Abstract
Broadband dielectric spectroscopy, heat capacity spectroscopy (3ω method), and viscosimetry have been used to study the dynamic glass transition of two glass-forming epoxy resins, poly [(phenyl glycidyl ether)-co-formaldehyde] and diglycidyl ether of bisphenol-A. In spite of their rather simple molecular structure, the dynamics of these systems is characterized by two well-separated crossover regions where the relaxation times of main transition and the two secondary relaxations β and γ approach each other. The main transition has three parts: The a process at high temperature, the a′ process between the two crossover regions, and the α process at low temperatures. Both the γ-crossover region [around a temperature Tc(γ)∼(1.4–1.5)Tg and a relaxation time τc(γ)≈10−10 s] and the β-crossover region [around Tc(β)∼(1.1–1.2)Tg and τc(β)≈10−6 s] could be studied within the experimentally accessible frequency–temperature window. Different typical crossover properties are observed in the two regions. The γ-crossover region is characterized by onset of the (a′,α) process, with a relaxation time about one decade greater than that of the quasicontinuous (a,γ) trace. The β-crossover region is characterized, besides splitting of main andβ relaxation times, by a change in the temperature dependence of the main-relaxation time as reflected by a bend in the Stickel plot of the continuous (a′,α) trace, the separation of individual temperature dependences of different transport properties such as impurity-ions diffusion coefficient and viscosity, and a temperature-dependent main relaxation time that starts to be in accordance (at lower temperatures) with the Adam–Gibbs model. The cooperativity of the main process between the γ and β crossover seems to be small. Below the β crossover, cooperativity increases up to values of order Nα∼100 near Tg, and configurational entropy seems to correlate with the main relaxation time.
References
76
Referenced
108
10.1016/S0022-3093(00)00409-9
/ J. Non-Cryst. Solids (2001)10.1016/S0022-3093(00)00238-6
/ J. Non-Cryst. Solids (2000)10.1039/TF9666202091
/ Trans. Faraday Soc. (1966)10.1063/1.1674335
/ J. Chem. Phys. (1970)10.1063/1.1676742
/ J. Chem. Phys. (1971)10.1021/j100704a038
/ J. Chem. Phys. (1970)10.1021/ma9506142
/ Macromolecules (1996){'key': '2024020711424121300_r8', 'first-page': '3016', 'volume': '56', 'year': '1997', 'journal-title': 'Phys. Rev. B'}
/ Phys. Rev. B (1997)10.1021/ma961933b
/ Macromolecules (1997){'key': '2024020711424121300_r10'}
10.1063/1.469071
/ J. Chem. Phys. (1995)10.1063/1.470961
/ J. Chem. Phys. (1996)10.1063/1.476063
/ J. Chem. Phys. (1998)10.1007/BF01323572
/ Z. Phys. B: Condens. Matter (1992)10.1063/1.1840448
/ J. Chem. Phys. (1967)10.1063/1.480752
/ J. Chem. Phys. (2000)10.1103/PhysRevLett.65.1595
/ Phys. Rev. Lett. (1990)10.1063/1.1696442
/ J. Chem. Phys. (1965)10.1063/1.476348
/ J. Chem. Phys. (1998)10.1103/PhysRevE.57.7346
/ Phys. Rev. E (1998)10.1063/1.479644
/ J. Chem. Phys. (1999)10.1209/epl/i1998-00477-3
/ Europhys. Lett. (1998)10.1063/1.479942
/ J. Chem. Phys. (1999){'key': '2024020711424121300_r24'}
10.1039/f29898500581
/ J. Chem. Soc., Faraday Trans. 2 (1989)10.1016/0167-7322(89)80097-2
