Polymers
·
2017
·Vol. 9
·期 8
·325
·
IF 3.364
Xiufeng Hao,Chundi Zhang,Lin Li,Hexin Zhang,Yanming Hu,Daifeng Hao,Xuequan Zhang
Vanadium complexes bearing naphthalene-bridged nitrogen-sulfonate ligand ([ê2(N,O)-8-(PhN)-1-naphthalenesulfonato]VOCl (1a) and [ê2(N,O)-8-(PhN)-1-naphthalenesulfonato]VCl2(1b)) were synthesized. Activated by ethylaluminium sesquichloride (EASC) and in the presence of ethyl trichloroacetate (ETCA) as reactivator, complexes1aand1bshowed activities of up to 39.1 kg polymer (mol V)−1h−1, affording the copolymers with high molecular weights (Mwup to 28 × 104) and narrow molecular weight distributions (Mw/Mn~ 3.0) as well as high propylene incorporation of up to 49.4%. Compared to the traditional VOCl3system, these complexes exhibited higher propylene incorporation ability and higher catalytic activities especially at high polymerization temperatures of 50 °C and above. Determined by DSC and13C NMR, the copolymers obtained with1aand1bhad more random structures than that with the VOCl3system.Keywords:vanadium catalyst;ethylene/propylene copolymerization;polyolefin
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2021
·
IF 5.541
Xiao-Li Zhou,Pin-Jing He,Wei Peng,Fan Lü,Li-Ming Shao,Hua Zhang
Pyrolysis of plastics is a promising technique towards high-value utilization and solvent-free treatment of plastic waste. However, low product selectivity and broad product distribution may restrict the application of plastic pyrolysis. In this study, polyolefins and polystyrene (PS) were converted into methane and carbon spheres through pyrolysis under autogenic atmosphere (AAP). To elucidate the product evolution and reaction mechanism of AAP, product distributions, compositions and properties at 450–700 °C were investigated. At 450 °C, polyolefins were converted into 89.3–96.91 wt% pyrolysis oil ; PS was converted into 88.4 wt% of pyrolysis oil, 2.3 wt% of gas and 9.3 wt% of char. As the increase of temperature, the yields of methane and pyrolysis char increased significantly. At 700 °C, the yields of pyrolysis chars were as high as ~45 wt% and 74.1 wt% for polyolefins and PS, respectively, and the rest products was mainly pyrolysis gas with less than 1 wt% of pyrolysis oil. Pyrolysis chars were well carbonized spheres with diameters of 2 − 8 µm. Pyrolysis gas contained 93.83–95.74 vol% of methane, and possessed higher heating values of 35.8–36.2 MJ m −3 . The pyrolysis products with high purity and narrow distribution can be attributed to the enhancement of AAP on the secondary reactions of primary decomposition products, such as cracking, hydrogenation, aromatization and condensation .
研究领域:
环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2023
·
IF 4.4
Guanyu Wang,Dan Xu,Jiaqi Tang,Bingzhi Liu,Zhandong Wang,Qiang Xu,Yanjun Hu,Jinsong Zhou,Shurong Wang
As an important component of organic solid wastes, disposal of plastic wastes (PWs) has always been a thorny issue. Thermochemical conversion is an efficient method. In-depth research on the influence of structural differences on their pyrolysis behavior is beneficial to promote the development of thermal treatment and conversion technology of PWs. The differences in the chemical structure of different polyolefin plastics at the molecule level are mainly reflected in their side chains. Herein, a series of typical polyolefin plastics with similar backbone structure and different side chain structures, including high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyvinyl alcohol (PVA) and ethylene-vinyl acetate copolymer (EVA), were selected for comprehensive pyrolysis characterization in this work. Advanced experimental analysis methods such as in-situ DRIFT and 2D-PCIS were adopted to investigate the evolution of two weak oxygen-containing side chains during pyrolysis of PVA and EVA, respectively. Besides, typical product distribution of six samples were systematically studied by combining SVUV-PIMS and GC/MS. Spectral analysis showed that OH side chain in macromolecular structure of PVA had the weakest thermal stability, and its oxidation reaction occurred earlier than dissociation and dehydration, while the acetoxy side chain in EVA polymers could not only be directly dissociated via deacetoxylation, but also be transformed into OH side chain via deacetylation that occurred simultaneously with deacetoxylation. Further combined with SVUV-PIMS and GC/MS, the distribution characteristics of pyrolysis products of polyolefin plastics and the rules of generation and release of typical products with temperature were obtained in detail. It was found that the release of typical oxygen-containing products was earlier or slightly earlier than the release of hydrocarbons in pyrolysis of PVA or EVA. However, the release of all hydrocarbons was almost simultaneous during the respective pyrolysis process of HDPE, PP and PS, suggesting that the evolution of oxygen-containing side chains with weak thermal stability occurred earlier under the drive of temperature. Based on the characterization results, the main evolution pathways of different side chains were proposed to explain the influence mechanism of different side chain structures on the pyrolysis behavior of polyolefin plastics. The cleavage of C C bonds mainly occurred in HDPE, PP and PS, while the evolution of side chains occurred first in PVC, PVA and EVA, and exerted different influence on the degradation of carbon skeleton.
