Thermal and mechanical properties of cyanate ester resin modified with acid-treated multiwalled carbon nanotubes

Multiwalled carbon nanotubes (MWCNTs) that were treated with mixed acids were used to reinforce the cyanate ester resin. Meanwhile, the relationship among structure, morphology, and property of the modified resin was investigated. The treated MWCNTs were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, and X-ray photoelectron spectroscopy (XPS). The XPS results showed that the oxygen content in the treated MWCNTs was higher than that of untreated MWCNTs and the FTIR results indicated the presence of oxygen-containing functional groups on the treated MWCNTs. The microstructure of the resin was characterized by scanning electron microscopy and transmission electron microscopy. The results showed that the dispersion properties of the treated MWCNTs in the resin matrix were improved and compared with the untreated analogue. Addition of MWCNTs to the resin had little effect on the thermodynamic properties of the resin system. Upon addition of 0.8 wt% of MWCNTs to the resin, the glass transition temperature of the cured resin changed from 298°C to 285°C, maintaining a relatively high value. For the resins containing 0.6 wt% of treated MWCNTs, the plane strain critical stress intensity factor and plane strain critical strain energy release rate in the system were determined to be 1.39 Pa·m0.5 and 364 J m−2, respectively, and the fracture toughness is increased by 45.7 and 76.0%, respectively. Furthermore, the modified resin system exhibits excellent toughness and thermal properties. Therefore, the modified resin may be suitable for future applications involving high performance composites and adhesives.

Exfoliated graphite nanoplatelets/poly(arylene ether nitrile) nanocomposites

In this work, we demonstrate a method for synthesis of exfoliated graphite nanoplatelets (xGnPs)/poly(arylene ether nitrile) (PEN) nanocomposites via an efficient in situ polymerization. The GnPs were treated by the ultrasonic bath to reduce the layers of the GnPs, where the PEN were intercalated subsequently. Therefore, the dispersion of xGnP in the PEN resin was enhanced through in situ polymerization, which was characterized and confirmed by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. It was found that the tensile strength and modulus were greatly enhanced with the addition of xGnP. For 2.5 wt% of xGnP-reinforced PEN, the tensile strength and modulus were increased to 115 MPa and 3121 MPa, respectively. Owing to the well dispersion of xGnP, the low rheological percolation of 2.5 wt% for PEN nanocomposites was obtained. Besides, with 1 wt% of xGnP, the corresponding initial decomposition temperature ( Tin) increased from 451°C in pure PEN to 470°C. The addition of xGnP showed enhanced thermal stability of PEN nanocomposites, which demonstrated a promising method for preparing advanced polymer-based nanocomposites.

Improving the properties of poly(arylene ether nitrile) composites reinforced by covalently modified multi-walled carbon nanotubes

To develop high-performance carbon nanotube (CNT)-based polymer nanocomposites, both the interface control and the dispersion of CNTs within the polymer hosts need to be considered. In this study, we show an effective way to modify the surface of multi-walled CNTs (MWCNTs) by applying a cyclization reaction between nitrile-modified MWCNTs and bis-phthalonitrile. Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to examine the structure and morphology of as-prepared functional CNTs. Phthalocyanines (Pcs) were found to be evenly coated on the surface of MWCNTs, resulting in good dispersion and strong interfacial adhesion between MWNCTs and the poly(arylene ether nitrile) (PEN) matrix. Compared with neat PEN, the tensile strength and tensile modulus of PEN nanocomposites with 2 wt% MWCNTs–Pc increased from 85.6 MPa to 108 MPa and from 2300 MPa to 3350 MPa, respectively. Furthermore, surface-functionalized CNTs can also form the physical MWCNT network within the PEN matrix, as confirmed by rheological and thermal stability tests. Additionally, a low rheological percolation threshold of 0.69 wt% was obtained, and the dielectric constant of PEN nanocomposites was increased from 3.3 for neat PEN to 16.6 with 5 wt% MWCNTs–Pc.