Plasticizing and thermal stabilizing effect of bio‐based epoxidized cardanol esters on PVC

Abstract

Poly(vinyl chloride) (PVC) is a widely used plastics in different industries. It is an intrinsically hard and brittle polymer and requires the use of plasticizers to improve the processability. Commonly used phthalate‐based plasticizers have serious toxicity issues and we present alternatives based on epoxidized soybean oil (ESO) and epoxidized cardanol esters (ECEs). ECEs are synthesized from cardanol and three fatty acids (oleic, ricinoleic, and myristic) using 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC) as a coupling agent. Their structure and purity are confirmed by Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance. Moreover, plasticized PVC films are prepared using a solvent‐free method. The replacement of 10 phr of ESO with 5 phr of ECE improves the plasticizing power due to the co‐solvency effect. Mechanical properties and thermal stability of plasticized PVC films are correlated with the chain length and the number of epoxy groups in ECE. The best plasticizing effect is observed for epoxidized cardanol‐myristate (ECD‐MA). ECD‐MA as a shorter‐chain secondary plasticizer is more compatible with ESO and allows higher conformational mobility of PVC chains. PVC/30ESO/5ECD‐MA polymer exhibits an exceptionally high initial thermal decomposition temperature (314.4°C) while preserving moderate ductility and tensile strength (263.4% and 23.3 MPa). Overall, this study highlights the potential applicability of ECD‐MA in combination with ESO as a sustainable, bio‐based plasticizer and heat stabilizer for flexible PVC products.

Development of biobased plasticizers with synergistic effects of plasticization, thermal stabilization, and migration resistance: A review

“…ESO was used as the main plasticizer and combined it with ECEs as the secondary plasticizers. 44 Due to the cosolvency effect between ESO and ECD-MA, we observed the best plasticizing effect for ESO + ECD-MA. As a result, PVC/30ESO/5ECD-MA sample possessed an initial thermal decomposition temperature as high as 314.4 C, along with high tensile strength and ductility (23.3 MPa and 263.4%).…”

“…Recently, we synthesized three epoxidized cardanol esters, namely epoxidized cardanol‐oleate (ECD‐OA, the same as CE18:1Ep), epoxidized cardanol‐ricinoleate (ECD‐RA), and epoxidized cardanol‐myristate (ECD‐MA, the same as CE14Ep) (Figure 14). ESO was used as the main plasticizer and combined it with ECEs as the secondary plasticizers 44 . Due to the cosolvency effect between ESO and ECD‐MA, we observed the best plasticizing effect for ESO + ECD‐MA.…”

“…The chemical structure of three epoxidized cardanol-esters. 44 plasticizing and migration resistance. The plasticizing effect is good with short alkyl chain lengths, but the plasticizer has poor migration, extraction, and volatilization resistance.…”

“…Combined with the current reported work, Section 3 briefly illustrates the progress of isosorbide‐based plasticizers' utilization in PLA, PVC, and thermoplastic starch (TPS) 9,30,42,43 . Moreover, combined with our recent work, Section 4 focuses on demonstrating the preparation of cardanol‐based plasticizers with synergistic effects of both plasticization and thermal stabilization according to a simple and efficient method 44–46 . By analyzing the relationship between chemical structure and plasticizing properties, we provide theoretical guidance for future research on the design of biobased plasticizers with the synergistic effects of plasticization, thermal stabilization, and migration resistance.…”

The influence of phenolic resin modified by cardanol on improving the processability of PVC

“…The effect of CPF addition on the shear viscosity of the blends Similar to that of DOP, [14][15][16][17] the addition of low viscosity CPF can also significantly reduce the processing temperature of PVC/CPF blends, reduce the torque required for blending, and the degree of decomposition of PVC will also be greatly reduced. Figure 4 shows the relationship between the steady-state shear rheological properties of PVC/CPF blends and PVC with different proportions and the shear rate.…”