A contribution to the study of the molecular mobility in polymeric materials by Thermal and Dielectric Analysis

Abstract

T h e s i s S u p e r v i s o r : P R O F . D r . M a r í a J e s ú s S a n c h i s S á n c h e z t o o b t a i n t h e d e g r e e o f D o c t o r o f P h i l o s o p h y a t t h e U n i v e r s i t a t P o l i t è c n i c a d e V a l è n c i a Prof. Dr. María Jesús Sanchis SánchezThe work presented in this thesis was carried out at the Universitat Politècnica de València and was financially supported by the Spanish Ministry of Economy and Competitiveness (Projects Nos. MAT2008-06725-C03-03 and MAT2012-33483)."Cuando quieres algo, todo el Universo conspira para que ACKNOWLEDGEMENTSTras estos años de trabajo, llega el momento de mostrar mi agradecimiento a todas las personas que me han acompañado y apoyado durante el desarrollo de mi tesis doctoral.En primer lugar, me gustaría expresar mi gratitud a mi directora de tesis María J.Sanchis por su inestimable ayuda durante todos estos años. Muchas gracias por confiar en mí, por darme esta oportunidad y por las incalculables horas invertidas tanto para el desarrollo de esta tesis como al mío propio.También me gustaría agradecer a mis estimadas compañeras Marta Carsí y Pilar Ortiz su ayuda y amistad en este largo recorrido que suponer realizar una tesis doctoral. He aprendido mucho de vosotras tanto científica como personalmente. En este punto, no puedo olvidarme de mi querida Aurora Alonso, que pese a no formar parte de nuestro grupo de investigación, me ha apoyado, aconsejado y dado su amistad durante todos estos años.Quiero mostrar mi agradecimiento a los profesores José M. García y Félix C. García ABSTRACTThe development of new and more complex polymeric materials involves challenging problems to basic sciences. The relationship between structure and molecular dynamics assumes great importance for the future development of novel technologies based on such polymers. Thus, the understanding of how small changes in the chemical structure affect the properties of the material is essential to progress in the technological and scientific area. An in-depth analysis of the molecular mobility leads to establish the structure-properties relationships. On this basis, the main aim of the present work is to study the molecular mobility of two different families of polymeric materials. For this purpose, the experimental techniques mainly used were Differential Scanning Calorimetry (DSC) and Dielectric Relaxation Spectroscopy (DRS) (Chapter 3).The first family of polymers characterized was a series of chemically cross-linked copolymers composed by Vinylpyrrolidone (VP) and Butyl Acrylate (BA) monomers. The study was divided in two parts, which are collected in Chapter 4 and 5.In the first place, Chapter 4 contains the influence of the monomer molar ratio (XVP/YBA) on the copolymer properties. Thus, a Fourier Transform Infrared Spectroscopy (FTIR) analysis verified dipole-dipole interactions between amide groups. The influence of these interactions on several parameters related to the molecular mobility was evidenced by the DSC, DRS and Dynamic Mechanical Analysis (DMA) techni...