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The preparation and characterization of sulfamic acid-intercalated layered double hydroxide
Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
The preparation and characterization of sulfamic acid-intercalated layered double hydroxide Yu Jiang, Xiaoyu Gu, Sheng Zhang n, Wufei Tang, Jingran Zhao Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China
art ic l e i nf o
a b s t r a c t
Article history: Received 29 October 2014 Accepted 19 December 2014
NH2 SO3 1 was intercalated into layered double hydroxide to prepare a novel sulfamic acid-intercalated MgAl-LDH (SA-LDH). Fourier transform infrared (FT-IR) analysis confirmed the presence of sulfamic acid in LDH. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were also used to characterize the structural morphology of SA-LDH, and the results revealed that the interlayer space of LDH had been enlarged from 0.76 to 0.91 nm and proved the formation of hydrogen bonds between SA-LDH. The SA-LDH was introduced into ethylene vinyl acetate (EVA) copolymer via melt blending, and the cone calorimetry test results demonstrated that the presence of SA-LDH could significantly improve the flame retardancy of EVA composite. & 2015 Published by Elsevier B.V.
Keywords: Layered double hydroxide Intercalation Composite materials XPS Flammability
1. Introduction LDH is a class of synthetic anionic clays with host-guest nanolayer material containing positively charged metal hydroxide sheets, intercalated anions as guest and water molecules [1–3]. LDHs have been widely investigated that was partly driven by the use of these materials as ion exchange hosts, fire retardant additives, catalytic agent, drug delivery and so on [4–7]. Its general formula is n MII1 xMIII )x/n mH2O, where MII and MIII are, respectively, x (OH)2(A 2þ divalent (Mg , Zn2 þ , Co2 þ ) and trivalent cations (Al3 þ , Fe3 þ , Mn3 þ ), and An is the charge balancing interlayer anion [8–10]. Recently, most of the ongoing investigations focus on lamellar compounds for their unique anion exchange and intercalation properties [11–13]. The sulfamic acid (SA) with a molecular formula of NH2SO3H is an effective flame retardant for many polymers and textile materials, therefore, it is expected that the intercalation of NH2 SO3 1 can improve the flame retardancy of LDH, which has not been reported so far. In this work, a novel sulfamic acid-intercalated MgAl-LDH (SALDH) was prepared and characterized. The interlayer anion of LDH was displaced through acid-base reaction between SA and CO23 , and carbon dioxide generated in the reaction. The structure and morphology of intercalated LDH were characterized, and the effect
n
Corresponding author. Tel.: þ 86 10 18610021239; fax: þ86 10 64436820. E-mail address: [email protected] (S. Zhang).
of SA-LDH on the flammability behavior of EVA was investigated by using cone calorimeter.
2. Experimental Preparation of SA-LDH: MgAl-CO23 -LDH (LDH) was purchased from Nan Tong Advanced Chemicals Ltd., China.10 g MgAl-CO23 LDH sample was firstly dispersed in 200 mL deionized water in a 500 mL three-necked flask before vigorously stirred by a magnetic stirrer for around 20 min, then 50 mL SA water solution which contained 10 g SA was added into the above slurry, and the mixture was stirred vigorously at 50 1C for 2 h. The precipitate was finally washed, filtered and dried at 50 1C for 10 h, and SA-LDH was obtained. The EVA/SA-LDH composite were obtained by melt blending using a micro two-screw extruder. The temperature of the micro extruder from the hopper to the die was 90/110/120 1C, and the screw speed was 40 rpm. Characterization: Wide angle X-ray diffraction (WXRD) were examined on a RigakuDmax2500VB2þ /PC diffractometer with Cu-Kα radiation source (λ¼0.154 nm). X-ray photoelectron spectroscopy (XPS) was examined on ThermoVG ESCALAB 250. Fourier transform infrared (FTIR) spectra were recorded on a Thermo Nicolet Nexus 670 (USA). The surface morphology and particle size were examined with JAPAN JEM-3010 transmission electron microscopy (TEM). The analysis was performed at 200 kV acceleration voltage and bright field illumination under ambient temperature and the samples were obtained by dispersing the particles into alcoholic solution with ultrasonic impact treatment. Fire Testing Technology cone calorimeter
http://dx.doi.org/10.1016/j.matlet.2014.12.096 0167-577X/& 2015 Published by Elsevier B.V.
