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Ren Y.,South China University of Technology | Lu J.,South China University of Technology | Jiang O.,Guangdong Winner Functional Materials Co. | Cheng X.,South China University of Technology | Chen J.,Guangdong Winner Functional Materials Co.
Cuihua Xuebao/Chinese Journal of Catalysis | Year: 2015

A post-synthetic modification strategy has been used to prepare three solid base catalysts, including Er(btc)(ED)0.75(H2O)0.25 (2, btc = 1,3,5-benzenetricarboxylates, ED = 1,2-ethanediamine), Er(btc)(PP)0.55(H2O)0.45 (3, PP = piperazine), and Er(btc)(DABCO)0.15(H2O)0.85 (4, DABCO = 1,4-diazabicyclo[2.2.2]octane), by grafting three different diamines onto the coordinatively unsaturated Er(III) ions into the channels of the desolvated lanthanide metal-organic framework (Er(btc)). The resulting metal-organic frameworks were characterized by elemental analysis, thermogravimetric analysis, powder X-ray diffraction, and N2 adsorption. Based on its higher loading ratio of the diamine, as well as its greater stability and porosity, catalyst 2 exhibited higher catalytic activity and reusability than catalysts 3 and 4 for the Knoevenagel condensation reaction. The catalytic mechanism of 2 has also been investigated using size-selective catalysis tests. © 2015, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Luo F.,Sichuan University | Wang K.,Sichuan University | Ning N.,Sichuan University | Geng C.,Sichuan University | And 5 more authors.
Polymers for Advanced Technologies | Year: 2011

As part of a continuous effort to develop high performance isotactic polypropylene (iPP) based on β-form crystalline and morphological change induced by rare earth nucleator (WBG), various WBG contents (from 0.025 to 1.0wt%) were adopted to prepare β-nucleated iPP at a fixed final molten temperature (240°C) in this study. The crystallinity, polymorphic composition, and crystalline morphology were inspected in detail by a series of crystallographic characterizations, including calorimeter, X-ray diffraction, polarized light microscopy (PLM), and electron microscopy. Furthermore, the self-organization and re-crystallization behavior of β-nucleating agent occurred during cooling was characterized by rheometry. Finally, the dependence of mechanical properties, including tensile strength, elongation at break, and impact strength, on WBG content was discussed based on the variations in β-form content and crystalline morphology. Interestingly, it is found that while the WBG content is below 0.1wt%, the toughness of β-nucleated iPP increases with increase in WBG content due to additional β-form content; as the WBG content is in range of 0.1-0.5wt%, the toughness increases at a lower rate with increase in WBG content due to β-crystalline morphological change. However, a decrease in toughness is observed while nucleator content is above 0.5wt% as WBG remains undissolved in iPP upon the adopted processing conditions. The result of this study provides valuable information for potential industrial applications. © 2010 John Wiley & Sons, Ltd.

Ding H.,Hebei University of Technology | Xiao S.,Hebei University of Technology | Wang H.,Hebei University of Technology | Chen X.,Hebei University of Technology | Zheng D.,Guangdong Winner Functional Materials Co.
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2011

In the study, a new rare-earth β-nucleating agent (WBGII) was used to modify ethylene-propylene random copolymer (PPR). By means of wide-angle X-ray diffraction (WAXD), differential scanning calorimeter (DSC) and polarizing optical microscope (POM), the crystallization behavior and morphology of PPR induced by WBGII were studied. The effect of β nucleating agent on mechanical property and heat distortion temperature (HDT) was researched also. The results show that β-form nucleating agent WBGII can change the crystal structure of PPR and rise the maximums of exothermic peaks (Tc) of non-isothermal crystallization from 95.8°C to 102.1°C. The tensile and bend capability decrease a little and the impact strength increases by 24%. The HDT is risen by 20°C.

Zhang J.,Hebei University of Technology | Zheng D.,Guangdong Winner Functional Materials Co. | Liang X.,Guangdong Winner Functional Materials Co. | Li J.,Hebei University of Technology | And 2 more authors.
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2012

WBG II is an efficient nucleating agent to prepare isotactic polypropylene (iPP) samples riching in β crystals. Depending on the melting tempreture (T melt), WBGII maybe partially or completely dissolve in the iPP melt. The structure and crystallization characteristics of the nucleated samples were studied by polarized light microscopy (PLM) and differential scanning calorimetry (DSC). It was found that the lateral surface of the needle crystals acted as β-nucleating agent when T melt was lower than 230°C. When T melt was higher than 230°C, we observed dendritic and microcrystalline structures, and a spectacular "flower"-like agglomerate. When T melt is different, iPP performs different crystallization behaviors.

Ding H.-L.,Hebei University of Technology | Guo L.-Y.,Hebei University of Technology | Li D.-J.,Hebei University of Technology | Zheng D.,Guangdong Winner Functional Materials Co. | And 2 more authors.
Chinese Journal of Polymer Science (English Edition) | Year: 2015

In this study, the effect of annealing temperature on the impact toughness of β-nucleated polypropylene random copolymer (PPR) and ethylene-propylene-diene terpolymer (EPDM) blends was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). Interestingly, the impact strength of β-PPR/20EPDM blend annealed at 120 °C is 1.8 times as high as that of unannealed samples. In addition, the crystalline structure, the relaxation of chain segments and fracture morphology of β-PPR/EPDM blends were also investigated to explore the toughening mechanism related to annealing. The results show that annealing at moderate temperatures results in the improvement of integrity of the crystal structure and the relative content of β-phase. The work provides a possible method to toughen the semicrystalline polymer at low temperatures by annealing. © 2015, Chinese Chemical Society, Institute of Chemistry, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.

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