Publications on polyethylene terephthalate (PET) continue to increase including the number of publications on recycling. PET is a versatile material with the ability to be remade from its polymer state through mechanical recycling and even back to its original monomer through advanced recycling. The scale of PET's use affords continued research and applications in improved recycling. Publications on new uses of discarded PET and the ability to clean and convert it into many forms including alternative materials are expanding with an attempt to complete circular use or improve the end of life. As indicated in life cycle assessment studies, increases in recycling lower the energy required to manufacture products. The future for PET will reduce energy demands further with the largest breakthroughs in recycling technologies and bio‐sourced resins trending toward zero energy and carbon negative solutions. Opportunities remain for improvement in the use of PET with light weighting. The testing of new resins, development of bio‐feedstocks, improvements in engineering, processing, recycling, and design continue to provide benefits. This review provides context for these developments.

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Disagreements about the mechanisms of cement hydration remain despite the fact that portland cement has been studied extensively for over 100 years. One reason for this is that direct observation of the change in microstructure and chemistry are challenging for many experimental techniques. This paper presents results from synchrotron nano X-ray tomography and fluorescence imaging. The data show unprecedented direct observations of small collections of C3S particles before and after different periods of hydration in 15 mmol/L lime solution. X-ray absorption contrast is used to make three dimensional maps of the changes of these materials with time. The chemical compositions of hydration products are then identified with X-ray fluorescence mapping and scanning electron microscopy. These experiments are used to provide insight into the rate and morphology of the microstructure formation.

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Recent advances in the processing of closed- [1][2][3][4][5] and opencell [6][7][8][9] metallic glass foam have focused increasing attention on the mechanical behavior of this emerging structural material. This interest evolved after recognizing that metallic glasses impregnated with pores can be effectively alleviated from their inherent brittle nature and yet retain a considerable fraction of their outstanding strength.[10] The mechanical behavior of open-and closed-cell metallic glass foams has recently been assessed by means of compressive experiments performed using standard mechanical testing procedures. Open-cell Zr 57 Nb 5 Cu 15.4 Ni 12.6 Al 10 foams investigated in the porosity range of 72-86 % are found to exhibit impressive compressive plasticity extending to nearly 80 % strains, however, they are found to yield at relatively low stresses ranging between 5 and 34 MPa. [7][8][9] In contrast, closed-cell Pd 43.5 Ni 7.5 Cu 30 P 20 and Pd 35 Pt 15 Cu 30 P 20 foams investigated in the porosity range of 36-64 % were found to exhibit substantially higher strengths, ranging between 250 and 600 MPa, but a more modest plasticity ranging between 20 and 30 % strains. [4,5] Plasticity in these closed-cell foams is shown to propagate by recurring non-catastrophic crushing events associated with the formation of collapse bands through the foam structure. More interestingly, ahead of a crushing event these foams are found to exhibit an unusual yielding response characterized by an extended stress plateau. This nonlinear foam yielding response bears resemblance to the yielding of a monolithic metallic glass near zero temperature. [11][12][13] This resemblance hints at a possible similarity between floppybonded networks (such as foams) and zero-temperature glasses, as originally proposed by Alexander. [14] In this communication we seek to investigate the underlying mechanisms governing the nonlinear yielding of these closed-cell foams by examining the intercellular interactions within a bulk-foam specimen by using real-time X-ray microtomography.For the loading experiment, we utilized a 70 % porosity closed-cell amorphous Pd 43 Ni 10 Cu 27 P 20 foam. In situ X-ray microtomography during loading was performed at beam line ID15A of the ESRF. [15,16] A cycle involving compressive loading towards a non-catastrophic collapse event followed by unloading was implemented. 18 radiographic images of the cellular structure were recorded at constant strain. The stress-strain diagram is presented in Figure 1. The stress spikes appearing in the loading curve are a consequence of ra- COMMUNICATION