This document summarizes the physics of tablet compression. It discusses the differences between compression and consolidation, properties that affect powder compaction like density and angle of repose, the compression cycle and events like rearrangement, deformation, fragmentation and bonding. It also outlines the forces involved in compression like frictional and radial forces. Compaction profiles and equations for studying compression are mentioned. The document provides an overview of the key concepts and processes in tablet compression.
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Physics of tablet compression
1. PHYSICS OF TABLET COMPRESSION
Presented By
Mr. Shubham Radhesham Biyani
M. Pharmacy (pharmaceutics)
Guided By
Prof. Mr. Chate sir
SCHOOL OF PHARMACY S R T M UNIVERSITY NANDED
430616
2. CONTENTS
I. Introduction
II. Difference between compression consolidation
III. Properties of powder/granule
IV. Compression cycle / process of compression
V. Forces involved in compression
VI. Compaction profile
VII. Equation for compression study
VIII. references
3. INTRODUCTION
? It is also known as ¡® physics of compaction¡¯ .
? It may be stated as compression- consolidation of two
phases (solid - gas) .
? compression:-
? It is the reduction in bulk volume of material due to
displacement of gaseous phase .
? Consolidation :-
? It is increase in mechanical strength of material due particle
¨C particle interaction .
4. DIFFERENCE BETWEEN COMPRESSION
CONSOLIDATION
compaction consolidation
1. It is defines as the formation of solid
specimen of defined geometry by
powder compression.
1 It is increase in mechanical strength of
material from particle ¨C particle
interaction .
2. The compression takes place in a die
by the action of two punches , the lower
and upper by which compression force is
applied .
5. PROPERTIES OF POWDER/GRANULE
? While studying physics of compression considering
following ¡®s factor :¨C
1. Angle of repose
2. Bulk density
3. Tapped density
4. Hausner ratio
5. carr¡¯s index or percentage compressibility
etc of material¡.
6. COMPRESSION CYCLE / PROCESS OF
COMPRESSION
In pharmaceutical tableting , an appropriate volume of
granules in die cavity is compressed between an upper &
lower punch to consolidate the material into a single solid
matrix , which is finally ejected from die cavity as a tablet ¡.
7. EVENTS IN PROCESS OF COMPRESSION
1. transitional repacking or particle rearrangement
2. Deformation at point of contact
3. Fragmentation
4. Bonding
5. Decompression
6. Ejection
8. TRANSITIONAL REPACKING OR PARTICLE
REARRANGEMENT
? Particle size distribution determines initial repacking..
? During initial stage of compression , particle subjected to low pressure , during
this particle moves with respect to each other & smaller particle enters in voids
between larger particle..
? As result volume decreases & density increases spherical particle undergoes
lesser rearrangement than irregular particle¡
9. DEFORMATION AT POINT OF CONTACT
? When a force is applied on a material deformation occur .
? If the deformation disappear completely (return to original
shape) upon release of stress , it is said to be ¡® elastic
deformation¡¯
? A deformation that not recover completely after removal of
stress known as ¡®plastic deformation¡¯.
? The force required initial plastic deformation is known as
¡®yield stress¡¯
? When granule particle so closely no further filling voids
occurs ,hence further increase of compression force cause
deformation at point of contact ¡
10. FRAGMENTATION
? Compression forces increases particle starts
fragmentation because of high load , particle
breaks into smaller fragment leading to formation of
new bonding area.
? Fragmentation undergoes densification & infiltration
of small fragments into voids .
11. BONDING
cold welding :-
When particle approach each other unsatisfied forces present on their
surface leads formation of strong attractive forces called ¡®cold
welding¡¯..
Fusion bonding:-
Particle irregular in shape heat transmission leads increase
mechanical strength .
Factor affecting bonding:-
i. Chemical nature of material
ii. Available surface
iii. Presence of surface contaminant
12. DECOMPRESSION
? The success or failure of intact tablet depends on stress induced by
¡®elastic rebounds¡¯ & the association deformation produced during
decompression & ejection .
Capping is due to unaxial relaxation in die cavity ..
Ejectio
nAs the lower punch rises & pushed tablet upward , there is continues
residual die wall pressure & energy may be expanded due to die wall
friction.
13. FORCES INVOLVED IN COMPRESSION
A. Frictional forces
B. Distribution forces
C. Radial forces
D. Ejection forces
16. REFERENCES
? Aulton, M. E. (2007). Alton's pharmaceutics:
The design and manufacture of medicines.
Edinburgh: Churchill Livingstone.
? Pharmaceutical dosage forms: Tablets. Vol. I.
Edited by HH Lieberman ...