Browsing by Author "Kull, Ken"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Thermomechanical characterization of thermoplastic polyimide to improve the chain interaction via crystalline domains(Society of Plastics Engineers, Inc., 2019-09) Nicholls, Alejandro Rivera; Craft, Garrett; Perez, Yesenia; Pellisier, Matthew; Stock, John Allan; Testemale, Maxime; Kull, Ken; Eubank, Jarrod F.; Harmon, Julie P.In a previous study on polyimides, we incorporated an aromatic diamine monomer with a methylene linker, 4,4'-methylenebis (2,6-dimethylaniline), to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to decrease rigidity. In this report, we explore the behavior of crystalline regions provided by the organized packing of polyethylene oxide into the formerly characterized polymers. The polymers were designed to exhibit thermal properties in between those of conventional aromatic polyimides and polymers with wholly aliphatic ether diamine links, with a target to improve the mechanical characteristics. Through dynamic mechanical analysis and differential scanning calorimetry, it is shown that the incorporation of polyethylene oxide diamine and the removal of methyl pending groups serve to improve the organized packing of the chains. All of this allows for a broader range in tenability of thermal and mechanical properties of the polyimide. Furthermore, the crystalline regions are an important component to maintain the temperature stability of polyimide while maintaining the processability. The polymers are characterized by Fourier-transform infrared spectroscopy, thermomechanical and calorimetric analysis, microhardness measurements, tensile testing, and wide-angle X-ray scattering. INTRODUCTION Highly ordered aromatic backbones allow polyimides (PIs) to have superb properties demonstrated by elevated thermal stability, solvent resistance, low coefficients of thermal expansion, low dielectric constants, high glass transition [...]Item Thermomechanical characterization of thermoplastic polyimides to improve the chain collaboration via ureidopyrimidone endcaps(Society of Plastics Engineers, Inc., 2019-11) Nicholls, Alejandro Rivera; Perez, Yesenia; Pellisier, Matthew; Rodde, Arnaud; Lanusse, Pierre; Stock, John Allan; Kull, Ken; Eubank, Jarrod F. ; Harmon, Julie P.In this report, we explored the effect of incorporating ureidopyrimidone (UPy) linkers in a series of polyimides (Pis) previously studied in our laboratory. The polymers consist of an aromatic diamine monomer with a methylene linker, 4,4'-methylenebis (2,6-dimethylaniline), used to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to decrease rigidity. The polymers were designed to exhibit thermal properties in between those of conventional aromatic PIs and polymers with wholly aliphatic ether diamine links, with an aim to improve the mechanical characteristics. Through dynamic mechanical analysis and differential scanning calorimetry, it is shown that the UPy linkers with their four-hydrogen bond sites are introduced to connect the chains in series. The connection strengthens the chain interactions and increases the range of the thermal and mechanical properties of the PI. Furthermore, the connecting regions are an important component to preserve the thermal stability of PIs while maintaining the processability. The polymers were characterized by FTIR, nuclear magnetic resonance, GPC, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, microhardness, and tensile testing.Item Thermomechanical characterization of thermoplastic polyimide–polyurea to improve the chain interaction via internal hydrogen bonds(Society of Plastics Engineers, Inc, 2019-09) Nicholls, Alejandro Rivera; Pellisier, Matthew; Perez, Yesenia; Stock, John Allan; Kull, Ken; Julien, Tamalia; Eubank, Jarrod F.; Harmon, Julie P.Recently, we have studied polyimides (PIs) synthesized by incorporating an aromatic diamine monomer with a methylene linker, 4,4'-methylenebis(2,6-dimethylaniline), to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to reduce rigidity. In this report, we incorporate a urea linkage into these materials in order to observe the effect of additional hydrogen bonding. The polymers are designed to exhibit thermal properties in between those of conventional aromatic PIs and polymers with wholly aliphatic ether diamine links. Herein, we demonstrate that the addition of 1,6 hexamethylene diisocyanate and the increase of hydrogen bonds at the urea linkage can be used to improve the thermal and mechanical properties of the PI. Furthermore, the imide ring is an important component to maintain the thermal stability characteristics in poly-imidepolyurea hybrids. The polymers were characterized by FTIR, thermomechanical and calorimetric analysis, micro-hardness, and tensile testing. INTRODUCTION A series of thermoplastic polyimide-polyureas (PIUs) with tractable properties and structural improvements are synthesized and characterized in this work. Polyimides (PIs) with highly ordered aromatic backbones demonstrate high thermal [...]