Determination of natural rubber/poly(methyl methacrylate) blend composition by TG/DSC technique

Natural rubber/Poly(methyl methacrylate) or NR/PMMA blends were prepared by polymerization of the methyl methacrylate monomer and natural rubber latex. Their PMMA content before and after Soxhlet extraction was determined by H-1-NMR spectrometry. In this work, the thermal properties of the same NR/PMMA blends were determined using simultaneous thermogravimetry/differential scanning calorimetry (TG/DSC). The composition of the samples was determined on the basis of the derivative thermogravimetric (DTG) data. As the decomposition of the samples took place by simultaneous processes, by varying the heating rates the shape of the DTG curves was optimized for the deconvolution into two individual peaks of the two-component polymer system. Assuming the compensation of the errors, from the deconvoluted curves the amounts of the components in the blends were calculated. TG/MS data showed that the deconvolution was justified as the first part of the DTG curve could be related mainly to the decomposition of NR, while at higher temperatures, the decomposition of PMMA took place. The thermogravimetric method of composition determination of the polymer is simple and rapid, and in addition, is cheap compared with the costs of other instrumental techniques. The results were acceptable when compared with the corresponding data of H-1-NMR studies, too.