THERMAL AND CATALYTIC DEGRADATION OF COMMINGLED PLASTICS

Thermogravimetry, in situ electron spin resonance (ESR) spectroscopy a nd in situ and ex situ X-ray diffraction (XRD) are employed to investi gate the thermal and catalytic degradation of a sample of commingled p lastics (CP). XRD studies show CP to contain about 90% polyethylene (P E) and 10% polypropylene (PPE) and a smaller amount of TiO2. Analysis of the weight loss data in argon to 550 degrees C yields an activation energy E approximate to 38 kcal mol(-1) for the thermal decomposition of CP. In XRD studies, a melting point of 135 degrees C is inferred w hereas the onset of irreversible degradation begins only around 360 de grees C. The in situ ESR experiments of CP and CP loaded with 10% Al2O 3 (nanoscale) and 10% sulfur, both under 500 psig of H-2, show that fo r CP alone an ESR signal indicative of degradation is first seen near 380 degrees C, whereas for the loaded CP this degradation temperature is reduced to 280 degrees C. This enhanced catalytic degradation detec ted by ESR is believed to be due to elemental sulfur.