The 8th Int'l Conference on Polymer Materials Science (PMS_D 2021), 第八届高分子材料科学国际研讨会_PMS_D 2021

Biography
Dr. Laurent Delbreilh University of Rouen Normandy, France
Title: INTEREST OF MOLECULAR MOBILITY INVESTIGATION FOR UNDERSTANDING AND IMPROVING APPLICATIVE BIOBASED POLYESTERS
Abstract: Polyesters are used in several domains of the industry for packaging applications mainly. Since decades for polyesters family, poly (ethylene terephthalate) (PET) represents a reference material for the packaging industry, especially when food contact and barrier properties are absolutely essential. Several attempts to replace PET with other biosourced polyesters that are compostable (poly(lactic acid) (PLA)) or even biodegradable in a natural environment (polyhydroxyalkanoates (PHA)) have not produced the expected results. One of the reasons for the drawbacks of these biopolymers is related to their relative brittleness compared to industrial polyesters. Several strategies have been employed to try the bring solutions for these biopolyesters at different levels from chemistry, formulation and processing. PLA lack of ductility is predominant in amorphous material and during thermal crystallization is accompanied by faulty barrier properties related to large amounts of defective rigid amorphous fraction (RAF) at the interface between mobile amorphous fractions (MAF) and crystallites. To reduce this problem plasticization strategy has been employed to enhance molecular mobility and reduce brittleness [1]. PHA main issue is related to its progressive embrittlement during room temperature storage just after processing during cold crystallization. The understanding of the embrittlement process was a key point [2] that led in a second time to propose a chemistry and processing strategy, in order to investigate molecular mobility in modified PHAs with the goal to reduce crystallization ability. The development of poly(ethylene 2,5-furandicarboxylate) (2,5-PEF) brought on the market one of the most credible biobased alternative to poly (ethylene terephthalate) (PET). Chemistry and copolymerisation strategies have been used to obtain a family of furan-based biopolymers with adjusted physical properties, glass transition temperatures and ability to crystallize [3]. On these very different biopolyesters, the study of molecular mobility and microstructures at different levels from very local fluctuations to segmental relaxation gave rise to the identification of the complexity and the heterogeneity of the biopolymers. The molecular mobility was investigated by crosscomparing the results obtained by advanced calorimetry techniques (FSC and MT-DSC), Dielectric Relaxation Spectroscopy (DRS) and Thermo-Stimulated Depolarization Currents (TSDC), with the aim of evaluating the local and segmental molecular mobilities. The time dependent evolutions of these biopolymers, due to crystallization, required the use of very strict thermal protocols in order identify the dramatic evolution from amorphous state to very complex semi-crystalline heterogenous materials. Molecular mobility analyzes in these semi-crystalline biopolymers appears to be a great challenge. References 1. Araujo, S.; Delpouve, N.; Domenek, S.; Guinault, A. et al. Macromolecules 2019, 52 (16), 6107 2. Esposito, A.; Delpouve, N.; Causin, V.; Dhotel, A.; Delbreilh, L.et al.. Macromolecules 2016, 49 (13), 4850 3. Bourdet, A.; Araujo, S.; Thiyagarajan, S.; Delbreilh, L.; Esposito, A.; Dargent, E. Polymer 2021, 213, 123225.
Biography: Dr. Laurent Delbreilh is an associate professor at University of Rouen Normandy in France since 2017 and he previously was assistant Professor in the same University since 2006. He is a scholar in the department of Physics in the University of Rouen and a researcher in the Laboratory, « Group of Physics of Materials » (GPM UMR 6634). He is currently a visiting Professor at the University of Nebraska Lincoln (USA). He is a member of the executive committee of the French Association of Calorimetry and Thermal Analysis (AFCAT) since 2015. Its research spans a wide range of domains in material physics in disordered systems with a common thread being understanding of the physics dedicated to the dynamic relaxation appearing in different glass-forming systems. He is particularly interested in understanding the glass transition in amorphous and semi-crystalline materials like polymers, biopolymers, pharmaceutics amorphous molecules… He uses physics approach for the understanding of coupled experimental studies with advanced calorimetry techniques (Fast Scanning Calorimetry, Temperature Modulated DSC) and Dielectric Relaxation Spectroscopy. Dr Delbreilh has published more than 70 papers in International journal and participated to more than 100 international and National conferences as speaker. His research works have been awarded two times in 2008 and 2010 by AFCAT and International Calorimetry and Thermal Analysis Conference (ICTAC).