MWNT Content (mwnt + content)

Distribution by Scientific Domains

Selected Abstracts

Preparation of High-Performance Conductive Polymer Fibers through Morphological Control of Networks Formed by Nanofillers

Hua Deng
Abstract A general method is described to prepare high-performance conductive polymer fibers or tapes. In this method, bicomponent tapes/fibers containing two layers of conductive polymer composites (CPCs) filled with multiwall carbon nanotubes (MWNT) or carbon black (CB) based on a lower-melting-temperature polymer and an unfilled polymer core with higher melting temperature are fabricated by a melt-based process. Morphological control of the conductive network formed by nanofillers is realized by solid-state drawing and annealing. Information on the morphological and electrical change of the highly oriented conductive nanofiller network in CPC bicomponent tapes during relaxation, melting, and crystallization of the polymer matrix is reported for the first time. The conductivity of these polypropylene tapes can be as high as 275,S,m,1 with tensile strengths of around 500,MPa. To the best of the authors' knowledge, it is the most conductive, high-strength polymer fiber produced by melt-processing reported in literature, despite the fact that only ,5,wt.% of MWNTs are used in the outer layers of the tape and the overall MWNT content in the bicomponent tape can be much lower (typically ,0.5,wt.%). Their applications could include sensing, smart textiles, electrodes for flexible solar cells, and electromagnetic interference (EMI) shielding. Furthermore, a modeling approach was used to study the relaxation process of highly oriented conductive networks formed by carbon nanofillers. [source]

Synthesis and properties of poly(butylene terephthalate)/multiwalled carbon nanotube nanocomposites prepared by in situ polymerization and in situ compatibilization

Fangjuan Wu
Abstract A novel cyclic initiator was synthesized from dibutyl tin(IV) oxide and hydroxyl-functionalized multiwalled carbon nanotubes (MWNTs) and was used to initiate the ring-opening polymerization of cyclic butylene terephthalate oligomers to prepare poly(butylene terephthalate) (PBT)/MWNT nanocomposites. The results of Fourier transform infrared and NMR spectroscopy confirmed that a graft structure of PBT on the MWNTs was formed during the in situ polymerization; this structure acted as an in situ compatibilizer in the nanocomposites. The PBT covalently attached to the MWNT surface enhanced the interface adhesion between the MWNTs and PBT matrix and, thus, improved the compatibility. The morphologies of the nanocomposites were observed by field emission scanning electron microscopy and transmission electron microscopy, which showed that the nanotubes were homogeneously dispersed in the PBT matrix when the MWNT content was lower than 0.75 wt %. Differential scanning calorimetry and thermogravimetric analysis were used to investigate the thermal properties of the nanocomposites. The results indicate that the MWNTs acted as nucleation sites in the matrix, and the efficiency of nucleation was closely related to the dispersion of the MWNTs in the matrix. Additionally, the thermal stability of PBT was improved by the addition of the MWNTs. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Synthesis and characterization of carbon nanotube/polypyrrole core,shell nanocomposites via in situ inverse microemulsion

Yijun Yu
Abstract We demonstrate here a feasible approach to the preparation of multiwalled carbon nanotube (MWNT)/polypyrrole (PPy) core,shell nanowires by in situ inverse microemulsion. Transmission electron microscopy and scanning electron microscopy showed that the carbon nanotubes were uniformly coated with a PPy layer with a thickness of several to several tens of nanometers, depending on the MWNT content. Fourier transform infrared spectra suggested that there was strong interaction between the ,-bonded surface of the carbon nanotubes and the conjugated structure of the PPy shell layer. The thermal stability and electrical conductivity of the MWNT/PPy composites were examined with thermogravimetric analysis and a conventional four-probe method. In comparison with pure PPy, the decomposition temperature of the MWNT/PPy (1 wt % MWNT) composites increased from 305 to 335 C, and the electrical conductivity of the MWNT/PPy (1 wt % MWNT) composites increased by 1 order of magnitude. The current,voltage curves of the MWNT/PPy nanocomposites followed Ohm's law, reflecting the metallic character of the MWNT/PPy nanocomposites. The cyclic voltammetry measurements revealed that PPy/MWNT composites showed an enhancement in the specific charge capacity with respect to that of pure PPy. 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6105,6115, 2005 [source]

Effect of Functionalized Carbon Nanotubes on Molecular Interaction and Properties of Polyurethane Composites

Nanda Gopal Sahoo
Abstract Summary: Functionalized MWNTs were incorporated into PU by solution mixing to improve the mechanical and thermal properties of composites. A homogeneous dispersion of MWNTs was successfully achieved in PU matrix as evidenced by scanning electron microscopy. It may be attributed to the hydrogen bonds existing between CO groups of hard segments of PU chains and COOH groups of the MWNT-COOH. The incorporation of the MWNTs effectively enhanced the crystallization of the PU matrix through heterogeneous nucleation, and the nucleation effect was more evident at 10 wt.-% functionalized MWNTs as compared to other composite systems. Mechanical properties of the PU-MWNTs composites were assessed as a function of MWNT concentration and dispersion of MWNT in PU matrix. The most significant improvement in mechanical properties was obtained, e.g., 740% increase in modulus and 180% increase in tensile strength over pure PU with 20% MWNT content. The thermal stability of composites due to thermal gravimetric measurements was significantly improved. A possible interaction of H-bonding existed between PU chain and MWNT-COOH. [source]