## 3 Results and Discussion
### Infrared Spectroscopic and Chemical Analysis
Another band situated at 1095 cm\({}^{-1}\) resulted from in-plane deformation of the C-C=O bond. A broad and flattened band in the range of 3200-3500 cm\({}^{-1}\) and another of medium intensity at 1017 cm\({}^{-1}\) indicated the presence of hydroxyl groups (which can arise as the result of keto-enol tautomerism or a side reaction of hemiacetal formation [41; 42; 43]). The most characteristic element of the limonene structure was its six-membered aliphatic ring. Its vibrations in pure limonene were observed as three medium-intensity bands in the range of 970-1060 cm\({}^{-1}\). Two (at 989 and 1015 cm\({}^{-1}\)) were visible in the spectrogram of L-DVB (Figure 3a). A significant reduction in intensity, or even the absence  
Figure 3: ATR-FTIR spectrograms of **(a)** C-DVB, L-DVB, and L-DVB and **(b)** Ao-DVB, Lo-DVB, and Ro-DVB. of bands caused by C=C at 1645 cm\({}^{-1}\) in cyclohexene ring and vinylidene moieties of limonene, indicates the considerable degree of conversion of these bonds during the polymerization process [44]. Limonene and pineine possess the same basic structural fragment; for this reason, the spectrum of P-DVB (Figure 3a) bands at 1016 and 990 cm\({}^{-1}\) was also present. However, the ratio of their intensities was completely different. In the case of P-DVB, the former was stronger, while the latter was hardly visible. The vibrations of the four-membered ring had their strongest band at 1445 cm\({}^{-1}\) but this wave number was also characteristic of aromatic ring stretching and methylene C-H scission vibrations. Carbon-carbon skeletal vibration of >C(CH3)2 group was observed at 1365-1385 and 1167 cm\({}^{-1}\); nevertheless, their intensities were weak. The occurrence of two medium intensity bands at 1083 and 1016 cm\({}^{-1}\) may also suggest the presence of oxygenated moieties on the polymer surface resulting from the side reaction of oxidation of double bonds [45; 46]. In the case of the oil-based materials (Figure 3b), besides the DVB characteristic bands, all the spectra also included those of ester moieties. They were observed as one separated band at 1744 cm\({}^{-1}\) caused by stretching of the C=O bond (in esters), and another band due to C-O stretching in the range of 1250-1006 cm\({}^{-1}\). The latter is more complex because it arises as a combination of several vibrations. The most characteristic were those of symmetric and asymmetric C-O-C stretching, observed as an intense band at about 1095 cm\({}^{-1}\) and a less intense one in the range 1250-1130 cm\({}^{-1}\), respectively. There was also a band at about 1020 cm\({}^{-1}\) in the discussed region. However, this could not be unequivocally attributed to one characteristic vibration. Its origin was probably an effect of overlapping not only C-O ester vibration but also ether, or to a lesser extent, alcohol, which can be formed as side reaction products. It is worth noting that a slight broadening of the carbonyl band of esters from the lower wavenumber values (up to 1680 cm\({}^{-1}\)), and a small deviation from the baseline of the spectra in the range of 3500-3200 cm\({}^{-1}\), may indicate partial hydrolysis of some ester bonds and formation of intramolecular hydrogen-bonded carboxylic acid. This suggestion was confirmed by acid values obtained in the analytical determination. Methylene group (-CH2-) is another characteristic structural fragment of oil-based materials. The presence of long-chain aliphatic carboxylic acids, which together with glycerol build triglycerides, contributes to an increase in the intensity of the methylene characteristic bands. In particular, this effect was visible for asymmetric and symmetric stretching vibrations at 2923 and 2854 cm\({}^{-1}\), as well as deformation and scissoring ones at about 1460 cm\({}^{-1}\). Slight differences in spectrograms result from the individual composition of the vegetable oils used in the syntheses [15; 39; 47; 48; 49].