Sheng H, Peng X, Guo H, Yu X, Tang C, Qu X, et al. Synthesis and thermal properties of a novel high temperature alkyl-center-trisphenolic-based phthalonitrile polymer. Mater Chem Phys 2013;142:740–7. [7] Guo H, Lei Y, Zhao X, Yang X, Zhao R, Liu X. Curing behaviors and properties of novolac/bisphthalonitrile blends. J Appl Polym Sci 2012;125:649–56. [8] Zhang T, Wang J, Derradji M, Ramdani N, Wang H, Lin ZW, et al. Synthesis, curing kinetics and thermal properties of a novel self-promoted fluorenebased bisphthalonitrile monomer. Thermochim Acta 2015;602:22–9. [9] Derradji M, Ramdani N, Zhang T, Wang J, Tt Feng, Wang H, et al. Mechanical and thermal properties of phthalonitrile resin reinforced with silicon carbide particles. Mater Des 2015;71:48–55. [10] Ramdani N, Wang J, Wang H, Tt Feng, Derradji M, Liu Wb. Mechanical and thermal properties of silicon nitride reinforced polybenzoxazine nanocomposites. Compos Sci Technol 2014;105:73–9.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
High thermal and thermomechanical properties obtained by reinforcing a bisphenol-A based phthalonitrile resin with silicon nitride nanoparticles Mehdi Derradji a, Noureddine Ramdani a, Tong Zhang a, Jun Wang a,n, Zai-wen Lin b, Ming Yang a, Xiao-dong Xu a, Wen-bin Liu a,n a Polymer Materials Research Center, Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China b Institute of Composite Materials, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China
art ic l e i nf o
a b s t r a c t
Article history: Received 27 December 2014 Accepted 25 February 2015 Available online 5 March 2015
A new kind of nanocomposites based on phthalonitrile resin reinforced with silicon nitride (SiN) nanoparticles was prepared by a hot compression molding technique. For different weight ratios ranging between 0% and 15%, the effect of nano-SiN particles on the thermal and thermomechanical properties has been studied. Results from thermal analysis revealed that the starting decomposition temperature and the residual weight at 800 1C were highly improved upon adding the reinforcing phase. At the maximum nano-SiN loading, dynamic mechanical analysis showed an enhancement in both storage modulus and glass transition temperature, reaching 4 GPa and 360 1C respectively. Scanning electron microscope analysis confirmed that these improvements are essentially attributed to the good dispersion and adhesion between the particles and the resin thanks to the particles treatment with silane coupling agent. & 2015 Elsevier B.V. All rights reserved.
Keywords: Nanoparticles Polymeric composites Nanocomposites Thermal analysis Thermal properties
1. Introduction Polymer-inorganic nanocomposites as a new class of materials resulting from the incorporation of inorganic nanoparticles into a polymeric matrix attracted a great number of scientific researches. The benefits that could be obtained in terms of thermal, mechanical, electrical, fire retardancy and optical properties depends largely on the type of nanoparticles incorporated, their size and shape, as well as their dispersion and adhesion within the matrix [1]. Phthalonitrile resin firstly developed by the U.S Naval Research Laboratory and further designated as the only candidate to satisfy the flame standards of United States Navy (MIL-STD-2031) [2] shows exceptional properties superior in many ways to other high performance thermosets such as polyimide and polybenzoxazine. Over the last few decades, the use of phthalonitrile resins as matrix for composites attracted a lot of attention for example Sastri et al. studied the phthalonitrile resins filled with carbon and glass fibers [2,3], also Liu et al. investigated the polyarylene ether nitriles terminated phthalonitrile composites [4,5]. To date and
n
Corresponding authors. Tel./fax: þ86 451 82589540. E-mail addresses: [email protected] (J. Wang), [email protected] (W.-b. Liu). http://dx.doi.org/10.1016/j.matlet.2015.02.122 0167-577X/& 2015 Elsevier B.V. All rights reserved.
