compression and consolidation

compression and consolidation

1. COMPRESSION AND CONSOLIDATION by Namile.Shyam Prasad M.pharm(pharmaceutics)

2. CONTENTS INTRODUCTION FUNDAMENTALS OF POWDER COMPRESSION METHODS COMPRESSION MACHINES CONCLUSION REFERENCES DERIVED PARA METERS

3. COMPRESSION the reduction in the bulk volume of a material as a result of the removal of the gaseous phase (air) by applied pressure CONSOLIDATION Involves an increase in the mechanical strength of a material resulting from particle-particle interactions. COMPACTION The compression and consolidation of a 2 phase (solid + gas) system due to an applied force.

4. FUNDAMENTALS OF POWDER COMPRESSION Attractive forces exist between particles vander Waal’s, H-bonding, Electrostatic consider a number of granules in a die to which a force is applied

5. DERIVED PARAMATERS solid-air interface, angle of repose, mass volume relationship, volume density, compressibilty

6. Solid-air interface Cohesion is the attraction between like particle; Experienced by particles in bulk. Adhesion is the attraction between unlike particle; Experienced by particles at surface.

7. Angle of repose The maximum angle possible between the surface of pile of non-cohesive (free-flowing) material and the horizontal plane. Angle of repose is an indication of the flow ability of the material.

8. Angle of Repose (θ) θ = tan -1 (h/r) where h = height of pile r = radius of the base of the pile Excellent flow ability if θ < 25 o Good flowability if 25 o < θ < 30 o Passable flowability if 30 o < θ < 40 o Very poor flowability if θ > 40 o h r

9. True volume (V T ) Granule volume (V G ) Bulk volume (V B ) Relative volume (V R ) V R = V B / V T V R tends to become unity as all air is eliminated from the mass during the compression process. VOLUME Open intraparticulate voids-those with in a single particle but open to the external environment. closed interparticulate voids-those within a single particle but closed to the external environment. Interparticulate voids-the air spaces between individual particles. Mass-Volume relationships

10. True density ( ρ T = M / V T ) Granule density ( ρ G = M / V G ) Bulk density ( ρ B = M / V B ) Relative density ( ρ R = M / V R ) Types of Density: M is the mass of powder DENSITY : The ratio of mass to volume is known as the density of the material

11. Carr’s (Compressibility) Index = [(V B – V Tap ) / V B ] x 100 ≈ E where V B = Freely settled volume of a given mass of powder V Tap = Tapped volume of the same mass of powder ≈ V T Measuring Compressibility: Carr’s (Compressibility) Index = [( ρ Tap – ρ B ) / ρ Tap ] x 100 ≈ E where ρ B = Freely settled bulk density of the powder ρ Tap = Tapped bulk density of the powder ≈ ρ T Compressibility: The ability of the powder bed to be compressed (under pressure) and consequently be reduced in volume.

12. Measuring Compressibility Excellent flowability if 5 < Carr’s Index < 15 good flowability if 12 < Carr’s Index < 16 Passable flowability if 18 < Carr’s Index < 21 poor flowability if 23 < Carr’s Index < 35 Very poor flowability if 33 < Carr’s Index < 38 Very very poor flowability if Carr’s Index > 40

13. METHODS Direct Compression

14. Dry Granulation

15. Wet Granulation

16. COMPRESSION MACHINES Hopper for holding and feeding granulation to be compressed Dies that define the size and shape of the tablet Punches for compressing the granulation within the dies Cam tracks for guiding the movement of the punches Feeding mechanisms for moving granulation from the hopper into the dies Components of compression machines

17. Single Punch Machine

18. Multistation tablet press

19. CONCLUSION

20. Adolfsson , Å., Caramella , C., Nyström , C., 1998. The effect of milling and addition of dry binder on the interparticulate bonding mechanisms in sodium chloride tablets. Int.J . Pharm. 160, 187-195. Adolfsson , Å., Gustafsson , C., Nyström , C., 1999. Use of tablet tensile strength adjusted for surface area and mean interparticulate distance to evaluate dominating bonding mechanisms. Drug Dev. Ind. Pharm. 25, 753-764. Adolfsson , Å., Nyström , C., 1996. Tablet strength, porosity, elasticity and solid state structure of tablets compressed at high loads. Int. J. Pharm. 132, 95-106. Reference

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