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Crosslinking modification is one of the important methods of polyethylene modification. The effects of crosslinking degree and resin structure on rheological properties, crosslinking properties, crystallization properties and mechanical properties of crosslinked high density polyethylene (XHDPE) were studied. The results show that when the mass fraction of crosslinking agent increases from 0 to 1.2%, the maximum energy storage modulus (G'max) and gel content of XHDPE increase, and the minimum value of loss factor (tanδmin) decreases gradually. With the increase of the content of crosslinking agent, the crystallinity and grain size of XHDPE decreases, and the crystallization capacity decreases. After the addition of crosslinking agent, the tensile yield strength of XHDPE decreases gradually, the elongation at break increases first and then decreases, and the impact strength increases significantly. With the same content of crosslinking agent, the energy storage modulus of XHDPE and the viscoelasticity of macromolecular network increase gradually with the increase of molecular weight of base resin. When the elongation at break of high molecular weight HDPE reaches the maximum, the content of crosslinking agent required is lower. High molecular weight HDPE base resin is beneficial to improve the mechanical properties of crosslinked samples. [ABSTRACT FROM AUTHOR]

The mineral zircon has a robust crystal structure, preserving a wealth of geological information through deep time. Traditionally, trace elements in magmatic and hydrothermal zircon have been employed to distinguish between different primary igneous or metallogenic growth fluids. However, classical approaches based on mineral geochemistry are not only time consuming but often ambiguous due to apparent compositional overlap for different growth environments. Here, we report a compilation of 11 004 zircon trace element measurements from 280 published articles, 7173 from crystals in igneous rocks, and 3831 from ore deposits. Geochemical variables include Hf, Th, U, Y, Ti, Nb, Ta, and the REEs. Igneous rock types include kimberlite, carbonatite, gabbro, basalt, andesite, diorite, granodiorite, dacite, granite, rhyolite, and pegmatite. Ore types include porphyry Cu-Au-Mo, skarntype polymetallic, intrusion-related Au, skarn-type Fe-Cu, and Nb-Ta deposits. We develop Decision Tree, XGBoost, and Random Forest algorithms with this zircon geochemical information to predict lithology or deposit type. The F1-score indicates that the Random Forest algorithm has the best predictive performance for the classification of both lithology and deposit type. The eight most important zircon elements from the igneous rock (Hf, Nb, Ta, Th, U, Eu, Ti, Lu) and ore deposit (Y, Eu, Hf, U, Ce, Ti, Th, Lu) classification models, yielded reliable F1-scores of 0.919 and 0.891, respectively. We present a web page portal (http://60.205.170.161:8001/) for the classifier and employ it to a case study of Archean igneous rocks in Western Australia and ore deposits in Southwest China. The machine learning classifier successfully determines the known primary lithology of the samples, demonstrating significant promise as a classification tool where host rock and ore deposit types are unknown. [ABSTRACT FROM AUTHOR]

Modified polyglycolic acid (PGA) was prepared by melt blending and reactive extrusion. The effects of chain extenders, crosslinking agents and lubricants on melt fluidity, dynamic rheological properties, thermal stability, and crystallization properties of modified samples were studied. The results show that the melt strength of samples are significantly improved by using ADR chain extender and BIBP crosslinking agent simultaneously, the melt mass flow rate is decreased by 73.6% compared to pure PGA. The thermal stability of modified samples is also improved, with increasing the 5% thermal decomposition temperature by 7 °C. With the addition of chain extender and crosslinking agent, the degree of crystallinity of PGA samples are decreased, the number of crystal nuclei are decreased, and the spherulite size are increased. The degree of cross-linking of the sapmles with adding chain extender and crosslinking agent at the same time is increased, resulting in imperfect crystallization and the formation of irregular crystals. Molecular motion are promoted by lubricants, and the crystallization temperature of PGA sample is decreased from 179.3 °C without addition to 173.9 °C after addition. [ABSTRACT FROM AUTHOR]

In order to improve the stability of polypropylene in the extrusion process, the modified polypropylene was prepared by melt extrusion technology, and the effects of antioxidant type, antioxidant ratio and hydrotalcite type on the processing stability of polypropylene were studied. The results show that the combination of hydroxylamine antioxidant and pentaerythritol phosphite antioxidant improve the processing stability of polypropylene, and the a value (red and green) is less than 0 and b value (yellow and blue) is less than 1.5 in multiple extrusion processing, and the melt flow rate increment is less than 5 g/10 min. Hydrotalcite with a large particle size and good dispersion is beneficial to improve the processing stability of polypropylene. The combination of hydroxylamine antioxidants, pentaerythritol phosphite antioxidants, and hydrotalcite with large particle size dispersion is conducive to improving the processing stability of polypropylene. [ABSTRACT FROM AUTHOR]

Radiative cooling is a passive cooling strategy that can radiate heat to outer space through the 8 to 13 μm waveband (atmospheric window) and is now widely used for buildings, wearable fabric, solar cells, and electronic devices. Daytime radiative cooling requires both high reflection in the solar spectrum and high absorption/emission in the 8 to 13 μm range. Previous multilayered structures were optimized by changing the thickness ratio of the layers, but the optical properties of multilayer thin films, such as absorptivity, transmissivity, and reflectivity, are determined by complex factors. In this work, several initial multilayer structures were selected and then the thickness of each layer was globally optimized; the theoretically smallest thickness with the best absorption performance was achieved in the 8 to 13 μm range, which significantly improved the cooling performance and reduced costs. We developed an optimized SiO2-Ta2O5 alternating multilayer photonic radiative cooling thin film and fabricated it using ion source assisted electron beam evaporation with an average emissivity of 0.876 within the 8 to 13 μm range and an average reflectivity of 0.963 in the 0.3 to 2.5 μm waveband; it achieved an average temperature reduction of 20.1°C lower than the uncoated substrate and 3.2°C lower than the ambient temperature under direct sunlight with an average solar power of 859.3 W/m2. [ABSTRACT FROM AUTHOR]