Dose rate effects on shape memory epoxy resin during 1 MeV electron irradiation in air

doi:10.1016/j.jmst.2020.06.020

Abstract

Abstract:

The effects of 1 MeV electron irradiation in air at a fixed accumulated dose and dose rates of 393.8, 196.9, 78.8, and 39.4 Gy s ^-1 on a shape memory epoxy (SMEP) resin were studied. Under low-dose-rate irradiation, accelerated degradation of the shape memory performance was observed; specifically, the shape recovery ratio decreased exponentially with increasing irradiation time (that is, with decreasing dose rate). In addition, the glass transition temperature of the SMEP, as measured by dynamic mechanical analysis, decreased overall with decreasing dose rate. The dose rate effects of 1 MeV electron irradiation on the SMEP were confirmed by structural analysis using electron paramagnetic resonance (EPR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The EPR spectra showed that the concentration of free radicals increased exponentially with increasing irradiation time. Moreover, the FTIR spectra showed higher intensities of the peaks at 1660 and 1720 cm ^-1, which are attributed to stretching vibrations of amide C=O and ketone/acid C=O, at lower dose rates. The intensities of the IR peaks at 1660 and 1720 cm ^-1 increased exponentially with increasing irradiation time, and the relative intensity of the IR peak at 2926 cm ^-1 decreased exponentially with increasing irradiation time. The solid-state ¹³C nuclear magnetic resonance (NMR) spectra of the SMEP before and after 1 MeV electron irradiation at a dose of 1970 kGy and a dose rate of 78.8 Gy s ^-1 indicated damage to the CH₂-N groups and aliphatic isopropanol segment. This result is consistent with the detection of nitrogenous free radicals, a phenoxy-type free radical, and several types of pyrolytic carbon radicals by EPR. During the subsequent propagation process, the free radicals produced at lower dose rates were more likely to react with oxygen, which was present at higher concentrations, and form the more destructive peroxy free radicals and oxidation products such as acids, amides, and ketones. The increase in peroxy free radicals at lower dose rates was thought to accelerate the degradation of the macroscopic performance of the SMEP.

Key words: Shape memory epoxy resin, Shape memory effect, Electron irradiation, Dose rate effect, Free radical, Chain scission

Longyan Hou, Yiyong Wu, Debin Shan, Bin Guo, Yingying Zong. Dose rate effects on shape memory epoxy resin during 1 MeV electron irradiation in air[J]. J. Mater. Sci. Technol., 2021, 67: 61-69.

Figures/Tables 10

Fig. 1. Chemical structures of DGEBA, DDM, and DGEBA-DDM crosslinked network. Carbons are labelled for later reference.

Fig. 2. Shape memory performance of SMEP (a) before and after 1 MeV electron irradiation at dose rates of (b) 393.8 Gy s-1, (c) 196.9 Gy s-1, (d) 78.8 Gy s-1, and (e) 39.4 Gy s-1.

Fig. 3. Shape memory properties of SMEP before and after 1 MeV electron irradiation at different dose rates.

Fig. 4. DMA results of SMEP before and after 1 MeV electron irradiation at different dose rates: (a) storage modulus and (b) loss modulus.

Fig. 5. (a) EPR spectra and (b) free radical concentration of SMEP after 1 MeV electron irradiation at different dose rates.

Fig. 6. FTIR spectra of SMEP before and after 1 MeV electron irradiation at different dose rates.

Fig. 7. Relative intensities (I/I1507) of IR peaks at 1660, 1720, and 2926 cm-1 before and after 1 MeV electron irradiation at different dose rates.

Fig. 8. Solid-state 13C NMR spectra of SMEP before and after 1 MeV electron irradiation at a dose of 1970 kGy and a dose rate of 78.8 Gy s-1. The spinning side bands are marked with asterisks.

Table 1 Peak assignments of 13C chemical shifts of SMEP before and after 1 MeV electron irradiation at a dose of 1970 kGy and a dose rate of 78.8 Gy s-1 (carbons as labelled in Fig. 1).

