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Instruments / Technical Area	Publication Details	Published
I22-Small angle scattering & Diffraction	Real-time investigation of the structural evolution of polyethylene during tenter-frame biaxial stretching Ilaria Squillante , Francesca Gentile , Adriano Guida , Martin Rosenthal , Finizia Auriemma , Roberto Pantani , Giuseppe Portale Macromolecules 3 DOI: 10.1021/acs.macromol.5c03217 Diamond Proposal Number(s): [36690] Show Abstract ▼ Abstract: The online structure development during tenter-frame biaxial stretching of linear low-density (LLDPE), high-density polyethylene (HDPE), and their 50/50 blend was investigated using synchrotron Wide-Angle X-ray Scattering (WAXS). During stretching, crystallite reorientation, crystallographic slip phenomena activated at yielding, and lamellar fragmentation at higher strains are responsible for a decrease in crystallinity. These processes induce a morphological transformation from the initial semisolid spherulitic morphology into an oriented fibrillar network with lamellae in edge-on orientation, and the b- and c-axes constrained within the film plane, as confirmed by ex-situ WAXS and SAXS. These phenomena are more important for HDPE, which exhibits higher susceptibility to biaxial stretching. Upon cooling, the morphology developed during stretching is preserved, as newly crystallized material grows epitaxially on the preexisting structure. These findings highlight the higher structural sensitivity of HDPE during semisolid biaxial stretching compared with LLDPE, providing unique information to understand and control the biaxial processing of polyethylene.	Mar 2026
I22-Small angle scattering & Diffraction	Designing and controlling transient supramolecular gels Dave J. Adams , Emma Bowley , Simona Bianco , Fin Hallam Stewart , Chloe Wallace , Rebecca Ginesi , Alex Loch , Martin Rosenthal , Andrew Smith Chemsystemschem DOI: 10.1002/syst.202400073 Diamond Proposal Number(s): [32866] Open Access Show Abstract ▼ Abstract: Supramolecular systems are often designed such that a steady state exists. However, the ability to design systems with pre-determined changes in state can lead to highly dynamic materials, with evolving supramolecular structures and adaptable material properties. This approach is of great interest from the perspective of designing adaptive systems as well as from a broader systems chemistry perspective. Here, we report how a transient system can be altered to access different mechanical properties and transitions by varying the trigger and temperature. The aging of these systems is also explored, as the networks continually evolve long past the common cut-off point of analysis of one day. We therefore provide new insights into the control of transient gels, as well as an understanding as to the underpinning supramolecular structures and how they evolve with time.	Nov 2024
	Evolution of stress fields during crack growth and arrest in a brittle-ductile CrN-Cr clamped-cantilever analysed by X-ray nanodiffraction and modelling M. Meindlhumer , L. R. Brandt , J. Zalesak , M. Rosenthal , H. Hruby , J. Kopecek , Enrico Salvati , C. Mitterer , R. Daniel , J. Todt , J. Keckes , A. M. Korsunsky Materials & Design DOI: 10.1016/j.matdes.2020.109365 Open Access Show Abstract ▼ Abstract: In order to understand the fracture resistance of nanocrystalline thin films, it is necessary to assess nanoscopic multiaxial stress fields accompanying crack growth during irreversible deformation. Here, a clamped cantilever with dimensions of 200 × 23.7 × 40 μm3 was machined by focused ion beam milling from a thin film composed of four alternating CrN and Cr layers. The cantilever was loaded to 460 mN in two steps and multiaxial strain distributions were determined by in situ cross-sectional X-ray nanodiffraction. Characterization in as-deposited state revealed the depth variation of fibre texture and residual stress across the layers. The in situ experiment indicated a strong influence of the residual stresses on the cross-sectional stress fields evolution and crack arrest capability at the CrN-Cr interface. In detail, an effective negative stress intensity of −5.9 ± 0.4 MPa m½ arose as a consequence of the residual stress state. Crack growth in the notched Cr layer occurred at a critical stress intensity of 2.8 ± 0.5 MPa m½. The results were complemented by two-dimensional numerical simulation to gain further insight into the elastic-plastic deformation evolution. The quantitative experimental and modelling results elucidate the stepwise nature of fracture advancement across the alternating brittle and ductile layers and their interfaces.	Nov 2020

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