Please cite this article as: Jiang Y, et al. The preparation and characterization of sulfamic acid-intercalated layered double hydroxide. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2014.12.096i
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Y. Jiang et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
was also used to evaluate the fire performance of the composite according to the standard ISO 5660 under a heat flux of 50 kW/m2 with a sample size of 100 100 3 mm3 in conditions comparable to a mild fire scenario.
Fig. 1. XRD patterns of (a) LDH and (b) SA-LDH.
Fig. 2. FT-IR spectra of (a) LDH, (b) SA-LDH, and (c) NH2SO3Na.
3. Results and discussion XRD analysis: Fig. 1 displays the XRD spectra of the LDH and SALDH. The patterns of LDH exhibits strong and sharp peaks of 0 0 l (l ¼3, 6, 9) at ¼11.21, 23.301 and 34.501, reflecting well-crystallized and ordered layered phases and the basal spacing of 0.77, 0.38 and 0.26 nm can be calculated, respectively, according to the Bragg equation. All diffraction peaks of 0 0 l (l ¼3, 6, 9) in SA-LDH left shift to 9.661, 19.391 and 34.421, indicating the corresponding basal spacing has been enlarged to 0.91, 0.76 and 0.26 nm, respectively. The increase in basal spacing indicates that NH2SO3 has been successfully intercalated into the interlayers of LDH. FT-IR spectra analysis: Fig. 2 displays the FTIRspectra of NH2SO3Na, LDH and SA-LDH.Both LDH and SA-LDH show the absorption bands of O–H stretching at about 3450 cm 1, δ(H–OH) vibrations at about 1625 cm 1, and the lattice vibration of the M–O and O–M–O (M¼ Mg and Al) groups in the low frequency region below 800 cm 1 [14]. The peak at 1370 cm 1 in the spectrum of LDH is assigned to the carbonate stretching, which has disappeared in the spectrum of SA-LDH with several emerged new peaks. Peaks at 1222, 1129, and 1055 cm 1 are corresponding to the vibrations of S¼O and the peak at 810 cm 1 is assigned to S–O. Peaks at 3320 and 3268 cm 1 are corresponding to the stretching vibration of –NH2 [15,16]. It could be concluded that NH2 SO3 1 has been successfully intercalated into the interlayers of LDH. XPS and TEM analysis: The binding energy values for the N element of SA and SA-LDH have been measured by XPS. Fig. 3 shows the XPS spectra of SA and SA-LDH, and it can be seen the peak binding energy of N in SA appears at 401.7 eV, however, a new peak appears at 399.5 eV in SA-LDH. Based on the peak fitting result shown in Fig. 3 (2), the area ratio of peak at 399.5 eV and 401.7 eV is about 65.6% and 34.4%, respectively. In other words the binding status of about two thirds of N has been altered after intercalation. This may be attributed to the formation of hydrogen bonds between N and H atoms in NH2SO3 (the sketch map is shown in supporting information). TEM images of LDH and SA-LDH are shown in Fig. 4. Plate like particles with edges can be observed. Compared with the homogeneous distribution of the LDH particles, intensive aggregation of SA-LDH particles is represented. This may be mainly due to the formation of hydrogen bonds between N, O and H in NH2 SO3 1 , which is consistent with the XPS analysis. Cone calorimeter analysis: Fig. 5 shows the cone test curves of EVA and its composites. One can see a second peak of heat release rate (PHRR2) after the initial peak (PHRR1) curve, which is presumably due to char-surface rupture or burn-out of the sample. PHRR1 and
Fig. 3. XPS spectra of SA and SA-LDH.
