Snežana Sinadinović-Fišer

Epoxidation of soybean oil in toluene with peroxoacetic and peroxoformic acids - kinetics and side reactions

The kinetics of the epoxidation of soybean oil and the extent of side reactions were studied at 40, 60, and 80 °C. Epoxidation was carried out in toluene with “in situ” formed peroxoacetic and peroxoformic acid and in the presence of an ion exchange resin as the catalyst. The reaction was found to be first-order with respect to the double bond concentration. At higher temperatures and at higher conversions a deviation from the first-order kinetics was observed. The rate constants for the epoxidation with peroxoacetic acid were 0.118 (h−1) at 40 °C, 0.451 (h−1) at 60 °C and 1.278 (h−1) at 80 °C, while those for peroxoformic acid were 0.264, 0.734, and 1.250 (h−1). The activation energy was found to be 54.7 kJ/mol for the epoxidation with peroxoacetic acid and 35.9 kJ/mol for that with peroxoformic acid. Three factors indicated that side reactions did not occur on a large scale: The absence of an OH band in the IR spectra, the formation of less than 2% of higher molecular weight products from gel permeation chromatography and the selectivity values between 0.9 and 1.

The Phase Structure of Novel Polycarbonate-Based Polyurethane-Organoclay Nanocomposites

Polycarbonate-based polyurethane nanocomposites were prepared using one step procedure by addition of either organically modified bentonite or montmorillonite (1 wt. %). All aliphatic components (polycarbonate diol, hexamethylene-diisocyanate and 1,4-butane diol) were used as reactants. The hard segment content of obtained thermoplastic polyurethanes was 30 wt. %. Scanning electron microscopy (SEM) was performed to investigate the morphology of obtained hybrid materials. The structure of synthesized elastomers was studied by Fourier transform infrared spectroscopy (FTIR). In order to obtain the degree of phase separation and investigate the hydrogen bonding constitution, deconvolution of –NH and –C=O IR regions was done, using Gaussian equations. It was determined that the degree of phase separation is not influenced by addition of organoclays, indicating uniform dispersion of silicate layers in the polyurethanes, which was also confirmed by SEM experiments.