ISSN:
1573-904X
Schlagwort(e):
dynamic differential scanning calorimetry
;
thermogravimetric analysis
;
methyl methacrylate
;
surface area
;
graft copolymers
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract Purpose. The purpose of this study was to determine the glass transition temperatures of new graft copolymers using Modulated Temperature Differential Scanning Calorimetry (MTDSC), and to assess the differences between starch and cellulosic derivatives of methyl methacrylate and between two different drying methods used in their preparation. Methods. Graft copolymers of methyl methacrylate were synthesized and dried by oven or freeze-drying. Surface area measurements and different thermal analysis techniques (Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and MTDSC) were used to characterize these copolymers. Results. DSC was not sensitive enough to identify the Tgs of the copolymers, however they were clearly identifiable by MTDSC. Tg values obtained may depend on the method of preparation that also altered their physical characteristics e.g. specific surface area. Cellulose derivatives showed lower Tgs than starch derivatives. The results also depended on the drying method used, thus, freeze dried products had slightly lower Tgs than oven dried products. Conclusions. MTDSC represents a useful thermal technique that allows the identification of glass transitions in these new copolymers with higher sensitivity and resolution than conventional DSC, separating the transition from overlapping phenomena such as decomposition or dehydration. The Tg of this new class of copolymers appeared to be dependent on polymer composition and drying method used.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1018971630036
