TY - JOUR
T1 - Mechanistic understanding regarding the functionality of microcrystalline cellulose and powdered cellulose as pelletization aids in wet-extrusion/spheronization
AU - Lenhart, Vincent
AU - Quodbach, Julian
AU - Kleinebudde, Peter
N1 - Publisher Copyright:
© 2019, Springer Nature B.V.
PY - 2020/3/1
Y1 - 2020/3/1
N2 - Abstract: Powdered cellulose (PC) and microcrystalline cellulose (MCC) show considerable different behavior during wet-extrusion and spheronization. While MCC is an appropriate pelletization aid, PC is not suitable. The differences were explained by either the “molecular-sponge” or the “crystallite-gel” hypothesis. To elucidate the differences in functionality, the effect of several polar solvents on liquid–solid interaction with PC and MCC was investigated. In addition, PC was homogenized via high pressure homogenization to reduce particle size without affecting the degree of polymerization. Mixer torque rheometry (MTR), laser diffraction and texture analysis were used to characterize the behavior of PC and MCC in wet pastes, suspensions and pellets. PC and MCC interacted differently with solvents like dimethyl sulfoxide, dimethylformamide and several glycols during MTR experiments. While PC mainly swells in appropriate solvents, MCC showed a particle size reduction, partly into colloidal dimensions. Solvents that induced liberation of colloidal fibers, also enabled a wet-extrusion/spheronization process. The quantity of colloidal cellulose only had minor effect on the resulting pellet quality. Also, the properties of the used solvent had only minor impact on the pellet size, shape and mechanical stability. PC contained small amounts of colloidal fibers after high pressure homogenization. With this pre-treated PC, wet-extrusion/spheronization process was also possible although the pellet quality is inferior to MCC pellets. Colloidal cellulose fibers have a major impact on the behavior of wet mass and on the feasibility for pellet production via wet-extrusion/spheronization. These insights provide new evidence for the “crystallite-gel” model. Graphic abstract: [Figure not available: see fulltext.].
AB - Abstract: Powdered cellulose (PC) and microcrystalline cellulose (MCC) show considerable different behavior during wet-extrusion and spheronization. While MCC is an appropriate pelletization aid, PC is not suitable. The differences were explained by either the “molecular-sponge” or the “crystallite-gel” hypothesis. To elucidate the differences in functionality, the effect of several polar solvents on liquid–solid interaction with PC and MCC was investigated. In addition, PC was homogenized via high pressure homogenization to reduce particle size without affecting the degree of polymerization. Mixer torque rheometry (MTR), laser diffraction and texture analysis were used to characterize the behavior of PC and MCC in wet pastes, suspensions and pellets. PC and MCC interacted differently with solvents like dimethyl sulfoxide, dimethylformamide and several glycols during MTR experiments. While PC mainly swells in appropriate solvents, MCC showed a particle size reduction, partly into colloidal dimensions. Solvents that induced liberation of colloidal fibers, also enabled a wet-extrusion/spheronization process. The quantity of colloidal cellulose only had minor effect on the resulting pellet quality. Also, the properties of the used solvent had only minor impact on the pellet size, shape and mechanical stability. PC contained small amounts of colloidal fibers after high pressure homogenization. With this pre-treated PC, wet-extrusion/spheronization process was also possible although the pellet quality is inferior to MCC pellets. Colloidal cellulose fibers have a major impact on the behavior of wet mass and on the feasibility for pellet production via wet-extrusion/spheronization. These insights provide new evidence for the “crystallite-gel” model. Graphic abstract: [Figure not available: see fulltext.].
KW - Crystallite-gel
KW - Microcrystalline cellulose
KW - Molecular sponge
KW - Pellets
KW - Powdered cellulose
KW - Wet-extrusion/spheronization
UR - http://www.scopus.com/inward/record.url?scp=85076624538&partnerID=8YFLogxK
U2 - 10.1007/s10570-019-02895-y
DO - 10.1007/s10570-019-02895-y
M3 - Article
AN - SCOPUS:85076624538
SN - 0969-0239
VL - 27
SP - 2189
EP - 2210
JO - Cellulose
JF - Cellulose
IS - 4
ER -