研究领域:
环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMISTRY OF MATERIALS
·
2023
·
IF 8.6
Xin Sun,Zheng-Yi Wang,Yang Wang,Xiang-Yun Du,Ji-Dong Liu,Cheng Zhang,Weili Li,Zheng-Bai Zhao
Heat dissipation has become a central issue for the development of the microelectronic industry. Thermal interface materials (TIMs) have been widely applied to electron component cooling, which is used to bond the heat spreader and the chip together. Most research on TIMs has only dealt with thermal conductivity enhancement. However, the mechanical properties and adhesion of TIMs are indispensable for practical applications, as well as postcleaning to remove TIMs. A graphene nanosheet/polyolefin elastomer (GNP/POE) film was designed and prepared by a facile method, in which the heat conduction paths were efficiently constructed, and the good mechanical properties of POE were reserved. The thermal conductivity of as-prepared GNP/POE film can reach 1.07 W m–1 K–1 at an extremely low filler loading of 0.62 wt %. Furthermore, the tensile strength, elongation at break, and adhesion of the prepared GNP/POE film are as good as those of commercial TIM productions. The prepared GNP/POE film can be used as TIMs for chip cooling and exhibits a good heat dissipation effect. Additionally, the prepared GNP/POE film can be peeled off from the chip without residue, after the chip has finished running, which is significant for practical production. This work provides valuable information and insight into the design and fabrication of TIMs in the future.
研究领域:
材料科学
·
热管理技术
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
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2017
·Vol. 55
·期 13
·2227-2233
·
IF 2.952
Zhi-Peng Yu,Na Liu,Ya-Lan Lin,Jian Huang,Hui-Qing Wang,Zong-Quan Wu
A cholesteryloxyallene (1) bearing chiral cholesteryl pendant group was designed and synthesized. Living polymerization of this monomer with an allylnickel complex as a catalyst give poly(cholesteryloxyallene)s (poly- 1 m s) in high yields with controllable molecular weights and narrow molecular weight distributions. These polymers were found to possess a dynamic helical conformation with a preferred handedness in n -hexane as confirmed by circular dichroism and absorption spectra as well as optical ratios. The helical conformation of the polymers was revealed to stabilize as the number of repeat units increased until the degree of polymerization reached 100. The helical conformation of poly- 1 100 could be controlled by altering the temperature of solutions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2227–2233
研究领域:
高分子化学
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材料科学
✓ 已验证
DOI
高影响因子
Polymers
·
2022
·Vol. 14
·期 11
·2200
·
IF 4.967
Jiaojiao Dong,Hao Wang,Qilong Zhang,Hui Yang,Jianlin Cheng,Zhaoyue Xia
The rapid development of the 5G communication technology requires the improvement of the thermal stability and dielectric performance of high-frequency copper clad laminates (CCL). A cyclic olefin copolymer (COC) resin was added to the original 1,2-polybutadienes (PB)/styrene ethylene butylene styrene (SEBS) binary resin system to construct a PB/SEBS/COC ternary polyolefin system with optimized dielectric properties, mechanical properties, and water absorption. Glass fiber cloths (GFCs) and SiO2were used to fill the resin matrix so to reduce the thermal expansion coefficient (CTE) and enhance the mechanical strength of the composites. It was found that the CTE of polyolefin/GFCs/SiO2composite laminates decreased with the increase of SiO2loading at first, which was attributed to the strong interfacial interaction restricting the segmental motion of polymer chains between filler and matrix. It was obvious that the addition of COC and SiO2had an effect on the porosity, as shown in the SEM graph, which influenced the dielectric loss (Df) of the composites directly. When the weight of SiO2accounted for 40% of the total mass of the composites, the laminates exhibited the best comprehensive performance. Their CTE and Dfwere reduced by 63.3% and 22.0%, respectively, and their bending strength increased by 2136.1% compared with that of the substrates without COC and SiO2. These substrates have a great application prospect in the field of hydrocarbon resin-based CCL.Keywords:polymer-based composites;substrate materials;dielectric properties;fillers
