Localizing the cross-links distribution in elastomeric composites by tailoring the morphology of the curing activator

The localization of the rubber vulcanization reaction close to the silica filler surface was investigated in isoprene rubber composites (IR NCs): the main goal was to highlight the role of curing agents’ dispersion and filler surface features on the spatial propagation of the rubber cross-links and the resulting mechanical behavior of the material. The study was realized by tailoring the morphology of the curing activator, i.e. by vulcanizing IR NCs with Zn@SiO2 double function filler, composed of Zn(II) single sites anchored on SiO2 filler, in comparison to silica filled IR NCs vulcanized with microcrystalline ZnO (m-ZnO). The microscopic cross-links distribution was measured by Transmission Electron Microscopy for network visualization (NVTEM) and Time Domain Nuclear Magnetic Resonance (TD-NMR). Besides the NCs mechanical behavior was characterized both at small strain and at fracture. In the presence of Zn@SiO2, higher cross-link density in proximity to SiO2 particles was evidenced, which gradually spreads from the filler surface to the bulk, induced by localization of the Zn(II) centers. IR NCs with Zn@SiO2 resulted stiffer (+45%) and with a lower fracture toughness (less than one third), compared to m-ZnO based NCs, which shows a quite homogeneous structure of the rubber cross-links network. The results highlighted the correlation between the composites structural features and their macroscopic behavior, paving the way to modulating the mechanical properties of elastomeric materials by tuning the nature of the curing agents

Rubber Clay Nanocomposites

The use of nanofillers allows the development of nanocomposites with improved properties and novel applications. The technological goal is possible due to the new compounding method that allows a particle dispersion in the nanometer scale increasing the specific surface area.Fil: Cova Sánchez, Mariajose. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; Argentina. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Bacigalupe, Alejandro. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentina. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; ArgentinaFil: Escobar, Mariano Martin. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mansilla, Marcela Angela. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Pseudo-spectral method for the modelling of quantization effects in nanoscale MOS transistors

This paper presents a systematic comparison between the numerical efficiency of the pseudo-spectral (PS) and finite difference (FD) methods for the solution of eigenvalue problems related to both n and p-MOS transistors, with different geometries and carrier dimensionalities. Our results indicate remarkable advantages of the PS compared to the FD method in terms of CPU time

Pseudo-spectral methods for the efficient simulation of quantization effects in nanoscale MOS transistors

This paper presents an in-detail investigation of the 6 possible advantages related to the use of the pseudospectral (PS) 7 method for the efficient description of the carrier quantization 8 in nanoscale n- and p-MOS transistors. To this purpose, we 9 have implemented, by using both the finite-difference (FD) and 10 PS methods, self-consistent Schr\uf6dinger\u2013Poisson solvers for both 11 a 2-D hole gas described by a k \ub7 p Hamiltonian (suitable for 12 p-MOSFETs) and a 1-D electron gas in the effective-mass ap- 13 proximation (for n-type fin-shaped FETs and nanowire FETs). 14 The PS and FD methods have been systematically compared in 15 terms of the CPU time and the number of discretization points by 16 monitoring not only the subband energies in the low-dimensional 17 carrier gas but also the calculation of some scattering-matrix 18 elements that are critically important for the transport modeling. 19 Our results indicate a remarkable reduction in the CPU time for 20 the PS method with respect to the FD method, which makes the PS 21 method very attractive for the modeling of the carrier quantization 22 in nanoscale MOSFETs

Macrocyclic oligomers as compatibilizing agent for hemp fibres/biodegradable polyester eco-composites

Ring:chain equilibria (RCE), existing under appropriate reaction conditions, between a linear polyester and the corresponding family of macrocyclic oligomers (MCOs), were exploited to develop an original compatibilizing pathway for preparing eco-composites based on hemp fibres and a biodegradable random co-polyester, namely poly(1,4-butylene adipate-co-terephthalate) (PBAT) with 50:50 adipate:therephthalate proportion. Cyclo-depolymerization (CDP) of PBAT was successfully carried out at high dilution using various solvents, catalysts, and reaction times. The reconversion of MCOs into linear chains by entropically-driven ring-opening polymerization (ED-ROP) occurs by simple heating in the bulk. This reaction, after optimization of catalyst amount, temperature, and reaction time, was used for the surface modification of hemp fibres. PBAT-based eco-composites containing hemp fibres as such or pre-modified by treatment with the MCOs were then prepared and characterized by morphological, mechanical and dynamic-mechanical analysis