best to our knowledge there had been quite no reports indicating the use of silicon nitride (SiN) nanoparticles as reinforcements in phthalonitrile resins. In this work, SiN nanoparticles treated with GX-540 silane coupling agent have been used as reinforcement in a typical based bisphenol-A phthalonitrile resin. The prepared nanocomposites with different weight ratios of the nanofillers ranging from 0% to 15% with an increment of 3% were cured, in the presence of 4-aminophenoxy phthalonitrile as curing agent, by a hot compression molding technique. The thermal and thermomechanical properties of the fabricated nanocomposites were investigated in terms of their nano-SiN loading.
2. Experimental Materials: 4-Aminophenol, 2,2-bis(4-hydroxyphenyl)propane, and 4-nitrophthalonitrile were obtained from Shanghai Aladdin Reagents. N,N-Dimethyl sulfoxide and potassium carbonate were purchased from Tianjin Kermel Chemical Reagent. The silicon nitride (α-Si3N4) nanoparticles were purchased from Hefei Kaier Nanometer and Technology. These nanofillers are in the form of white powder with a crystalline structure having a density of 3.44 g/cm3 and an average diameter of particles of 50 nm. The silane coupling agent GX-540 ((CH3O)3SiC3H6NH2) was friendly
82
M. Derradji et al. / Materials Letters 149 (2015) 81–84
filler) in ethanol and stirred for 3 h. The collected nanoparticles from filtration were then dried over-night under vacuum at 80 1C. Spectrum from Fig. 2a proves that the nanoparticles were successfully treated. Baph monomers and Apph curing agent were thoroughly mixed at a weight ratio of 90:10 respectively, and then the proper amount of the treated nanoparticles of SiN was added
supplied from GBXF SILICONES CO., Ltd. 4-Aminophenoxy phthalonitrile (Apph) and 2,2-bis [4-(3,4-dicyanophenoxy)phenyl] propane (Baph) monomers, illustrated in Fig. 1, were synthesized in our laboratory according to the literature [6,7]. Preparation of phthalonitrile/SiN nanocomposites: The SiN nanoparticles were mixed with GX-540 silane coupling agent (2 wt% of
CN
NH2
O
CN
4-Aminophenoxy phthalonitrile (Apph) CN
NC CH3 NC
O
C
O
CN
CH3
2, 2-bis [4-(3,4-dicyanophenoxy)phenyl] propane (Baph) Fig. 1. Chemical structrures of Baph and Apph.
Fig. 2. (a) FTIR spectrum of native SiN and treated SiN, (b) DSC thermograms of Baph/SiN nanocomposites at the heating rate of 20 1C/min, (c) FTIR spectrum of neat resin before and after the curing, and (d) thermal stability of P(Baph)/SiN nanocomposites.
M. Derradji et al. / Materials Letters 149 (2015) 81–84
ranging from 3 to 15 wt% at increments of 3 wt%. The mixtures were melted, vigorously stirred and then quenched to room temperature. Owing to obtain a void free thermosets, the mixtures were first dried in a vacuum oven at 120 1C for 5 h, then transferred to an appropriate steel mold according to the DMA shapes requirements. The samples were finally cured by the hot compression molding technique by the curing procedure of 240 1C for 2 h, 260 1C for 3 h, 280 1C for 6 h, and 300 1C for 6 h. Hereafter, the cured nanocomposites were noted as P(Baph)/SiN. Characterization techniques: The FTIR spectra were recorded by a Perkin-Elmer Spectrum 100 spectrometer. DSC analysis was performed on a TA Q200 calorimeter. Thermogravimetric (TG) tests were performed on a TA Instruments Q50 at a heating rate of 20 1C/min from 50 to 820 1C under nitrogen atmosphere at a flow rate of 50 mL/min. The DMA test was carried out with a TA Q800 dynamic mechanical analyzer. The fracture surface morphology of the P(Baph)/SiN nanocomposites was explored using SEM microscope (JOEL, model JSM-5800LV) at 15 kV with gold coating on the samples.
