Emulsion and Suspension Stability (3)Physical Forces that Govern Stability Recap Flashcards Preview

#B32PAI Pharmaceutics > Emulsion and Suspension Stability (3)Physical Forces that Govern Stability Recap > Flashcards

Flashcards in Emulsion and Suspension Stability (3)Physical Forces that Govern Stability Recap Deck (6)
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1

What particles are subject to Brownian Motion?

Particles less than about 2 microns in diameter, constantly moving due to BM

2

What factors affect BM / kinetic energy?

Temperature and external forces such as shaking

3

As particles approach one another what forces do they experience?

Forces of repulsion due to electrostatic interactions (Vr)
Forces of attraction due to VDW forces (Va)
Steric forces if they have a non-ionic surfactant on their surfaces (Energy of steric interactions (hinderance) =Vs
These energies combine to give total overall potential energy

4

What is the primary minimum?

Permanent aggregation of particles when attraction is maximum and repulsion is minimum

5

What is the primary maximum?

Repulsive barrier to aggregation when attraction is moderate and repulsion is moderate
Stable suspension / emulsion

6

What is the secondary minimum?

Repulsion is minimal, attraction is weak but enough to cause flocculation