Dermatologicals: Rheology

Question 1

For this non-Newtonian sys, viscosity INCREASES as more shear force is applied.

Answer 1

Dilatant flow

Question 2

Order the following in terms of water content (starting w/ the least water content):
viscous thicker liquids, liquids, viscoelastics, solids, elastics

Answer 2

Solids, elastics, viscoelastics, viscous thicker liquids, liquids

Question 3

Define rheology

Answer 3

The study of the changes in form, shape, and flow of matter

Question 4

For this non-Newtonian sys, shear force must exceed a yield value before any flow takes place.

Answer 4

Plastic flow/Bingham flow

Question 5

4 types of non-Newtonian systems?

Answer 5

1. Plastic flow
2. Pseudoplastic flow
3. Dilatant flow
4. Thixotropic flow

Question 6

This term describes a non-Newtonian system’s tendency towards structural breakdown when a shear force is applied to it.

Answer 6

Thixotropy

Question 7

What do hysteresis loops indicate?

Answer 7

Degree of structural breakdown

Question 8

What is the term that describes the internal friction of fluid that makes it resist flow?

Answer 8

Viscosity

Question 9

T or F: A thinner hysteresis loop indicates a longer time to return to original structure and viscosity.

Answer 9

F

Question 10

Does temp affect viscosity?

Answer 10

Yes

Question 11

Newtonian or non-Newtonian sys?

Viscosity = constant, regardless of shear stress (force) applied to flow.

Answer 11

Newtonian

Question 12

T or F: Most dermatologicals exhibit Newtonian flow.

Answer 12

F

Question 13

For this non-Newtonian sys, there is a non-linear increase in shear rate/flow rate as shear force is applied.

Answer 13

Pseudoplastic flow