Application of model-free kinetics to the study of thermal degradation of polycarbonate

Summary

Thermal analysis of polystyrene (PS) particles synthesized in the presence of cetyltrimethylammonium bromide (CTAB) and carboxymethyl cellulose (CMC), with the degree of substitution 0.7 and average molecular mass (<Emphasis Type=”Italic”>MM</Emphasis>) of 90000 and 250000 g mol<Superscript>-1</Superscript> was carried out. PS chains grown in the presence of CMC having <Emphasis Type=”Italic”>MM</Emphasis> of 90000 g mol<Superscript>-1</Superscript> presented glass temperature (<Emphasis Type=”Italic”>T</Emphasis><Subscript>g</Subscript>) at 375 K, which is in agreement with the literature value. However, the PS chains grown in the presence of longer CMC chains (<Emphasis Type=”Italic”>MM</Emphasis> = 250000 g mol<Superscript>-1</Superscript>) presented <Emphasis Type=”Italic”>T</Emphasis><Subscript>g</Subscript> at 352 K. This 23 K decrease in the <Emphasis Type=”Italic”>T</Emphasis><Subscript>g</Subscript> value was caused by the increased polydispersity, which was confirmed by gel permeation chromatography. Thermogravimetry showed five mass loss steps between 298 and 873 K.