Daowei Ding

Mesoporous magnetic carbon nanocomposite fabrics for highly efficient Cr(VI) removal

We have demonstrated that magnetic carbon nanocomposite fabrics prepared by microwave assisted heating are advanced adsorbents in the removal of Cr(VI) with a much higher removal capacity of 3.74 mg g−1 compared to 0.32 mg g−1 for cotton fabrics and 0.46 mg g−1 for carbon fabrics. The enhanced Cr(VI) removal is attributed to the highly porous structure of the nanocomposites. The adsorption kinetics follow the pseudo-second-order model, which reveals a very large adsorption capacity and high adsorption rate. The removal process takes only 10 min, which is much faster than conventional adsorbents such as activated carbon and biomass that often requires hours of operation. The significantly reduced treatment time and the large adsorption capacity make these nanocomposite fabrics promising for the highly efficient removal of heavy metals from polluted water.

Electrically Conductive Polypropylene Nanocomposites with Negative Permittivity at Low Carbon Nanotube Loading Levels

Polypropylene (PP)/carbon nanotubes (CNTs) nanocomposites were prepared by coating CNTs on the surface of gelated/swollen soft PP pellets. The electrical conductivity (σ) studies revealed a percolation threshold of only 0.3 wt %, and the electrical conductivity mechanism followed a 3-d variable range hopping (VRH) behavior. At lower processing temperature, the CNTs formed the network structure more easily, resulting in a higher σ. The fraction of γ-phase PP increased with increasing the pressing temperature. The CNTs at lower loading (0.1 wt %) served as nucleating sites and promoted the crystallization of PP. The CNTs favored the disentanglement of polymer chains and thus caused an even lower melt viscosity of nanocomposites than that of pure PP. The calculated optical band gap of CNTs was observed to increase with increasing the processing temperature, i.e., 1.55 eV for nanocomposites prepared at 120 °C and 1.70 eV prepared at 160 and 180 °C. Both the Drude model and interband transition phenomenon have been used for theoretical analysis of the real permittivity of the nanocomposites.

Anticorrosive conductive polyurethane multiwalled carbon nanotube nanocomposites

Conductive polyurethane (PU) nanocomposite coatings filled with multiwalled carbon nanotubes (MWNTs) fabricated by employing an in situ surface-initiated-polymerization (SIP) method were tested for corrosion prevention of stainless steel (SS). The nanocomposites exhibited a good response of electrical conductivity change to the strain during the cyclic tensile strain test. The anticorrosion properties of these nanocomposite coatings on the SS surface were evaluated in 3.0 wt% NaCl aqueous solution by monitoring the open circuit potential (Eocp) and tracing quasi-stationary polarization (Tafel) of the nanocomposite-coated stainless steel (MWNT/PU–SS) electrode. Electrochemical impedance spectroscopy (EIS) was also obtained to give an insight into the anticorrosion protection of SS. The nanocomposite displayed a good chemical stability over long immersion in a corrosive environment. A significant positive shift of nearly 1.0 V in the Eocp was observed from the Eocp–time curve. Extrapolation of Tafel plots gave a much more positive corrosion potential (Ecorr) and a lower corrosion current (Icorr). A protection efficiency as high as 97.70% was obtained. An equivalent circuit of the coating was proposed to fit the EIS data, confirming an effective corrosion protection for SS. The results indicate that the polyurethane matrix combined with the well dispersed MWNT reinforcements provided a significant physical barrier against the attack of corrosive ions in the solution for SS while providing a channel for the conductivity.

