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S1 Pharmaceutics > Compaction > Flashcards

Compaction Flashcards

1
Q

What is compression ?

A
  • particles forced into close proximity, reducing powder porosity and volume
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2
Q

What is compaction ?

A
  • Particles cohere to form a solid specimen (compact/tablet) of defined geometry
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3
Q

What does compaction require ?

A
  • requires compression
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4
Q

What is the relationship between powder blend compression and tablet hardness?

A
  • a well-compressed blend results in a stronger tablet with better integrity
  • influences its bioavailability by ensuring proper dissolution and absorption in the body.
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5
Q

What are the 4 phases of the tablet compression cycle?

A
  1. Filling
  2. Packing and initial compression(precompression)
  3. Main compression
  4. Decompression and ejection (final tablet)
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6
Q

How does compaction affect the mechanical strength of a powder bed?

A
  • during compaction, as particles move closer together during volume reduction, bonds are established between them
  • these particle-particle interactions increase the mechanical strength of the powder bed, contributing to a stronger tablet.
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7
Q

What happens to porosity, bulk volume, and bulk density during particle rearrangement?

A
  • Porosity and bulk volume decrease
  • while bulk density increases.
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8
Q

What is the result of particle deformation during compression?

A
  • the contact surface area and cohesion increase
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9
Q

What are the two possible outcomes after the compressive force is removed?

A
  • Elastic recovery (low cohesion, no compaction) and - plastic deformation (high cohesion, compaction)
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10
Q

What happens to particles under low compaction pressure?

A
  • Particles are rearranged to form a closely packed structure.
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11
Q

How do smaller particles affect the packing arrangement in a powder?

A
  • smaller particles fill the voids between larger particles, resulting in a closer packing arrangement
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12
Q

What happens when the compression force increases?

A
  • energy is evolved in the form of heat due to interparticulate friction
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13
Q

How does an increase in particle surface area affect interparticulate bonds?

A
  • It increases the possibility of forming interparticulate bonds.
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14
Q

What powder characteristics affect the formation of inter- or intraparticulate bonds?

A
  • Particle size, particle size distribution, density, surface properties, and interparticulate voids.
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15
Q

What does the extent of volume reduction in a powder bed depend on ?

A
  • the mechanical properties of the powder.
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16
Q

What happens when brittle materials undergo volume reduction?

A
  • they fragment extensively, resulting in tablets with high porosity due to many bonding points that prevent further volume reduction.
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17
Q

How do ductile materials behave during volume reduction?

A
  • form tablets with low porosity because plastic deformation allows particles to move very close to each other
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18
Q

How do different crystal morphologies affect packing structure?

A
  • Different crystal morphologies, such as spherical, cubical, and acicular, have different tendencies to pack into a close structure
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19
Q

What happens when compression force is applied to a powder bed?

A
  • causes the development of stress, leading to local deformation of the particles
20
Q

What is elastic deformation?

A
  • elastic deformation occurs when the material regains its original state after the stress is removed.
21
Q

What is elastic deformation?

A
  • elastic deformation occurs when the material regains its original state after the stress is removed
  • resume original shape instantaneously
22
Q

What is plastic deformation?

A
  • happens when the material loses its original state and does not return to it after the stress is removed
  • results are permanent
23
Q

What factors influence the type of deformation a material undergoes?

A
  • depends on the material’s physical properties, as well as the rate, magnitude, and duration of the applied force and induced stress.
24
Q

What is compression pressure?

A
  • an external force applied inward on the solid surface of an object
  • deforming it either permanently or temporarily, depending on the material and force magnitude.
25
Q

What does the magnitude of compression force determine?

A
  • it determines whether a compact (tablet) forms
  • well as the tablet’s volume, porosity, density
  • tablet tensile strength.
26
Q

What does the Heckel equation describe in relation to pharmaceutical powders?

A
  • describes the compaction properties of pharmaceutical powders, relating porosity and compression pressure.
27
Q

What is the Heckel equation ?

A
  • look online
28
Q

What does a typical Heckel plot represent?

A
  • a typical Heckel plot represents three different powder compression regions during tablet formation.
29
Q

What happens in Region I of a Heckel plot?

A
  • the curvature is due to particle rearrangement and fragmentation.
30
Q

What occurs in Region II of a Heckel plot?

A
  • In Region II, particle deformation, either plastic or elastic, controls the mechanism of powder compression
31
Q

What is observed in Region III of a Heckel plot?

A
  • elastic deformation of the compact controls the powder compression process.
32
Q

How does plasticity affect particle deformation?

A
  • plasticity increases the contact area between particles
  • plastic deformation prevents elastic recovery.
33
Q

How does plasticity affect particle deformation?

A
  • plasticity increases the contact area between particles
  • plastic deformation prevents elastic recovery.
34
Q

How does crystallinity affect compactability?

A
  • amorphous particles are more compactable than crystalline particles
35
Q

How does particle morphology influence compactability?

A
  • Needle-like particles are less compactable than equidimensional particles.
36
Q

How do hydrates compare to anhydrous particles in terms of compactability?

A
  • Hydrates are more compactable than anhydrous particles because the water of hydration can act as a plasticizer.
37
Q

What happens in Region 1 of tensile strength during compression?

A
  • compression occurs, but no compact (tablet) is formed.
38
Q

What occurs in Region 2 in terms of tablet tensile strength?

A
  • a higher compression pressure results in a greater tablet tensile strength
39
Q

What is observed in Region 3 regarding tensile strength?

A
  • the maximum tensile strength is achieved.
40
Q

What is tensile strength in tablets the result of?

A
  • the result of inter-particle bonding within the tablet.
41
Q

How is tensile strength typically determined?

A
  • determined using a diametric compression test.
42
Q

What does greater tablet tensile strength indicate?

A
  • greater the tablet tensile strength, the more resistant the tablet is to crushing.
43
Q

What assumption is made when measuring tensile strength?

A
  • It assumes simple tensile failure
44
Q

What is the tensile strength equation

A
  • σt = 2F/ pi x d x h
    Tensile strength of tablets depends on:
  • F Tablet fracture force or crushing strength (in
    Newtons)
  • d Tablet diameter
  • h Tablet thickness
45
Q

How does the shape of a tablet affect its tensile strength?

A
  • Tablets with extreme shapes
  • such as flat faces or deep convex shapes, are inherently weaker and have lower tensile strength.
46
Q

Reasons for capping and lamination

A
  • Too dry granules
  • High speed compression
  • Rapid decompression
  • Air entrapment

S1 Pharmaceutics (11 decks)

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