Please cite this article as: Jiang Y, et al. The preparation and characterization of sulfamic acid-intercalated layered double hydroxide. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2014.12.096i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
Y. Jiang et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Fig. 4. The TEM images of LDH (A) and SA-LDH (B).
4. Conclusion Layered double hydroxides intercalated with NH2SO3 were successfully prepared and its structure is verified by FTIR, XRD, TEM and XPS analysis. Key characteristic bands of NH2SO3 were observed in the FT-IR spectrum of SA-LDH. The basal spacing was enlarged from 0.76 to 0.93 nm, and the formation of hydrogen bonds between SA-LDH was proposed. EVA composites containing SA-LDH were prepared via melt blending and it has been demonstrated that the presence of SA-LDH can significantly improve the fire resistance of EVA. Acknowledgements
Fig. 5. HRR curves of (a) EVA, (b) EVA/20 wt.% LDH and (c) EVA/20 wt.% SA-LDH.
PHRR2 for EVA/20 wt.% SA-LDH are 633.8 kW/m2 and 612.4 kW/m2, respectively, which are reduced 28.2% and 34.5% compared with that of the sample EVA/20 wt.% LDH. This further demonstrates SA intercalation can improve the flame retardant efficiency of LDH. Time to PHRR1(t1), time to PHRR2(t2) and other parameters are also showed in Fig. 5. It can be seen that the presence of SA can increase the (t2 t1) value of EVA composite sample from 66 to 160 s, indicating the SA-LDH could further delay the fire spreading speed in fire scenario.
The authors wish to thank the National Natural Science Foundation of China (Grant nos. 21061130552/B040607, 51002069) for the financial support during this research. 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.2014.12.096. References [1] Wang Q, Dermot O’Hare. Chem Rev 2012;112:4124–55. [2] Shabanian M, Basaki N, Khonakdar HA, Jafari SH, Hedayati K, Wagenknecht U. Appl Clay Sci 2014;90:101–8.
Please cite this article as: Jiang Y, et al. The preparation and characterization of sulfamic acid-intercalated layered double hydroxide. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2014.12.096i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
Y. Jiang et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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[3] [4] [5] [6] [7]
Nyambo C, Kandare E, Wilkie CA. Polym Degrad Stab 2009;94:513–20. Fu PJ, Chen GM, Liu J, Yang JP. Mater Lett 2009;63:1725–8. Ay AN, Zümreoglu-Karan B, Temel A, Mafra L. Appl Clay Sci 2011;51:308–16. Manzi-Nshuti C, Hossenlopp JM, Wilkie CA. Polym Degrad Stab 2009;94:782–8. Nyambo C, Songtipya P, Manias E, Jimenez-Gasco MM, Wilkie CA. J Mater Chem 2008;18:4827–38. [8] Li F, Duan X. Struct Bond 2006;119:193–223. [9] Choy JH, Kwak SY, Jeong YJ, Park JS. Angew Chem Int Ed 2000;39:4041–5. [10] Wang H, Xiang X, Li F. J Mater Chem 2010;20:3944–52.
