Powder technology Flashcards
1
Q
Interpaticular forces
A
- Friction
- Mechanical interlocking of particles
- Cohensive forces
- Liquid bridges
2
Q
Friction
A
- Surface properties between particle and particle wall
3
Q
Mechanical interlocking
A
- Size of particle (dependent)
- Position of the particle
4
Q
Cohesive forces
A
- Van der walls
- Electrostatic (particle charge interactions, electrical potential contact difference)
5
Q
Liquid bridges
A
Liquid between particles that cause and increase in interaction between solids.
- Capillary forces
- Surface tension
6
Q
Angle of response
A
- Base of dimeter with a fixed diameter and funnel 2-4nm
- Angle >50 not good flow
- <50 good flow
7
Q
Tap density
A
- 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
8
Q
Flow through an orfice
A
- Direct method to measure flow properties
- No general scale of flowability
9
Q
Particle size >250nm
A
- Good flow
10
Q
Particle size <100nm
A
- Flow problems
11
Q
Properties of formulation additives
A
- Small
- Hard
- Unreactive
- Insoluble
- Keep particles separated
- Improve flow
12
Q
Modolling powder flow
A
- Size
- Density
- Moisture content
- Shape
- Packaging
- Formulation additives
- Equipment method used
13
Q
Ways to measure powder technology
A
1) Sheer cell measurement
2) Angle of response
3) Tap density
4) flow through an orifice
