Synthesis of Cyclohexanecarboxylic Acid-Based Methoxypolyethylene Glycols and Polyethylene Glycol Ester as Efficient Plasticizer for Poly(vinyl chloride)

Herein, two categories and four kinds of novel eco-friendly plasticizers, cyclohexanecarboxylic acid-based methoxypolyethylene glycols (H-MPEG200 and H-MPEG400) and cyclohexanecarboxylic acid-based polyethylene glycol (H-PEG200 and H-PEG400), are synthesized via the esterification reaction. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR) certified the successful synthesis of precise target structure. Thermogravimetric analysis (TGA) results revealed that both H-MPEG and H-PEG have better thermal stability than dioctyl phthalate (DOP). Subsequently, the plasticization efficiency of H-MPEG and H-PEG is investigated systematically by replacing a portion of DOP in a soft poly(vinyl chloride) (PVC) system. The rheological results indicated that the fusion time, fusion torque, and equilibrium torque of PVC blends have a slight decrease in comparison to that of DOP at a similar content of total plasticizer. The TGA analysis demonstrated the PVC films plasticized with H-PEG400 or H-MPEG exhibited better thermal stability than other plasticizers. Among them, H-MPEG has higher plasticizing efficiency than DOP, in which the glass transition temperature (T_g) is −2.34 °C for PVC/H-MPEG200 and −6.27 °C for PVC/H-MPEG400, respectively. Meanwhile, the H-PEG and H-MPEG showed outstanding compatibility with the PVC matrix, endowing the PVC blends with high transmittance.