10 [11] Wang DY, Leuteritz A, Kutlu B, Landwehr MA, Jehnichen D, Wagenknecht U, et al. J Alloys Compd 2011;509:3497–501. Q2 11 [12] Wang DY, Das A, Costa FR, Leuteritz A, Wang YZ, Wagenknecht U, et al. 12 Langmuir 2010;26:14162–9. 13 [13] Liu XS, Gu XY, Zhang S, Jiang Y, Sun J, Dong MZJ. Appl Polym Sci 2013;130:3645–51. 14 [14] Ye L, Qu B. Polym Degrad Stab 2008;93:918–24. 15 [15] Marchewka MK, Drozd M. Spectrochim Acta A. 2012;99:223–33. 16 [16] Muthusubramanian P, Sundara Raj A. J Raman Spectrosc 1983;14:221–4. 17
Please cite this article as: Jiang Y, et al. The preparation and characterization of sulfamic acid-intercalated layered double hydroxide. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2014.12.096i
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Q1 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
The preparation and characterization of sulfamic acid-intercalated layered double hydroxide Yu Jiang, Xiaoyu Gu, Sheng Zhang n, Wufei Tang, Jingran Zhao Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China
art ic l e i nf o
a b s t r a c t
Article history: Received 29 October 2014 Accepted 19 December 2014
NH2 SO3 1 was intercalated into layered double hydroxide to prepare a novel sulfamic acid-intercalated MgAl-LDH (SA-LDH). Fourier transform infrared (FT-IR) analysis confirmed the presence of sulfamic acid in LDH. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were also used to characterize the structural morphology of SA-LDH, and the results revealed that the interlayer space of LDH had been enlarged from 0.76 to 0.91 nm and proved the formation of hydrogen bonds between SA-LDH. The SA-LDH was introduced into ethylene vinyl acetate (EVA) copolymer via melt blending, and the cone calorimetry test results demonstrated that the presence of SA-LDH could significantly improve the flame retardancy of EVA composite. & 2015 Published by Elsevier B.V.
Keywords: Layered double hydroxide Intercalation Composite materials XPS Flammability
1. Introduction LDH is a class of synthetic anionic clays with host-guest nanolayer material containing positively charged metal hydroxide sheets, intercalated anions as guest and water molecules [1–3]. LDHs have been widely investigated that was partly driven by the use of these materials as ion exchange hosts, fire retardant additives, catalytic agent, drug delivery and so on [4–7]. Its general formula is n MII1 xMIII )x/n mH2O, where MII and MIII are, respectively, x (OH)2(A 2þ divalent (Mg , Zn2 þ , Co2 þ ) and trivalent cations (Al3 þ , Fe3 þ , Mn3 þ ), and An is the charge balancing interlayer anion [8–10]. Recently, most of the ongoing investigations focus on lamellar compounds for their unique anion exchange and intercalation properties [11–13]. The sulfamic acid (SA) with a molecular formula of NH2SO3H is an effective flame retardant for many polymers and textile materials, therefore, it is expected that the intercalation of NH2 SO3 1 can improve the flame retardancy of LDH, which has not been reported so far. In this work, a novel sulfamic acid-intercalated MgAl-LDH (SALDH) was prepared and characterized. The interlayer anion of LDH was displaced through acid-base reaction between SA and CO23 , and carbon dioxide generated in the reaction. The structure and morphology of intercalated LDH were characterized, and the effect
n
Corresponding author. Tel.: þ 86 10 18610021239; fax: þ86 10 64436820. E-mail address: [email protected] (S. Zhang).
of SA-LDH on the flammability behavior of EVA was investigated by using cone calorimeter.
2. Experimental Preparation of SA-LDH: MgAl-CO23 -LDH (LDH) was purchased from Nan Tong Advanced Chemicals Ltd., China.10 g MgAl-CO23 LDH sample was firstly dispersed in 200 mL deionized water in a 500 mL three-necked flask before vigorously stirred by a magnetic stirrer for around 20 min, then 50 mL SA water solution which contained 10 g SA was added into the above slurry, and the mixture was stirred vigorously at 50 1C for 2 h. The precipitate was finally washed, filtered and dried at 50 1C for 10 h, and SA-LDH was obtained. The EVA/SA-LDH composite were obtained by melt blending using a micro two-screw extruder. The temperature of the micro extruder from the hopper to the die was 90/110/120 1C, and the screw speed was 40 rpm. Characterization: Wide angle X-ray diffraction (WXRD) were examined on a RigakuDmax2500VB2þ /PC diffractometer with Cu-Kα radiation source (λ¼0.154 nm). X-ray photoelectron spectroscopy (XPS) was examined on ThermoVG ESCALAB 250. Fourier transform infrared (FTIR) spectra were recorded on a Thermo Nicolet Nexus 670 (USA). The surface morphology and particle size were examined with JAPAN JEM-3010 transmission electron microscopy (TEM). The analysis was performed at 200 kV acceleration voltage and bright field illumination under ambient temperature and the samples were obtained by dispersing the particles into alcoholic solution with ultrasonic impact treatment. Fire Testing Technology cone calorimeter
http://dx.doi.org/10.1016/j.matlet.2014.12.096 0167-577X/& 2015 Published by Elsevier B.V.
