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Antoine Tardy Kash A. Bhullar Dong Q. Lim Stuart C. Thickett Per B. Zetterlund 《Journal of polymer science. Part A, Polymer chemistry》2017,55(9):1590-1600
The field of polymer chemistry is currently experiencing major research efforts into development of novel techniques for synthesis of polymers with well‐controlled microstructure. Recently, a new method has been reported [McHale et al., Nat. Chem. 2012, 4, 491–497] whereby high molecular weight and low dispersity polymer can be obtained by a radical polymerization process via the use of solely physico‐chemical interactions. This work was based on the combination of H‐bonding templated polymerization confined within nanoreactors of self‐assembled block copolymers. Herein, this system is thoroughly investigated to fully elucidate the underlying mechanism. Modification of physico‐chemical parameters, kinetic parameters as well as observations of size exclusion chromatography (SEC) results and colloidal behavior in various solvents provide revised insights into the mechanism. Through detailed NMR and SEC investigations, it is demonstrated that the SEC secondary peak originally believed to be the high molecular weight “daughter” polymer actually corresponds to nanoparticles containing the daughter polymer. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1590–1600 相似文献
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Study of three-dimensional deformation of a pallet using phase-shiff shadow moiré and finite-element analysis 总被引:3,自引:0,他引:3
We present the results of a comparative study on the static deformation of a pallet, made from oil-palm fiberreinforced composite
material, using the phase-shift shadow moiré method and finite-element analysis (FEA). The pallet was designed and analyzed
using a commerical software package. The effect of various joint types on the deformation profile was studied to obtain a
simplified model to represent the actual design. A one-fifth scale model of the pallet was fabricated and the deformation
due to static loading was measured using the phase-shift shadow moiré method. The comparison between the measurement and FEA
results on the deformed profile showed a maximum difference of 13.7% at the center of the some of the deck boards, but a smaller
difference at other deck boards. The FEA results also produced a larger deformation gradient compared to the measurements. 相似文献
998.
The axial and radial distributions of static pressures and vertical particle velocities of conical spouted beds have been simulated and compared with experimental data. Simulation results show that, among all factors investigated, the Actual Pressure Gradient (the APG term) in conical spouted beds, introduced as the default gravity term plus an empirical axial solid phase source term, has the most significant influence on static pressure profiles, followed by the restitution coefficient and frictional viscosity, while other factors almost have no effect. Apart from the solid bulk viscosity, almost all other factors affect the radial distribution of the axial particle velocity, although the influence of the APG term is less significant. For complex systems such as conical spouted beds where a fluidized spout region and a defluidized annulus region co-exist, the new term introduced in this work can improve the CFD simulation. Furthermore, for other systems with the Actual Pressure Gradient different from either fluidized beds or packed beds, the new approach can also be applied. 相似文献
999.
An experimental investigation of the three-dimensional boundary layer induced by a Rankine-like vortex with its axis normal
to a stationary disk is described. The velocity field through the boundary layer was measured for Reynolds number Re (based on the tangential velocity and radius at the disk edge) ranging from 10 000 to 25 000 at various radial distances
by means of a 4-beam, 2-component Laser Doppler Anemometer. Our results show that the nature of the boundary layer is affected
by two factors: an inflexional instability caused by the crossflow velocity profile and a stability factor caused by the favorable
pressure gradient. At lower Reynolds number, the radial pressure gradient has a very strong stabilizing effect on the boundary
layer and acts to revert it to its laminar state upstream of the effusing core. At higher Re the inflexional instability caused by the crossflow velocity dominates while the stabilizing influence of the favorable pressure
gradient recedes. As such, laminar reversion likely occurs closer to the effusion core. Thus, the point of laminar reversion
moves closer to the effusion core as the Reynolds number is increased.
Received 23 May 1996 / Accepted 29 July 1996 相似文献
1000.
C. W. Lim C. M. Wang S. Kitipornchai 《Archive of Applied Mechanics (Ingenieur Archiv)》1997,67(3):179-190
Summary This paper presents the exact relationships between the deflections and stress resultants of Timoshenko curved beams and
that of the corresponding Euler-Bernoulli curved beams. The curved beams considered are of rectangular cross sections and
constant radius of curvature. They may have any combinations of classical boundary conditions, and are subjected to any loading
distribution that acts normal to the curved beam centreline. These relationships allow engineering designers to directly obtain
the bending solutions of Timoshenko curved beams from the familiar Euler-Bernoulli solutions without having to perform the
more complicated shear deformation analysis.
Accepted for publication 26 July 1996 相似文献