/ J. Mol. Liq. (1989){'key': '2024020711424121300_r27'}
{'key': '2024020711424121300_r28', 'first-page': 'L451', 'volume': '13', 'year': '2001', 'journal-title': 'J. Phys.: Condens. Matter'}
/ J. Phys.: Condens. Matter (2001)10.1016/S0009-2614(00)00185-8
/ Chem. Phys. Lett. (2000){'key': '2024020711424121300_r30'}
10.1103/PhysRevLett.54.2674
/ Phys. Rev. Lett. (1985)10.1016/S0040-6031(97)00028-2
/ Thermochim. Acta (1997)10.1016/S0040-6031(01)00546-9
/ Thermochim. Acta (2001)10.1103/PhysRevB.61.15092
/ Phys. Rev. B (2000)10.1063/1.1319616
/ J. Chem. Phys. (2000)10.1103/PhysRevE.60.3086
/ Phys. Rev. E (1999)10.1021/ma9504025
/ Macromolecules (1996)10.1103/PhysRevLett.61.341
/ Phys. Rev. Lett. (1988)10.1103/PhysRevB.42.8179
/ Phys. Rev. B (1990)10.1088/0034-4885/55/3/001
/ Rep. Prog. Phys. (1992)10.1063/1.471919
/ J. Chem. Phys. (1996)10.1103/PhysRevE.54.3853
/ Phys. Rev. E (1996)10.1021/ma9713318
/ Macromolecules (1998)10.1063/1.477376
/ J. Chem. Phys. (1998)10.1103/PhysRevE.60.1099
/ Phys. Rev. E (1999){'key': '2024020711424121300_r46', 'first-page': '1103', 'volume': '60', 'year': '1999', 'journal-title': 'Phys. Rev. E'}
/ Phys. Rev. E (1999)10.1016/S0022-2860(98)00871-0
/ J. Mol. Struct. (1999){'key': '2024020711424121300_r48'}
{'key': '2024020711424121300_r49'}
10.1063/1.479847
/ J. Chem. Phys. (1999)10.1103/PhysRevLett.73.2935
/ Phys. Rev. Lett. (1994)10.1103/PhysRevLett.70.3459
/ Phys. Rev. Lett. (1993)10.1063/1.1286035
/ J. Appl. Phys. (2000)10.1016/0022-3093(82)90089-8
/ J. Non-Cryst. Solids (1982)10.1021/jp991153f
/ J. Phys. Chem. B (2000){'key': '2024020711424121300_r56'}
{'key': '2024020711424121300_r57', 'first-page': '542', 'volume': '18', 'year': '1917', 'journal-title': 'Phys. Z.'}
/ Phys. Z. (1917)10.1016/S0022-3093(98)00831-X
/ J. Non-Cryst. Solids (1999)10.1021/jp973439v
/ J. Phys. Chem. B (1998)10.1080/13642810208221313
/ Philos. Mag. B (2002)10.1002/actp.1997.010480904
/ Acta Polym. (1997){'key': '2024020711424121300_r62'}
10.1039/FS9720600023
/ Faraday Symp. Chem. Soc. (1972)10.1063/1.1731229
/ J. Chem. Phys. (1960){'key': '2024020711424121300_r65'}
{'key': '2024020711424121300_r66'}
10.1002/polb.1993.090310308
/ J. Polym. Sci., Polym. Phys. Ed. (1993){'key': '2024020711424121300_r68'}
{'key': '2024020711424121300_r69'}
10.1016/0032-3861(85)90014-X
/ Polymer (1985)10.1063/1.465470
/ J. Chem. Phys. (1993)10.1021/ma9714068
/ Macromolecules (1998)10.1063/1.1355288
/ J. Chem. Phys. (2001){'key': '2024020711424121300_r74', 'first-page': '4405', 'volume': '13', 'year': '2001', 'journal-title': 'J. Phys.: Condens. Matter'}
/ J. Phys.: Condens. Matter (2001)10.1002/1521-3927(20010801)22:12<869::AID-MARC869>3.0.CO;2-R
/ Macromol. Rapid Commun. (2001){'key': '2024020711424121300_r76'}
@article{Corezzi_2002, title={Two crossover regions in the dynamics of glass forming epoxy resins}, volume={117}, ISSN={1089-7690}, url={http://dx.doi.org/10.1063/1.1486214}, DOI={10.1063/1.1486214}, number={5}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Corezzi, S. and Beiner, M. and Huth, H. and Schröter, K. and Capaccioli, S. and Casalini, R. and Fioretto, D. and Donth, E.}, year={2002}, month=aug, pages={2435–2448} }