Gerassimos Spathis

Section of Mechanics
National Techical University of Athens

Date of Birth:    4/4/1949
Business Address:    5 Heroes of Polytechnion Av., Zografou Campus, Athens 15773, Greece, National Technical University of Athens (NTUA), School of Applied Mathematical and Physical Sciences, Section of Mechanics.
Education:               1975, PhD, under the title: Renormalisation Group Fixed Points Near the Origin" University of Sussex, England 1972,  Diploma , Department of Physics, Athens University (8 5/11)

Professional Carreer:
Present Position:        2005- Professor , Section of Mechanics, NTUA.
Previous positions:    1980-1982: Researcher at the Laboratory for TESTING MATERIALS NTUA.
                                  1982-1985: Lecturer at the Section of Mechanics, NTUA.
                                  1985-1995, Assistant Professor, Section of Mechanics, NTUA.
                                  1995-2005, Associate Professor, Section of mechanics, NTUA

Research interests
Mechanics and Physics of polymers and polymeric composite materials, in terms of theoretical and experimental analysis. Study of a variety of polymeric systems, such as amorphous glassy polymers, semicrystalline, vulcanized elastomers, fiber and particulate polymer composites. Introduction of theoretical expressions which describe the elastic modulus of polymer composites. Constitutive description of vulcanized elastomers, (pure and reinforced with carbon black). Theoretical study of nonlinear viscoelasticity (stress relaxation, creep, monotonic loading).   Experimental and theoretical study of plastic behaviour (yield, strain softening, strain hardening, rate effect) of  amorphous glassy  polymers.
Experimental and theoretical description of polymeric composites (particulate, unidirectional fiber composites). Constitutive laws for strain hardening.
Theoretical description of the rate of plastic deformation of the polymeric structure. Free-volume distribution, statistical description and its relation to the onset of yielding in the polymeric structure.

Participation in Research Projects: Coordinator / partner in international and national projects.

Publications: about 50 journal papers, about 30 presentations in national and international conferences. Chapter in book

Science Citation Index: About 400 references.

Teaching Activities:
1980 - Now: Mechanics of Deformable Body, Linear Viscoelasticity, Introduction to Plasticity, Mechanics and Physics of Polymers and Polymeric Composites (undergraduate level),    Materials science, Nonlinear Viscoelasticity, Anelastic Behaviour of Materials (postgraduate level).

Administration activities:


1. G.Spathis, "Z Boson Effects in Electron-Positron Scattering at EPIC Energies at 14 Gev", Nuclear Physics B87, p.351, 1975.
2. D.Bailin, A.Love and G.D.Spathis, Renormalization group fixed points in Yukawa theories, Nuclear Physics B 93, p.165, 1975.
3. D.Bailin, A.Love and G.D.Spathis, "Nonleptonic Decays in Asymptotically nearly-free Theories", Nuclear Physics B 3 ), p.865, 1977.
4. G.C.Papanicolaou, P.S.Theocaris and G.D.Spathis, "Adhesion Efficiency Between Phases in Fibre-Reinforced Polymers by Means of the Concept of Boundary Interphase", Colloid and Polymer Sci. Vol.258, p. 12' ) 1, 1980.
5. P.S.Theocaris, G.C.Papanicolaou and G.D.Spathis, "Physical Model for the Thermal Expansion Behaviour of Fibre-Reinforced Viscoelastic Composites", Fibre Science and Technology, Vol. 15, p.187, 1981.
6. G.D.Spathis, E.P.Sideridis and P.S.Theocaris, "Adhesion Efficiency and Volume Fraction of the Boundary Interphase in Metal-Filled Epoxies", Int.J.Adhesion and Adhesives, Vol. I , p. 195, 1981.
7. P.S.Theocaris, G.Spathis and E.Sideridis, Elastic and viscoelastic properties of fibre-reinforced composite materials, Fibre Science and Technology, Vol. 17, p.169, 1981.
8. P.S.Theocaris and G.Spathis, "Glass-Transition Behaviour of Particle Composites Modelled on the Concept of Interphase", Jnl.of Applied Polymer Sci., Vol. 27, 1982.
9. P.S.Theocaris, G.Spathis and V. Kefalas, "The Adhesion Coefficient of Fiber-Reinforced Polymers Evaluated by Dynamic Measurements", Colloid and Polymer Science, Vol.260, 1982.
10. P.S.Theocaris,V.Kefalas and G.Spathis, "Retardation Spectra for the Existence of Interphase in Fiber Composites", Jnl. of Applied Polym. Sci., Vol.28, p.3641, 1983.
11. G.Spathis,B.Kefalas and P.S.Theocaris "The loss Tangent Behaviour at the interphase of fiber compsites" Interrelations between Processing Structure and Properties of Polymeric Materilas, edited by J.C.Seferis and P.S.Theocaris 1984.
12. G.Spathis, E.Kontou and P.S.Theocaris, 'Dynamic Mechanical Properties of an Iron-epoxy Particulate Composite", Journal of Rheology, Vol. 28(2), p.161, 1984.
13. G.Spathis, E.Kontou and P.S.Theocaris, "Network Structure of Plasticized Epoxy Resins by Dynamic Measurements", Rheologica Acta, Vol.24, p.63, 1985.
14. E.Kontou, G.Spathis and P.S.Theocaris, "The Heterogeneity of the Network Structure of Epoxy Polymers Studied by Dynamic and DSc-Tests", Journal of Polymer Science,Vo. 23, p.1493, 1985.
15. J.Milios and G.Spathis, Dynamic behaviour of two-phase viscoelastic materials, Composites Science and Technology, Vol.25, p.301, 1986.
16. G.Spathis, E.Kontou and P.S.Theocaris, "Network Characterization of a Polyfunctional Crosslinked System", Journal of Macromolecular Science-Physics, B26(4), P.509, 1987.
17. G.Spathis, E.Kontou and P.S.Theocaris, "Structural Changes in Glassy Polymers Studied by Thermal Analysis and Dynamic Mechanical Tests", Journal of Polymer Science, part A 25, p.1285, 1987.
18. J.Milios and G.Spathis, "Dynamic Interaction of a Propagating Crack with a Hole Boundary", Acta Mechanics, Vol.72, p.283, 1988.
19. P.S.Theocaris, V.Kefalas and G.Spathis, "Evaluation of Interfacial Grafting Between Matrix and Gel Inclusions in High Impact Polystyrene",Journal of Reinforced Plastics and Composites, Vol.7, p.66, 1988.
20. J.Milios, V.Kefalas, E.Sideridis and G.Spathis, “Dynamic Properties of Epoxy Resins” Handbook of Ceramics and Composites, Vol.1, p.137, Marcel Dekker Inc.1989
21. Kontou and G.Spathis, "Elastic Behaviour of Natural Rubber Filled Vulcanizates", Journal of Applied Polymer Sci., Vol.39, p.649-654, 1990.
22. G.Spathis, E.Kontou and V.KefalasL.Apekis, C.Christodoulides and P.Pissis M.011ivon and S.Quinquenet" Relaxation Phenomena and Morphology of Polyurethane Block Copolymers", Journal of Macromolecular Science-Physics, B29(1), p.31-48, 1990.
23. E.Kontou, G.Spathis, M.Niaounakis and V.Kefalas, "Physical and Chemical Crosslinking Effects in Polyurethane Elastomers", Colloid and Polymer Science, Vol.268, p.66, 1990.
24. G.Spathis, "Polyurethane Elastomers Studied by the Mooney-Rivlin Equation for Rubbers", Jnl.Applied Polym. Sci., Vol.43, p.613-620, 1991.
25. G.Spathis, E.Kontou and A.Saklabani, "The Effect of Accelerator on the Crosslink-Density and Mechanical Behaviour of an SBR-Filled Elastomer", Jnl. of Reinforced Plastics and Composites, Vol. 10(4), p.391-399, 1991.