Reinforced magnetic epoxy nanocomposites with conductive polypyrrole nanocoating on nanomagnetite as a coupling agent

The new function of polypyrrole (PPy) to serve as a coupling agent has been demonstrated in preparing conductive epoxy resin nanocomposites with PPy coating on magnetite (f-Fe3O4) nanoparticles. The effects of magnetic nanofiller loading level on the rheological behavior, thermal stability, dynamic mechanical properties, mechanical properties, electrical conductivity, dielectric properties and magnetic properties were systematically studied. Compared with pure epoxy suspension, a reduced viscosity was observed in epoxy nanosuspensions with 5.0 wt% f-Fe3O4 nanoparticles, and the viscosity increased with further increasing f-Fe3O4 nanoparticle loading. Increased glass transition temperature (Tg) and enhanced mechanical tensile strength were observed in the cured solid epoxy polymer nanocomposites (PNCs) with f-Fe3O4 nanoparticles. The volume resistivity of the cured epoxy PNCs with 30.0 wt% fFe3O4 nanoparticles was decreased almost 7 orders of magnitude compared with the cured pure epoxy (1.6 � 10 13 U cm). The cured epoxy PNCs exhibited good magnetic properties, and the surface functionality and epoxy matrix have little effect on the magnetic moment of the Fe3O4 nanoparticles. The role of PPy nanocoating on the nanocomposite formation mechanism was investigated by using the Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) tests.

Transparent anhydride–cured epoxy nanocomposites reinforced with polyaniline stabilized nanosilica

Transparent anhydride–bisphenol-A epoxy systems filled with pristine nanosilica were prepared and compared with the counterparts with the nanosilica coated with surface initiated polymerization (SIP) prepared phosphoric acid (H3PO4) doped polyaniline (PANI). The rheological investigation on the bisphenol-A epoxy nanosuspensions demonstrated that the surface coating increased the interaction between the nanosilica and the resin matrix. The tensile strength of anhydride–epoxy (83.79 MPa) was increased to 87.00 and 88.78 MPa for the epoxy with the as-received and functionalized nanosilica, respectively. The real permittivity of the nanocomposites was increased after the introduction of PANI functionalized nanosilica. The H3PO4 doped PANI decreased the heat release rate of epoxy from 563.0 to 508. 3 W g−1, confirming the fire retardancy behavior of the PANI coating. The obtained cured anhydride–epoxy nanocomposites filled with nanosilica are highly transparent in visible light, and have potential applications in the optical field.

Significantly enhanced mechanical and electrical properties of epoxy nanocomposites reinforced with low loading of polyaniline nanoparticles

The polyaniline (PANI)/epoxy nanocomposites with enhanced mechanical and electrical properties were prepared by three different techniques. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to study the chemical structure and surface morphology of the PANI nanoparticles, which were synthesized by the oxidation polymerization method. The effects of PANI loading and preparation method on the mechanical and electrical properties of PANI/epoxy nanocomposites were comparatively studied. The SEM images of the PANI/epoxy nanocomposites after doing the tensile test were used to study the dispersion of PANI nanoparticles in the epoxy matrix. The tensile strength of 5.0 wt% PANI/epoxy nanocomposites (107.27 MPa) was much higher than that of our previous PANI/epoxy nanocomposites (about 60.0 MPa) with the same PANI loading. The volume resistivity of the PANI/epoxy nanocomposites was also decreased compared to the reported literature. The toughness and Youngs modulus of the PANI/epoxy nanocomposites were also studied and presented in this paper.

Applications of Calorimetry on Polymer Nanocomposites

In this chapter, the application of two commonly used calorimetries, i.e., differential scanning calorimetry (DSC) and microscale combustion calorimetry (MCC), will be introduced. DSC is mainly used to study the melting and crystallization behaviors of polymers/polymer nanocomposites. Here, the nanofiller-dependent melting and crystallization behaviors will be emphasized. MCC is employed to evaluate the flammability of polymeric materials and their polymer matrix nanocomposites. The heat release-related parameters are of great significance for determining the fire risks for flammable polymers and will be used to interpret the mechanism for the flammability reduction.

Nano-Chemical Engineering and Nano-Processes in Manufacturing Multifunctional Nanocomposites

Nano-Chemical engineering and nano-processes are critical in manufacturing multifunctional nanocomposites which are used for wide applications. Innovations made in nano-chemical engineering and nano-processes have enhanced performances of existing nanocomposites and developed new types of nanocomposites. On the other hand, the nano-chemical engineering and nano-processes can be affected by the design of the nanocomposites.