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  • Author or Editor: Zhiyong Wei x
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Abstract  

In this study, α-phase nucleating agent (NA) 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol (DMDBS), β-phase rare earth NA (WBG), and their compound NAs were introduced into isotactic polypropylene (iPP) matrix, respectively. Crystallization kinetics and subsequent melting behavior of the nucleated iPPs were comparatively studied by differential scanning calorimetry (DSC) under both isothermal and nonisothermal conditions. For the isothermal crystallization process, it is found that the Avrami model successfully described the crystallization kinetics. The active energy of nonisothermal crystallization of iPP was determined by the Kissinger method and showed that the addition of nucleating agents increased the activation energy. Melting behavior and crystalline structure of the nucleated iPPs are dependent on the nature of NAs and crystallization conditions. Higher proportion of β-phase can be obtained at higher content of β-nucleating agent and lower crystallization temperature or lower cooling rate.

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Abstract

Crystallization behavior of isotactic polypropylene (iPP)/magnesium salt whisker (MSW) composites modified by compatibilizer PP-g-MAH was studied under both isothermal and nonisothermal conditions. Analysis of the isothermal crystallization showed that the Avrami model successfully described the crystallization process. On the basis of Lauritzen–Hoffman theory, a regime transition was observed at about 139 °C for the iPP/MSW composite, and a decrease in the fold surface free energy was calculated with the addition of MSW and PP-g-MAH. The addition of MSW filler and PP-g-MAH compatibilizer distinctly improved the crystallization temperature and accelerated the total crystallization rate of iPP. It was observed that MSW induced the formation of β-iPP but PP-g-MAH suppressed the formation of β-iPP.

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Abstract  

In this work, elemental distributions in the rat olfactory bulbs (OB) were measured by synchrotron radiation X-ray fluorescence (SRXRF) 9 hours after unilateral intranaris application of MnCl2 solution. The effects of deposition of exogenous Mn in the OB on the distributions of other elements, particularly calcium, were also investigated. The results show that the application of MnCl2 solution in the nasal cavity resulted in inhomogeneous deposition of Mn in the OB, with the highest Mn content found in the ipsilateral glomerular layer (GL). Locations in the ipsilateral hemisphere of the OB with higher Mn content were found to be associated with significantly higher calcium and zinc contents, suggesting the presence of excess exogenous Mn may affect the homeostasis of other trace elements such as calcium and zinc.

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