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Abstract : The molecular structure of PMMA gels and aggregates in bromobenzene and ortho-xylene has been investigated by small-angle neutron scattering. It is found that in bromobenzene the gels are constituted of connected, prolate cylinder-like structures. A large proportion of these structures about 90 % possess a radius of about 1.5 nm. The remaining possess larger radii from 3.0 to 5.3 nm. On heating, the melting process seems to proceed via two-steps : melting of the junction domains while the cylinder-like structures remain virtually unaffected. Scattering curves that differ significantly are obtained in ortho-xylene. They are also interpreted with cylinder-like objects of larger radii up to 10 nm. As with bromobenzene, melting seems to take place in two steps. These results prove to be relevant for interpreting rheological data that will be presented in a forthcoming paper.





Autor: Nazir Fazel Zarmina Fazel Annie Brûlet Jean-Michel Guenet

Fuente: https://hal.archives-ouvertes.fr/



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