In order to get poly(vinylidene fluoride) (PVDF) films containing high beta-phase content, multiwalled carbon nanotubes (MWCNTs) were blended with PVDF. For drawn samples, the content of piezoelectric beta-form crystal was increased with MWCNT addition due to the rapid crystallization rate offered by the nucleating action of MWCNT, but soon reached a plateau. Poling on the drawn samples helps additional beta-phase formation when the added MWCNT content was less than 0.2 wt%; at this MWCNT amount, almost pure beta-phase crystal was obtained. More MWCNT addition induced depolarization to reduce the beta-phase content. Undrawn samples show monotonous increase of beta-phase content with MWCNT amount when subjected to poling.

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Semicrystalline Poly(vinylidene fluoride)(PVDF) was melt blended by multiwalled carbon nanotube (MWNT) at various contents (0.01 $ 5 wt%) using internal mixer. The relationships between morphology and physical properties based on PVDF and MWNT were investigated. As the MWNT content is increased, the apparent supercooling required for PVDF crystallization and the size of spherulites in PVDF decrease. In the WAXD profiles, the incorporation of MWNT produced a large shoulder at 2u ¼ 20.78 with increasing the MWNT content, corresponding to the polar b-form crystal of PVDF. The experimental percolation threshold for the electrical conductivity in PVDF was estimated and clearly occured between 2 and 2.5 wt%. Similar tendency was also observed in thermal conductivity and permittivity.

We studied the effect of the surface functionalization and crystalline phase change of poly(vinylidene fluoride) (PVDF) films on their adhesion and piezoelectric properties. The surface modification of PVDF was carried out with ion beam and/or plasma treatment. These surface modifications were found to alter the interfacial strength between PVDF and metal electrodes and the crystal structure of the piezoelectric PVDF film. A remarkable improvement was found in the interfacial adhesion of the films with thermally deposited metal electrodes, but some piezoelectricity of PVDF film was lost due to the changes in the crystal phase. The proper treatment condition for enhancing the adhesion and retaining piezoelectric structure was suggested.

Reactive extrusion for recycled PP/nylon blends from commingled plastic wastes was investigated through thermal, morphological, mechanical and rheological studies. From SEM investigation, we found improved surface morphologies with homogeneous domains in the recycled 75/25 PP/nylon blends compatibilized with copolymers containing maleic anhydride (MA) as a reactive functional group; SEBS-g-MA, PP-g-MA, PE-g-MA. Especially, SEBS-g-MA thermoplastic elastomer which is highly reactive with amine terminal group of nylon, resulted in a large increase of impact strength above nearly 200%. This compatibilization effect resulted from the increase of interfacial adhesion and the reduction of domain size of dispersed phase in PP/nylon blend system. To confirm the existence of this network structure, we measured a dynamic rheological properties.

Semicrystalline Poly(vinylidene fluoride)(PVDF)=Multi-walled carbon nanotube (MWNT) blends were melt compounded in an internal mixer. The relationships between structures and physical properties of PVDF=MWNT blends were studied. With increasing the content of MWNT, the apparent supercooling required for PVDF crystallization and the size of spherulites in PVDF were decreased. MWNT can be used as a nucleating agent. In the crystalline structures, the incorporation of MWNT produced a polar b-form crystal of PVDF. The permittivity of PVDF=MWNT blends was increased with increasing the MWNT content. The critical conductivity saturation point for the electrical conductivity in PVDF=MWNT blends was confirmed. Similar tendency was also observed in thermal conductivity.

Background/Aim: γ-Irradiation has been proven to be the most effective method to inactivate K562 cells, but γ-irradiators are not available in some institutes. This study was designed to compare the effects of X-ray and γ-irradiation on K562 cells in natural killer (NK) cell expansion. Materials and Methods: To expand NK cells, isolated peripheral blood mononuclear cells (PBMCs) were co-cultured with γ-irradiated or X-ray-treated K562 cells plus IL-2 and IL-15. Characteristics of expanded NK cells were identified by flow cytometry. Results: NK cell expansion rate tended be to lower in the X-ray-treated group (68.9±32.6) than the γ-irradiated group (78±28.7), but the difference was not significant (p=0.39). Furthermore, NK cell functions or receptor expression were similar in the two groups. Conclusion: Our results suggest that X-ray treatment can be used as an alternative to γ-irradiation for K562 cells inactivation in human NK cell expansion.Natural killer (NK) cells are CD3-CD56+ and belong to a lymphocyte subpopulation capable of recognizing and killing cancer cells without prior immunization. It is well-known that NK cells (i.e., NK-92) are potential tools for cancer

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