研究领域:
材料科学
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电子工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nature Communications
·
2023
·Vol. 14
·期 1
·1-10
·
IF 16.6
Miao Yingxuan,Zhao Yunxuan,Waterhouse Geoffrey I. N.,Shi Run,Wu Li-Zhu,Zhang Tierui
The widespread use of polyolefin plastics in modern societies generates huge amounts of plastic waste. With a view toward sustainability, researchers are now seeking novel and low-cost strategies for recycling and valorizing polyolefin plastics. Herein, we report the successful development of a photothermal catalytic recycling system for transforming polyolefin plastics into liquid/waxy fuels under concentrated sunlight or xenon lamp irradiation. Photothermal heating of a Ru/TiO 2 catalyst to 200–300 °C in the presence of polyolefin plastics results in intimate catalyst-plastic contact and controllable hydrogenolysis of C-C and C-H bonds in the polymer chains (mediated by Ru sites). By optimizing the reaction temperature and pressure, the complete conversion of waste polyolefins into valuable liquid fuels (86% gasoline- and diesel-range hydrocarbons, C 5 -C 21 ) is possible in short periods (3 h). This work demonstrates a simple and efficient strategy for recycling waste polyolefin plastics using abundant solar energy.
研究领域:
环境科学
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材料科学
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能源科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
EUROPEAN POLYMER JOURNAL
·
2021
·
IF 4.598
Bo Wu,Yi Xu,Nan Wu,Xianzhong Tang
Dielectric materials play a crucial role in 5G communication technological applications such as printed circuit board (PCB) high-frequency substrate materials. Unfortunately, the fabrication of desirable dielectric performance in organic–inorganic composites is a great challenge because of lack of good interfacial compatibility and uniform dispersion between fillers and polymer. In this work, silicon dioxide (SiO 2 ) was synchronously functionalized by γ-methacryloxypropyltrimethoxysilane (MPS, s-SiO 2 ) and 1,2-polybutadiene (PB, v-SiO 2 ), which were then used as fillers to fabricate the s-SiO 2 /polyolefin or v-SiO 2 /polyolefin laminates. All the v-SiO 2 /polyolefin laminates exhibited better dielectric, thermal and mechanical properties than those of s-SiO 2 /polyolefin laminates under the same filler content. Specially, the 50 wt% v-SiO 2 /polyolefin laminate displays a low dielectric constant (3.42) and loss (3.55 × 10 -3 ) at 10 GHz. Meanwhile, it also shows good stability of dielectric properties in a wide range of high-frequency. This work is conducive to develop laminates with superior dielectric properties and apply to PCB high-frequency substrate field.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
ADVANCED MATERIALS
·
2024
·
IF 27.4
Jianye Gao,Jun Zhao,Zerong Xing,Minghui Guo,Haijiao Xie,Wangjing Ma,Jing Liu
Upcycling waste plastics is highly promising to tackle global white pollution while achieving sustainable development. However, prevailing approaches often encounter challenges in scalable engineering practices due to either insufficient plastic upcycling capability or arduousness in the separation, recovery, and purification of catalysts, which inevitably augments the cost of plastic upcycling. Here, the microwave-powered liquid metal synergetic depolymerization is presented to facilitate low-cost plastic upcycling. By leveraging the fluidity of liquid metals and their exceptional chemical-bond activation ability under microwave field, this method efficiently converts various polyolefins into narrowband hydrocarbon oil (Oil yield: 81 wt.% for polypropylene (PP), 85.9 wt.% for polyethylene (PE)) and high-value olefin monomers (C 2-4 selectivity: 50% for PE, 65.3% for PP) over 30 successive cycles, resulting in a high turnover frequency of 2.83 kg Plastic mL Liquid metal −1 . These captivating advantages offered by electromagnetically-powered liquid metals are also supported by their self-separation features, thereby paving the way for large-scale engineering solutions in waste plastic upcycling.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Zhexian Wang,Hongkui He,Yunbo Zhai,Zhixiang Xu,Yongxing Chen,Xiangmin Liu
