THERMOCHIMICA ACTA
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2018
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IF 2.189
Feng Bao,Lishuai Zong,Nan Li,Yuanyuan Song,Yunxing Pan,Jinyan Wang,Xigao Jian
In this study, a series of poly(phthalazinone fluorenyl ether ketone ketone) (PPFEKK) copolymers were designed and synthesized via nucleophilic aromatic substitution polymerization of 1,4-bis(4-fluorobenzoyl)benzene (BFBB), 4-(4-hydroxyphenyl)(2 H)-phthalazin-1-one (DHPZ) and 9,9-bis(4-hydroxyphenyl)fluorene (BHPF) to investigate the effects of bulky fluorene units on the processability and thermal degradation behavior of the polymers. The structures of the PPFEKKs were investigated and confirmed by FTIR, 1 H NMR, wide-angle X-ray diffraction (WAXD) and gel permeation chromatography (GPC) techniques. Traditional thermal measurements showed that the T d 5% and T d 10% values of the copolymers increased as the content of BHPF units increased from 0 to 100 mol%, while their glass transition temperatures gradually decreased. The rheological measurements showed that the processability of the copolymers significantly improved upon incorporation of BHPF units; the poly(aryl ether)s were less viscous and thus more processable. The thermal degradation kinetics were clarified using TGA with Kissinger’s method. The copolymer undergoes two thermal degradation processes: as the content of BHPF units in the copolymers increased from 0 to 100 mol%, the activation energy of the first degradation reaction increased from 228 to 254 kJ mol −1 , and the activation energy of the second degradation reaction increased from 271 to 298 kJ mol −1 . The resulting films displayed excellent tensile strength (higher than 76 MPa), and their Young’s modulus values were inversely proportional to their BHPF contents. Dynamic mechanical analysis showed storage modulus values at 30 °C of approximately 2662, 2826, 2698, 2791 and 2830 MPa for the prepared polymers. Furthermore, the PPFEKKs were soluble in a variety of organic solvents, making them suitable for film casting.
研究领域:
高分子化学
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材料科学
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产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2015
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IF 7.435
Peng Yi-Zhu,Ma Wan-Hong,Jia Man-Ke,Zhao Xiao-Rong,David M. Johnson,Huang Ying-Ping
In this study, a weakly polar pesticide acetochlor in water was tried to degrade by BiOBr catalysts under visible light irradiation. Its degradation reaction rate increased exponentially with increasing catalyst dosage, which was significantly different from conventional photocatalytic patterns established for polar or water-soluble pollutants. Thus, the rate-dosage relationship of BiOBr/acetochlor was compared to that of BiOBr/Rhodamine B (RhB) (a typical strong polar dye pollutant in water) at different BiOBr dosages. The degradation rate of RhB increased with the BiOBr dosage and then plateaued due to more catalyst particles blocking the light into the inner solution, which is a typical behavior for heterogeneous photocatalysis of polar organic compounds in aqueous solution. While acetochlor behaved differently, its degradation rate increased exponentially with the BiOBr dosage, and no plateau was observed even up to 9.0 g/L BiOBr dosage. This special rate-dose relationship for weakly polar acetochlor was correlated with a unique adsorption property of BiOBr to acetochlor in water solution. There was a re-distribution effect that always exclude excessive acetochlor adsorbed on BiOBr surface regardless either substrates or BiOBr overdose. This finally resulted in every BiOBr particle having enough adsorption sites available for dissolved dioxygen to function thereby accelerate the degradation of weakly polar organic compounds in water.
研究领域:
环境化学
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光催化
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水污染控制
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环境功能材料
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污染物降解机制
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DOI
高影响因子
POLYMERS FOR ADVANCED TECHNOLOGIES
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2017
·Vol. 28
·期 11
·1438-1447
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IF 1.907
Xin Liu,Xuewen Guo,Yunfei Zhi,Shaoyun Shan,Yonghao Ni,Qingming Jia
The recent development of sulfur dioxide (SO 2 ) polymerization has seen a renaissance in its chemistry, especially poly(olefin sulfone)s from the copolymerization of SO 2 , and unsaturated hydrocarbons can be found to have many applications, including transient electronic packaging, drug delivery, and electron beam-resistant materials. In this work, a type of functional poly(norbornene sulfone) was synthesized via two different polymerization methods. Aiming to understanding the effects of different polymerization methods on poly(olefin sulfone)s and gain further understanding on the kinetics of poly(olefin sulfone)s's thermal instability, we investigated their detailed thermal degradation behaviors using thermogravimetry and analyzed the resultant kinetics in accordance with three kinetic models. The results supported the conclusion that although the poly(norbornene sulfone)s obtained have different activation energy, the thermal degradation kinetics are the same and also obey the D n type. Copyright © 2017 John Wiley & Sons, Ltd.
研究领域:
高分子化学
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材料科学
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热分析
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功能高分子
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可控降解材料
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DOI
高影响因子
Desalination and Water Treatment
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2024
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IF 1
Pingping Cheng,Fangyuan Sun,Wei Wang,Jingwei Feng,Zhen-Hu Hu,Shoujun Yuan,Qiquan Wang
5-Fluorouracil (5-FU) and cytarabine (Ara-C) are two commonly used antineoplastic drugs, which are ecotoxic and genotoxic and frequently detected in hospital wastewater. Potassium permanganate (KMnO 4 ) has been widely used to remove organic pollutants from wastewater. The oxidative deg- radation of 5-FU and Ara-C in aqueous solution by KMnO 4 has not been reported. In this study, the oxidative degradation of 5-FU and Ara-C with KMnO 4 in aqueous solution was investigated. 5-FU was oxidized rapidly by KMnO 4 due to the olefinic group in the central heterocyclic ring. The degradation kinetics of 5-FU was well described by the equation of –d[5-FU]/dt = k app [5-FU] t 0.77 [KMnO 4 ] t 0.86 . The degradation kinetics of Ara-C followed a generalized second-order rate law. The apparent rate constant (k app ) of these two target compounds was strongly depended on the reaction temperature, pH, humic acid (HA) and water quality. The apparent activation energies (E a ) of 5-FU and Ara-C were 32 and 40 kJ·mol –1 , respectively, indicating that 5-FU was more easily decomposed by KMnO 4 as compared with Ara-C. The maximum values of k app for 5-FU and Ara-C were 1.73 × 10 –4 μM –0.63 ·s –1 at pH 7.4 and 1.52 M –1 ·s –1 at pH 3.5, respectively. The oxidative degradation of 5-FU was inhibited by HA, while the oxidation of Ara-C was enhanced by HA. Reaction of both 5-FU and Ara-C was influenced by water quality. Thus, this study provides new insights into the degradation of antineoplastic drugs.
研究领域:
环境化学
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药物污染
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水处理
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降解动力学
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抗肿瘤药物
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DOI
高影响因子
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