Combining Flash DSC, DSC and broadband dielectric spectroscopy to determine fragility

Abstract

New experimental results focused on Flash DSC, DSC and broadband dielectric spectroscopy investigations are reported in this work. The fictive temperatures and fragility indexes are estimated from Flash DSC experiments and compared to values obtained from classical DSC. The consistency of the Tool-NarayanaswamyMoynihan model and fragility concept is then investigated over a large range of cooling rates. Indeed, the Flash DSC allows exploring thermal properties of materials over a continuous and broad range of heating and cooling rates, complementary to rates usually available with DSC. The reliability of investigations is also demonstrated by comparing results obtained from two model amorphous polymeric systems: polystyrene and poly(ethylene terephthalate)-glycol. The temperature dependence of the cooling rate obtained by Flash DSC and DSC is also compared to the temperature dependence of the relaxation times obtained from broadband dielectric spectroscopy, experiment considered as the reference concerning the fragility measurements. The comparison of these two dependencies implies a better understanding about the origin of the temperature dependence of the cooling rate.

Impact of chirality on the Glass Forming Ability and the crystallization from the amorphous state of 5-ethyl-5-methylhydantoin, a chiral poor glass former

“…One of the most recent tools developed by Mettler Toledo is the Flash DSC (Fast Scanning Calorimetry or FSC hereafter) device based on a calorimeter chip (Mathot et al, 2011;van Herwaarden et al, 2011;Schick, 2010a, 2010b) which can accurately provide very high cooling rates (up to 4000 °C/s) in a wide range of temperature and therefore could permit to avoid recrystallization of most highly crystallogenic systems. Furthermore, this technique has largely proven its worth in the investigation of disordered polymeric and metallic systems (Cangialosi et al, 2016;Dhotel et al, 2015;Gao et al, 2016;Monnier et al, 2017bMonnier et al, , 2017aMonnier et al, , 2017cSchick and Androsch, 2016;Simon and Koh, 2016). Therefore, up to our knowledge, few studies are reported in the case of small organic molecular compounds (Corvis et al, 2015a(Corvis et al, , 2015bKawakami et al, 2012;Magoń et al, 2015;Schammé et al, 2017;Shamim et al, 2015).…”

From a Three-Phase Model to a Continuous Description of Molecular Mobility in Semicrystalline Poly(hydroxybutyrate-co-hydroxyvalerate)

“…Quenching was performed in situ on the chip sensor, and then the sample was heated at the same rate for comparison. The mass of the samples was estimated by comparing the values of ΔC p (T g ) obtained by Flash DSC and conventional MT-DSC on quenched PHBV, following a procedure already reported elsewhere 51,66. The heat flow signals were normalized to the sample mass(11,44, and 36 ng, respectively) and evenly shifted for the sake of clarity.…”

From monomers to self-assembled monolayers: the evolution of molecular mobility with structural confinements

“…36 Particularly, this technique is frequently used to investigate relaxation processes in glassforming materials, 37,38 polymers, [39][40][41][42][43][44][45] and is also increasingly employed when studying structural connement. [46][47][48][49][50][51][52] It can also be valuable when studying structural transitions within highlyordered liquid and plastic crystals.…”