Experimental study and comparative assessment on heat stabilized UPVC parts based on alternative standard test methods

The quality of the manufactured poly(vinyl chloride) (PVC) products depends on the type and amount of modifier or additive used in the formulation. Determination of this quality was performed according to the standard tests. In this study swelling test and degree of gelation, were used along with the two comparative methods including Differential Scanning Calorimetryand tensile tests. For this purpose, the PVC samples stabilized with the three type's commercial stabilizers, including commercial lead-based, Ca/Zn and OBS conducted with melt mix method in the laboratory internal mixer. In terms of thermal properties by the relation between the measured enthalpy of fusion of two crystallites phases, with chemical swelling results proved the qualitative re-sults of the dichloromethane resistance test (DCMT). Glass transition temperature of the modified PVC with all examined heat stabilizers were determined equal to ۷۹°C for PVC stabilized with Ca/Zn compared with the value of about ۷۷°C in lead stabilized PVC and ۷۶°C in OBS stabilized PVC. The onset temperature corresponded to melting point of primary crystallites represented in highest value, around ۱۹۵.۱°C for PVC - Ca/Zn sample. Quantified degree of gelation measured with enthalpy ratio of two crystalline phases showed good agreement with the results of the chemical swelling test. From mechanical analysis, tensile strength at room temperature of PVC stabilized with Ca/Zn stabilizer showed the highest value among the other stabilizers. From all the results, it is evident that Ca/Zn showed high potential use as a safe and effective heat stabilizer for PVC to substitute traditional lead compounds

کلیدواژه ها:

PVC-U ، Heat stabilizer ، Swelling ، Differential Scanning Calorimetry ، tensile properties