The multiple melting behavior of poly(butylene succinate) (PBSu) was studied with differential scanning calorimetry (DSC). Three different PBSu resins, with molecular weights of 1.1 ϫ 10 5 , 1.8 ϫ 10 5 , and 2.5 ϫ 10 5 , were cooled from the melt (150°C ) at various cooling rates (CRs) ranging from 0.2 to 50 K min Ϫ1 . The peak crystallization temperature (T c ) of the DSC curve in the cooling process decreased almost linearly with the logarithm of the CR. DSC melting curves for the melt-crystallized samples were obtained at 10 K min Ϫ1 . Double endothermic peaks, a high-temperature peak H and a low-temperature peak L, and an exothermic peak located between them appeared. Peak L decreased with increasing CR, whereas peak H increased. An endothermic shoulder peak appeared at the lower temperature of peak H. The CR dependence of the peak melting temperatures [T m (L) and T m (H)], recrystallization temperature (T re ), and heat of fusion (⌬H) was obtained. Their fitting curves were obtained as functions of log(CR). T m (L), T re , and ⌬H decreased almost linearly with log(CR), whereas T m (H) was almost constant. Peak H decreased with the molecular weight, whereas peak L increased. It was suggested that the rate of the recrystallization decreased with the molecular weight. T m (L), T m (H), T re , and T c for the lowest molecular weight sample were lower than those for the others. In contrast, ⌬H for the highest molecular weight sample was lower than that for the others. If the molecular weight dependence of the melting temperature for PBSu is similar to that for polyethylene, the results for the molecular weight dependence of PBSu can be explained.

The multiple melting behavior of poly(butylene succinate) (PBSu) was studied with differential scanning calorimetry (DSC). Three different PBSu resins, with molecular weights (MWs) of 1.1 × 105, 1.8 × 105, and 2.5 × 105, were isothermally crystallized at various crystallization temperatures (Tc) ranging from 70 to 97.5 °C. The Tc dependence of crystallization half‐time (τ) was obtained. DSC melting curves for the isothermally crystallized samples were obtained at a heating rate of 10 K min−1. Three endothermic peaks, an annealing peak, a low‐temperature peak L, and a high‐temperature peak H, and an exothermic peak located between peaks L and H clearly appeared in the DSC curve. In addition, an endothermic small peak S appeared at a lower temperature of peak H. Peak L increased with increasing Tc, whereas peak H decreased. The Tc dependence of the peak melting temperatures [Tm(L) and Tm(H)], recrystallization temperature (Tre), and heat of fusion (ΔH) was obtained. Their fitting curves were obtained as functions of Tc. Tm(L), Tre, and ΔH increased almost linearly with Tc, whereas Tm(H) was almost constant. The maximum rate of recrystallization occurred immediately after the melting. The mechanism of the multiple melting behavior is explained by the melt‐recrystallization model. The high MW samples showed similar Tc dependence of τ, and τ for the lowest MW sample was longer than that for the others. Peak L increased with MW, whereas peak H decreased. In spite of the difference of MW, Tm(L), Tm(H), and Tre almost coincided with each other at the same Tc. The ΔH values, that is crystallinity, for the highest MW sample were smaller than those for the other samples at the same Tc. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2039–2047, 2005

Eight spirostanol saponins, including four new compounds, and two known furostanol saponins were isolated from the fresh bulbs of Lilium candidum. The structures of new compounds were determined to be (25R,26R)-26-methoxyspirost-5-ene-3 beta,17 alpha-diol 3-O-¿O-alpha-L-rhamnopyranosyl-(1-->2)-O-[beta-D-glucopyranosyl-(1-->4)] -beta-D-glucopyranoside¿, (25R,26R)-26-methoxyspirost-5-ene-3 beta,17 alpha-diol 3-O-¿O-alpha-L-rhamnopyranosyl-(1-->2)-O-[6-O-acetyl-beta-D-glucopyranos yl- (1-->4)]-beta-D-glucopyranoside¿, (25R,26R)-26-methoxyspirost-5-ene-3 beta,17 alpha-diol 3-O-¿O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside¿ and (25S)-spirost-5-ene-3 beta,27-diol 3-O-¿O-beta-D-glucopyranosyl-(1-->3)-O-alpha-L-rhamnopyranosyl-(1-->2)-O - [beta-D-glucopyranosyl-(1-->4)]-beta-D-glucopyranoside¿, respectively, on the basis of spectroscopic analysis, including two-dimensional NMR techniques, and the result of hydrolysis. The inhibitory activity of the isolated saponins on Na+/K+ ATPase was evaluated.

The effect on the metallurgical structure and wear behavior of Al-Si alloy and steel produced by nitrogen ion implantation and ion beam mixing deposition (simultaneous nitrogen ion implantation and Ti vapor deposition) using an ion beam source were studied.A combination of X-ray diffraction, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) was used to determine the metallurgical structure and chemical composition, and to investigate.The chemical bonding state of the ion treated surfaces.X-ray diffraction data showed that TiN films were formed at room temperature by ion beam mixing treatment.It is demonstrated, that a mixing layer was observed between the substrate and TiN film.AlN was observed when nitrogen ions were implanted in Al-Si alloy. The pin-on disk wear test showed a decrease in the coefficient of friction and an increase in wear resistance for surface treated by both nitrogen ion implantation and ion beam mixing.

No abstract

No abstract

No abstract

No abstract