2d and 3d analysis of the microstructure of pla/layered silicate nanocomposites and its effect on the physical properties

Laburpena

From a technological and environmental point of view, a growing interest in the development of new biobased polymers and their composites is taking place. This research work has been focused on the studyof Poly (lactic acid)(PLA)/ layered silicate nanocomposites formed by semi-industrial melt blendingprocesses.In the design of new bio based nanocomposites, the microstructure plays a key role. However, the studyof the microstructure is still a major challenge nowadays. In this regard, the main goal of this thesis isthe development of the 2D and 3D analysis of the microstructure of PLA/clay systems.In order to achieve the main objective, besides using conventional techniques such X-Ray and TEMmicrographs, a more detail description and a quantification of the microstructure was pursued.Concerning the 2D characterization, in order to overcome the limit of the TEM micrographs due to thesmall area visualized compared to that of the bulk material, a TEM automated image analysis (TEMAIA)was proposed and applied. This methodology enabled the analysis of a large enough amount ofTEM micrographs so that they were statistically representative of the whole material. In reference to the3D characterization, in order to avoid the projection effect of the TEM micrographs that lead toincomplete 2D quantifications of the microstructural parameters, in special of the thickness, electrontomography was performed. To attain a 3D quantification, a methodology to accurately, objectively andeasily carry out the segmentation was developed.Finally, the effect of the microstructure on the mechanical and thermal stability has been evaluated. Inaddition, the quantified microstructural parameters have been introduce into micromechanics modelsand then, applied.