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Leng J.-H.,University of Sichuan | Liu H.,Chengdu Product Quality Supervision and Inspection Institute | He B.-B.,University of Sichuan | Yang B.,University of Sichuan | And 2 more authors.
Chinese Journal of Polymer Science (English Edition) | Year: 2013

Although addition of β-nucleating agent directly into homo-polypropylene (PPH) is a useful method to improve β-crystal content and toughen PPH, polypropylene random copolymer (PPR) makes this method powerless due to its random structure and low crystallinity. In this study, the β-nucleated PPR with high β-crystal content was prepared by a novel high effective β-nucleating system which consists of β-nucleation agent (TMB-5) and modified zeolite 13X (M13X). It was found that M13X and TMB-5 had a synergistic influence on improving β-crystal content and toughening PPR. The content of β-crystal in PPR/M13X/TMB-5 was significantly larger than the sum of that in PPR/M13X and PPR/TMB-5. Besides, fracture behavior, phase morphology and relaxation of matrix chain segments were also investigated. The results showed that M13X and TMB-5 improved the mobility of amorphous chain segments at low temperature and contributed to much energy dissipation. This work provides a powerful method to modify PPR. © 2013 Chinese Chemical Society, Institute of Chemistry, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg. Source


Yang B.,University of Sichuan | Liu H.,Chengdu Product Quality Supervision and Inspection Institute | He B.,University of Sichuan | Leng J.,University of Sichuan | Chen X.,University of Sichuan
Polymer Composites | Year: 2013

In this article, two novel copolyamide charring agents, ES-6 and M-170, were served as charring agents or synergist with ammonium polyphosphate (APP) and dipentaerythritol (DPER) for the flame-retarded polypropylene (PP). The flame-retardant system was characterized by limiting oxygen index (LOI), tensile strength, Izod impact strength, thermogravimetric analyses, differential scanning calorimeter (DSC), and scanning electron microscope (SEM). Compared with polyamide 6 (PA6), ES-6 and M-170 had better dispersion and compatibility in the PP matrix and enhanced mechanical properties. Meanwhile, as low melting point polyamides, ES-6 and M-170 could decrease processing temperature and effectively inhibit side reaction, especially the degradation of APP. In addition, the synergistic effect between ES-6 and DPER was also investigated. The results showed that the synergistic system containing ES-6 had better flame retardancy and mechanical performance in comparison with the system only using DPER or the system containing PA6. © 2013 Society of Plastics Engineers. Source


Yang B.,University of Sichuan | Leng J.,University of Sichuan | He B.,University of Sichuan | Liu H.,Chengdu Product Quality Supervision and Inspection Institute | And 2 more authors.
Journal of Reinforced Plastics and Composites | Year: 2012

The influences of the glass fiber content and initial length on the mechanical properties of long glass fiber reinforced nylon 66 (LGF-PA66) were investigated, and then the appropriate glass fiber content (30%) and initial glass fiber length (10 mm) were determined to study the effect of three kinds of compatibilizers (maleic anhydride grafted polypropylene (PP-g-MAH), maleic anhydride grafted polyolefin elastomer (POE-g-MAH) and maleic anhydride grafted ethylene propylene diene monomer (EPDM-g-MAH)) on the mechanical properties of the LGF-PA66 composites. It is found that a maximum tensile strength is reached for the composites when any of the different compatibilizers are 2.5 wt%. However, the influence of PP-g-MAH on the impact strength of composites is different from the others. Tensile strength and notched impact strength models were applied to interpret the experimental results of the mechanical properties. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/ journalsPermissions.nav. Source


Yang T.,University of Sichuan | Zheng B.,University of Sichuan | Liang H.,Chengdu Product Quality Supervision and Inspection Institute | Wan Y.,Chengdu Product Quality Supervision and Inspection Institute | And 2 more authors.
Talanta | Year: 2014

Ascorbic acid (AsA), also known as vitamin C, is a vital small-molecule antioxidant with multiple functions in vivo. It's the major natural antioxidant found in plants and is also an essential component of human nutrition. AsA plays a key role in many diseases-related biological metabolism. Therefore, sensitive and selective detection of AsA is greatly important in pharmaceutical, clinical and food industry. Here a sensitive and selective sensor for ascorbic acid detection based on the recovered fluorescence of NAPS-NO (N-propyl-triethoxysilane-4-(4-ylamino-1-oxy-2,2,6,6-tetramethylpiperdine)- naphthalimide) probe is described. The fluorescence of the naphthalimide moiety of NAPS-NO is inhibited by the nitroxide group, which is covalently linked to the fluorophore. Then, ascorbic acid reacts rapidly with the nitroxide moiety of NAPS-NO to form hydroxylamine, and the fluorescence properties of the naphthalimide moiety are recovered and the ESR signal decayed. Over a wide range from 80 nM to 50 μM, a good linear relationship between the fluorescence intensity and the concentration of ascorbic acid was found and the detection limit was estimated to be as low as 20 nM. To confirm the practical usefulness of the fluorophore-nitroxide probe, we demonstrated the use of NAPS-NO for the measurement of AsA in human blood serum and also successfully determined the concentration of AsA in HEK 293 cell lysate. Results from confocal laser scanning microscopy experiments demonstrated that this chemosensor is cell permeable and can be used as a fluorescent probe for monitoring ascorbic acid in living cells. © 2014 Published by Elsevier B.V. Source


He B.,University of Sichuan | Liu H.,Chengdu Product Quality Supervision and Inspection Institute | Leng J.,University of Sichuan | Yang B.,University of Sichuan | And 3 more authors.
Journal of Reinforced Plastics and Composites | Year: 2011

In this article, long glass fiber-reinforced polypropylene (LFPP) was prepared using self-designed impregnation device. The effects of some processing parameters including impregnation time and temperature, compatibilizer and melt flow index (MFI) of matrix which was adjusted by chemical degradation masterbatch on the impregnation quality, and mechanical properties of injection molded LFPP were discussed. Our studies show that increase in MFI of polypropylene, impregnation time and temperature, as well as addition of compatibilizer maleic anhydride grafted polypropylene (PP-g-MAH), can improve impregnation quality and mechanical properties of LFPP. The results will be useful in making high performance LFPP. © The Author(s) 2010. Source

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