Rheology of PVC Plastisol--V: storage modulus and network formed by particle contact

Area of Science:

• Materials Science
• Polymer Science
• Rheology

Background:

• Previous work identified pseudo-plastic behavior in PVC plastisols with increasing frequency due to immobilized layer formation.
• Dynamic viscosity and storage modulus of the mobile phase were previously evaluated.

Purpose of the Study:

• To model the relationship between storage modulus, varying frequencies, and the fine/coarse particle ratio in PVC plastisols.
• To analyze particle-particle contacts (fine-fine, fine-coarse, coarse-coarse) within a network model.

Main Methods:

• Utilized a model network of particle-particle contacts to analyze storage modulus.
• Evaluated the average number of contact points per particle (f-f, f-c, c-c) at different frequencies.
• Assessed the number of particles participating in the network as a relative measure.

Main Results:

• At lower frequencies, more fine-fine contacts exist but fewer particles participate, creating a loose network.
• Fine-coarse contacts show fewer points per particle across frequencies.
• Coarse-coarse contacts, though limited, significantly contribute to modulus magnitude due to particle size.

Conclusions:

• Higher frequencies lead to fewer fine-fine contacts but increased particle participation, tightening the network.
• Fine-coarse contact trends mirror higher frequencies.
• Coarse-coarse contacts increase significantly at higher frequencies, impacting overall network properties.