TY - JOUR
T1 - Phase separation in amorphous hydrophobically modified starch–sucrose blends
T2 - Glass transition, matrix dynamics and phase behavior
AU - Hughes, David J.
AU - Bönisch, Gabriela Badolato
AU - Zwick, Thomas
AU - Schäfer, Christian
AU - Tedeschi, Concetta
AU - Leuenberger, Bruno
AU - Martini, Francesca
AU - Mencarini, Giacomo
AU - Geppi, Marco
AU - Alam, M. Ashraf
AU - Ubbink, Job
PY - 2018/11/1
Y1 - 2018/11/1
N2 - The phase behavior and matrix dynamics of amorphous blends of octenyl succinic anhydride (OSA) modified starch and sucrose was studied as function of blend composition and water content. Phase separation into two amorphous phases, one enriched in OSA starch and the other in sucrose, was confirmed by differential scanning calorimetry (DSC). DSC and 1H solid-state NMR show that the phase separation is only partial. The glass transition temperature (Tg) of the OSA starch-rich phase was found to be ∼30–100 K higher than the Tg of the sucrose-rich phase, depending on blend composition and water content. A novel type of coupling between changes in physical state of the sucrose-rich phase and plasticizer redistribution is proposed, leading to an unexpected increase of the glass transition temperature of the modified starch-rich phase at higher matrix water contents. A quantitative model for the phase separation of the anhydrous blends into two amorphous phases is presented. The model predicts that, with increasing blend sucrose content, the weight fraction of the sucrose-rich phase decreases, while the sucrose content of both the OSA starch-rich phase and the sucrose-rich phase increases. This novel phenomenon is relevant in the understanding of the stability and performance of multiphase food and pharmaceutical components.
AB - The phase behavior and matrix dynamics of amorphous blends of octenyl succinic anhydride (OSA) modified starch and sucrose was studied as function of blend composition and water content. Phase separation into two amorphous phases, one enriched in OSA starch and the other in sucrose, was confirmed by differential scanning calorimetry (DSC). DSC and 1H solid-state NMR show that the phase separation is only partial. The glass transition temperature (Tg) of the OSA starch-rich phase was found to be ∼30–100 K higher than the Tg of the sucrose-rich phase, depending on blend composition and water content. A novel type of coupling between changes in physical state of the sucrose-rich phase and plasticizer redistribution is proposed, leading to an unexpected increase of the glass transition temperature of the modified starch-rich phase at higher matrix water contents. A quantitative model for the phase separation of the anhydrous blends into two amorphous phases is presented. The model predicts that, with increasing blend sucrose content, the weight fraction of the sucrose-rich phase decreases, while the sucrose content of both the OSA starch-rich phase and the sucrose-rich phase increases. This novel phenomenon is relevant in the understanding of the stability and performance of multiphase food and pharmaceutical components.
KW - Amorphous phase separation
KW - Differential scanning calorimetry
KW - Glass transition
KW - OSA starch
KW - Solid-state NMR
KW - Sucrose
UR - http://www.scopus.com/inward/record.url?scp=85049843484&partnerID=8YFLogxK
U2 - 10.1016/j.carbpol.2018.06.056
DO - 10.1016/j.carbpol.2018.06.056
M3 - Article (Academic Journal)
C2 - 30143108
AN - SCOPUS:85049843484
SN - 0144-8617
VL - 199
SP - 1
EP - 10
JO - Carbohydrate Polymers
JF - Carbohydrate Polymers
ER -