This book presents current research in the study of thermoplastic and thermosetting polymers, including the fabrication of aromatic polyester composites containing carbon nanotubes; thermoplastic and thermosetting composites with natural fibres; phase separation of PMMA-modififed vinyl-ester thermosets; thermoplastic and thermosetting polymers from vegetable oils and the mechanisms of impregnation during compression molding of thermoplastic matrix composites.