Please cite this article as: Jiang Y, et al. The preparation and characterization of sulfamic acid-intercalated layered double hydroxide. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2014.12.096i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101
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Y. Jiang et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
was also used to evaluate the fire performance of the composite according to the standard ISO 5660 under a heat flux of 50 kW/m2 with a sample size of 100 100 3 mm3 in conditions comparable to a mild fire scenario.
Fig. 1. XRD patterns of (a) LDH and (b) SA-LDH.
Fig. 2. FT-IR spectra of (a) LDH, (b) SA-LDH, and (c) NH2SO3Na.
3. Results and discussion XRD analysis: Fig. 1 displays the XRD spectra of the LDH and SALDH. The patterns of LDH exhibits strong and sharp peaks of 0 0 l (l ¼3, 6, 9) at ¼11.21, 23.301 and 34.501, reflecting well-crystallized and ordered layered phases and the basal spacing of 0.77, 0.38 and 0.26 nm can be calculated, respectively, according to the Bragg equation. All diffraction peaks of 0 0 l (l ¼3, 6, 9) in SA-LDH left shift to 9.661, 19.391 and 34.421, indicating the corresponding basal spacing has been enlarged to 0.91, 0.76 and 0.26 nm, respectively. The increase in basal spacing indicates that NH2SO3 has been successfully intercalated into the interlayers of LDH. FT-IR spectra analysis: Fig. 2 displays the FTIRspectra of NH2SO3Na, LDH and SA-LDH.Both LDH and SA-LDH show the absorption bands of O–H stretching at about 3450 cm 1, δ(H–OH) vibrations at about 1625 cm 1, and the lattice vibration of the M–O and O–M–O (M¼ Mg and Al) groups in the low frequency region below 800 cm 1 [14]. The peak at 1370 cm 1 in the spectrum of LDH is assigned to the carbonate stretching, which has disappeared in the spectrum of SA-LDH with several emerged new peaks. Peaks at 1222, 1129, and 1055 cm 1 are corresponding to the vibrations of S¼O and the peak at 810 cm 1 is assigned to S–O. Peaks at 3320 and 3268 cm 1 are corresponding to the stretching vibration of –NH2 [15,16]. It could be concluded that NH2 SO3 1 has been successfully intercalated into the interlayers of LDH. XPS and TEM analysis: The binding energy values for the N element of SA and SA-LDH have been measured by XPS. Fig. 3 shows the XPS spectra of SA and SA-LDH, and it can be seen the peak binding energy of N in SA appears at 401.7 eV, however, a new peak appears at 399.5 eV in SA-LDH. Based on the peak fitting result shown in Fig. 3 (2), the area ratio of peak at 399.5 eV and 401.7 eV is about 65.6% and 34.4%, respectively. In other words the binding status of about two thirds of N has been altered after intercalation. This may be attributed to the formation of hydrogen bonds between N and H atoms in NH2SO3 (the sketch map is shown in supporting information). TEM images of LDH and SA-LDH are shown in Fig. 4. Plate like particles with edges can be observed. Compared with the homogeneous distribution of the LDH particles, intensive aggregation of SA-LDH particles is represented. This may be mainly due to the formation of hydrogen bonds between N, O and H in NH2 SO3 1 , which is consistent with the XPS analysis. Cone calorimeter analysis: Fig. 5 shows the cone test curves of EVA and its composites. One can see a second peak of heat release rate (PHRR2) after the initial peak (PHRR1) curve, which is presumably due to char-surface rupture or burn-out of the sample. PHRR1 and
Fig. 3. XPS spectra of SA and SA-LDH.
