Page 652 - Handbook of Thermal Analysis of Construction Materials

620 Chapter 15 - Roofing Materials

Figure 1. Relationship between the weight loss for the oil and polymer components for
specimen S2.

A comparison between the TG and DMA results with those from the
tensile and elongation tests indicated that as shown in Table 1, the strength
of the membranes, which was not significantly affected by the heat exposure
(S1, S2), remained fairly constant or decreased slightly after exposure.
However, for the other sample (S3), it was observed that the strength at break
increased with heat-aging, indicating that the sample became more brittle.
Similarly, the elongation-at-break data for this sample (unheated) was lower
than for the other two non-heated membrane materials.
From the results of the study, Paroli, et al., [38] concluded that both
TG and DMA can be used to evaluate the properties of various roofing
membranes. The use of dynamic mechanical analyzers facilitates the
determination of the glass transition temperature, which can be used to
explain the change in mechanical properties of roofing membranes.
Thermogravimetry provides information on the volatiles and polymer
components of the membrane. Moreover, these thermoanalytical tech-
niques can be used to assess the validity of the accelerated aging process that
exposes membranes to elevated temperatures and thus reduces the time
required to evaluate the effect of heat on the mechanical properties of
polymer-based roofing materials. Finally, the equivalency of material
response at different temperatures could help in establishing standard
requirements.