Thermal Degradation of Poly(vinyl chloride): Effect of Nanoclay and Low Density Polyethylene Content

One of the most serious problems encountered in poly(vinyl chloride) (PVC) processing is due to low thermal stability of the PVC. In this work, the presence of organoclay and low density polyethylene (LDPE) of variable contents were studied in relation to the thermal degradation of PVC. The samples were prepared using an internal mixer with (10, 20 and 30 phr) LDPE and (1, 3, 5 and 7 phr) nanoclay at 180ºC and 45 rpm of rotor speed. The morphology of nanoclay was evaluated by X-ray diffraction and transmission electron microscopy. Thermal degradation was tracked by polyene and carbonyl indices using Fourier transform infrared and thermal gravimetric analysis. The results revealed that exfoliation morphology was obtained at 1 and 3 phr concentrations of nanoclay and the intercalation morphology was observed at higher nanoparticle concentration. The addition of LDPE had no significant effect on the dispersion status of nanoparticles. The lowest polyene and carbonyl indices were related to 1 phr concentration of nanoclay. TGA Results showed that the onset temperature of degradation shifted to higher temperature due to the presence of nanoparticles and LDPE and the highest shift was attributed to the sample containing 1 phr of nanoclay and 10 phr of LDPE. Mechanical properties of the samples showed direct correlations with nanoclay and LDPE contents and thermal degradation of PVC. The mechanisms for the prevention of thermal degradation reaction of PVC by LDPE and nanoparticle are proposed and discussed.