FUEL
·
2023
·
IF 7.4
Kezhen Qian,Wenmin Tian,Siwei Yan,Wentao Li,Lijie Yin,Derun Guo,Zixu Yang,Dezhen Chen,Yuheng Feng
The effects of pretreatment and structure of zeolite on aromatization of high-density polyethylene (HDPE) and polypropylene (PP) over different Ga-promoted zeolites (HZSM-5, hierarchical HZSM-5, HY, Hβ, and USY) were investigated. Hydrogen reduction of Ga-promoted HZSM-5 resulted in a higher yield of alkenes during HDPE pyrolysis but did not lead to increased production of total aromatic hydrocarbons. The reduction and subsequent oxidation of Ga/Z5 led to the formation of GaO + species with high dehydrogenation activity. This resulted in a remarkable 65% yield of aromatics, with a BTEX (benzene, toluene ethylbenzene and xylene) overall yield of 60% and a selectivity of 90% of the liquid product. Increasing the Ga loading decreased the BTEX yield due to pore blockage and a decrease in the amount of Brønsted acid sites. The BTEX yield over Ga-promoted zeolites was found to be strongly related to the pore size of the zeolite, whereas its yield over the parent zeolite was not strongly dependent on the pore size. Diffusion of the cracking intermediates was found to have a more significant impact on the aromatization of PP than HDPE. The highest BTEX yield for HDPE was achieved with Ga-promoted HZSM-5, while Ga-promoted hierarchical HZSM-5 exhibited the highest BTEX yield for PP. Furthermore, Ga(1)/Hβ-Redox demonstrated remarkable selectivity (90%) towards ethylene and propylene in the gas phase, surpassing other zeolites (37%-68%).
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
Polymer-Plastics Technology and Materials
·
2020
·
IF 0
Yang Pan,Guangfeng Wu,Huifang Ma,Shujie Zhou,Huixuan Zhang
Herein, graft-modified ethylene-1-octene copolymer (POE-g-GMA) and styrene-butadiene-styrene triblock copolymer (SBS-g-GMA) were found to be excellent reactive compatibilizers for immiscible poly(ethylene terephthalate) (PET)/high-density polyethylene (HDPE) blends via in-situ reaction compatibilization. With increase in compatibilizer amount, uniform phase morphology was observed in all the blends. Thus, exhibiting enhanced mechanical properties, especially, the notched Izod impact strength. In comparison with SBS-g-GMA, compatibilizer POE-g-GMA demonstrated greater impact on the compatibility. The addition of 15% POE-g-GMA produced blends with best mechanical properties. Besides, both POE-g-GMA and SBS-g-GMA enhanced the melt viscosity of PET/HDPE blends.
研究领域:
材料科学
·
聚合物工程
✓ 已验证
产品关联
DOI
POLYMER ENGINEERING AND SCIENCE
·
2024
·Vol. 64
·期 7
·2988-3002
·
IF 3.2
Sun Yun,Xuefeng Pan,Feng Zhang,Xuelian He
The cavitation process of high-performance HDPE/UHMWPE blends with a uniform dispersion of UHMWPE during cold stretching was investigated. It was observed that incorporating a small amount of UHMWPE into the HDPE matrix resin can serve as a nucleating agent, increasing the number of contact sites and accelerating the crystallization rate. This leads to the formation of thicker lamellar crystals and tethered molecules, ultimately enhancing the mechanical properties of the HDPE matrix. Furthermore, the relationship between the natural tensile ratio and strain-hardening modulus was confirmed. Microstructural changes within the blends were also explored. As the drawing tangles in the middle, the cavities subsequently evolve by collapsing and merging to align parallel to the tensile direction, culminating in tensile damage forming a large crack in the final macroscopic form. As a result, the presence of more tethered molecules in the later stages of stretching inhibits further cavity growth. Highlights The HDPE/UHMWPE blends were prepared by solution blending and ultrasound-assisted twin-screw extrusion. The mechanisms underlying the formation and evolution of cavities in HDPE/UHMWPE blends, which lead to stress whitening during tensile damage, were examined by using DSC and SAXS/WAXD. The relationship between microstructure and mechanical properties was analyzed by cold-drawing the molded blended sheets at room temperature.
