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Polyimide films with Al2O3 composite layers were prepared by KOH solution surface hydrolysis, ion exchange and heat treatment. Scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray diffractometry (XRD), thermo gravimetric analyzer (TGA), breakdown voltage tester, high frequency pulse voltage machine were performed to characterize the micromorphology, thermal stability, mechanical properties, electric breakdown strength, and corona resistance time of composite films. Results indicated that the thermal properties of the composite film are better than the original film. The corona resistance time of the composite film was longer than that of the pristine film. The composite film had the longest corona resistance time and reached 101.2min while the KOH treatment time was 90min.

Agricultural biomass wastes of longan seed and mangosteen skin were collected as precursors to prepare activated carbons (LS-AC-5 and MS-AC-5, respectively) through carbonization at medium temperature and KOH activation at high temperature. Their pore structures, structural properties and surface morphologies were characterized by X-ray diffractometer, Brunauer–Emmett–Teller surface measurement system, and scanning electron microscopy, respectively. Effects of contact time and pH on adsorption performances of samples were investigated by removal of Pb(II) ions and Rhodamine-b from aqueous solutions. Experimental adsorption isotherms of Rhodamine-b and Pb(II) ions on LS-AC-5 and MS-AC-5 fitted well with the Langmuir model. Results further showed that MS-AC-5 exhibited a larger surface area of 2960.56 m2/g and larger portions of micropores and mesopores (pore volume of 1.77 cm3/g) than LS-AC-5 (surface area: 2728.98 m2/g; pore volume: 1.39 cm3/g). Maximum monolayer adsorption capabilities of 1265.82 and 117.65 mg/g for Rhodamine-b and Pb(II) ions on MS-AC-5 were higher than those on LS-AC-5 (1000.20 and 107.53 mg/g), respectively.

Polyimide films treated with an alkali and ion exchange undergo surface-confined hydrolysis to produce polyimide composites. On the other hand, it is unclear what impact this method has on the mechanical properties of PI films. This paper reports the effects of the mechanical properties of PI films exposed to an alkali (KOH) solution with different treatment time. The mechanical properties of the re-cycloimidization PI films were improved when the proper initial KOH treatment time was used. The reason might be that PI could effectively reduce the formation of the shear zone to cracks due to the increase in ductility after the proper KOH treatment and more ductile PI chains led to re-orientation at the drawing process. Therefore, the strength and elongation of the re-cycloimidization PI films were better than those of the pristine PI films. This study focused on the effects of the KOH treatment on the mechanical properties of the PI film for the first time and proposed a mechanism to explain the reason that the appropriate time of KOH treatment can enhance the mechanical properties. The results presented here can provide guidelines for preparing composite PI films via ion-exchange by the proper KOH treatment time in future studies.

Ag3PO4/TiO2nanocomposite was fabricated by an in situ precipitation method and then blended into poly(vinylidene fluoride) (PVDF) casting solution to prepare the ultrafiltration membrane via wet phase inversion technique. The water flux and bovine serum albumin (BSA) rejection rate of membrane were investigated; meanwhile, the ultrafiltration membrane morphologies and structural properties were analyzed using scanning electron microscope (SEM) and X-ray diffraction. Compared with the control membrane, the permeate performance of blended membranes was improved while possessing a steady BSA retention due to enhanced hydrophilicity. Mechanical tests revealed that the modified membranes exhibited a larger tensile strength and breakage elongation. SEM images and the halo zone testing were employed to assess the antibacterial performances of the nanocomposite membranes against Escherichia coli. The antibacterial tests confirmed that the modified membranes showed an effective antibacterial property against E. coli.