Powder technology

Question 1

Interpaticular forces

Answer 1

• Friction
• Mechanical interlocking of particles
• Cohensive forces
• Liquid bridges

Question 2

Friction

Answer 2

• Surface properties between particle and particle wall

Question 3

Mechanical interlocking

Answer 3

• Size of particle (dependent)

- Position of the particle

Question 4

Cohesive forces

Answer 4

• Van der walls

- Electrostatic (particle charge interactions, electrical potential contact difference)

Question 5

Liquid bridges

Answer 5

Liquid between particles that cause and increase in interaction between solids.

• Capillary forces
• Surface tension

Question 6

Angle of response

Answer 6

• Base of dimeter with a fixed diameter and funnel 2-4nm
• Angle >50 not good flow
• <50 good flow

Question 7

Tap density

Answer 7

• Simple method to predict flow characteristics
• Indication of bulk size/density/size and shape and surface area.
• low compression index and low hanser ratio give better flow

Question 8

Flow through an orfice

Answer 8

• Direct method to measure flow properties

- No general scale of flowability

Question 9

Particle size >250nm

Answer 9

• Good flow

Question 10

Particle size <100nm

Answer 10

• Flow problems

Question 11

Properties of formulation additives

Answer 11

• Small
• Hard
• Unreactive
• Insoluble
• Keep particles separated
• Improve flow

Question 12

Modolling powder flow

Answer 12

• Size
• Density
• Moisture content
• Shape
• Packaging
• Formulation additives
• Equipment method used

Question 13

Ways to measure powder technology

Answer 13

1) Sheer cell measurement
2) Angle of response
3) Tap density
4) flow through an orifice