Polymer/Carbon Nanotube Nanocomposite Fibers:Process-Morphology-Property Relationships

摘要

Nanocomposites based on polymers dispersed with carbon nanotubes arernbeginning to receive substantial attention today because the nanotubes offer thernpotential to impart unique mechanical, electrical and thermal properties. Theirrnstiffness values are on the order of 1TPa, strengths of 50 to 200 Gpa and failurernstrains on the order of 5 to 20%. One of the obstacles to widespread use of thernnanotubes is the inability to orient them in one particular direction. This study isrnfocused on aligning carbon nanotubes in polypropylene and a thermotropic liquidrncrystalline polymer (trade name Vectra) matrix by melt spinning. Two differentrnweight percentages (0.5% and 1.0%) of nanotubes were used for the synthesis of thernnanocomposite fibers. The effect of the nanotubes on the crystallization andrnmechanical behavior of polypropylene is also discussed. Morphologicalrncharacterization of the fibers synthesized has been conducted using DifferentialrnScanning Calorimetry and Wide Angle X-Ray Diffraction. Mechanicalrncharacterization was done in the tensile mode for fibers. Significant improvement inrnmechanical properties like tensile modulus and tensile strength were observedrnwhich is characteristic of highly aligned nanotube system. Correlation of the carbonrnnanotube alignment and dispersion in the polymer matrix was studied usingrnTransmission Electron Microscopy. Thermal stability characterization was donernusing Thermo Gravimetric Analyzer. A substantial increase in the onset ofrndecomposition was found which indicated good dispersion of nanotubes in thernpolymer.rnMorphological characterizations of Vectra fibers were done using WidernAngle X-Ray diffraction. Moderate improvements in mechanical properties such asrntensile modulus and tensile strength were observed which is characteristic of goodrndispersion of the nanotube in the system. A moderate increase in the onset ofrndecomposition was found for all nanocomposite compositions.