Deformation kinetics analysis of polymeric matrices

Area of Science:

• Materials Science
• Chemical Engineering
• Pharmaceutical Technology

Background:

• Tablet compression is crucial in pharmaceutical manufacturing.
• Understanding polymer deformation kinetics is key to controlling tablet properties.
• Poly(methyl methacrylate-co-methacrylic acid) (PMMA/coMAA) serves as a model viscoelastic polymer.

Purpose of the Study:

• To quantify deformation kinetic parameters: activation volume (Vact) and activation energy (Eact).
• To investigate the predominant barrier to deformation in PMMA/coMAA.
• To provide data for a time-dependent particle deformation model.

Main Methods:

• Performed stress relaxation studies at varying temperatures using an instrumented Instron testing apparatus.
• Quantified shear stress rates via solid density, microindentation hardness, and contact area testing.
• Applied different strain rates (1, 2, and 5 mm/min) during experiments.

Main Results:

• Activation volume (Vact) values ranged from 63.8 to 79.1 b(3) across tested strain rates.
• Activation energy (Eact) for flow increased with strain rate, from 145 kJ/mole(-1) to 506 kJ/mole(-1).
• Results indicate strain hardening effects influencing polymer deformation.

Conclusions:

• The determined activation volumes and energies are essential for modeling tablet compaction.
• These parameters provide insights into the viscoelastic behavior of PMMA/coMAA during compression.
• The findings contribute to better control over tablet production parameters.