Chemical shift (ppm)	Assignment	Type of carbon	Reduction in relative peak intensity (%)	Error (±)
156.4	C-9	Aromatic C-O	8.29	0.42
143.7	C-5, C-12	Aromatic tertiary carbon	5.52	0.28
127.9	C-2, C-3, C-11	Aromatic CH	—	—
113.7	C-4, C-10	Aromatic CH	—	—
69.3	C-7, C-8	Aliphatic C-O	6.73	0.34
54.9	C-6	CH₂-N	—	—
50.3	C-b	Oxirane methylidyne CH	4.36	0.22
44.6	C-a	Oxirane methylene CH₂	—	—
41.3	C-1, C-13	Quaternary carbon	5.56	0.28
31.1	C-14	Methyl group CH₃	1.19	0.06

Fig. 9. Schematic illustrations of possible reaction mechanism of SMEP irradiated by 1 MeV electrons in air. (a), (b) Formation of nitrogenous free radicals, phenoxy-type free radicals, and ketones, (c), (d) formation of acids, and (e) formation of amides.

References 45

[1]	H. Gao, F. Xie, Y. Liu, J. Leng, Polym. Degrad. Stab. 156(2018) 245-251.
[2]	K.S. Santhosh Kumar, R. Biju, C.P. Reghunadhan Nair, React. Funct. Polym. 73(2013) 421-430.
[3]	Y. Liu, C. Han, H. Tan, X. Du, Mater. Sci. Eng. A 527 (2010) 2510-2514.
[4]	J. Leng, F. Xie, X. Wu, Y. Liu, J. Intell, Mater. Syst. Struct. 25(2014) 1256-1263.
[5]	L. Hou, Y. Wu, B. Guo, D. Shan, Y. Zong, Mater. Lett. 222(2018) 37-40.
[6]	L. Hou, Y. Wu, D. Shan, B. Guo, Y. Zong, Smart Mater. Struct. 28(2019), 115003.
[7]	W. Zhang, M. Wang, W. Liu, C. Yang, G. Wu, Polym. Degrad. Stab. 167(2019) 201-209.
[8]	A.B. Reynolds, R.M. Bell, N. Bryson, T.E. Doyle, M.B. Hall, L.R. Mason, L. Quintric, P.L. Terwilliger, Radiat. Phys. Chem. 45(1995) 103-110.
[9]	A. Buttafava, A. Tavares, M. Arimondi, A. Zaopo, S. Nesti, D. Dondi, M. Mariani, A. Faucitano, Nucl. Instrum. Methods Phys. Res. Sect. B 265 (2007) 221-226.
[10]	E.N. Hoffman, T.E. Skidmore, J. Nucl. Phys. Mater. Sci. Radiat. Appl. 392(2009) 371-378.
[11]	K.T. Gillen, R.L. Clough, J. Polym. Sci.: Polym. Chem. Ed. 23(1985) 2683-2707.
[12]	T. Seguchi, S. Hashimoto, K. Arakawa, N. Hayakawa, W. Kawakami, I. Kuriyama, Radiat. Phys. Chem. 17(1981) 195-201.
[13]	V. Placek, B. Bartonicek, V. Hnat, B. Otahal, Nucl. Instrum. Methods. Phys. Res.Sect. B 208 (2003) 448-453.
[14]	S. Lewandowski, S. Duzelier, J. Eck, S. Dagras, C. Tonon, H. Jochem, P. Jouanne, E. Laurent, J.M. Desmarres, J. Spacecr. Rockets 53 (2016) 1146-1151.
[15]	I. Kuriyama, N. Hayakawa, Y. Nakase, J. Ogura, H. Yagyu, K. Kasai, IEEE Trans.Dielectr. Electr. Insul. 14(1979) 272-277.
[16]	L. Hou, Y. Wu, J. Xiao, B. Guo, Y. Zong, Polym. Degrad. Stab. 166(2019) 8-16.
[17]	S. Chen, H. Yuan, Z. Ge, S. Chen, H. Zhuo, J. Liu, J. Mater. Chem. C Mater. Opt.Electron. Devices 2 (2014) 1041-1049.
[18]	Y. Shao, C. Lavigueur, X.X. Zhu, Macromolecules 45 (2012) 1924-1930.