26. G.Spathis, E.Kontou and G.Bourkas, "A New Equation of the Relaxation Process in the Nonequilibrium State: Application to Creep and Dynamic Hxperiments in Epoxy Resins", The Society of Rheology, Vol.3 5(8),,p. 148 1 - 1497, 1991.
27. L.Apekis, P.Pissis, C.Chiistodoulides, G.Spathis, M.Niaounakis, E.Kontou, E.Schlosser, A.Schonals and H.Goering, "Physical and Chemical Network Effects in Polyurethane Elastomers", Colloid and Polymer Science, Vol.90,p.144-150, 1992.
28. G.Spathis, Relaxation behaviour in the transition region of glassy systems, Polymer, Vol. 35(4), p.791-795, 1994.
29. G.Spathis, M.Niaounakis, E.Kontou, L.Apekis, P.Pissis and C.Christodoulides, Morphological Changes in Segmented Polyurethane Elastomers by Varying the NCO/OH Ratio", Jnl. Applied Polym.Sci., Vol.54, p.831-842, 1-842, 1994.
30. G.Spathis, Non-Gaussian stress-strain constitutive equation for crosslinked elastomers, Polymer,Vol. 36(2),p.309, 1995.
31. G.Spathis and E.Kontou, "Viscoelastic Response of Elastomers in Large Deformations", Polymer Gels and Networks, Vol.3,p.209-220, 1995.
32. E.Kontou, G.Spathis and C.Kavadias, "Viscoplastic Behaviour of PMMA blends - The Effect of Moisture Absorption", Jnl. of Reinforced Plastics and Composites, vol 16(4),p.306, 1997.
33. G. Spathis and C.Maggana, A non-linear viscoelastic model for predicting the yield stress of amorphous polymers, Polymer, 38, pp.2371-2377, (1997).
34. G.Spathis, "Theory for the plastic deformation of glassy polymers", Jnl. of Materials Science, 32, pp. 194' )- 1950 (1997).
35. G.Spathis Non-linear constitutive equations for viscoelastic behaviour of elastomers at large deformations Polymer Gels and Networks, 5,(1997) 55-68.
36. G.Spathis and E.Kontou, Experimental and theoretical description of the plastic behaviour of semicrystalline polymers,Polymer, Vol.39, Nr(1),pp 135-142,(1998).
37. E.Kontou and G.Spathis "Structural Rearrangements During Yielding of Glassy Polymers" Polymer Engineering and Science, vol. 38(9), p.1443-1449,(1998).
38. G.Spathis and E.Kontou "An Experimental and Analytical Study of the Large Strain Response of Glassy Polymers With a Non-Contact Laserextensometer",Journal of Applied Polymer Science, vol.71, p.2007, (1999)
39. M. Blanas, E.Kontou and G.Spathis "A Mechanical Model for the Prediction of the Elastic properties of Polymeric Resins Reinforced With Liduid Crystal Polymers"Journal of Reinforced Plastics and Composites, vol. I 8(5),p.3 90-412 (1999).
40. P. Farasoglou, E.Kontou and G. Spathis,J.L.Gomez-Ribelles,and G.Gallego Ferrer "Processing Conditions and Compatibilizing effects on reinforcement of Polypropylene Liquid Crystalline polymer blends",Polymer Composites, Polymer Composites, vol.21 (1), p.84-95, 2000.
41. G.Spathis,G.Bourkas,V.Kytopoulos and E.Sideridis `Elastic Modulus of Particulate Composites using a Multiphase Model' Jnl of Reinforced Plastics and Composites, vol. 1 9(l 1),p.883-910, (2000).
42. G.Spathis and E.Kontou Mechanism of Plastic Deformation for Polycarbonate under Compression by a Laserextensometer Technique'Jnl of Applied Polymer Science,vol.79,p.2534-2542, (2000)
43. G.Spathis and E.Kontou `Non-Linear Viscoelastic and Viscoplastic Response of Glassy Polymers' Polymer Engineering and Science , vol.41(8), p. 1337, 2001.
44. E.Kontou, M.Niaounakis and G.Spathis Thermomechanical behavior of metallocene ethylene-α-olefin copolymers, European Polymer Journal, 38(2002) 8(2002) 2477-2487
45. E.Kontou and G.Spathis, "Interrelation between Long Term Viscoelasticity and Viscoplastic Response of Semicrystalline Polymers" ,accepted for in press, J.Applied Polymer Science (2003)
46. G. Spathis and E.Kontou Non-linear viscoplastic behavior of fiber reinforced polymer composites, Journal of Composites Science and Technology 64, 2333-2340, (2004).
47. G.Spathis and E.Kontou A non-linear Viscoelastic Model for the Prediction of Double Yielding in a LLDPE film" J. Appl. Pol. Sci, in press (2004).
48. E.Kontou, G.Spathis, Application of finite strain viscoplasticity to polymeric fiber composites, International Journal of Plasticity, Vol. 22, p. 1287-1303,  (2006).
49. Pandermarakis, Z.G., Spathis, G., Tsamasphyros,G., Constructing a modulus map for linear elastic composites: The case of rigid reinforcements ‘Polymer Composites Vol.28, pp. 593-604 (2007).
50. G. Spathis, E. Kontou, “Modeling of non-linear viscoelasticity at large deformations”, J. Mater. Sci., vo 43(6), p.2046-2052, (2008).
51. G,Spathis, E.Kontou, Strain inhomogeneity effect on yielding of polymer nanocomposites, Polymer, vol.49,p. 4462-4468 (2008).


