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Polyamide thin film composite (TFC) reverse osmosis (RO) membranes were prepared in this study.

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The crystallization behavior and isothermal crystallization kinetics of neat poly(L-lactic acid) (PLLA) and PLLA blended with ionic liquid (IL), 1-butyl-3-methylimidazolium dibutylphosphate, were researched by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X-ray diffraction (WXRD). Similar to the non-isothermal crystallization behavior of neat PLLA, when PLLA melt was cooled from 200 to 20 C at a cooling rate of 10 C min 21 , no crystallization peak was detected yet with the incorporation of IL. However, the glass transition temperature and cold crystallization temperature of PLLA gradually decreased with the increase of IL content. It can be attributed to the significant plasticizing effect of IL, which improved the chain mobility and cold crystallization ability of PLLA. Isothermal crystallization kinetics was also analyzed by DSC and described by Avrami equation. For neat PLLA and IL/PLLA blends, the Avrami exponent n was almost in the range of 2.5-3.0. It is found that t 1/2 reduced largely, and the crystallization rate constant k increased exponentially with the incorporation of IL. These results show that the IL could accelerate the overall crystallization rate of PLLA due to its plasticizing effect. In addition, the dependences of crystallization rate on crystallization temperature and IL content were discussed in detail according to the results obtained by DSC and POM measurements. It was verified by WXRD that the addition of IL could not change the crystal structure of PLLA matrix. All samples isothermally crystallized at 100 C formed the a-form crystal.

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In this study, effects of heat setting treatment (preset heat setting ratio λ and heat setting temperature T setting ) on the crystalline structures, orientation status, microporous structures, gas permeability, and electrochemical performance of the separators were studied in detail by means of differential scanning calorimetry (DSC), infrared dichroism, scanning electron microscope (SEM), ultrasmall angle X-ray scattering (U-SAXS), Gurley value test, and electrochemical measurement. It was found that with the decrease of λ or the increase of T setting , the melting temperature and degree of crystallinity change regularly and the orientation degree decreases gradually, resulting in small-sized micropores and lower porosity and S/V ratio of the separator. Finally, the gas permeability and ionic conductivity of the separator decreased while the dimensional stability increased. By tuning λ and T setting , the microstructure, morphology, and performance of the separators can be efficiently controlled.

Compression stress on thickness direction of separators exists in assembling and operation of all lithium ion batteries (LIBs). In this study, influences of compression on microporous morphologies, electrolyte uptake behavior, and electrochemical properties of three types of commercial separators (PP-U, PP-B, and PE-B) for LIBs manufactured via different processes, were investigated. Results of scanning electronic microscope (SEM) and X-ray measurements revealed special stacked-multilayer structures of PP-B and PE-B, while PP-U was featured of micropores arranged in lines separated by lamellae in both surface view and section view. Compression was found to be key factor influencing the microporous structures, electrolyte uptake, and electrochemical properties of separators. Different microporous structures of separators were important factors determining the structural stability (tolerance to compression) of the separator and therefore influencing their performances before and after compression. A novel delamination experiment was designed to explain different structural stabilities of separators under compression. A related mechanism was proposed.