Abstract
The influence of pH on the mechanical relaxation of LM-pectin in the presence of co-solute has been investigated by means of differential scanning calorimetry, ζ-potential measurements and small deformation dynamic oscillation in shear. pH was found to affect the conformational properties of the polyelectrolyte altering its structural behavior. Cooling scans in the vicinity of the glass transition region revealed a remarkable change in the viscoelastic functions as the polyelectrolyte rearranges from extended (neutral pH) to compact conformations (acidic pH). This conformational rearrangement was experimentally observed to result in early vitrification at neutral pH values where dissociation of galacturonic acid residues takes place. Time-temperature superposition of the mechanical shift factors and theoretical modeling utilizing WLF kinetics confirmed the accelerated kinetics of glass transition in the extended pectin conformation at neutral pH. Determination of the relaxation spectra of the samples using spectral analysis of the master curves revealed that the relaxation of macromolecules occurs within ∼0.1 s regardless of the solvent pH.
| Original language | English |
|---|---|
| Pages (from-to) | 182-188 |
| Number of pages | 7 |
| Journal | Carbohydrate Polymers |
| Volume | 127 |
| Early online date | 30 Mar 2015 |
| DOIs | |
| Publication status | Published - 20 Aug 2015 |
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Influence of pH on mechanical relaxations in high solids LM-pectin preparations. / Alba, K.; Kasapis, S.; Kontogiorgos, V.
In: Carbohydrate Polymers, Vol. 127, 20.08.2015, p. 182-188.Research output: Contribution to journal › Article
TY - JOUR
T1 - Influence of pH on mechanical relaxations in high solids LM-pectin preparations
AU - Alba, K.
AU - Kasapis, S.
AU - Kontogiorgos, V.
PY - 2015/8/20
Y1 - 2015/8/20
N2 - The influence of pH on the mechanical relaxation of LM-pectin in the presence of co-solute has been investigated by means of differential scanning calorimetry, ζ-potential measurements and small deformation dynamic oscillation in shear. pH was found to affect the conformational properties of the polyelectrolyte altering its structural behavior. Cooling scans in the vicinity of the glass transition region revealed a remarkable change in the viscoelastic functions as the polyelectrolyte rearranges from extended (neutral pH) to compact conformations (acidic pH). This conformational rearrangement was experimentally observed to result in early vitrification at neutral pH values where dissociation of galacturonic acid residues takes place. Time-temperature superposition of the mechanical shift factors and theoretical modeling utilizing WLF kinetics confirmed the accelerated kinetics of glass transition in the extended pectin conformation at neutral pH. Determination of the relaxation spectra of the samples using spectral analysis of the master curves revealed that the relaxation of macromolecules occurs within ∼0.1 s regardless of the solvent pH.
AB - The influence of pH on the mechanical relaxation of LM-pectin in the presence of co-solute has been investigated by means of differential scanning calorimetry, ζ-potential measurements and small deformation dynamic oscillation in shear. pH was found to affect the conformational properties of the polyelectrolyte altering its structural behavior. Cooling scans in the vicinity of the glass transition region revealed a remarkable change in the viscoelastic functions as the polyelectrolyte rearranges from extended (neutral pH) to compact conformations (acidic pH). This conformational rearrangement was experimentally observed to result in early vitrification at neutral pH values where dissociation of galacturonic acid residues takes place. Time-temperature superposition of the mechanical shift factors and theoretical modeling utilizing WLF kinetics confirmed the accelerated kinetics of glass transition in the extended pectin conformation at neutral pH. Determination of the relaxation spectra of the samples using spectral analysis of the master curves revealed that the relaxation of macromolecules occurs within ∼0.1 s regardless of the solvent pH.
KW - DSC
KW - Glass transition
KW - Okra
KW - Pectin
KW - Relaxation
UR - http://www.scopus.com/inward/record.url?scp=84926450549&partnerID=8YFLogxK
U2 - 10.1016/j.carbpol.2015.03.051
DO - 10.1016/j.carbpol.2015.03.051
M3 - Article
VL - 127
SP - 182
EP - 188
JO - Carbohydrate Polymers
JF - Carbohydrate Polymers
SN - 0144-8617
ER -