6533b827fe1ef96bd1286f13
RESEARCH PRODUCT
Characterization of a sucrose/starch matrix through positron annihilation lifetime spectroscopy: unravelling the decomposition and glass transition processes
Gilles DuplâtreIsabelle FabingS. K. SharmaGaëlle Roudautsubject
SucroseTime FactorsCondensed matter physicsStarchSpectrum AnalysisTransition temperatureAnalytical chemistryGeneral Physics and AstronomyElectronsStarchDecompositionPhase TransitionPositroniumchemistry.chemical_compoundchemistryThermogravimetryVolume fractionTransition TemperatureGlassPhysical and Theoretical ChemistryTriplet stateGlass transitionSpectroscopydescription
The triplet state of positronium, o-Ps, is used as a probe to characterize a starch-20% w/w sucrose matrix as a function of temperature (T). A two-step decomposition (of sucrose, and then starch) starts at 440 K as shown by a decrease in the o-Ps intensity (I(3)) and lifetime (τ(3)), the latter also disclosing the occurrence of a glass transition. Upon sucrose decomposition, the matrix acquires properties (reduced size and density of nanoholes) that are different from those of pure starch. A model is successfully established, describing the variations of both I(3) and τ(3) with T and yields a glass transition temperature, T(g) = (446 ± 2) K, in spite of the concomitant sucrose decomposition. Unexpectedly, the starch volume fraction (as probed through thermal gravimetry) decreases with T at a higher rate than the free volume fraction (as probed through PALS).
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2010-10-01 | Physical Chemistry Chemical Physics |