Resumen de Métodos físico-químicos de caracterización de las fibras de polilactida
Lucila Araceli Montero Palacios
The interest of studying this fiber resides in the fact that it is a biodegradable polymer that is obtained from annually renewable resources, besides being a fiber that is beginning to be introduced in the market. Nowadays there is no deep knowledge about the variation in its fine structure (332699) during its textile process and we wish to study it in order to improve, if possible, the processes in which it is extracted. The determination on the variation of the microstructure of the polylactide fibres (PLA) during its textile process and the influence over the most relevant properties, are all part of the characterized study of this thesis. Along its fabrication and chemical-textile manipulation processes, polylactide fibres are submitted to a series of thermal, hydrothermal and mechanical treatments to which the fibers structure can be sensitive and therefore its mechanical and dyeing properties. These changes in its fine structure or microstructure can reflex in more or less important modifications on its degree of crystallinity or orientation. We have used as raw material polylactide filaments (POY) textured with different temperatures and stretching relationships. The overall objective of this thesis is to know, through the available techniques and physio-chemical methods, the effect that different extracting processes produce over the fine structure of this fiber. We will specifically study the variation on the microstructure of PLA with the textured variables (stretching and temperature relationship), just as after a subsequent application of a process of thermal stabilizer on all the substrata. In order to reach this general objective we have established the next specific objectives: ¿To determine the microstructure through physic-chemical characterized techniques such as critical dissolution time, differential solubility and iodine sorption. To compare the results of the fine structure obtained through physic-chemical techniques with the crystallinity and the orientation. In order to determine crystallinity we recur to differential scanning calorimetry techniques (DSC) and to density gradient column and orientation will be determined by sonic modulus. ¿To know the variation with the mechanical parameter processing such as tenacity, elongation, elasticity modulus and rupture work. To know the importance of the differences in the fine structure found on the application that was produced by the dyeing. To know the behavior to ageing that PLA fibres suffer in different conditions of temperature, moist and light exposure. For this we will analyze the loss of resistance (load- elongation curve) and the molecular weight of these substrata. ¿The study of texturized and stabilized polylactide degradability.
