Highly conductive multiwall carbon nanotube and epoxy composites produced by three-roll milling

Nanocomposites of a spirocyclic phosphazene epoxy (SP-epoxy) resin with graphene were prepared through the exfoliation of graphite platelets and thermal curing process. Transmission electric microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed the chemical exfoliation and following thermal reduction for the graphene. The TEM observation also demonstrated that the reduced graphene oxide, as the single- and/or few-layered stacking sheets, was homogeneously dispersed in the SP-epoxy matrix. The presence of graphene improved both the tensile and flexural properties of the nanocomposites as a result of the great surface area of graphene sheets in contact with the matrix. These nanocomposites also achieved a considerable increase in glass transition temperature, thermal decomposition temperatures, and storage modulus. It is highly emphasized that the SP-epoxy/graphene nanocomposites also presented a low percolation threshold of 0.375 vol % and achieved high electrical conductivity at a...

Fabrication of Spirocyclic Phosphazene Epoxy-Based Nanocomposites with Graphene via Exfoliation of Graphite Platelets and Thermal Curing for Enhancement of Mechanical and Conductive Properties

High Performance Flexible Piezoelectric Pressure Sensor Based on CNTs-Doped 0-3 Ceramic-Epoxy Nanocomposites

In this study, the effect of carbon nanotube (CNT) modification on the tensile and thermal properties of CNT/basalt/epoxy composites was investigated. CNT/basalt/epoxy composites were fabricated by impregnating woven basalt fibers into epoxy resin mixed with CNTs. Three groups of composites were fabricated, consisting of unmodified, acid-modified (oxidized), and silane-modified (silanized) CNTs, each at 1 wt.%. Tensile tests and dynamic mechanical analysis (DMA) were performed on each group of composites to determine the mechanical and thermal properties of the CNT/basalt/epoxy composites, depending on the surface modification of CNTs. The tensile strength and Young's modulus of silanized CNT/basalt/epoxy composites were 34 and 60% greater, respectively, than that of unmodified CNT/basalt/epoxy composites. Also the silanized composites had a higher storage modulus and T g than unmodified and oxidized composites. The enhancement of the mechanical and thermal properties of silanized CNT/basalt/epoxy composites is attributed to improved dispersibility and strong interfacial interaction between the silane functionalized CNTs and the epoxy in the basalt fabric/epoxy composites.

The tensile and thermal properties of modified CNT-reinforced basalt/epoxy composites

For the liquid epoxy nanosuspensions with both fibril and spherical polypyrrole (PPy) nanostructures, a stronger PPy nanofibers/epoxy interaction and more temperature stable behavior with a lower flow activation energy of nanosuspensions with nanofibers (54.34 kJ mol−1) than that with nanospheres (71.15 kJ mol−1) were revealed by rheological studies. As well as the common enhancing mechanism of limiting crack propagation in the polymer matrix, the nanofibers further initiated the shear bands in the epoxy resin to give a higher tensile strength (90.36 MPa) than that of pure epoxy (70.03 MPa) and even that of the epoxy nanocomposites with nanospheres (84.53 MPa). With a larger specific surface area, the nanofibers rather than nanospheres were observed to reduce the flammability of epoxy more efficiently by assisting more char formation of the epoxy resin. The hydroxyl groups formed between the protons of the doped acid in the PPy nanofillers and the epoxy broke the conjugate structure of PPy, leading to a higher bandgap in the nanocomposites (Eg1 = 3.08 eV for 1.0 wt% PPy nanofibers) than that of pure nanofillers (1.8 eV for PPy nanofibers and 1.2 eV for PPy nanospheres). Due to the high aspect ratio, the PPy nanofibers could form the conductive path more easily than the PPy nanospheres to provide a lower percolation threshold value. The real permittivity was observed to increase with increasing the PPy nanofiller loading, and the enhanced permittivity was interpreted by the interfacial polarization.

Polypyrrole doped epoxy resin nanocomposites with enhanced mechanical properties and reduced flammability

New type of piezo-damping epoxy-matrix composites with multi-walled carbon nanotubes and lead zirconate titanate

Piezo-damping epoxy-based composites containing various amounts of multi-walled carbon nanotubes (CNT) and piezoelectric lead zirconate titanate (PZT) were prepared, and their performances were investigated. The composites exhibited a percolation threshold in the range of 1–1.5 g CNT per 100 g epoxy, in which a continuous electro-conductive network formed. Dynamic mechanical thermal analysis reveals that the loss factors of the composites were improved by incorporation of the PZT and the CNT at above critical electrical percolation loading. Based on this new type rigid piezo-damping material, the PZT contributes to the transformation of mechanical noise and vibration energies into electric energy, while the CNT serve in shorting of the generated electric current to the external circuit. Thermal stability and mechanical properties were also improved by incorporating these two fillers. An optimum formulation for the rigid piezo-damping materials can be designed on the basis of the results of this study.

Fabrication and performances of epoxy/multi-walled carbon nanotubes/piezoelectric ceramic composites as rigid piezo-damping materials

This paper focuses on the characterization of the physico-chemical properties, surface modification, residual copper content and in situ hybrid inorganic particle modification of polypropylene (PP) composites reinforced by waste printed circuit board powder (WPCBP). A series of WPCBP/SiO2 hybrids (TSW) were prepared by a sol–gel method at different pH values. Characterization results revealed the in situ generation of SiO2 on the surface of WPCBP, and showed that with an increase in pH value, the size of SiO2 particles increased gradually and the copper content decreased in the TSW powder. The mechanical properties, oxidation induction time (OIT) and thermal properties of PP composites were improved by reinforcement with TSW, which might be ascribed to the formation of serrated interfaces. This work not only develops a powerful method to enhance the properties of PP/WPCBP composites, but also provides an environmentally sustainable approach to the high-added-value reutilization of WPCBP.

https://www.mdpi.com/2073-4360/14/5/1045/pdf?version=1646475632

Fabrication and Mechanical Properties of High-Durability Polypropylene Composites via Reutilization of SiO2 In-Situ-Synthesized Waste Printed Circuit Board Powder

Sheng Tian

Papers

New type of piezo-damping epoxy-matrix composites with multi-walled carbon nanotubes and lead zirconate titanate

Fabrication and performances of epoxy/multi-walled carbon nanotubes/piezoelectric ceramic composites as rigid piezo-damping materials

Fabrication and Mechanical Properties of High-Durability Polypropylene Composites via Reutilization of SiO2 In-Situ-Synthesized Waste Printed Circuit Board Powder