Lecture 5 - mechanism of compaction on pharmaceutical powders Flashcards
what is compression
reduction in bulk volume by eliminating voids and bringing particles closer in contact
what is compressibility
ability of a powder to reduce in volume size under pressure
due to displacement of gaseous phase
what is consolidation
increased mechanical strength due to inter particulars contact
why are elastic materials difficult to compress
they can cap or laminate
also can return back to normal size when compressing
what do plastic materials undergo
and what are they sensitive to
permanent deformation
machine speed and lubrication
why are fragmenting materials good
they have low sensitivity to additives, they are strain rate insensitive and have no effect on particle shape
why are fragment (brittle) materials bad
they give high friability values and they end to chip easily
what combination of materials is beneficial and attractive
plastic and brittle
examples of elastic materials
paracetamol
ibuprofen
examples of plastic materials
avicel
starch
NaCl
Fragmentation examples
calcium phosphate and lactose
what are the methods of assessing plasto-elasticity of pharmaceutical powders
Scanning electron microscopy (SEM)
Percentage Elastic Recovery of the compressed tablets
Energy analysis
Force – volume relationships: Heckel analysis
Strain Rate Sensitivity (SRS)
Stress relaxation
Tablet crushing strength
Tensile strength
Specific surface area of powder after compression
