Rhodamine B (RhB) is considered as a potential source of water pollution because it is harmful to the environment and humans, and thus, it should be removed from the water system. Hydrogels derived from polysaccharides have been received much attention for dye adsorption. In this study, acrylic acid (AAc)-grafted xanthan gum hydrogel (XGH) was synthesized by electron beam irradiation. The effects of AAc concentration and the adsorbed dose on the gel fraction and swelling ratio were studied. The XGH hydrogel structure was characterized by FTIR and SEM analyses. As a result, the sample with 75% gel fraction was selected to investigate the adsorption behaviors toward RhB. The adsorption kinetic data were in good agreement with pseudo-secondorder mode. The adsorption isotherms fitted well with the Langmuir equation with an ultrahigh maximum adsorption capacity of 2612.12 to 2777.77 mg/g at 293 to 323 K, which is a significant breakthrough in RhB uptake. Na 2 CO 3 and HCl were used to regenerate the RhB-loaded XGH. The removal efficiency was found to be nearly unchanged after five adsorption−desorption cycles. Finally, the selectivity of XGH toward cationic/anionic mixing dyes was investigated.

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The quantitative characterization of microstructure is most desirable for the establishment of structure-property relationships in polymer nanocomposites. In this work, the effects of graphene on the microstructure, mechanical, electrical, and thermal properties of the obtained graphene/polyethylene (PE) composites were investigated. In order to reveal the structure-performance relationship of graphene/PE composites, especially for the effects of the relative free volume fraction (fr) and interfacial interaction intensity (β), positron annihilation lifetime spectroscopy (PALS) was employed for its quantitative description. The relative free volume fraction fr gives a good explanation of the variation for surface resistivity, melting temperature, and thermal stability, and the variation of tensile strength and thermal conductivity agree well with the results of interfacial interaction intensity β. The results showed that fr and β have a significant effect on the properties of the obtained graphene/PE composites, and the effect on the properties was revealed.

In2O3 nanoparticles are fabricated by a sol–gel method, and annealed under air atmosphere from 400 to 1200 °C. X‐ray diffraction patterns display that all samples are the cubic bixbyite structure, grain size remains nearly unchanged below 700 °C, but remarkable increases from 35 to 72 nm after annealing up to 1200 °C. Electron microscopy also confirms the grain growth during high‐temperature annealing, and the transmission electron microscopy characterizes good crystallinity inside the grains. Raman spectroscopy indicates that the crystallinity of annealed samples is improving and the concentration of oxygen vacancies is decreasing with the increase in annealing temperature. Positron annihilation lifetime measurements identify that there are a large number of monovacancies and vacancy clusters on the surface of nanoparticles. With the increase in annealing temperature, the monovacancies keep a slight recovery and their concentration increases, but the vacancy clusters become smaller vacancies and their concentration decreases. Room‐temperature ferromagnetism exists in the samples after annealing at 400–1000 °C, and the magnetization decreases gradually with the increase in annealing temperature, which is in coincidence with the recovery of vacancy clusters after annealing. These findings suggest that ferromagnetism in annealed In2O3 nanocrystals might be due to the indium–oxygen vacancy clusters rather than grain size effects.

Giving a deep insight into the microstructure, and realizing the correlation between microstructure and properties is very important to the precise construction of high-performance graphene/polymer nanocomposites (GPN). For the promising application in microstructure characterization, much attention has been focused on the effective technique of positron annihilation lifetime spectroscopy (PALS). Based on the introduction of the basic principle, this review summarized the application progress of PALS in the correlation of microstructure and properties for GPN, especially for the characterization of free volume and interfacial interaction, and the correlation of these microstructures and properties.