[19]	F. Djouani, Y. Zahra, B. Fayolle, M. Kuntz, J. Verdu, Radiat. Phys. Chem. 82(2013) 54-62.
[20]	R. Li, Y. Gu, Z. Yang, M. Li, S. Wang, Z. Zhang, J. Nucl. Phys. Mater. Sci. Radiat.Appl. 466(2015) 100-107.
[21]	C. Galant, B. Fayolle, M. Kuntz, J. Verdu, Prog. Org. Coat. 69(2010) 322-329.
[22]	C. Sun, Y. Wu, J. Xiao, R. Li, D. Yang, S. He, J. Appl. Phys. 110(2011), 124909.
[23]	M. Marrale, A. Longo, S. Panzeca, S. Gallo, F. Principato, E. Tomarchio, A. Parlato, A. Buttafava, D. Dondi, A. Zeffiro, Nucl. Instrum. Methods Phys.Res. B339(2014) 15-19.
[24]	C. Sun, Y. Wu, J. Xiao, S. Yu, Z. Yi, Z. Shen, L. Wang, Y. Wang, Nucl. Instrum.Methods Phys. Res. B 397 (2017) 39-44.
[25]	T. Devanne, A. Bry, N. Raguin, M. Sebban, P. Palmas, L. Audouin, J. Verdu, Polymer 46 (2005) 237-241.
[26]	A. Idesaki, H. Uechi, Y. Hakura, H. Kishi, Radiat. Phys. Chem. 98(2014) 1-6.
[27]	B. Liu, W. Huang, Y. Ao, P. Wang, Y. An, H. Chen, Polym. Degrad. Stab. 147(2018) 97-102.
[28]	Y. Hama, K. Shinohara, J. Polym. Sci.: Polym. Chem. Ed. 8(1970) 651-663.
[29]	Y. Zahra, F. Djouani, B. Fayolle, M. Kuntz, J. Verdu, Prog. Org. Coat. 77(2014) 380-387.
[30]	K. Wu, K. Cheng, C. Wang, C. Yang, Y. Lai, Mater. Express 6 (2016) 28-36.
[31]	S. Meure, D. Wu, S.A. Furman, Vib. Spectrosc. 52(2010) 10-15.
[32]	F. Carrasco, P. Pages, T. Lacorte, K. Briceno, J. Appl. Polym. Sci. 98(2005) 1524-1535.
[33]	A. Rivaton, L. Moreau, J.L. Gardette, Polym. Degrad. Stab. 58(1997) 321-332.
[34]	Y. Pei, K. Wang, M. Zhan, W. Xu, X. Ding, Polym. Degrad. Stab. 96(2011) 1179-1186.
[35]	Y. Ngono Ravache, M.F. Foray, M. Bardet, Polym. Adv. Technol. 12(2001) 515-523.
[36]	H. Yan, C.X. Lu, D.Q. Jing, X.L. Hou, Chin. J. Polym. Sci. 32(2014) 1550-1563.
[37]	F. Diao, Y. Zhang, Y. Liu, J. Fang, W. Luan, Nucl. Instrum. Methods Phys. Res., Sect. B 383 (2016) 227-233.
[38]	A. Nowicki, G.Y. Przybytniak, I. Legocka, K. Mirkowski, Radiat. Phys. Chem. 94(2014) 22-25.
[39]	C. Sun, Y. Wu, Y. Shi, J. Xiao, L. Yue, Y. Zhang, Polym. Degrad. Stab. 97(2012) 178-184.
[40]	A. Kondyurin, P. Naseri, K. Fisher, D.R. McKenzie, M.M.M. Bilek, Polym.Degrad. Stab. 94(2009) 638-646.
[41]	J.D. Memory, R.E. Fornes, R.D. Gilbert, J. Reinf. Plast. Compos. 7(1988) 33-65.
[42]	J.P. Harmon, A.G. Taylor, G.T. Schueneman, E.P. Goldberg, Polym. Degrad. Stab. 41(1993) 319-322.
[43]	V.A. Agubra, H.V. Mahesh, J. Polym. Sci. Part B: Polym. Phys. 52(2014) 1024-1029.
[44]	A.J. Parashuram, B.S. Rao, N.S.R. Reddy, Radiat. Eff. Defects. Solids. 159(2004) 423-430.
[45]	N. Longiéras, M. Sebban, P. Palmas, A. Rivaton, J.L. Gardette, Polym. Degrad.Stab. 92(2007) 2190-2197.