Conţinutul numărului revistei |
Articolul precedent |
Articolul urmator |
1040 5 |
Ultima descărcare din IBN: 2024-04-16 16:55 |
SM ISO690:2012 DRANCĂ, Ion, LUPASCU, F. Implications of global and local mobility in amorphous excipients as determined by DSC and TM DSC
. In: Chemistry Journal of Moldova, 2009, nr. 2(4), pp. 105-115. ISSN 1857-1727. |
EXPORT metadate: Google Scholar Crossref CERIF DataCite Dublin Core |
Chemistry Journal of Moldova | ||||||
Numărul 2(4) / 2009 / ISSN 1857-1727 /ISSNe 2345-1688 | ||||||
|
||||||
Pag. 105-115 | ||||||
|
||||||
Descarcă PDF | ||||||
Rezumat | ||||||
The paper explores the use of differential scanning calorimetry (DSC) and temperature modulated differential scanning calorimetry (TM DSC) to study α- and β- processes in amorphous sucrose and trehalose. Amorphous sucrose was prepared by lyophilization while amorphous trehalose was prepared by dehydration of trehalose dihydrate. The variation in the effective activation energy of α-relaxation through glass transition has been determined by applying an isoconversional method. β-relaxations were studied by annealing glassy samples
at different temperatures and subsequently heating at different rates in a differential scanning calorimeter. The effect of heating rate on the β-relaxation peak temperature formed the basis for the calculation of the activation energy. The higher density of glassy trehalose resulted in larger activation energy of α-relaxation compared to sucrose. The effect of temperature on viscous flow was greater in trehalose which can have implications on lyophile collapse. The size of the cooperatively rearranging regions was about the same for sucrose and trehalose
suggesting similar dynamic heterogeneity at their respective glass transition temperatures. The activation energy of β-relaxations increased with annealing temperature due to increasing cooperative motions and the increase was larger in sucrose. The temperature at which β-relaxation was detected for a given annealing time was much less in sucrose implying that progression of local motions to cooperative motions occurred at lower temperatures in sucrose.
|
||||||
Cuvinte-cheie molecular mobility; excipients (sucrose & trehalose); α- and β-relaxations; activation energy; DSC & TM DSC |
||||||
|