Effect of MWCNT carboxylation on mechanical, thermal and morphological behaviour of phenol formaldehyde nanocomposites

Abstract

Phenol-formaldehyde resin is an inevitable polymer material because of their excellent properties like heat resistance, chemical resistance, creep resistance, and low water sorption. But the drawback associated with PF matrix is buckling and brittleness. The incorporation of nanofillers can effectively reduce these problems. Carbon nanotubes is one among the nanofiller which is widely used to enhance the mechanical, thermal, electrical properties of the host matrix.The present study deals with the synthesis and comparison of two Phenol-formaldehyde nanocomposites incorporated with pristine multiwalled carbon nanotubes and carboxylated multiwalled carbon nanotubes via in-situ polymerisation technique. The effect of filler loading (MWCNT, MWCNT-COOH) with different weight percentages (0.05 wt%, 0.08 wt%, 0.12 wt%, 0.15 wt%) has been investigated in this study. Pristine MWCNT was functionalised with carboxyl groups and confirmed by XRD, FT-IR, CHN analysis, X-ray photoelectron spectroscopy, AFM and Raman spectra. All these analysis showed successful funtionalisation of pure MWCNT. The prepared nanocomposites were compared by mechanical, thermal and morphological analysis. The effect of both fillers on tensile strength, stress-strain, young’s modulus and elongation at break were also analysed. The addition of MWCNT and MWCNT-COOH have enhanced the mechanical and thermal properties of the prepared nanocomposite. The mechanical properties of PF-MWCNT nanocomposite showed a maxima for 0.12 wt% and for PF-MWCNTCOOH nanocomposite it was 0.08 wt%. Higher thermal stability was exhibited for 0.15 wt% MWCNT loading. The thermal stability enhanced by the addition of MWCNT COOH upto 0.12 wt% and then declined. Moreover the prepared nanocomposites were morphologically characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM) and from the fracture analysis it is clear that the reinforcements brought plastic deformation of phenol-formaldehyde nanocomposite from brittle to more ductile material. From the TEM image it was clear that the presence of carboxyl groups attached on MWCNT reduced agglomeration in PF matrix. Halpin-Tsai modelling was done for comparing experimental and theoretical values of tensile modulus and it illustrates good correlation.

Enhanced the properties of carbon‐paste nanocomposite by carboxylation of multi‐walled carbon nanotubes

“…Furthermore, the endothermic peaks up to 650°C are thermal decomposition of nanocomposites. Finally, the chemical treatment increased the thermal stability of D‐CMC/GNP/O‐CNT35 and improved its amorphous property 40,41 …”

“…Finally, the chemical treatment increased the thermal stability of D-CMC/GNP/O-CNT35 and improved its amorphous property. 40,41…”

The effect of nanocarbon inclusion on mechanical, tribological, and thermal properties of phenolic resin‐based composites: An overview

“…Further, based on these above presented work results, wet dispersion was ascribed to no or little improvement and insignificant in some cases of composite properties enhancement. However, there were another contradiction on those studies, reported by Ravindran et al 172 where they used functionalized or modified MWCNT side wall surfaces with carboxyl (COOH) and hydroxyl (OH) groups through dual acidic (HNO 3 /H 2 SO 4 ) treatment, and then the functionalized MWCNT (MWCNT‐COOH) were in situ dispersed in resole resin monomers via ultrasonication. The study founded a substantial improvement of mechanical strength (tensile) about 169%, 185%, and 90% at low loadings of functionalized MWCNT for 0.05 wt%, 0.08 wt%, and 0.12 wt% respectively, which were about 6.32%, 68.4%, and 115.2% for unmodified MWCNT/phenolic nanocomposites compared to the neat resin.…”

Effect of carbon nanotubes on thermoset curing and mechanical properties of carbon fiber reinforced epoxy resin laminates fabricated by self‐resistance electric heating

“…In general, the carboxyl groups on the CNTs can enhance the interfacial strength between CNTs and epoxy resin matrix, leading to the improvement of load transfer capabilities. 37 Additionally, the carboxyl group promotes the dispersion of carbon nanotubes in the resin matrix due to the increase of repulsive force among CNTs. 38 Meanwhile, the temperature gradient of the CFRP laminate composites with CNTs was smaller than that of the CFRP laminate composites without CNTs.…”

“…This spectrum is made up of two peak values that can be decomposed into a primary peak at 284.6 eV generated by the photoelectrons emitted from graphite configuration and a secondary peak at 288.9 eV derived from the photoelectrons emitted from the carboxyl group. In general, the carboxyl groups on the CNTs can enhance the interfacial strength between CNTs and epoxy resin matrix, leading to the improvement of load transfer capabilities 37 . Additionally, the carboxyl group promotes the dispersion of carbon nanotubes in the resin matrix due to the increase of repulsive force among CNTs 38 …”