(473d) Capillary Imbibition Techniques Used to Characterize the Structural Changes in Microcrystalline Cellulose Due to Wet and Dry Processes
AIChE Annual Meeting
2023
2023 AIChE Annual Meeting
Particle Technology Forum
Powder and Particulate Characterization and Measurement
Monday, November 6, 2023 - 4:24pm to 4:42pm
Microcrystalline cellulose (MCC) is a common excipient used in the pharmaceutical industry.
It has been reported that wetting and subsequent drying decreases its binding ability
during tabletting as well as its swelling (and contribution to disintegration) due to irreversible
hydrogen bonding, otherwise known as ‘hornification’. Hornification of MCC could result
from intermediate manufacturing processes such as wet granulation and it is therefore important
to understand its effect on the physical properties of the powder and its producs,
e. g. pharmaceutical tablets. Here, we consider how wetting and drying cycles changes the
wettability properties of microcrystalline cellulose (MCC-Avicel 101). In order to characterize
wettability, we perform the following experiments: (i) drop penetration in a slightly
compressed power bed, (ii) capillary imbibition in a packed powder column, and (iii) drop
penetration into tablets. We consider three cases for the MCC powder, the original dry
powder as well as the powder obtained after one or two cycles of wetting and drying. In
each case, the powder is sieved and separated into two samples, depending on particle size,
25 < ϕ < 75 μm and B) 75 < ϕ < 125 μm.
The drop penetration experiments are performed with both water and a silicon oil
(Polydimethylsiloxane-PDMS) drops, and an effective contact angle between water and MCC
is obtained from the comparison assuming the silicon oil perfectly wets the powder. The penetration
of water is a combined effect between capillary penetration and swelling, and the
effective contact angle is a result of these effects. We investigate the effect of hornification
due to wetting and drying cycles on this effective contact angle. The column imbibition experiments
are also performed using water and PDMS and we mesure the liquid mass uptake
as function of time to obtain the effective contact angle from the comparison. Finally, we
study the penetration times of water drops deposited on tablets made at 8 kN compression
force (for one of the particle size range 25 < ϕ < 125 μm). The penetration of water in
tablets obtained by direct compression of MCC show the (undesired) effect of hornification,
in that penetration time increases.
We compare the effective contact angle between water and MCC obtained with the three
different characterization methods for the original MCC as well as MCC after one and two
wetting and drying cycles. We present the effect of hornification for both powder samples
consisting of larger and smaller powder particles and the correlation between the different
methods. Finally, we discuss the possibility to determine relevant effective contact angles
and their transferability in different processes for powder materials that swell.
It has been reported that wetting and subsequent drying decreases its binding ability
during tabletting as well as its swelling (and contribution to disintegration) due to irreversible
hydrogen bonding, otherwise known as ‘hornification’. Hornification of MCC could result
from intermediate manufacturing processes such as wet granulation and it is therefore important
to understand its effect on the physical properties of the powder and its producs,
e. g. pharmaceutical tablets. Here, we consider how wetting and drying cycles changes the
wettability properties of microcrystalline cellulose (MCC-Avicel 101). In order to characterize
wettability, we perform the following experiments: (i) drop penetration in a slightly
compressed power bed, (ii) capillary imbibition in a packed powder column, and (iii) drop
penetration into tablets. We consider three cases for the MCC powder, the original dry
powder as well as the powder obtained after one or two cycles of wetting and drying. In
each case, the powder is sieved and separated into two samples, depending on particle size,
25 < ϕ < 75 μm and B) 75 < ϕ < 125 μm.
The drop penetration experiments are performed with both water and a silicon oil
(Polydimethylsiloxane-PDMS) drops, and an effective contact angle between water and MCC
is obtained from the comparison assuming the silicon oil perfectly wets the powder. The penetration
of water is a combined effect between capillary penetration and swelling, and the
effective contact angle is a result of these effects. We investigate the effect of hornification
due to wetting and drying cycles on this effective contact angle. The column imbibition experiments
are also performed using water and PDMS and we mesure the liquid mass uptake
as function of time to obtain the effective contact angle from the comparison. Finally, we
study the penetration times of water drops deposited on tablets made at 8 kN compression
force (for one of the particle size range 25 < ϕ < 125 μm). The penetration of water in
tablets obtained by direct compression of MCC show the (undesired) effect of hornification,
in that penetration time increases.
We compare the effective contact angle between water and MCC obtained with the three
different characterization methods for the original MCC as well as MCC after one and two
wetting and drying cycles. We present the effect of hornification for both powder samples
consisting of larger and smaller powder particles and the correlation between the different
methods. Finally, we discuss the possibility to determine relevant effective contact angles
and their transferability in different processes for powder materials that swell.