In order to obtain multifunctional structural composites characterized by good thermal and mechanical properties and high electrical conductivity as well as better processability, Carbon NanoFibers (CNFs) are increasingly playing a strategic role in advanced structural applications. In this work, epoxy nanocomposites filled with different CNF weight percentages capable to impart electron conduction and high curing degree to epoxy resins have been investigated. The remarkable mechanical properties strictly related to the high curing degree (almost 100%) reached with the chosen formulation and curing treatment, together with the values in the electrical conductivity and the state of the nanofiller dispersion and interconnections, analyzed by Tunneling Atomic Force Microscopy (TUNA) technique, highlight an interesting applicative potential for the formulated material in the aeronautical sector. TUNA technique is a valid tool for the study of the arrangement of charged particles within an insulating matrix and significant information can be obtained not only on the distribution of the nanoparticles but also on the interaction between host matrices and nanofillers. The nanocomposites filled with CNF heat-treated at 2500°C (CNF2500) are characterized by the presence of conductive paths at a relatively very low nanofiber content, causing an increase of conductivity beyond the electrical percolation threshold (EPT) due to an effective connection among carbon nanofibers, which are integrated into the epoxy matrix (T20BD) and become part of the cross-linked structure. The presence of conductive network inside the epoxy resin is clearly visible in the TUNA images. In this work, the Curing Degree (DC) has been obtained in dynamic and isothermal regime. All the analyzed formulations show DC values higher than 92% also in isothermal regime. The nanofiller causes an increase in the efficiency of curing process in isothermal regime, which is usually the real condition of curing in industrial processes. We can see that the DC of all samples containing embedded CNF2500 is very high compared to unfilled epoxy resin. All CNFs filled epoxy samples reach a value of CD of almost 100%. The results on the resin filled with CNF nanoparticles highlight an interesting behaviour with respect to the curing degree proving the proper formation of the crosslinked network.

Thermal analysis and electrical performance by Tunneling Atomic Force Microscopy of carbon nanofiber-based nanocomposites

Marialuigia Raimondo
;
Carlo Naddeo;Liberata Guadagno
2021-01-01

Abstract

In order to obtain multifunctional structural composites characterized by good thermal and mechanical properties and high electrical conductivity as well as better processability, Carbon NanoFibers (CNFs) are increasingly playing a strategic role in advanced structural applications. In this work, epoxy nanocomposites filled with different CNF weight percentages capable to impart electron conduction and high curing degree to epoxy resins have been investigated. The remarkable mechanical properties strictly related to the high curing degree (almost 100%) reached with the chosen formulation and curing treatment, together with the values in the electrical conductivity and the state of the nanofiller dispersion and interconnections, analyzed by Tunneling Atomic Force Microscopy (TUNA) technique, highlight an interesting applicative potential for the formulated material in the aeronautical sector. TUNA technique is a valid tool for the study of the arrangement of charged particles within an insulating matrix and significant information can be obtained not only on the distribution of the nanoparticles but also on the interaction between host matrices and nanofillers. The nanocomposites filled with CNF heat-treated at 2500°C (CNF2500) are characterized by the presence of conductive paths at a relatively very low nanofiber content, causing an increase of conductivity beyond the electrical percolation threshold (EPT) due to an effective connection among carbon nanofibers, which are integrated into the epoxy matrix (T20BD) and become part of the cross-linked structure. The presence of conductive network inside the epoxy resin is clearly visible in the TUNA images. In this work, the Curing Degree (DC) has been obtained in dynamic and isothermal regime. All the analyzed formulations show DC values higher than 92% also in isothermal regime. The nanofiller causes an increase in the efficiency of curing process in isothermal regime, which is usually the real condition of curing in industrial processes. We can see that the DC of all samples containing embedded CNF2500 is very high compared to unfilled epoxy resin. All CNFs filled epoxy samples reach a value of CD of almost 100%. The results on the resin filled with CNF nanoparticles highlight an interesting behaviour with respect to the curing degree proving the proper formation of the crosslinked network.
2021
9788836230396
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4859221
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