Please cite this article as: Jiang Y, et al. The preparation and characterization of sulfamic acid-intercalated layered double hydroxide. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2014.12.096i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
Y. Jiang et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Fig. 4. The TEM images of LDH (A) and SA-LDH (B).
4. Conclusion Layered double hydroxides intercalated with NH2SO3 were successfully prepared and its structure is verified by FTIR, XRD, TEM and XPS analysis. Key characteristic bands of NH2SO3 were observed in the FT-IR spectrum of SA-LDH. The basal spacing was enlarged from 0.76 to 0.93 nm, and the formation of hydrogen bonds between SA-LDH was proposed. EVA composites containing SA-LDH were prepared via melt blending and it has been demonstrated that the presence of SA-LDH can significantly improve the fire resistance of EVA. Acknowledgements
Fig. 5. HRR curves of (a) EVA, (b) EVA/20 wt.% LDH and (c) EVA/20 wt.% SA-LDH.
PHRR2 for EVA/20 wt.% SA-LDH are 633.8 kW/m2 and 612.4 kW/m2, respectively, which are reduced 28.2% and 34.5% compared with that of the sample EVA/20 wt.% LDH. This further demonstrates SA intercalation can improve the flame retardant efficiency of LDH. Time to PHRR1(t1), time to PHRR2(t2) and other parameters are also showed in Fig. 5. It can be seen that the presence of SA can increase the (t2 t1) value of EVA composite sample from 66 to 160 s, indicating the SA-LDH could further delay the fire spreading speed in fire scenario.
The authors wish to thank the National Natural Science Foundation of China (Grant nos. 21061130552/B040607, 51002069) for the financial support during this research. 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.2014.12.096. References [1] Wang Q, Dermot O’Hare. Chem Rev 2012;112:4124–55. [2] Shabanian M, Basaki N, Khonakdar HA, Jafari SH, Hedayati K, Wagenknecht U. Appl Clay Sci 2014;90:101–8.
Please cite this article as: Jiang Y, et al. The preparation and characterization of sulfamic acid-intercalated layered double hydroxide. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2014.12.096i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
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[3] [4] [5] [6] [7]
Nyambo C, Kandare E, Wilkie CA. Polym Degrad Stab 2009;94:513–20. Fu PJ, Chen GM, Liu J, Yang JP. Mater Lett 2009;63:1725–8. Ay AN, Zümreoglu-Karan B, Temel A, Mafra L. Appl Clay Sci 2011;51:308–16. Manzi-Nshuti C, Hossenlopp JM, Wilkie CA. Polym Degrad Stab 2009;94:782–8. Nyambo C, Songtipya P, Manias E, Jimenez-Gasco MM, Wilkie CA. J Mater Chem 2008;18:4827–38. [8] Li F, Duan X. Struct Bond 2006;119:193–223. [9] Choy JH, Kwak SY, Jeong YJ, Park JS. Angew Chem Int Ed 2000;39:4041–5. [10] Wang H, Xiang X, Li F. J Mater Chem 2010;20:3944–52.
10 [11] Wang DY, Leuteritz A, Kutlu B, Landwehr MA, Jehnichen D, Wagenknecht U, et al. J Alloys Compd 2011;509:3497–501. Q2 11 [12] Wang DY, Das A, Costa FR, Leuteritz A, Wang YZ, Wagenknecht U, et al. 12 Langmuir 2010;26:14162–9. 13 [13] Liu XS, Gu XY, Zhang S, Jiang Y, Sun J, Dong MZJ. Appl Polym Sci 2013;130:3645–51. 14 [14] Ye L, Qu B. Polym Degrad Stab 2008;93:918–24. 15 [15] Marchewka MK, Drozd M. Spectrochim Acta A. 2012;99:223–33. 16 [16] Muthusubramanian P, Sundara Raj A. J Raman Spectrosc 1983;14:221–4. 17
Please cite this article as: Jiang Y, et al. The preparation and characterization of sulfamic acid-intercalated layered double hydroxide. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2014.12.096i