Sofiane ABDALLAH ELHIRTSI

Formation et expèrience:

- Ingénieur d'état en Génie Chimique (Propriétés Physico-chimiques des Matériaux) de l'Ecole Polytechnique d'Alger.

- Mastère spécialisée Matériax Plastiques et Composites (ITECH Lyon).

Activité au PIMM:

Doctorant depuis Octobre 2012 sous la direction du Professeur Abbas TCHARKHTCHI et du Docteur Sedigheh FARZANEH. On travaille sur les Polymères à Mémoire de Forme (SMP) et l'influence du vieillissement sur leur comportement, notamment la relation entre l'Effet Mémoire de Forme et l'Effet Mémoire de Propriétés (Farzaneh, S., et al, 2013, Shape memory effect and properties memory effect of polyurethane (Link))

Publications

1. Abdallah-Elhirtsi, S., Fitoussi, J., Rashmi, B.-J., Prashantha, K., Farzaneh, S., Lacrampe, M.-F., Krawczak, P. and Tcharkhtchi, A. (2015), Study of partial shape memory effect of polymers by multicycle tests. Polym Compos, 36: 1145–1151. doi: 10.1002/pc.23472.(Link)

In this work, an experimental investigation on a partial shape memory polymer (PSMP) which is transformed into shape memory material is presented. Multicycle shape memory tests are performed on thermoplastic polyurethane (TPU) at 70°C. At the end of each cycle, the capacity of the shape memory material increases. At the end of the first cycle, the recovery rate of TPU is only 67%; this partial shape memory effect (PSME) has been improved by successive cycles of shape memory tests. After the fourth cycle, it becomes nearly 100% shape memory material. The results of the fifth and sixth cycles confirm this modification. These original results indicate that a polymer with partial shape memory effect may be transformed into an SMP without any chemical modification. This increase of SME could be related to the creation of residual stresses during the tensile tests. The residual stresses are the origin of the driving force responsible for shape memory effect.

2. Tcharkhtchi, A.; Abdallah-Elhirtsi, S.; Ebrahimi, K.; Fitoussi, J.; Shirinbayan, M.; Farzaneh, S. Some New Concepts of Shape Memory Effect of Polymers. Polymers 2014, 6, 1144-1163.(Link)

In this paper we introduce the concept of partial shape memory effect (PSME). It is worth mentioning that between the polymers with shape memory effect (SME) and those without SME, there are polymers which have an intermediate behavior. This concept is important because it helps us to understand the difference between an shape memory polymer (SMP) and a non-SMP via the behavior of the polymers with partial shape memory effect (PSME).

3. Tcharkhtchi, A., Farzaneh, S., Abdallah-Elhirtsi, S., Esmaeillou, B., Nony, F., & Baron, A. (2014). Thermal Aging Effect on Mechanical Properties of Polyurethane. International Journal of Polymer Analysis and Characterization, 19(7), 571-584.(Link)

This study concerns the effect of thermal aging on mechanical properties of polyurethane. Polyurethane samples were exposed at 85° and 120°C under inert atmosphere. Mechanical tests were carried out on these samples the aging period. Tensile tests were performed to see the effect of aging on elastic modulus (E), stress (σr), and strain (ϵr) at break. It was shown that there are two distinct periods. Due to aging, E and σr increase in the first period, then they decrease in the second period. ϵr decreases first and then increases. Fatigue tests were performed on unaged and aged samples. It was shown that the fatigue behavior of polyurethane (PU) is improved the same way during the first stage of aging. In the second step, the number of cycles to failure increases due to aging. The results show that aging has an important effect on mechanical properties of PU. The strain at break decreases during the first step of aging due to post-cross-linking and then increases due to chain scission in the network. Based on these results, the effect of cross-linking and chain scission on the mechanical properties of PU was discussed.