Shape Memory Epoxy Networks with Chemical and Physical Crosslinks

A. B. LEONARDI; L. A. FASCE; I. A. ZUCCHI; C. E. HOPPE; E. R. SOULÉ; C. J. PÉREZ; R. J. J. WILLIAMS

EUROPEAN POLYMER JOURNAL

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2011 vol. 47 p. 362 - 369

0014-3057

Epoxies are an important family of shape memory polymers (SMP) due to their excellentstability and thermo-mechanical endurance and the high values of shape fixity and shaperecovery. Actuators based on these materials can be designed for large tensile elongations(e.g., 75% or higher) or large recovered stresses (e.g., 3 MPa or higher). However, meetingthese requirements simultaneously is a difficult task because changes in the crosslink densityaffect both variables in opposite ways. We show that an SMP based on an epoxy networkwith both chemical and physical crosslinks could be strained up to 75% in fourrepeated shape memory cycles with tensile stresses close to 3 MPa. Shape fixity and shaperecovery values were close to 98% and 96%, respectively, for everyone of the cycles, withoutany significant change between the first and subsequent cycles.