Exploring the Limits of High‑<i>T</i>_g Epoxy Vitrimers Produced through Resin-Transfer Molding

Over the past few years, scientists have developed new ways to overcome the recycling issues of conventional thermosets with the introduction of associative covalent adaptable networks (i.e., vitrimers) in polymer materials. Even though various end-use vitrimers have already been reported, just a few of them have targeted high-performance industrial applications. Herein, we develop a promising high-performance epoxy vitrimer based on a commercially available resin widely used in aeronautics with the highest glass transition temperature (Tg) of 233 °C ever reported for a vitrimer. A complete study of its physicochemical properties and cure kinetics was conducted, enabling the construction of the first time–temperature–transformation (TTT) diagram reported in the literature. This diagram allows a full determination of the processing and curing parameters leading to the manufacturing of vitrimer samples by the resin-transfer molding (RTM) process. The reshapability and limits therefrom of this high-Tg vitrimer were evaluated by three successful thermoforming cycles without degradation

Timing of granite emplacement, crustal flow and gneiss dome formation in the Variscan segment of the Pyrenees

<p>The Variscan segment of the Pyrenees is well suited to study the timing of crustal-scale deformations as crustal flow and gneiss dome formation. This has been constrained from a synthesis of available structural and geochronological data of intrusive rocks, as well as new zircon U–Pb age determinations via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). After a stage of moderate thickening by fold–thrust belt development in the upper crust between 323 and 308 Ma, the Variscan segment of the Pyrenees experienced crustal flow at <em>c.</em> 306 Ma and then gneiss dome formation at <em>c.</em> 304 Ma. Localization of the deformation along reverse-dextral shear zones occurred at <em>c.</em> 300 Ma. The Variscan segment of the Pyrenees recorded a high-temperature regime, which allowed crustal flow of the middle crust, but with limited amounts of heat which induced rapid cooling. The development of this enigmatic orogenic segment of the Variscan belt is closely contemporaneous with the formation of the Cantabrian Orocline and could correspond to a lithospheric-scale shear zone that accommodated buckling of the orocline. Late Variscan lithospheric delamination and asthenospheric upwelling associated with buckling in the core of the Cantabrian Orocline could explain the short-period high-temperature regime in the Variscan segment of the Pyrenees. </p

Anisotropy of magnetic susceptibility of the Pyrenean granites

<p>In this paper, we report on a compilation of more than 2200 sites (more than 10,000 individual measurements) where anisotropy of magnetic susceptibility (AMS) was studied in granites from the Variscan Pyrenees. The standardization and homogenization of this information has allowed us to produce three <a href="https://doi.org/10.1080/17445647.2017.1302364" target="_blank">Main Maps</a> that synthesize all the information related with the AMS of the Pyrenean granites. We also describe the problems found during the construction of the database (variable geo-positioning, different published information, etc.). The information derived from 21 granite bodies, the database, and the synthesis maps (magnetic susceptibility, Km, and the orientation of the magnetic foliation, plane perpendicular to k3, and of the magnetic lineation, k1) allow us to see for the first time a complete image of this important kinematic and petrographic indicator.</p