On the latent limit of detection of thermogravimetric analysis

Thermochemical Transition in Non-Hydrogen-Bonded Polymers and Theory of Latent Decomposition

“…Thus, in the second scan the % mass loss due to dehydration is estimated to be . This value is very close to the LLoD value for PP and PP-g-MA (measured under nitrogen atmosphere) which has been reported to be ~0.03 wt.% [ 14 ]. The respective ratio of the areas of the negative peak at 1713 cm −1 in the 2nd–1st subtracted spectrum and 3rd–2nd subtracted spectrum is 2.2 (the mass loss due to dehydration in the third scan is 2.2 times smaller than the one of the second scan) corresponding to 0.019 wt.% mass loss due to dehydration in the third heating.…”

“…The first TGA heating of PP-g-MA which was used in this study was presented recently in the discussion of LLoD [ 14 ] and, precisely, up to 180 °C mass loss of 0.37 wt.% occurs. This mass loss occurs at a temperature range which overlaps with the DSC peak of PP-g-MA.…”

“…The cumulative peak corresponds to the value of 167.4 mJ as measured by DSC, thus the first fit peak corresponds to . In the DSC experiment, the mass sample was 2.3 mg. From the TGA the % mass loss is known (0.37 ± 0.1 wt.%) [ 14 ]. By assuming that all this mass loss arises from water produced by the dehydration of acid groups, it follows that the mass loss during the first DSC scan was .…”

“…One major factor is the fact that some portions of the decomposition products may not be able to vaporize [ 13 ] at the temperature range of the thermochemical transition and thus, the heat measured by DSC does not correspond to the mass loss detected by TGA [ 12 ]. In addition, recently the latent limit of detection (LLoD) of TGA was reported [ 14 ]. Briefly, it was reported that due to the buoyancy exerted on the sample during a TGA measurement, there is a hidden limit (LLoD) for the % degree of actual mass loss which must be surpassed in order for the TGA sensor to be able to detect (apparent) weight loss [ 14 ].…”

“…In addition, recently the latent limit of detection (LLoD) of TGA was reported [ 14 ]. Briefly, it was reported that due to the buoyancy exerted on the sample during a TGA measurement, there is a hidden limit (LLoD) for the % degree of actual mass loss which must be surpassed in order for the TGA sensor to be able to detect (apparent) weight loss [ 14 ]. Thus, the combination of the absence of volatility of the polymers’ decomposition products in the early decomposition stage, along with LLoD of TGA, can provide a reasonable justification for the occurrence of decomposition with no detectable mass loss in TGA, as is the case for the glass transition of PVA [ 12 ].…”