研究领域:
材料科学
·
高分子物理
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2022
·Vol. 14
·期 3
·433
·
IF 4.967
Chuanbo Liu,Shutian Liu,Conglin Dong,Chengqing Yuan,Xiuqin Bai
Reducing the deformation of polymer matrix materials can decrease the fluctuation of coefficient of friction (COF), and friction-induced vibration and its amplitudes. HDPE composites with T-ZnOw as a fixed strengthening filler were modified with the addition of Si3N4particles at different concentrations. The COFs, wear rates, micro-morphologies, and friction-induced vibrations were obtained by conducting sliding tests against carbon steel balls in an aqueous environment at a low velocity and high load. The mechanism of the reduction in frictional fluctuation due to the addition of Si3N4particles was revealed through the frictional responses. The results demonstrated that 4 wt% addition of Si3N4in HDPE can enhance the strain–stress property and improve the lubrication by forming a lubricating film. Therefore, the surface deformation and the fluctuations of COFs and its vibrations were reduced. The aggregation phenomenon and reduced strain–stress response at a high concentration of Si3N4disrupted the positive fluctuating reduction, and resulted in a rough surface with severe tearing and cracking deformations. Additionally, it led to fluctuating wear behaviors with high COF and vibrations. The results obtained in this study can elucidate the effects of adding Si3N4particles to enhance lubrication in polymer composites. Additionally, the results provide a new research method for designing and manufacturing polymer-based composites with low friction-induced fluctuations.Keywords:HDPE composite;Si3N4;surface deformation;fluctuation reduction
研究领域:
材料科学
·
摩擦学
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产品关联
DOI
PubMed
高影响因子
CHEMISTRY & BIODIVERSITY
·
2024
·Vol. 21
·期 6
·e202400150
·
IF 2.3
Long Ren,Yupu Xu,Wenjun Chen,Changsen Zhang
Experiments were conducted in this study on the co-hydropyrolysis of three components of biomass (cellulose, hemicellulose, and lignin) and HDPE by using SR-Pd/Trap-HZ-5 as catalyst. To control the variable, we use the same experiment conditions in co-hydropyrolysis: Si/Al ratio of 50, Pd load 1 %, catalyst to reactant ratio of 1 : 10, 1 MPa, 400 °C, reaction time 1 h. Use XRD, TEM, BET, and NH 3 -TPD to confirm catalyst successful synthesis; use pine sawdust (PW) co-hydropyrolysis with HDPE to analyse catalytic activity; and use GC/MS to characterize the chemical composition of the bio-oil from the co-hydropyrolysis of biomass components and HDPE. The results show that cellulose has a significant synergistic effect with aromatic hydrocarbon production, whose selectivity was 93.3 %; hemicellulose has a synergistic effect; aromatic selectivity can reach 75.1 %; and a negative synergistic effect between lignin and HDPE was shown as the selectivity of aromatic hydrocarbons decreased from 62.1 % to 15.6 %. Graphical
研究领域:
能源与燃料化学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Zhipeng Huo,Yidong Lu,Zuoyang Chen,Jie Zhang,Hong Zhang,Guoqiang Zhong
In this research, a series of Eu 2 O 3 /B 4 C/HDPE composites containing micromorphology tunable Eu 2 O 3 submicron spheres as fillers are prepared for shielding neutron and gamma ray. The influence of microstructure of Eu 2 O 3 fillers on thermal stability, mechanical, and radiation shielding properties of composites are studied in detail. The growth process of Eu 2 O 3 precursor (Eu(OH)CO 3 ) follows the LaMer and Ostwald ripening mechanism. The FESEM reveal that the microstructure of synthesized Eu 2 O 3 is submicron sphere and the particle size decreases with addition of urea content in the reactant solution. HRTEM and SEAD images reveal that the overall crystal morphology of the Eu 2 O 3 fillers is polycrystalline. BET analyses reveal that the hysteresis loops of nitrogen adsorption-desorption isotherms changes from Type H1 to H3 after Eu 2 O 3 fillers are ball-milled, which is attributed to the suppression of nanoparticle agglomeration by ball milling. The FESEM images and EDS mapping of the fracture surfaces of the composites reveal that Eu 2 O 3 fillers are evenly distributed in the HDPE matrix. It is revealed that under the condition that the agglomeration of the nanoparticles is effectively suppressed, the higher BET-specific surface area and smaller size of Eu 2 O 3 fillers are conducive to the various properties of the composites. The superior composite containing Eu 2 O 3 (R = 1:30)/B 4 C/HDPE has a 99.1 % neutron shielding rate with 15 cm thickness under a 252 Cf neutron source and a 73.1 % gamma shielding rate with 15 cm thickness under a 137 Cs gamma source.
