A comparative evaluation between the FTIR spectra of CO and MCO reveals a broad, intense and strong absorption band at 3400 cm-1 for MCO. This is attributed to the increase in the number of hydroxyl (OH) groups in MCO after transesterification reaction [17]. Further, the results depicted in table 2 validates the above observation. Both the materials exhibited peak at 1734 cm-1 indicating the presence of the ester carbonyl group. Meanwhile, the band visualized at 1100 cm-1 in CO can be assigned to the secondary OH group. However, MCO revealed an absorption band at 1051 cm-1 which might be due to the introduction of primary OH groups (Scheme 2) after thetransesterification process which was absent in the case of CO.
The FTIR spectra of the UBPU 1.4 and MBPU 1.4 films are represented in Fig 2. It is noticeable that the –NH peak for MBPU 1.4 appears at a lower wavenumber as compared with UBPU 1.4. Coleman et.al. [36] have reported that in case of H-bonded polyurethane the –NH bond appears at lower wavenumber as compared with the PUs devoid of H-bonding. Usually the hydrogen bonding (H-bonding) is formed between two types of proton donors i.e. (urethane N-H and urea N-H) and four types of …show more content…
As revealed from table 7, MBPU 1.4 exhibits shorter H-bond length, which, confirms its higher H-bonding as compared with UBPU 1.4. This result was predictable by taking into account the difference in reactivity of OH groups and the number of dangling chains in CO and MCO respectively. It is to be noted that the presence of the primary hydroxyl (OH) groups in terminal position of MCO renders higher reactivity towards the NCO groups in Tolonate TM X FLO 100 resulting in the formation of H-bonded N-H of relatively higher intensity. Moreover, the presence of less dangling chains [39] in MBPU inhibits the steric hindrance effect resulting in the formation of stronger H- bonds and enhanced intermolecular
The FTIR spectra of the UBPU 1.4 and MBPU 1.4 films are represented in Fig 2. It is noticeable that the –NH peak for MBPU 1.4 appears at a lower wavenumber as compared with UBPU 1.4. Coleman et.al. [36] have reported that in case of H-bonded polyurethane the –NH bond appears at lower wavenumber as compared with the PUs devoid of H-bonding. Usually the hydrogen bonding (H-bonding) is formed between two types of proton donors i.e. (urethane N-H and urea N-H) and four types of …show more content…
As revealed from table 7, MBPU 1.4 exhibits shorter H-bond length, which, confirms its higher H-bonding as compared with UBPU 1.4. This result was predictable by taking into account the difference in reactivity of OH groups and the number of dangling chains in CO and MCO respectively. It is to be noted that the presence of the primary hydroxyl (OH) groups in terminal position of MCO renders higher reactivity towards the NCO groups in Tolonate TM X FLO 100 resulting in the formation of H-bonded N-H of relatively higher intensity. Moreover, the presence of less dangling chains [39] in MBPU inhibits the steric hindrance effect resulting in the formation of stronger H- bonds and enhanced intermolecular