3. Results and discussion The curing processes of the Baph/SiN systems were recorded by DSC, and the obtained results are shown in Fig. 2b. All the compositions exhibit an exothermic peak at about 235 1C which indicates that the nanoparticles do not participate or enhance the curing of the nanocomposites. Furthermore, spectrum from Fig. 2c proves that the Apph has effectively cured the Baph monomers and triazine structure has been formed [8]. The thermal stability of the pure resin and its related nanocomposites at different amounts of nano-SiN was performed to determine the degradation temperatures at 5% weight loss (T5%) and 10% weight loss (T10%) as well as the percentage of the Table 1 Thermal and thermomechanical properties of the P(Baph)/SiN nanocomposites. Specimen code
G’ at 501C (GPa)
Tg (1C)
T5%(1C)
T10%(1C)
Yc (%,8001C)
P(Baph) P(Baph)/SiN03 P(Baph)/SiN06 P(Baph)/SiN09 P(Baph)/SiN12 P(Baph)/SiN15
1.7 2.3 2.8 3.1 3.4 4.0
300 318 338 341 349 360
459.8 467.0 474.1 480.2 488.7 496.8
488.7 508.1 513.6 519.4 539.7 547.2
69.7 76.6 77.7 79.5 82.0 83.5
83
residual weight at 800 1C (char yield Yc). The TGA curves of all samples are shown in Fig. 2d. Table 1 resumes all the properties discussed above. T5% and T10% of the unfilled resin were 459.8 and 488.7 1C respectively, and the char yield was 69.7%. These parameters were all increased with the increase of the amount of the nanoparticles reaching their highest values at 15 wt% of nano-SiN content. In fact T5% and T10% increased by approximatively 37 and 58 1C respectively and the char yield at 800 1C reached a value of 83.5%. These considerable enhancements in T5% and T10% are related to the shielding effect of the nano-SiN particles that act as a barrier reducing the motion and insulating the materials from the heat source [9]. Moreover, these enhancements can be related to the good dispersion and the ameliorated adhesion between the nanofillers and the polymeric matrix thanks to the treatments of the particles with GX540 silane coupling agent. Dynamic mechanical analysis was performed in order to get an insight about the variations of the storage modulus (G0 ) along with the glass transition temperature (Tg) of the P(Baph)/SiN nanocomposites. The storage modulus which gives information about the stiffness of the materials is presented in Fig. 3a, and the glass transition temperature which defines the frontier between the glassy state and the rubbery state is plotted in Fig. 3b. Table 1 resumes the thermomechanical parameters of the neat resin and its subsequent nanocomposites. As seen from the Fig. 3a, the storage modulus at 50 1C for the unfilled resin is 1.7 GPa and this value sharply increased when adding the nano-SiN reaching 4 GPa at the maximum fillers loading. The Tg of the samples was obtained from the maximum of Tan Delta peaks, the unfilled resin cured with Apph exhibited a Tg of 300 1C. When analyzing data from Fig. 3b, it is easy to notice that in contrast with the neat resin, the SiN based nanocomposites showed a much more ameliorated Tg values. In fact, a value of 360 1C has been recorded when the amount of the nanoparticles reached 15 wt%. Moreover, a decrease in the height of Tan Delta has been noticed upon adding the nanofillers, this is due to the dilution phenomena caused by the addition of the nanoparticles. Also the Tan Delta peak became more broadened and its height lowered when the amount of the fillers increased, indicating that the relaxation process occurred due to the interactions between the polymeric matrix and the reinforcing phase [10]. These improvements in the thermomechanical properties are mainly attributed to the good dispersion and adhesion of the nanoparticles in the resin, owing to the particles treatment with the GX-540 silane coupling agent. These variations in the storage modulus and the Tg values also reflect changes in the
Fig. 3. Evolution of storage modulus (a) and Tan delta (b) of the cured P(Baph)/SiN nanocomposites.
