Dynamic Creep and Fatigue Properties of Novel Elastomeric Biomaterials

• Applicant: Professor Dr.-Ing. Volker Altstädt
• Subject Area: Polymer Materials
• Term: from 2007 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 30492292

• Final Report Year: 2009

Final Report Abstract

Due to the insufficient fatigue and dynamic creep properties of currently used thermoplastic urethanes and silicones in bio-medical applications, new materials are required. Therefore, different novel nano-structured poly (aliphatic/aromatic-ester) multiblock copolymers (PEDs) with various dosages of e-beam irradiation, as well as newly developed arborescent polystyrene-block-polyisobutylene-block-polystyrenes (SIBS) block copolymers were investigated regarding these properties. Within this project Altstädt et al. were able to show that e-beam irradiation is responsible for the formation of an additional network structure in the material. This secondary network is responsible for the improvement of the dynamic creep and fatigue properties of these potential biomaterials. Regarding the novel dendritic SIBS block copolymers it was found that the introduced chemical network structure has only a minor influence on the (thermo-) mechanical properties. Furthermore, Altstädt et al. as well as Puskas et al. concluded that polyisobutylene-based dendritic TPEs have a lower susceptibility to dynamic creep. In addition, these dendritic SIBS were polymerized with a lower amount of the PS/PMS hard phase, which lead to more flexible materials with an improved fatigue performance compared to medical grade silicone. In conclusion, this study is an example of a unique interdisciplinary project, which combined engineering, chemistry and biological aspects in order to provide suitable candidates for materials for medical applications. Within two years this project gained a fundamental understanding of the structure-property relationship of novel nano-structured poly (aliphatic/aromatic-ester) multiblock copolymers (PEDs) and arborescent polystyrene-block-polyisobutylene-block-polystyrenes (SIBS) block copolymers.

Publications

• "Dynamic Creep and Fatigue Performance of Thermoplastic Elastomers as Biomaterials", Polymer Processing Society 24th Annual Meeting June 15-19, 2008, Salerno Italy, ISBN 88- 7897 - 025 - 5
  C. Götz, F. Fischer, M. El Fray, M. Piatek, G.T. Lim and V. Altstädt
  
• "Novel High Temperature Styrenic TPE Nanocomposites", Fall 175th Technical Meeting of the Rubber Devision of the American Chemical Society, Inc., Oct. 14-16, 2008, Louisville, KY (USA), ISSN 1547-1977
  G.T. Lim, E. Foreman-Orlowski, P. Pavka, C. Goetz, V. Altstädt and J. E. Puskas
  
• "Effect of Architecture on the Fatigue Properties of SIBS Biomaterials", Ohio Innovation Summit 2009, April 20- 23, 2009, Dayton, Ohio, USA
  P. Pavka, C. Götz, G.T. Lim, U.A. Handge, J.E. Puskas and V. Altstädt
  
• "Influence of E-Beam Irradiation on Poly(aliphatic/aromatic-ester) Multiblock Copolymers Used as Biomaterials", International Rubber Conference 2009, June 29- July 02, 2009, Nürnberg Germany
  C. Götz, U.A. Handge, M. Piatek, M. El Fray and V. Altstädt
  
• Dynamic Stress Relaxation of Thermoplastic Elastomeric Biomaterials; Polymer 50, pp. 245-249 (2009)
  J.E. Puskas, M. El Fray, M. Tomkins, L.M. Dos Santos, F. Fischer, V. Altstädt
  
• Fatigue Testing of Implantable Specimens; Effect of Sample Size and Branching on the Dynamic Fatigue Properties of Polyisobutylene-based Biomaterials; Polymer 50, pp. 591-597 (2009)
  J.E. Puskas, M. El Fray, L.M. Dos Santos, F. Fischer, C. Götz, V. Altstädt