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Mechanical stability of fractal colloidal gels

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Mechanical stability of fractal colloidal gels
作者:	Manley, Suliana.
面頁冊數:	88 p.
附註:	Adviser: David A. Weitz.
附註:	Source: Dissertation Abstracts International, Volume: 65-05, Section: B, page: 2460.
Contained By:	Dissertation Abstracts International65-05B.
標題:	Physics, Condensed Matter.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3131921
ISBN:	0496791613

Mechanical stability of fractal colloidal gels
Manley, Suliana.

Mechanical stability of fractal colloidal gels [electronic resource] - 88 p.

Adviser: David A. Weitz.

Thesis (Ph.D.)--Harvard University, 2004.

Colloidal particles with attraction diffuse and stick to form highly disordered aggregates whose structures are well-described as mass fractals. Thus, even at low particle volume fractions, &phis;, aggregates grow to fill space and form an elastic network. In this study, we focus on understanding the mechanical properties of colloid gels. In the process, we explore the limits to gelation and gel stability.

ISBN: 0496791613Subjects--Topical Terms:

226939
Physics, Condensed Matter.

Mechanical stability of fractal colloidal gels
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502 $a Thesis (Ph.D.)--Harvard University, 2004.
520 # $a Colloidal particles with attraction diffuse and stick to form highly disordered aggregates whose structures are well-described as mass fractals. Thus, even at low particle volume fractions, &phis;, aggregates grow to fill space and form an elastic network. In this study, we focus on understanding the mechanical properties of colloid gels. In the process, we explore the limits to gelation and gel stability.
520 # $a Gel networks are generally out-of-equilibrium systems; similar to glasses, they undergo aging. In Chapter 6, we discuss preliminary work on aging as it depends on attraction and &phis;.
520 # $a In Chapter 2, we discuss the limits to gelation at low-&phis;. We show that the dynamics of large fractal colloid aggregates are well described by a combination of translational and rotational diffusion and internal elastic fluctuations, allowing both the aggregate size and internal elasticity to be determined by dynamic light scattering. We find that gravitational stress limits the cluster growth on earth, even under near buoyancy-matched conditions, whereas thermal fluctuations limit the growth of fractal structures in the absence of gravity.
520 # $a In Chapter 3, we study the mechanical properties of gels formed from strongly aggregating silica colloids. Surprisingly, we find that their elastic moduli, G', continue to increase long after network formation, leading to an increase in elasticity of several orders of magnitude over a few hours. We present a model based on the sintering of the particles which accounts for the observed time dependence.
520 # $a In Chapter 4, we examine the collapse of silica colloidal gels; this occurs when the gravitational stress exerted on the lower part of a sample is greater than its yield stress. We show that the collapse dynamics are related to the rheological properties of the gel as it yields.
520 # $a In Chapter 5, we study the effects of surfactant concentration on a model concentrated emulsion. Surfactant concentration helps to set droplet sizes; thus, it plays an important role in determining the mechanical properties and stability of these kinds of gels.
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