A Comparison of the Glass Transition Temperatures of Artificially Aged and Field-Aged Roof Membranes Through the Use of Dynamic Mechanical Analysis

Abstract

The authors studied the effect of heat and ultraviolet (UV) exposure as well as natural weathering on the glass transition temperature of PVC roof membranes. The glass transition temperature of the unexposed specimens and those exposed to heat, artificial (UV) and natural weathering obtained from the E' and E" curves, as per ASTM Practice for Dynamic Mechanical Analysis and Thermogravimetry of Roofing and Waterproofing Membrane Material (D 6382) and ASTM Test Method for Plastics: Dynamic Mechanical Properties: In Flexure (Dual Cantilever Beam) (D 5418), range from -48°C to -33°C and from -39°C to -28°C, respectively. The ΔTg values obtained from the E' curve varied between -6°C and 4°C and those from the E" curve varied between -4°C and 9°C. The results indicate that some naturally exposed membranes have similar ΔTgs to some of the artificially aged samples.