Sritham, Eakasit
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Sritham, Eakasit
Alternative Name
Sritham, E.
Sritham, Earasit
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Email
eakasit.sr@kmitl.ac.th
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Item type:Publication, Enthalpy relaxation in sucrose-maltodextrin-sodium citrate bioglass(2017-10-01); Gunasekaran, SundaramGlass transition characteristics of sucrose (SC)-maltodextrin (MD)-sodium citrate (NaCit) bioglass system were investigated using differential scanning calorimetry. Samples were formulated with different SC:MD (7:3, 5:5 and 3:7 by mass) and NaCit/SC (0, 0.1 and 0.2 by mole) ratios, and were equilibrated to residual moisture contents of 0.27–0.35 %wb. Isothermal aging experiments were conducted with the degree of undercooling from 12 to 57 °C and aging times of 8, 20, 47 and 71 h. In general, the Kohlrausch-Williams-Watts (KWW) decay function fit well with the experimental enthalpy relaxation data. The enthalpy relaxation time (τ<sup>KWW</sup>) and the time required for 50% completion of theoretical possible maximum enthalpy relaxation at constant temperature (t<inf>ϕ(t)=0.5</inf>) increased with increasing MD content; lowering the aging temperature had similar effects on τ<sup>KWW</sup> and t<inf>ϕ(t)=0.5</inf>. In the system with high SC and NaCit concentrations (SC:MD = 7:3 and NaCit/SC = 0.2), a substantial increase in τ<sup>KWW</sup> and t<inf>ϕ(t)=0.5</inf> were observed when aging temperature <inf>decreased slightly;</inf> these systems also exhibited the greatest apparent activation energy. The findings reveal that NaCit can enhance the stability of low-moisture bioglass by primarily interacting with SC and form large less-mobile clusters, which helps to improve glass transition temperature and restrict the matrix mobility. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Insight into the property and behavior of saccharides in amorphous state(2016-01-01); Gunasekaran, S.This study was aimed at investigating the calorimetric property and the mechanical behavior of amorphous saccharide system. A mixture of sucrose and maltodextrin was chosen as a model system. The mixtures were formulated with three different sucrose/maltodextrin (SC/MD) ratios. It was found that the T<inf>g</inf> increased with increasing maltodextrin concentration. Within the range of moisture content less than 4%, the average values of mid-T<inf>g</inf> were 73, 80 and 105°C for the systems with SC/MD of 7/3, 5/5 and 3/7, respectively. A strong plasticization effect of water on T<inf>g</inf> was also observed. A difference in mechanical behavior for large- and small-molecular weight saccharides was revealed with the small strain oscillatory shear test. Maltodextrin (large-molecular weight saccharide) contributed to an elastic or solid-like characteristic, which suggests that the molecular motions are primarily involved in stretching and bending of glycosidic linkages. The large number of strong glycosidic linkages present in maltodextrin might be responsible for the high rigidity of the system. In contrast, sucrose (small-molecular weight saccharide) contributed to a viscous or liquid-like characteristic. The findings suggest that type and number density of glycosidic linkages significantly define the mechanical behavior of amorphous saccharide systems.