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Niu H.,CAS Institute of Chemistry | Chen X.,Petrochina | Liu Y.,Petrochina | Xu Y.,Petrochina | And 2 more authors.
Shiyou Huagong/Petrochemical Technology | Year: 2014

β-Crystalline-specified polypropylene (PP) homopolymer resins were synthesized with a novel functional Ziegler-Natta catalyst system in an industrial loop reactor. The functional Ziegler-Natta catalyst exhibited high activity and stereospecificity compared to commercial PP catalysts. The homopolymers showed good particle morphology. Two β-crystalline-specified PP resins with melting indexes (10 min) of 0.42 and 2.80 g were prepared by controlling polymerization parameters. The results of WAXD and DSC revealed that although α-crystallites were the main crystalline structure in the PP powder samples, β-crystallites dominated the crystalline type with approximate content of 80% after a melting-crystallization procedure; this structure was proved to be stable in repeated cooling-heating cycles. The β-crystalline-specified PP resins indicated β-spherocrystal morphology in addition to small amount of α-spherocrystal after crystallization. Mechanical experiments showed that the β-crystalline-specified PP resins had excellent impact-resistance at ambient temperature. Source


Qian W.,China University of Petroleum - Beijing | Wang J.,China University of Petroleum - Beijing | Liu S.,China University of Petroleum - Beijing | Guo S.,China University of Petroleum - Beijing | And 3 more authors.
RSC Advances | Year: 2015

A novel Nd coordination polymer [Nd(N-phgly)(Pha)(H2O)](H2O)2 has been solvothermally synthesized and characterized crystallographically. It is a novel 3D framework supramolecular structure coordination polymer that contains two different carboxylate liqands N-phthaloylglycine (N-phgly) and phthalic acid (Pha). The complex was characterized by elemental analysis, FT-IR spectra, X-ray single-crystal diffraction, a thermal gravimetric analyzer and powder XRD. It was incorporated into isotactic polypropylene (iPP). Then, the performance, non-isothermal crystallization behaviors, crystalline morphologies and optical properties of modified iPP were evaluated and studied. These results show that the complex is an effective and novel nucleating agent. It results in an increase in the overall crystallization rate and a decrease in the spherulite size of iPP. The Izod impact strength of NA-iPP is higher than the pure iPP. The addition of it makes the stiffness and impact resistance of iPP improve obviously. Meanwhile, the nucleated iPP displays a good balance between toughness and stiffness. Besides, the optical characteristics are also improved. © The Royal Society of Chemistry. Source


Li J.,Hebei University of Technology | Liang X.,Guangdong Winner New Materials Technology Co. | Zheng D.,Guangdong Winner New Materials Technology Co. | Guo L.,Hebei University of Technology | And 2 more authors.
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2013

Homo-polypropylene (PPH) was modified with a mixture of amides and rare β nucleating agents, and the microstructure and mechanical properties of modified PPH were studied. It is found that the notched impact strength of PPH modified with a complex of β nucleating agents exceeds that with any single β nucleating agent at the same dose, and reaches approximately 4.6 times of that of pure PPH. The synergistic toughening effect is obvious, while the rigidity is maintained. The crystalline form of the compound system is "snowflake-like" distinguished from that of any single system at a particular temperature as observed through polarized light microscopy (PLM). X-ray diffraction (XRD) curves indicate that relative content of β-crystal of PPH is between the two single ones'. Second melting curves of differential scanning calorimeter (DSC) show that the β-crystalline form in a dominant position among the overall crystallization; compared with the β-peak position in a single nucleating system, the position moves towards the low temperature. Source


Wang Y.,China University of Petroleum - Beijing | Liu K.,China University of Petroleum - Beijing | Chen J.,Guangdong Winner New Materials Technology Co. | Zheng D.,Guangdong Winner New Materials Technology Co. | Guo S.,China University of Petroleum - Beijing
Shiyou Huagong Gaodeng Xuexiao Xuebao/Journal of Petrochemical Universities | Year: 2015

Development of high efficient, environmentally friendly, low cost as well as multifunctional rubber antioxidants has been widely focused on. In this article, a new type Schiff base rubber antioxidant with combined advantages of hindered phenol and hindered amine antioxidants has been synthesized and applied in the natural rubber. The influence of the new synthesized rubber antioxidant on vulcanized performance, physical and mechanical properties, thermal stability and thermal aging kinetic was investigated in the thermal aging process of vulcanized natural rubber. The results showed that the synthesized antioxidant obviously shortened the curing time tC90 and improved the cure rate. Meanwhile, it exhibited better protective effect for thermal oxygen aging performance of NR vulcanizates, compared to the antioxidant traditional BHT. ©, 2015, Fushun Petroleum Institute. All right reserved. Source

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