Epoxidized Cassia fistula Seed Oil as Bio-Based Plasticizer for Poly(vinyl chloride) Soft Films

Abstract

The soft poly(vinyl chloride) (PVC) films were prepared by a solution casting method using the epoxidized form of the oil (ECFSO) extracted from the seeds of Cassia f istula (a nonedible source), dioctyl phthalate (DOP), and DOP + ECFSO mixtures as plasticizers. The plasticization effects were evaluated in terms of thermal and mechanical properties, wide-angle X-ray scattering (WAXS) measurements, migration, and volatility of the plasticizer from the films. The use of ECFSO or its binary mixtures with DOP as plasticizers resulted in better thermal stability, improved mechanical properties, and a drastic decrease in the glass transition temperature (T g ) of the films as compared to DOP plasticized ones. The WAXS profiles showed no significant change in the order of the arrangement of PVC chains, and therefore the plasticization effects are mainly attributed to the enhanced chain mobility. The detailed analysis of the ATR-FTIR spectral measurements on the PVC films revealed major changes in the stretching frequencies of C�O of the plasticizers and HC−Cl of the PVC chains. Density functional theory (DFT) calculations and their careful analysis clearly establish the presence of hydrogen bond type interactions of the hydrogens of the −CH 2 Cl units of the hydrogenated repeat unit of the PVC with carbonyl and epoxy groups of the ECFSO plasticizer. Due to these hetero interactions, the migration of the plasticizer to the surface and solvent phase was found to be the lowest. The ECSFO based plasticizers have a good potential to partly or fully replace the DOP for producing high performing and environmentally safe PVC soft films.

Effect of epoxidized Cassia fistula seed oil (ECFSO) on poly(vinyl chloride) films in the presence of stabilizers

“…The FTIR spectra Similar characteristic peaks are also reported for the unplasticized PVC film. [48][49][50] Besides that, the C=O group frequency were shifted to lower for the plasticized PVC films, indicating the interaction or plasticization mechanism between the plasticizer and PVC polymer. As shown in Figure 1, the results of the present study are in good correlation with those recently reported, which showed that the spectral features of plasticized PVC films exhibited similar patterns.…”

“…As shown in Figure 1, the results of the present study are in good correlation with those recently reported, which showed that the spectral features of plasticized PVC films exhibited similar patterns. [48,49] It is worth to note that the band at 1063 cm -1 corresponds to C-O of THF was observed in pure as well as in plasticized PVC materials. It suggests that PVC materials still contain some trace amounts of THF.…”

“…Finally, each film sample specimen was reweighed and the volatility rate (in %) was calculated by equation 10. [21,48] 𝑉𝑜𝑙𝑎𝑡𝑖𝑙𝑖𝑡𝑦 𝑟𝑎𝑡𝑒 = (…”

“…The interaction between PVC and plasticizer are recently reported by us. [48] Therefore, in this study we selected the unit of PVC (HVC), plasticizer (epoxy methyl ester of ECFSO), and stabilizers (Calcium stearate, and one pack containing PbO) for their interactions at the molecular level.…”

“…The higher occupied and lower unoccupied orbitals (HOMO-LUMO) have the ability of electron donor and acceptor, respectively. [40,48,55] The total dipole m moment (TDM in debye) and band gap along with other quantum chemical parameters (in eV) were calculated in the gaseous phase using the DFT/B3LYP/SDD level of theory. The representation of the FMOs (HOMO-LUMO) and their corresponding positive and negative regions are shown in However, the energy difference between the HOMO and LUMO values is termed as a band gap (Egap).…”