Time filter

Source Type

Desjardins P.,Regroupement Quebecois sur les Materiaux de Pointe RQMP | L'Esperance G.,Ecole Polytechnique de Montreal
Polymer | Year: 2010

An in situ Neumann triangle-focused ion beam-atomic force microscopy (NT-FIB-AFM) method has been used to measure modified PS/HDPE interfacial tensions in ternary PS/PP/HDPE blends prepared by melt mixing and demonstrating partial wetting. The ternary blend was modified with SEB, SB and SEBS copolymers. Results related to the position of the PS droplet at the interface show that a symmetrical diblock copolymer is somewhat more efficient in decreasing the interfacial tension compared to an asymmetrical one of similar molecular weight, while the SEBS triblock copolymer appears to have no effect at all. Using the NT-FIB-AFM method, the lowest modified PS/HDPE interfacial tension is 3.0 ± 0.4 mN/m for the symmetric diblock, compared to 4.2 ± 0.6 mN/m (N = 34) for the unmodified interface. This corresponds to an apparent areal density in SEB copolymer equal to 0.16 ± 0.03 molecules/nm2, which is near reported saturation values. By varying the concentration of the copolymer, an emulsification curve reporting the value of the PS/HDPE modified interfacial tension as a function of the apparent areal density of the copolymer at the PS/HDPE interface has been obtained. The interfacial tension values obtained by the NT-FIB-AFM approach are significantly higher than the 0.5 ± 0.2 mN/m (N = 3) result obtained by using the classical breaking thread method with the same materials. This discrepancy does not appear to be due to a poor migration of the copolymer to the PS/HDPE interface, but could instead be attributed to the interfacial elasticity of the compatibilized interface, a phenomena that has not been accounted for so far in experimental studies on the morphology of compatibilized multicomponent polymer blends. © 2010 Elsevier Ltd. All rights reserved.

St-Antoine B.C.,Regroupement Quebecois sur les Materiaux de Pointe RQMP | St-Antoine B.C.,Ecole Polytechnique de Montreal | Menard D.,Regroupement Quebecois sur les Materiaux de Pointe RQMP | Menard D.,Ecole Polytechnique de Montreal | And 2 more authors.
Nano Letters | Year: 2011

We designed a thermopile based on a PN doping profile engineered in a suspended film of single-walled carbon nanotubes (SWNTs). Using estimates of the film local Seebeck coefficients, the SWNT thermopile was optimized in situ through depositions of potassium dopants. The overall performances of the thermopile were found to be comparable to state-of-the-art SWNT bolometers. The device is characterized at room temperature by a time response of 36 ms, typical of thermal detectors, and an optimum spectral detectivity of 2 × 10 6 cm Hz1/2/W in the visible and near-infrared. This paper presents the first thermopile made of a suspended SWNT film and paves the way to new applications such as broadband light (including THz) detection and thermoelectric power generation. © 2010 American Chemical Society.

Carignan L.-P.,Regroupement Quebecois sur les Materiaux de Pointe RQMP | Carignan L.-P.,Poly Grames and Research Center | Carignan L.-P.,Ecole Polytechnique de Montreal | Caloz C.,Poly Grames and Research Center | And 3 more authors.
IEEE MTT-S International Microwave Symposium Digest | Year: 2010

A dual-band integrated self-biased edge-mode isolator based on the double ferromagnetic resonance of a CoFeB ferromagnetic nanowire (FMNW) substrate, controllable by the geometrical and composition parameters of the FMNWs, is presented. The dispersion diagram of the FMNW edge-mode isolator, taking into account the effective permittivity and permeability of the FMNW medium, predicts two frequency bands of operation. These bands are demonstrated experimentally using FMNWs of 40 nm diameter with a lattice constant of 110 nm. In the presented prototype, isolations of 17 dB at 27.3 GHz and 4.4 dB at 31.2 GHz are observed under zero external applied field. The isolation of the second frequency band is increased to 18.3 dB by applying a small DC magnetic field of 0.13 T. The integrability, self-biased, double resonance, millimeter-wave and dispersion engineering properties of the FMNW medium opens up new possibilities for a diversity of magnetic devices and systems. © 2010 IEEE.

Rousseau B.,Regroupement Quebecois sur les Materiaux de Pointe RQMP | Rousseau B.,University of Montreal | Rousseau B.,Hydro - Quebec | Timoshevskii V.,Hydro - Quebec | And 5 more authors.
Electrochemistry Communications | Year: 2015

We propose NaFeZr2F11 and NaFeTi2F11 as novel materials for Na intercalation cathodes. The average sodium intercalation voltage for these compounds is about 4.0 V from first principles computations. The origin of this large voltage for a nominal Fe2+/Fe3+ redox couple is proposed to be a combination of the fluorine "booster" effect, the inductive effect and the stiffness of the proposed structure upon desodiation. © 2015 Elsevier B.V. All rights reserved.

Discover hidden collaborations