Characterization of PVC cable insulation materials and products obtained after removal of additives

Organic solvents cyclohexane, dichloromethane, hexane, and tetrahydrofuran were tested to separate the dioctylphthalate (DOP) as plasticizer from the poly(vinyl chloride) (PVC)-based materials. It was found that the efficiency of ultrasound-enhanced hexane extraction of the DOP from PVC is 70% and the efficiency of the separation of the DOP and other compounds from the PVC by dissolution in THF followed by subsequent precipitation was 98-99%. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to characterize the thermal behavior of PVC materials before and after extraction of plasticizers. It was found that during heating in the range 20-800 degrees C the total mass loss measured for the nontreated, extracted, and precipitated PVC samples was 71.6, 66.6, and 97%, respectively. In the temperature range 200-340 degrees C, the release of DOP, HCl, and CO2 was observed by simultaneous thermogravimetry (TG)/FTIR. The effect of plasticizers on thermal behavior of PVC-based insulation material was characterized by DSC in the range -40-140 degrees C. It was found that, concerning the PVC cable insulation material before treatment, the value of the glass transition temperature (T-g) was 1.4 degrees C, whereas for the PVC sample extracted by hexane, the value of T-g was 39.5 degrees C and for the PVC dissolved in THF and subsequently precipitated, the value of T-g was 80.4 degrees C. Moreover, the PVC samples after extraction of plasticizers, fillers, and other agents were tested to characterize their thermal degradation. The TG and FTIR results of chemically nontreated, extracted, and precipitated samples were compared. The release of DOP, HCl, CO2, and benzene was studied during thermal degradation of the samples by FTIR. (c) 2005 Wiley Periodicals, Inc.