Characterization of the crystallinity and mechanical properties of CTFE & CTFE copolymeric films as a function of cooling rate and the implications on adhesion

• Main Author: Longhenry, Joy Ciferri
• Other Authors: Materials Science and Engineering
• Format: Others
• Language: en
• Published: Virginia Tech 2014
• Subjects: packaging - microwave circuits; LD5655.V855 1995.L664
• Online Access: http://hdl.handle.net/10919/41378; http://scholar.lib.vt.edu/theses/available/etd-03032009-040803/

<p>Polychlorotrifluoroethylene (CTFE) and CTFE copolymeric films are being used in the electronic packaging industry as insulating dielectric layers between microwave circuits. Since these films are semicrystalline and, in this application, are being used as hot melt adhesives, the cooling rate is an important processing variable, affecting the crystallinity of the CTFE films which in turn affect many properties including dielectric characteristics and mechanical properties. In this study, the crystallinity of CTFE and CTFE copolymeric films as a function of cooling rate was characterized by WAXS and FTIR. As expected, the degree of crystallinity decreased as the cooling rate increased. Analysis of mechanical properties as a function of cooling rate by tensile testing showed that the mechanical behavior of the films became more ductile with faster COOling rates. Since the cooling rate has also been shown to significantly influence adhesion in previous studies, the effect of cooling rate on the bond strength between CTFE and a glass substrate was analyzed. Peel testing with a lab-built Polychlorotrifluoroethylene (CTFE) and CTFE copolymeric films are being used in the electronic packaging industry as insulating dielectric layers between microwave circuits. Since these films are semicrystalline and, in this application, are being used as hot melt adhesives, the cooling rate is an important processing variable, affecting the crystallinity of the CTFE films which in turn affect many properties including dielectric characteristics and mechanical properties. In this study, the crystallinity of CTFE and CTFE copolymeric films as a function of cooling rate was characterized by WAXS and FTIR. As expected, the degree of crystallinity decreased as the cooling rate increased. Analysis of mechanical properties as a function of cooling rate by tensile testing showed that the mechanical behavior of the films became more ductile with faster COOling rates. Since the cooling rate has also been shown to significantly influence adhesion in previous studies, the effect of cooling rate on the bond strength between CTFE and a glass substrate was analyzed. Peel testing with a lab-builtPolychlorotrifluoroethylene (CTFE) and CTFE copolymeric films are being used in the electronic packaging industry as insulating dielectric layers between microwave circuits. Since these films are semicrystalline and, in this application, are being used as hot melt adhesives, the cooling rate is an important processing variable, affecting the crystallinity of the CTFE films which in turn affect many properties including dielectric characteristics and mechanical properties. In this study, the crystallinity of CTFE and CTFE copolymeric films as a function of cooling rate was characterized by WAXS and FTIR. As expected, the degree of crystallinity decreased as the cooling rate increased. Analysis of mechanical properties as a function of cooling rate by tensile testing showed that the mechanical behavior of the films became more ductile with faster cooling rates. Since the cooling rate has also been shown to significantly influence adhesion in previous studies, the effect of cooling rate on the bond strength between CTFE and a glass substrate was analyzed. Peel testing with a lab-built apparatus was performed on CTFE/glass laminates revealing that the adhesive bond strength increased as the cooling rate was increased. Thus, optimum adhesion is achieved with faster cooling rates. This was attributed to the higher fracture energy and greater ductility of the adhesive which have been shown to be important factors in the relationship between cooling rate and adhesion. In addition to these investigations, the morphology at the interface was examined by optical microscopy since the crystallization of semicrystalline polymers adjacent to a substrate can result in a substrate-induced morphology known as transcrystallinity along the interface. These optical microscopy studies were inconclusive.</p> === Master of Science