Studies on uniaxially drawn poly(vinylidene fluoride) films

Poly(vinylidene fluoride) (PVDF), under certain conditions, shows a crystal transition between the alpha (TGT (G) over bar) and beta (TTT) forms, where T, G, and (G) over bar, respectively, denote trans, gauche, and minus gauche. We investigated the mechanism of this crystal transition by FT-TR and X-ray diffraction, which yielded consistent results. We also carried out differential scanning calorimeter experiments.

Miscibility of linear low density polyethylene (LLDPE)-graft-poly(methyl methacrylate) with poly(vinylidene fluoride) (PVF2) and its application as compatibilizer LLDPE/PVF2 blends

Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to study the miscibility of blends of a graft copolymer of poly(methyl methacrylate) on linear low density polyethylene (LLDPE-g-PMMA, G-3) with poly(vinylidene fluoride)(b) (PVF2) and the compatibilization of blends of LLDPE/PVF2. The specific interaction between PMMA side chains and PVF2 in G-3/PVF2 binary blends is weaker than that between the homopolymers PMMA and PVF2. There are two states of PVF2 in the melt of a G-3/PVF2 (60/40, w/w) blend, one as pure PVF2 and the other interacting with PMMA side chains. The miscibility between PMMA side chains and PVF2 affects the crystallization of PVF2. LLDPE-g-PMMA was demonstrated to be a good compatibilizer in LLDPE/PVF2 blends, improving the interfacial adhesion and dispersion in the latter. Diffusion of PMMA side chains into PVF2 in the interfacial region reduces the crystallization rate and lowers the melting point (T-m) and the crystallization temperature (T-c) of PVF2 in the blends.

AN INTEGRATED CALCIUM-FLUORIDE CRYSTAL IR THIN-LAYER CELL AND ITS APPLICATION TO IDENTIFICATION OF ELECTROCHEMICAL REDUCTION PRODUCT OF BILIRUBIN

An integrated CaF2 crystal optically transparent infrared (ir) thin-layer cell was designed and constructed without using any soluble adhesive materials. It is suitable for both aqueous and nonaqueous systems, and can be used not only in ir but also in uv-vis studies. Excellent electrochemical and spectroelectrochemical responses were obtained in evaluating this cell by cyclic voltammetry and steady-state potential step measurements for both ir and uv-vis spectrolectrochemistry with ferri/ferrocyanide in aqueous solution, and with ferrocene/ferrocenium in organic solvent as the testing species, respectively. The newly designed ir cell was applied to investigate the electrochemical reduction process of bilirubin in situ, which provided direct information for identifying the structure of the reduction product and proposing the reaction mechanism.

RADIATION EFFECTS ON POLY(VINYLIDENE FLUORIDE)

Melt-crystallized poly(vinylidene fluoride)s (PVF2) with different crystallization histories were irradiated with gamma-rays within the range of irradiation doses 0-83 Mrad. The effects on the crystalline structure and mechanical properties have been measured, compared, and discussed. The degree of crystallinity of the samples was found to increase with radiation dose. The differential scanning calorimeter scans of the quenched samples indicate that there are two melting peaks, and that the area of the lower temperature peak increases while the area of higher temperature peak decreases with increasing dose. Yield stress and breaking stress for all samples are not significantly affected by irradiation but elongation at break is.

VALENCY AND ITS CHANGE PROCESS OF SAMARIUM ION IN SAMARIUM FLUORIDE SYSTEM

Nonstoichiometric series SmF(x) (2.0 less-than-or-equal-to x less-than-or-equal-to 3.0) have been synthesized by reduction of samarium trifluoride with hydrogen for several times, and the stoichiometric samarium difluoride has been obtained. The structure of nonstoichiometric samarium fluoride series and the valency of samarium ion are briefly discussed. The valent change process of samarium ion at high temperatures in different atmospheres is investigated.

STUDY ON GAMMA-RADIATION INDUCED LAMELLAR DAMAGE MECHANISM OF POLY(VINYLIDENE FLUORIDE)

This paper studies gamma-radiation induced lamellar damage mechanism of poly(vinylidene fluoride), using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), electronic paramagnetic resonance (EPR) and gel fraction determination. We believe that it is ''lamellae core damage'' rather than ''lamellae surface damage'' that results in the decrease of the crystallinity.

XPS STUDIES OF RADIATION-INDUCED STRUCTURAL-CHANGES IN POLYVINYLIDENE FLUORIDE

In this work the radiation-induced structural changes in PVDF were studied using XPS. It was found that for PVDF irradiated at 150-degrees-C, double bonds were formed mainly through the further dehydrofluorination of crosslinked and/or branched molecules, whereas for samples irradiated at 20-degrees-C the dehydrofluorination of macromolecular radicals to form stable polyene radicals is the main source of unsaturated structures.

A NEW HYDROGEN SENSOR WITH RARE-EARTH COMPLEX FLUORIDE

A new type of solid-state galvanic cell for detecting a small amount of hydrogen in air at room temperature is proposed. The sensor cell is a potentiometric cell using Ce0.95Ca0.05F2.95 as solid-state electrolyte. The cell exhibits good sensing properties to hydrogen in air at room temperature.

Cadmium toxicity to embryonic-larval development and survival in red sea bream Pagrus major

At 18 degrees C and 33 psu, 24 and 48 h LC50 values of cadmium (Cd) for red sea bream Pagrus major embryos were 9.8 and 6.6 mg l(-1), respectively, while 24,48, 72, and 96 h LC50 values for larvae were 18.9,16.2, 8.0, and 5.6 mg l(-1), respectively, indicating that embryos were more sensitive to Cd toxicity than larvae. Cd concentrations at >= 0.8 mg l(-1) led to low hatchability (0-90% in >= 0.8 mg l(-1) solutions vs. 97-100% in lower ones), delay in time to hatch, high mortality (38-100% vs. 1-10%), morphological abnormality (42-100% vs. 1-10%), reduced length (3.55-3.60 vs. 3.71-3.72 mm) in the embryos and larvae. They were Cd concentration dependent and potential biological significant endpoints for assessing the risk of Cd to aquatic organisms. Heart beat and yolk absorption of the larvae were significantly inhibited at some high concentrations but they were not as sensitive as other endpoints to Cd exposure. (C) 2008 Elsevier Inc. All rights reserved.