טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentEster Segal
SubjectChemical Sensing Materials Based on Electrically Conductive
Immiscible Polymer Blends
DepartmentDepartment of Chemical Engineering
Supervisors Professor Emeritus Siegmann Arnon (Deceased)
Professor Emeritus Narkis Moshe


Abstract

The polymer sensors field is presently recognized as one of the forefront cutting edge activities in polymer science. Development, characterization and performance understanding of chemical sensing materials, based on electrically conductive immiscible polymer blends are the focus of this research project.

Two families of electrically conductive immiscible polymer blends were studied as sensing materials for a homologous series of alcohols. The systems studied include: carbon black (CB)-containing multiphase matrices consisting of either polypropylene (PP) or high-impact polystyrene (HIPS) as the major phase and thermoplastic polyurethane (TPU) as the minor dispersed phase; and polyaniline (PANI) dispersed within a polystyrene (PS) matrix. Extruded filaments, produced by a capillary rheometer at various shear rate levels were used in the sensing experiments. The electrical resistance of these filaments was found to be selectively sensitive to the various alcohols. Moreover, the responses displayed by these filaments are fast, reproducible and reversible. The sensing behavior of these blends is determined by the nature of the blend components, blend composition and processing conditions. It has been established that the sensing mechanism of these immiscible blends is different and more complex compared with neat PANI or the corresponding individual polymers with CB.

The studied sensing materials are unique in their structures, sensing performance and ability to be designed/modified in accordance with specific demands. The fundamentals of the chemical sensing mechanisms involved in these materials were elucidated based on conductivity/structure interrelations. The suggested new mechanisms can be employed in designing new chemical sensing materials.