SWELLING is associated with
an increase in size or volume of a product.
Swelling applications include
tablets, gels, films, pellets, mucosal tissues, super-absorbent
polymers, sponges, aquaculture feed, chemical and yeast leavened
products, etc. Depending on application, swelling can be quantified
by measuring changes in force or distance by either (i) compressing a
product a slight distance and then measuring how force increases as
the product swells, or (ii) applying and maintaining a small force
onto the product and measuring the distance change as swelling occurs.
The Texture Analyser can be used
to monitor the change in height of a product from its original height
over a period of swelling or volume/height increase. By tracking the
distance required to move to maintain a chosen force the rate of
decay can be plotted and calculated to the end point or period of no
If the product is likely to expand
horizontally, then it should be constrained to focus the swelling
forces and expansion vertically.
Common questions for swelling
applications include: When did the product achieve a certain
percentage swelling (10%, 50% or 90%)? How fast does it swell or
disintegrate? When did swelling activity end, slow down or diminish?
What would happen if more catalyst was introduced at certain times?
Among the measurements which can be obtained are: the initial rate of
swelling; maximum amount of swelling and length of time to occur and
the swelling rate as the product was saturated.