The photoaging processes of microplastics (MPs) under various conditions, including environmental factors and soluble organic matter, have been extensively investigated. However, a notable gap exists in the literature regarding comparative experiments on the photoaging of polyolefin-type MPs, and research on different light sources is particularly scarce. This research involved exposing representative MPs (polystyrene (PS), polyvinyl chloride (PVC), and polyethylene (PE)) to light with different wavelength ranges (200–2000 nm and 320–780 nm). Results indicated that PS and PVC , with benzene rings and C-Cl chains, exhibited higher susceptibility to photoaging compared to PE, leading to changes in physicochemical properties. In 200–2000 nm, including UVC (200–280 nm) and UVB (280–315 nm), a pronounced PS and PVC photoaging process was observed due to their higher energy, which resulted in noticeable yellowing of the morphology. PE showed less pronounced effects, except for noticeable aging in the 320–780 nm range within 6 h (UV–vis spectrum), with a slow depolymerization rate over 72 h. Furthermore, a limited aging of polyolefins was observed under dark conditions. In summary, this study provides crucial insight into the accelerated photoaging of polyolefin-type MPs under different light source, which offers novel perspectives and references for future research directions.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS LETTERS
·
2018
·
IF 2.687
Peng Qu,Xiaolin Liu,Sijing Wang,Chen Xiao,Shanshan Liu
Moderate dehydrofluorinated PVDF (MD PVDF) composed of polyene and untreated PVDF was produced by elimination reaction in polyvinyl pyrrolidone (PVP) and KOH aqueous solution. Dielectric films of MD PVDF were fabricated by solution casting method to study the energy density performance of the polymer. The energy density of MD PVDF was enhanced and the maximum energy density was 10.5 J/cm 3 at 450 kV/mm with an efficiency of 46%. The enhanced energy density was attributed to combined effects of high conductivity of polyene and charges blockage of untreated PVDF. This work may provide a new way to enhance the energy density performance of polymer dielectrics by moderate dehydrofluorination.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
POLYMER
·
2019
·
IF 3.771
Fuzhou Wang,Guoyong Xu,Qingshan Li,Ryo Tanaka,Yuushou Nakayama,Takeshi Shiono
The first example of a 3-alkene polymerization has been successfully achieved with 3-heptene in the presence of phenyl-substituted α- diimine nickel precatalysts activated by dMMAO, and compared with the corresponding linear alkenes, i.e., 1-pentene, 2-hexene and 4-octene polymerizations. The microstructures of the produced poly(3-heptene), which consists of ethyl , propyl and butyl branches indicated the 3,4- and 4,3-insertion, followed by chain-walking, with incorporation of a small fraction of long methylene sequences of 1,7-enchainment via monomer-isomerization. Late-transition metal catalyzed polymerization reactions of internal alkenes to synthesize novel polyolefin materials are highly important and also highly challenging. Upon activation with dried modified methylaluminoxane (dMMAO), the first example of a 3-alkene polymerization has been successfully achieved for 3-heptene catalyzed by phenyl-substituted α- diimine nickel complexes in comparison, and compared with the polymerizations of the corresponding linear alkenes, i.e., 1-pentene, 2-hexene and 4-octene. The results indicate that the polymerization of 3-heptene was achieved via chain-walking to generate branched amorphous polymers with glass transition temperature of ca. −68 °C. The microstructures of the produced poly(3-heptene) indicated the 3,4- and 4,3-insertion followed by chain-walking, the latter being predominant. The NMR analyses of the polymers showed that the obtained poly(3-heptene) possessed ethyl, propyl and butyl branches and a small amount of the long methylene sequence of 1,7-enchainment via monomer-isomerization. The branches structures were significantly dependent on the polymerization temperature, and the content of propyl branches derived from 3,4-insertion decreased with an increase in the polymerization temperature.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）