https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sat, 14 Mar 2026 23:49:07 GMT 2026-03-14T23:49:07Z http://hdl.handle.net/10985/8057 Metallocene Polypropylene Crystallization Kinetic During Cooling in Rotational Molding Thermal Condition SARRABI, Salah; BOYER, S.A.E; LACRAMPE, Marie-France; KRAWCZAK, Patricia; TCHARKHTCHI, Abbas This article is part of an ambitious project. The aim is to simulate mechanical properties of rotomolded part from micro-structure consideration. Main objective here is to consider metallocene polypropylene crystallization kinetic (PP) during cooling stage in rotational molding. Crystallization kinetic of metallocene PP is so rapid that microscopy cannot help to observe nucleation and growth. Crystallization rate can be estimated by a global kinetic. Given that cooling in rotational molding is dynamic with a constant rate, Ozawa law appears more appropriate. Ozawa parameters have been estimated by differential scanning calorimetry. In rotational molding thermal condition, Avrami index identifies a complex nucleation intermediate between spontaneous and sporadic. Ozawa rate constant is 68 times higher than this obtained for Ziegler–Natta PP. By coupling transformation rate from Ozawa model and a thermal model developed earlier, the difference between theory and experimental is less than 1%. To optimize rotational molding, study has been completed by sensitivity to adjustable parameters. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/8057 2013-01-01T00:00:00Z SARRABI, Salah BOYER, S.A.E LACRAMPE, Marie-France KRAWCZAK, Patricia TCHARKHTCHI, Abbas This article is part of an ambitious project. The aim is to simulate mechanical properties of rotomolded part from micro-structure consideration. Main objective here is to consider metallocene polypropylene crystallization kinetic (PP) during cooling stage in rotational molding. Crystallization kinetic of metallocene PP is so rapid that microscopy cannot help to observe nucleation and growth. Crystallization rate can be estimated by a global kinetic. Given that cooling in rotational molding is dynamic with a constant rate, Ozawa law appears more appropriate. Ozawa parameters have been estimated by differential scanning calorimetry. In rotational molding thermal condition, Avrami index identifies a complex nucleation intermediate between spontaneous and sporadic. Ozawa rate constant is 68 times higher than this obtained for Ziegler–Natta PP. By coupling transformation rate from Ozawa model and a thermal model developed earlier, the difference between theory and experimental is less than 1%. To optimize rotational molding, study has been completed by sensitivity to adjustable parameters. http://hdl.handle.net/10985/10180 Study of partial shape memory effect of polymers by multicycle tests ABDALLAH-ELHIRTSI, Sofiane; RASHMI, Baralu-Jagannatha; PRASHANTHA, Kalappa; FARZANEH, Sedigheh; LACRAMPE, Marie-France; KRAWCZAK, Patricia; TCHARKHTCHI, Abbas; FITOUSSI, Joseph 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 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 SME. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10180 2015-01-01T00:00:00Z ABDALLAH-ELHIRTSI, Sofiane RASHMI, Baralu-Jagannatha PRASHANTHA, Kalappa FARZANEH, Sedigheh LACRAMPE, Marie-France KRAWCZAK, Patricia TCHARKHTCHI, Abbas FITOUSSI, Joseph 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 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 SME.