1. V.Kefalas, G.Spathis and E.Kontou, “Dynamic Mechanical Analysis of High Impact Polystyrene”, Proc.Comp. 86, Engineering Applications of New Composites, The University of Patras 25-29 August 1986, Patras Greece, Omega Scientific,     England (1988).
2. L.Apekis, P.Pissis and C.Christodoulides, G.Spathis, E.Kontou and V.Kefalas, “Dielectric Properties of Polyurethane Block Copolymers”, Proceedings of     the 6th International Symposium on Electrets, Oxford, England, (1988).
3. L.Apekis, C.Christodoulides, P.Pissis, G.Spathis, E.Kontou and V.Kefalas, “Dielectric Study of Polyurethane Block Copolymers”,
4. E.Kontou, G.Spathis, V.Kefalas, L.Apekis, C.Christodoulides and P.Pissis,“Structure-Property Interrelation in Thermoplastic Polyurethanes”, Comp 88, Phase Interaction in Composite Materials, Second International Symposium,     Patras Greece, August (1988).
5. L.Apekis, C.Christodoulides, P.Pissis, G.Spathis, E.Kontou and V.kefalas, “Thermally Stimulated Depolarization Current Measurements in Polyurethane Block Copolymers”, Sixth International Seminar on Polymer     Physics, Gomodingen (W.Germany) October (1988).
6. L.Apekis, C.Christodoulides, P.Pissis, G.Spathis, E.Kontou,V.Kefalas, ‘ Study of glass transition of polymers by dielectric and thermomechanical methods’ Hellenic Conference of Solid State Physics, Xanthi, September 1989.
7. L.Apekis, P.Pissis, C.Christodoulides, G.Spathis, E.Kontou, V.Kefalas, M.Niaounakis‘Study of the structure-properties relationship by dielectric and thermomechanical methods’ Conference on new advanced technology materials in Greece, Athens, December 1989.
8. G.Spathis and E.Kontou, Viscoelastic response of elastomers in large deformations, 2nd International Discussion Meeting on Relaxation in Complex Systems, 28 June-8 July, Alicante Spain, (1993).
9. E.Kontou, G.Spathis, F.Romero Colomer, M.Lopez Torres and J.L.Gomez     Ribelles, “Thermomechanical Behaviour of Polypropylene-Liquid Crystalline Blends”, J.MED.CAT ‘97, Universitat de les Illes Balears, June 24-27, (1997).
10. C.Maggana, G.Spathis, E.Kontou and P.Pissis,“Water Effect to the a-Relaxation Process of Epoxy Resin Systems ”Proceedings of the 5th  European Conference on Advanced Materials and Processes and Applications, Materials, Functionality and Design,Edited by L.A.J.L. Sarton and H.B. Zeedijk, Maastricht-NL, 21-23 April 1997.
11. M.Lopez, F.Romero, J.L.Gomez, M.Monleon, E.Kontou, G.Spathis, P.Farasoglou, P.Pissis and A.Kiritsys, “Morphology and Mechanical Properties of Blends of Polypropylene and a Main Chain Liquid Crystal Polymer”,International Symposium on Polymeric Materials, Terrassa, 8-10 September 1997, Spain
12 Ε.Κontou and G.Spathis ‘Theoretical and Experimental Investigation of non-linear viscoelastic and viscoplastic response of amorphous polymers’3nd International Meeting of the Hellenic Society of Rheology , Patras,Greece , June 10-14 ,(2001).
13. E.Kontou,M.Niaounakis,G.Spathis Thermomechanical Behavior and Morphology of Metallocene Ethylene –a- olefin Copolymers’ 4th International Discussion Meeting on Relaxation in Complex  Systems, 17-23 June, Crete, (2001).
14. G.Spathis, E.Kontou, “ Strain Localization Effect on Yielding of G;assy Polymers” ICSAM-2007, September 2007, Patras