Individual Carbon Nanotubes (CNTs) have a great mechanical strength that needs to be transferred into macroscopic fiber assemblies. One approach to improve the mechanical strength of the CNT assemblies is by creating covalent bonding among their individual CNT building blocks. Chemical cross-linking of multiwall CNTs (MWCNTs) within the fiber has significantly improved the strength of MWCNT thread. Results reported in this work show that the cross-linked thread had a tensile strength six times greater than the strength of its control counterpart, a pristine MWCNT thread (1192 MPa and 194 MPa, respectively). Additionally, electrical conductivity changes were observed, revealing 2123.40 S·cm⁻¹ for cross-linked thread, and 3984.26 S·cm⁻¹ for pristine CNT thread. Characterization suggests that the obtained high tensile strength is due to the cross-linking reaction of amine groups from ethylenediamine plasma-functionalized CNT with the epoxy groups of the cross-linking agent, 4,4-methylenebis(N,N-diglycidylaniline).

We report a route to produce 1,4-dioxane from oxirane by using ZrO₂/TiO₂ as catalyst. The composite oxide ZrO₂/TiO₂ was prepared by a coprecipitation method and the catalytic performance was tested through the synthesis of 1,4-dioxane from oxirane in a pipe reactor. The X-ray diffraction (XRD) shows that ZrO₂ and TiO₂ are in crystal form. When the mass percentage of ZrO₂ is 25%, the composite oxide ZrO₂/TiO₂ presents as an amorphous form. The sample 25%ZrO₂/TiO₂ exhibits a specific surface area of 269.5 m²·g⁻¹ and pore volume of 1.34 mL·g⁻¹. The catalyst has 670 µmol·g⁻¹ of NH₃-TPD acid, and the characterization of ammonia infrared spectroscopy (NH₃-FTIR) shows that both Brønsted and Lewis acids are present on the surface of the catalyst. The reaction mechanism was analyzed according to the distribution of product. The test of catalytic performance showed 100.0% conversion of oxirane and 86.2% selectivity of 1,4-dioxane at the optimal operation conditions: atmospheric pressure, reaction temperature 75 °C and gaseous hourly space velocity of 1200.0 h⁻¹. The catalyst exhibits good catalytic performance stability after continuous use for 720 h.