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M. Derradji et al. / Materials Letters 149 (2015) 81–84
Fig. 4. SEM micrographs of fracture surface of the P(Baph)/SiN nanocomposites at various SiN contents: (a) 0%, (b) 6%, (c) 9%, and (d) 15%.
materials rigidity because the nano-SiN restrict the segmental motion inside the matrix. SEM analysis was performed to get clear images about both the dispersion and adhesion of the nano-SiN nanoparticles inside the polymeric matrix. Fig. 4 shows images of the unfilled resin and its related nanocomposites at 6, 9 and 15 wt% nanofillers. As seen from Fig. 4 the neat resin presents smooth and featureless fracture surface morphology confirming the brittle character of this kind of thermosets. In the other hand, SEM images for the nanocomposites have highlighted the fact that as far as the particles are treated with the GX-540 silane coupling agent, the nano-SiN particles are not only well dispersed in the matrix but also their adhesion with the resin is highly improved. Moreover, through SEM micrographs, it was possible to observe that no voids or air gaps were detected. These results could be attributed to the good characteristics of the phthalonitrile resin which even unfilled can be polymerized into voids free thermosets. 4. Conclusions Silicon nitride nanoparticles were successfully treated with GX540 silane coupling agent and used to prepare a new kind of nanocomposites based on a typical phthalonitrile resin. The prepared nanocomposites exhibited improvements in stiffness and glass transition temperatures as seen from the DMA test. An excellent thermal stability was achieved through the addition of the nano-SiN fillers. SEM results revealed that the improvements in the thermal and thermomechanical properties are not only due
to the good dispersion of these nanoparticles in the resin but also to the ameliorated adhesion achieved among the treatment of the particles by the GX-540 coupling agent.
References [1] Kango S, Kalia S, Celli A, Njuguna J, Habibi Y, Kumar R. Surface modification of inorganic nanoparticles for development of organic–inorganic nanocomposites—a review. Prog Polym Sci 2013;38:1232–61. [2] Sastri SB, Armistead JP, Keller TM. Phthalonitrile–carbon fiber composites. Polym Compos 1996;17:816–22. [3] Sastri SB, Armistead JP, Keller TM. Phthalonitrile–glass fabric composites. Polym Compos 1997;18:48–54. [4] Liu M, Xu M, Tong L, Huang X, Yang X, Liu X. Nitrile functionalized Al2O3 reinforced polyarylene ether nitriles terminated with phthalonitrile composites. J Polym Res 2014;21:414–21. [5] Tong L, Pu Z, Chen Z, Huang X, Liu X. Effect of nanosilica on the thermal, mechanical, and dielectric properties of polyarylene ether nitriles terminated with phthalonitrile. Polym Compos 2014;35:344–50. [6] Sheng H, Peng X, Guo H, Yu X, Tang C, Qu X, et al. Synthesis and thermal properties of a novel high temperature alkyl-center-trisphenolic-based phthalonitrile polymer. Mater Chem Phys 2013;142:740–7. [7] Guo H, Lei Y, Zhao X, Yang X, Zhao R, Liu X. Curing behaviors and properties of novolac/bisphthalonitrile blends. J Appl Polym Sci 2012;125:649–56. [8] Zhang T, Wang J, Derradji M, Ramdani N, Wang H, Lin ZW, et al. Synthesis, curing kinetics and thermal properties of a novel self-promoted fluorenebased bisphthalonitrile monomer. Thermochim Acta 2015;602:22–9. [9] Derradji M, Ramdani N, Zhang T, Wang J, Tt Feng, Wang H, et al. Mechanical and thermal properties of phthalonitrile resin reinforced with silicon carbide particles. Mater Des 2015;71:48–55. [10] Ramdani N, Wang J, Wang H, Tt Feng, Derradji M, Liu Wb. Mechanical and thermal properties of silicon nitride reinforced polybenzoxazine nanocomposites. Compos Sci Technol 2014;105:73–9.