Authors:K Benešová, M Pekař, L Lapčík, and J Kučerík
thermal and thermooxidative behavior of sodium salt of hyaluronic acid (HA)
and its n-hexyl, n-decyl, n-tetradecyl
and n-hexadecyl ether derivatives having
an equal degree of substitution have been studied by means of differential
scanning calorimetry (DSC) and thermogravimetry (TG). Derivatives were prepared
by a substitution of H atom at the OH bound to the sixth C of N-acetyl-D-glucosamin of HA unit by n-hexyl, n-decyl, n-tetradecyl
and n-hexadecyl chains. Both thermal and
thermooxidative degradation of HA and derivatives resulted in multistep process.
The main interest of this work was focused on processes occurring in the course
of the first decomposition step. Experimental DSC data showed lower stability
of derivatives and, remarkably lower heat evolution in comparison with original
HA. On the other hand, TG measurement recorded lower mass loss for derivates
which indicated appearance of new types of crosslinking reactions. Oxidative
stability was evaluated by means of DSC that provided the induction period
and the protection factor determination. Derivates showed remarkably lower
stability in comparison with original HA; comparing each other, the highest
oxidation stability showed n-decyl and n-tetradecyl derivates.
Authors:Corina Duda-Seiman, T. Vlase, Gabriela Vlase, D. Duda-Seiman, P. Albu, and N. Doca
thermooxidativedegradation possess both practical and scientific significance. Also a possible interaction between the active substance and different excipients is relevant for the establishment of dosage forms.
The decomposition reaction of
Authors:P. Albu, C. Bolcu, Gabriela Vlase, N. Doca, and T. Vlase
-oxidation [ 1 – 3 ].
In a previous paper [ 4 ], it was proved the importance of an elaborated kinetic analysis of the thermooxidativedegradation for the selection of an appropriate stabilizer. Also, in a recent paper [ 5 ], a synergetic effect by using
Authors:Sigrid Lüftl, Bruno Balluch, Walter Smetana, and Sabine Seidler
flow rate of 90 mL min −1 .
The thermal and thermooxidativedegradation of polymeric materials is a complex process involving successive and/or parallel steps. Nevertheless the kinetic analysis of non-isothermal thermogravimetric data is
Authors:Zuzana Cibulková, Andrea Černá, Peter Šimon, Ján Uhlár, Karol Kosár, and Peter Lehocký
has been tested in diene elastomers [ 4 ]. In our previous papers, the effect of p -phenylenediamines in preventing thermooxidativedegradation of polyisoprene rubber [ 5 , 6 ] has been investigated by non-isothermal DSC measurements. DSC