Micromeritics

Question 1

Science of small particles and study of particle size distribution

Answer 1

Micromeritics

Question 2

Unit of Particle Size

Answer 2

Micrometer
Nanometer

Question 3

Fundamental properties of powders

Answer 3

Particle Size and size distribution
Volume
Number
Shape
Surface Area

Question 4

Derived Particle Properties

Answer 4

Bulk Density, Granule Volume, Porosity

Question 5

Methods of particle size determination

Answer 5

Optical Microscopy
Sieving Method
Sedimentation Method
Automated particle Counter

Question 6

Most accurate method for particle size determination; microscope eyepiece is fitted with a micrometer where the diameter can be measured

Answer 6

Optical Microscopy

Question 7

Range of Analysis for Optical Microscopy

Answer 7

0.2 um to 100 um

Question 8

Advantages of Optical Microscopy

Answer 8

Direct observation of shape and size
Aggregation of particles can be detected
The field can be projected and a photograph can be taken
Easy to handle

Question 9

Disadvantages of Optical Microscopy

Answer 9

Diameter is obtained from only 2D
No estimation of depth or thickness
Slow, tedious, time-consuming

Question 10

3 Expression of Diameter

Answer 10

Martin’s
Ferret’s
Projected Area of Circle

Question 11

Distance between pairs of parallel tangents to the projected outline of the particle in fixed directions

Answer 11

Feret’s Diameter

Question 12

Diameter measured from the length of the particle at the point that divides a particle into two equal projected areas

Answer 12

Martin’s Diameter

Question 13

Diameter of a circle having the same area as the projected area of the particle resting in stable position

Answer 13

Projected area diameter

Question 14

Range of analysis of Sieving Method

Answer 14

50um to 1500um

Question 15

Advantages of Sieving Method

Answer 15

Specially useful for weight distribution
Inexpensive
Simple

Question 16

Disadvantages of Sieving Method

Answer 16

Sample should be dried every time
Induction of attrition during shaking -> reduction of particle size
Very small particles cannot be used

Question 17

Used for evaluation of suspension, emulsions, and determination of molecular weight of polymers

Answer 17

Sedimentation Method

Question 18

Sedimentation Rate is based on

Answer 18

Stoke’s Law

Question 19

Instrument used in Sedimentation Method

Answer 19

Andreasen Pipet/Apparatus

Question 20

Electrical resistance of a conducting liquid is increased by the addition of an insulating material

Answer 20

Coulter Counter

↑ Electrical Resistance
↑ Particle Vol ↑ Particle Size

Question 21

Single particle optical counter

Count particles rather than size

Answer 21

Light Blockage

↑Light Blockage ↑ Particle Size

↓Transmitted Light

Question 22

Measure of the void volume in a powder material

Answer 22

Porosity/Void Fraction

Question 23

Represents the fraction of the powder volume that is occupied by the voids

Answer 23

Porosity/Void Fraction

Question 24

Types of Porosity

Answer 24

Intraparticle
Interparticle

Question 25

Space within the particle

Answer 25

Intraparticle space or voids

Question 26

Space between the particle

Answer 26

Interparticle space/voids

Question 27

Types of Volume

Answer 27

1. True Volume/ Particle (Vp) 2. Granular Volume (Vg) 3. Bulk Volume (Vb)

Question 28

Volume of the solid particles **excluding** both **Intra** and **Inter** particulate voids

Answer 28

True Volume (Vp)

Question 29

True volume of the particle with Intraparticle space or voids

Answer 29

Granule Volume (Vg)

Question 30

True volume of the particle with both Intraparticle and Interparticle space or voids

Answer 30

Bulk volume (Vb)

Question 31

Intraparticle Porosity Formula

Answer 31

𝑉𝑔−𝑉𝑏 _________________×100 𝑉𝑔

Question 32

Interparticle Porosity

Answer 32

𝑉𝑏−𝑉𝑔 ______________ ×100% 𝑉𝑔

Question 33

Total particle

Question 33

Total particle Porosity

Answer 33

𝑉𝑏−𝑉𝑝 --------------- ×100% 𝑉𝑏

Question 34

Mass per unit volume

Answer 34

Density

Question 35

Density determined using Helium densiometer

Answer 35

True Density (p) p = m/v

Question 36

Density determine using Liquid Displacement

Answer 36

Granule density (pg) p = m / Vg

Question 37

Density determined using Graduated Cylinder

Answer 37

Bulk Density (pb) p = m / Vb

Question 38

Reciprocal of Density

Answer 38

Specific Volume

Question 39

Reciprocal of Bulk Density

Answer 39

Bulkiness or Specific Bulk Volume ↑Bulkiness ↓Particle Size

Question 40

Characteristics of Powder with Good Flowability

Answer 40

Inc. Particle Size Smooth Surface High Density Low internal porosity Low Electrostatic Charge Spherical Shape Low temperature

Question 41

Characterization of Powder Flow

Answer 41

Angle of Repose Compressibility Index

Question 42

Maximum angle possible between the surface of a pile powder and horizontal plane

Answer 42

Angle of Repose

Question 43

Angle of Repose

Answer 43

tan𝜃= h/r

Question 44

Angle of repose and Flowability

Answer 44

Excellent <25 Good 25-30 Poor 30-40 Very Poor >40

Question 45

Angle of Repose and Flowability

Answer 45

Excellent 25 - 30 Good 31 - 35 Fair 36 - 40 Passable 41 -45 Poor 46 - 55 Very Poor 56 - 65 Very, very poor >66

Question 46

Ability to decrease in volume under pressure

Answer 46

Compressibility

Question 47

Carr's Compressibility index

Answer 47

𝑉𝑜−𝑉𝑓 ----------------𝑥 100 𝑉𝑜

Question 48

Hausner's Ratio

Answer 48

𝑉𝑜 ---- 𝑉𝑓 or Tapped Density ------------- Bulk Density