Silica Dispersion for Applications in Rubber Processing

The use of silica as a reinforcing agent is an important and emergent technological advancement in rubber compounding. The improved performance of silica-reinforced rubber composites is made possible through treatment of the silica by coupling agents (CA) such as bi-functional alkoxysilane molecules. The CA chemically binds to surface silanol groups so that interparticle and particle-polymer interactions are modified in a manner that improves the silica dispersion quality as well as the processability of silica-reinforced rubber composites. However, the control of CA-silica reactions during composite manufacturing processes remains a challenge due to the lack of a fundamental understanding of CA reaction mechanisms and kinetics.In this work, we studied the wetting behavior in beds of silica particles possessing complex microstructures using liquid infiltration analysis. Simultaneous measurement of the rate of liquid mass uptake and the volume occupied by that liquid within the particle bed provides information about the fraction of pore volume that participates in liquid infiltration along with the effective size of the geometric unit that governs infiltration kinetics. This provides the quantitative information for interpreting effects of silica microstructure on liquid infiltration behavior during dispersion.We developed a new thermogravimetric analysis (TGA) technique to study the kinetics of binding of a CA molecule onto silica, and the bound-rubber formation on surface-modified silica. Derivative TGA curves of the CA-functionalized silica show distinct peaks which correspond to the alkoxysilane bound to one or two surface silanol sites. Binding at two silanol sites is postulated to occur in a two-step series reaction model. The bound rubber formation is attributed to be the direct binding of a polymer chain with a number of nonpolar interactive sites provided by the CA molecules on the silica surface. We have demonstrated that the TGA technique is a powerful tool for direct studies of coupling reactions. Moreover, we developed the first model analysis for the torque requirements for the dispersion of silica in the batch mixing of solution styrene-butadiene rubber. We have provided a method for correlating material and processing parameters with silica dispersion behavior, and this model allows predictions of silica dispersion at practical mixing conditions applicable to scale-up process optimization.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Chemical Engineering

Grantor dc:publisher

Case Western Reserve University School of Graduate Studies

Year dc:date

2013

Author dc:creator

• Law, Yuk Yu

Contributors dc:contributor

• Feke, Donald
• Manas-Zloczower, Ica

• Chemical Engineering
• Silica
• Rubber
• Dispersion
• Coupling agents
• Alkoxysilane

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=case1363116801

OAI identifier oai:identifier

oai:etd.ohiolink.edu:case1363116801