טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentNatalie Artzi
SubjectPolymer/Clay Nanocomposite Systems: Development,
Characterization and Processing-Structure-
Property Relationships
DepartmentDepartment of Chemical Engineering
Supervisor Professor Emeritus Narkis Moshe


Abstract

Polymer nanocomposites with layered silicates as an inorganic filler (nano-reinforcement) are the focus of this research project. These nanocomposites are found to have significantly enhanced properties when compared to the neat polymers or conventional composites through addition of very low clay contents owing to the clay nanosize dispersion. Treated commercial clays were used in combination with EVOH as the matrix with and without compatibilizers (EVA-g-MA or LLDPE-g-MA). In a separate study Nylon-6/EVOH blend was reinforced with organoclays and their behavior studied.

EVOH has a high interaction level with some of the treated clays, resulting in modification of its crystallization behavior, namely, lower crystallization rate, melting temperature and enthalpy levels. A model of clay fracturing coupled with onion-like delamination, in addition to advanced intercalation level, was suggested in an attempt to explain the development of the nanocomposites’ morphology.

The addition of compatibilizers to the clay-containing EVOH system aiming at increasing the EVOH/clay interaction level has resulted in diverse effects depending on the compatibilizer type and content. While addition of EVA-g-MA has led to mechanical properties improvement at some compatibilizer contents, the addition of LLDPE-g-MA has deteriorated the properties at all contents. The levels of interaction, intercalation and exfoliation, plasticization, crystallinity depression and reinforcement effects are processing controlled, leading to dissimilar derived properties.

Clay-containing Ny-6/EVOH blend is a unique system, in which chemical reactions in addition to hydrogen bonding between the Ny-6/EVOH components may take place, thus affecting the morphology, thermal and mechanical properties.