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# Tom Rieker - NSF <trieker@nsf.gov>
# requesting 2 days, at minimum=1 days
# beamline 33ID, USAXS study: carbon black mass fractal aggregates
# instrument 33ID-D USAXS
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# top:/home/www/beamtime-requests/req00517.txt
# UNICAT Member Beam Time Request  #517
# created Fri Dec 05 23:40:32 CST 2003
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beamline:
	33ID

collaboration:
	No

collaborator_Pete:
	ON

contact:
	trieker@nsf.gov

days:
	2

description:
	Carbon black and silica are two of the most important polymer fillers used in industry.   However, not all forms of these materials provide mechanical reinforcement when mixed with polymers.  Good reinforcing materials typically are mass fractal structures –aggregates on the order of 100’s of nm made by the coalescence of primary particles, 10’s of nm in size.  In mass fractal aggregates the mass distribution follows a unique scaling behavior – M ~ rDm, leading to open, highly porous structures with a range of pore sizes between the dimensions of the primary particles and the aggregates themselves.   

In recent work I was able to show using small-angle x-ray scattering that carbon black mass fractal aggregates interpenetrate both when neat materials are compressed (1) and when mixed into a polymer above the percolation threshold (2).  Small-angle scattering is a powerful technique for probing the structure of materials on length scales from a few Angstroms to micrometers, and is especially well suited for the study of correlations found in mass, pore, or surface fractal structures.   More recent small-angle scattering experiments have shown anisotropic scattering patterns likely due to shear during processing (3).  This can be interpreted as a non-uniform interpenetration of the fractal aggregates or a deformation of the aggregates themselves.  The later seemed unlikely as fractal filler particles are thought to be stiff and expected to break rather than deform.  However, recent electron microscopy experiments on carbon black mass fractal aggregates show that they are quite elastic (at least when illuminated (heated) by an electron beam) (4).  

I propose to conduct small-angle x-ray scattering experiments on the UNI-CAT Bonse-Hart instrument at the Advanced Photon Source on carbon black and silica filled polymers to investigate both anisotropic interpenetration and possible deformation of these fillers.   This instrument is unique in the world in its ability to collect anisotropic small-angle scattering data over the length scales required (5).   I am requesting a series of carbon black and silica filled polymers from PPG Industries in which the loading of the filler is varied from about 1 to 30% by weight.  Data will be collected for samples as produced, stretched by known amounts and relaxed, and stretched and held.  Scattering data on filled samples below percolation should yield information on the deformation of individual aggregates.  While experiments on higher loading will provide insight into interpenetration and disentanglement of the aggregates.


(1)	C.M. Sorensen, C. Oh , P.W. Schmidt, T.P. Rieker, Scaling description of the structure factor of fractal soot composites, Phys. Rev. E, Vol. 58, pp. 4666-4672, 1998.
(2)	T.P. Rieker, M. Hindermann-Bischoff , F. Ehrburger-Dolle , Small-angle X-ray scattering study of the morphology of carbon black mass fractal aggregates in polymeric composites, Langmuir, Vol. 16, pp. 5588-5592, 2000.
(3)	F. Ehrburger-Dolle, M. Hindermann-Bischoff, F. Livet, F. Bley, C. Rochas, and E. Geissler, Anisotropic Ultra-small-angle X-ray Scattering in Carbon Black Filled Polymers, Langmuir, Vol. 17, pp. 329-334, 2001
(4)	S.K. Friedlander, K. Ogawa, and M. Ullmann, Elastic Behavior of Nanoparticle Chain Aggregates: A Hypothesis for Polymer – Filler Behavior, J. Polym. Sc.: part B Polymer Physics, Vol. 38, pp 2658-2665, 2000.  And, Y.J. Suh, and S.K. Friedlander, Origins of the Elastic Behavior of Nanoparticle Chain Aggregates:  Measurements using Nanostructure Manipulation Device, J. Appl. Phys., Vol. 93, pp. 3515 – 3523, 2003.
(5)	J. Ilavsky, A. Allen, G. Long, and P. Jemian, Effective pinhole-collimated ultrasmall-angle x-ray scattering instrument for measuring anisotropic microstructures, Review of Scientific Instrument, Vol. 73, pp.1660-1662, 2002.  And, http://www.uni.aps.anl.gov/usaxs/

equipment_required:
	

experiment:
	USAXS study: carbon black mass fractal aggregates

foreign_nationals:
	

hazards:
	none

instrument:
	33ID-D USAXS

instrument_other:
	

minimumdays:
	1

name:
	Tom Rieker - NSF

new_request:
	ON

nonmembers:
	

unacceptable+dates:
        February 17-22, 2004.  I'll need 2-3 weeks notice to get samples ready.


z34ID_details:
	


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