研究领域:
材料科学
·
辐射防护
·
核工程
✓ 已验证
产品关联
DOI
高影响因子
POLYMER TESTING
·
2019
·
IF 2.943
Santosh Khanal,Yunhua Lu,Saad Ahmed,Muhammad Ali,Shiai Xu
The combination of synergistic agent with intumescent flame retardant (IFR) systems provides a promising way to prepare high performance IFR composites. In this study, the effects of the synthetic zeolite 4 A in combination with the IFR system consisting of ammonium polyphosphate (APP) and tris (2-hydroxyethyl) isocynurate (THEIC) on thermal degradation , mechanical properties , flame retardancy and char formation of high-density polyethylene composites were investigated by limiting oxygen index (LOI) measurement, cone calorimetry , scanning electron microscopy and laser Raman spectroscopy . The LOI value of HD/FR/Z-0.5 composite with an optimum content of 0.5 wt. % zeolite 4 A and 25 wt. % of total flame retardant reaches 26.3 %. A low loading of zeolite 4 A can improve the bench-scale combustion performance as determined by cone calorimetry, and promote the formation of more compact char residue with a highly graphitic structure. However, a low loading of zeolite in combination with the IFR system consisting of APP and THEIC produces no significant changes in mechanical performance.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Materials Today Communications
·
2022
·
IF 3.662
Zhouyao Yue,Huashan Wang,Xiurong Hou,Yuting Shi,Xin Zhang
Positive temperature coefficient (PTC) materials usually have NTC effect, and the effect is poor. In this paper, conductive carbon black (CB) and amorphous elastomer (TPO) were introduced into high-density polyethylene (HDPE) by melting mixing and hot pressing methods and treated with peroxide crosslinking to improve the PTC properties of conductive composites. The results show that the percolation threshold reduces from 24 wt% to 22 wt% for crosslinked elastic networks. At the same time, the room temperature resistance of the composite material does not show monotonicity after three cycles, which has good reproducibility and eliminates the NTC effect of the composite material. This work provides both a simple way to produce high-performance PTC materials and a new idea to improve the stability of PTC materials.
研究领域:
材料科学
·
高分子科学
·
电气工程
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2024
·
IF 4.7
Chen Li,Liting Wei,Min Chen,Jiayi Zhang,Yang Yang,Boping Liu,Yulong Jin
CrO x /VO x /TiO 2 -SiO 2 was prepared via solvent-free and conventional wet-impregnation process with ethanol as solvent. The results of ICP-OES, N 2 adsorption-desorption, SEM-EDX, Raman and DR-Uv-vis spectra indicate that well-dispersed Cr and V sites in isolated state were the main species. Bimodal ultra-high molecular weight polyethylene/high-density polyethylene in-reactor blends (UHMWPE/HDPE IRBs) could be synthesized with polymerization activity ＞ 1×10 7 gPE·mol −1 Cr·h −1 . Moreover, the two catalysts displayed similar catalytic behaviors in temperature sensitivity, H 2 response and 1-hexene copolymerization efficiency, and their polymer products also show comparable molecular weight and molecular weight distribution , which implies analogous structures of their well-dispersed active sites. By contrast, the catalyst prepared by wet-impregnation process with water as solvent exhibited poor dispersity, which is reflected by its much lower activity and very different catalytic behaviors and polymer properties when compared with the well-dispersed catalysts. Therefore, the economic and green solvent-free process is promising for preparing highly-active CrO x /VO x /TiO 2 -SiO 2 .
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CURRENT APPLIED PHYSICS
·
2018
·
IF 2.058
Ling-yan Li,Shuang-lin Li,Yan Shao,Rui Dou,Bo Yin,Ming-bo Yang
In this work, Polyvinylidene Fluoride (PVDF)/polystyrene (PS)/high density polyethylene (HDPE) ternary blends displayed a core-shell structure where HDPE was the core, PS was the shell, and this core-shell system dispersed in PVDF matrix. Here, multiwall carbon nanotubes (MWCNTs) and ferroferric oxide (Fe 3 O 4 ) was incorporated. F-F composites with MWCNTs was in PS shell and Fe 3 O 4 was in PVDF matrix and E-F composites with MWCNTs was in PS shell and Fe 3 O 4 was in HDPE core were fabricated by melt blending. It was indicated that the core-shell morphology between PS and HDPE was well retained with the incorporation of Fe 3 O 4 and MWCNTs. Both the electrical conductivity of F-F and E-F composites were similar without no obvious change with the incorporation of Fe 3 O 4 . Composites with greater than 20 dB shielding effectiveness were easy to obtain. The highest SE we observed was for the F-F composite with 1 vol% Fe 3 O 4 and 1 vol% MWCNTs was 25 dB at 9.5 GHz, and the SE was over 20 dB in the whole measured frequency(X-band). The E-F composites with SE greater than 20 dB in X-band was at 2 vol% Fe 3 O 4 and 1 vol% MWNCTs. Such effective and lightweight nanocomposites were obtained, resulting from the synergetic effect of MWCNTs and Fe 3 O 4 nanoparticles .
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
POLYMERS FOR ADVANCED TECHNOLOGIES
·
2017
·Vol. 29
·期 2
·982-988
·
IF 1.907
Jiayu Xian,Jieting Geng,Yan Wang,Lin Xia
Shape-memory polymers are important smart materials with potential applications in smart textiles, medical devices, and sensors. We prepared trans-1,4-polyisoprene, low-density polyethylene (LDPE), and high-density polyethylene (HDPE) shape-memory composites using a simple mechanical blend method. The mechanical, thermal, and shape-memory properties of the composites were studied. