کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9460518 | 1312181 | 2005 | 16 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
A lattice chain model for the thermal restructuring of nanoparticle chain aggregates
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
علم هواشناسی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Chain aggregates composed of nanoparticles of carbon black, silica, titania and other metal oxides are produced commercially using aerosol reactors. Properties of nanoparticle chain aggregates (NCA), such as restructuring when heated in gaseous suspension, may play an important role during synthesis. It is hypothesized that in some cases a separate step in NCA creation is the restructuring of the chains initially formed by rigid body addition processes, for example cluster-cluster aggregation. A model of a freely rotating bead chain (zero activation energy for particle rotation) is adapted here from the polymer literature to describe nanoparticle chain restructuring resulting from interaction with the surrounding gas. The link between the physical properties of the surrounding gas and the dynamics of the nanoparticle chain is provided through the diffusion coefficient of the chain center of mass. We have studied the restructuring dynamics for primary particles of various diameters, different chain lengths and at different temperatures, and the model predicts a fast transition from a non-equilibrium initial chain configuration to a relaxed state. For a stretched chain of 64 particles, each 35Â nm in diameter, in air at 1800Â K and atmospheric pressure, the characteristic time for relaxation was 0.34Â ms. This time is consistent with a 12Â ms upper limit in restructuring time for soot aggregates reported in the literature. It is possible that in practice the approach to equilibrium may be delayed by constraints on particle rotation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Aerosol Science - Volume 36, Issue 1, January 2005, Pages 27-42
Journal: Journal of Aerosol Science - Volume 36, Issue 1, January 2005, Pages 27-42
نویسندگان
Adamos Dalis, Sheldon K. Friedlander,