Synthesis of telechelic natural rubber (TNR)
NR was chemically modified to carboxyl telechelic natural rubber
(CTNR) and then CTNR was transformed in hydroxyl telechelic natural rubber
(HTNR). The 1H-NMR spectrum of NR is presented in Figure 4.24, in which the
chemical shift at 5.1 ppm belongs to methine proton (C=CH) of NR. The methylene
(CH2) and methyl proton (CH3) were assigned at 2.0 ppm and 1.6 ppm,
respectively. Figure 4.25 illustrates the 1H-NMR spectrum of CTNR and all the
chemical shifts of CTNR are listed in Table 4.17 [20-28]. After reaction with the
oxidative agent, a new chemical shift was seen at 9.7 ppm, corresponding to the
aldehyde group (CH=O) at the end of the CTNR chain. The chemical shifts of
methyl and methylene protons close to the carbonyl terminal groups appeared in the
range of 2.1 to 2.5 ppm.