Synergistic Effects of Plasticizer Types on the Mechanical, Thermal, and Morphological Properties of PVC Compounds for Cable Application

Poly (vinyl chloride) (PVC) is widely used in many products due to its increased flexibility and processability. It is preferred in many industrial applications, especially in the plasticized PVC cable industry due to its excellent insulation properties. PVC is quite hard and can be difficult to process. Therefore, it requires additives such as plasticizers. Plasticizers typically reduce the glass transition temperature (Tg) and provide flexibility by reducing the workable temperature level. In the PVC compound production industry, phthalate-based plasticizers are preferred due to their low cost. Commonly used plasticizers are adipates, azelates, trimethylates, phthalates, benzoates, and chlorinated paraffins. The aim of the study was to investigate the plasticizer changes in PVC compounds used in cable insulation applications by synergistic effects of adipate, trimellitate, and phthalate-based plasticizers such as dioctyl terephthalate (DOTP), 2-ethyl hexyl adipate (DOA), and tris(2-ethylhexyl) benzene-1,2,4-tricarboxylate (TOTM). In this study, the effects of plasticizer additives were investigated on the structural, morphological, thermal, and mechanical properties of PVC compounds in the cable industry. Fabricated test products were characterized using characterization methods such as Fourier transform infrared-attenuated total reflectance (FTIR-ATR), scanning electron microscope–energy-dispersive X-ray (SEM-EDX) spectroscopy, thermal gravimetric analysis (TGA), tensile test, and density test. Successfully fabricated samples were tested before and after aging. The highest elongation at break of PVC flat sheet (244.96%) was obtained with the use of DOA plasticizer. The highest tensile strength was measured as 17.85 MPa for the sample containing 50 phr DOTP. Furthermore, no significant mass loss was observed up to 238 °C, while substantial decomposition occurred in the samples containing 50 phr DOTP, 50 phr DOA, and 50 phr TOTM between 238–338 °C, followed by gradual degradation at 483 °C and 683 °C. As a result, it has been determined that the use of DOA plasticizer in PVC compounds used in the cable industry is more effective than DOTP and TOTM plasticizers.