Modification chimique de la cellulose nanofibrillée par les alcoxysilanes : application à l'élaboration de composites et mousses

In this thesis, nanofibrillated cellulse (NFC) has been isolated from oat straw and chemically modified by alkoxysilanes in water medium. Silylated NFC has been subsequently used to elaborate novel biobased composite materials and foamsChapter I presents some general aspects about nanocelluloses – in particular Nanofibrillated Cellulose (NFC) - and their use in composite materials and foams.Chapter II is dedicated to the functionalization of NFC by methyltrimethoxysilane - chosen as a model silane - and to the comprehensive examination of the silylated material. Reaction conditions such as pH, reaction time and initial silane concentration have been particularly in-vestigated and optimized using two distinct experimental protocols. The modifications have been characterized at the molecular level by various physicochemical techniques. The proper-ties of the silylated nanofibrils i.e. the morphology, crystallinity, wettability, hygroscopicity and thermal stability, have been subsequently examined. Chapter III investigates the impact of silylation on the mechanical and hygroscopic properties of NFC-reinforced composites prepared with two distinct polymeric matrices: poly(lactic acid) (PLA) and polydimethylsiloxane (PDMS).Chapter IV examines the impact of silylation on the properties of NFC-foams prepared by freeze drying, in particular on the porosity, compressive properties, thermal conductivity, wet-tability, hygroscopicity and oleophilicity.

在本论文中，已从燕麦稻草中分离出纳米原始蜂窝基（NFC），并在水培养基中通过烷基硅烷化学修饰。 （NFC） - 及其在复合材料和泡沫中的使用。第II章专用于甲基三甲氧基硅烷对NFC的功能化 - 选择作为模型的硅烷 - 以及对用pH，反应时间和反应时间和反应时间，反应时间和反应时间，反应时间和反应时间，反应时间，反应时间，反应时间和反应材料的全面检查。最初的硅烷浓度特别涉及使用，并使用两个不同的实验方案进行了优化。随后对热稳定性进行了研究。 sillation对通过冷冻干燥制备的NFC泡沫特性的影响，尤其是对孔隙度，压缩特性，导热率，湿态，湿润性和吸水性的影响。