Processing and characterization of multifunctional thermoplastic composites reinforced with carbon fibers and carbon nanotubes buckypapers

Author(s)

Luis Felipe de Paula Santos

• Document type: Doctoral Thesis
• Press: Guaratinguetá. 2022-01-06.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Engenharia. Guaratinguetá
• Defense date: 2021-12-01
• Advisor: Edson Cocchieri Botelho; Michelle Leali Costa; Bruno Ribeiro

Abstract

Multifunctional composites have been expanding over the last decade, allowing the design of materials that not only have the function of mechanical support but also add thermal, electrical, and magnetic improvements to materials. In addition, it is crucial to obtain laminates that promote both a reduction in weight and volume, increasing its efficiency. This work aims to obtain and to characterize carbon nanotube buckypapers with and without poly (ether imide) (PEI) mats, as well as evaluate their influence on the thermal and mechanical properties of carbon fiber reinforced thermoplastic composites. Scanning electron microscopy, porosimetry, X-ray diffraction (XRD), and Raman spectroscopy results showed a highly porous structure for BP and the power applied to the ultrasonic tip did not cause significant damage to the crystal structure of carbon nanotubes. The thermal stability of the PEI/CF laminates showed an increase by the incorporation of the BP whereas, the addition of BP with PEI mats (BP-CM) in PAEK/CF laminate did not influence significantly its thermal stability. Although, adding only BP (BP-SM) in both laminates showed a reduction in their thermal stability. Considering the PAEK laminate, the BP-SM promoted a reduction of both melting (Tm) and crystallization (Tc) temperatures. However, for both laminates with BP-CM, only a reduction of the crystallization temperature was noted. Dynamic mechanical analysis (DMA) results revealed that the addition of BP-CM promoted an increase of the flexibility for both composites. Finally, the addition of buckypapers led to a reduction in the interlaminar strength in mode-I (GIC), which means less energy dissipation, limited roughness, and a smaller amount of micro-fracture mechanisms were observed. On the other hand, an increase of the interlaminar resistance (GIIC) was observed in mode-II, indicating the carbon nanotubes acted as “bridges” between matrix and fibers, increasing the dissipated energy, the formation of damage mechanisms, and roughness of the composites. It is crucial to mention that both modes were conducted under static and dynamic conditions (AU)

• FAPESP's process: 18/07867-3 - Processing and characterization of multifunctional thermoplastic composites reinforced with carbon fibers and buckypaper of carbon nanotubes
• Grantee: Luis Felipe de Paula Santos
• Support Opportunities: Scholarships in Brazil - Doctorate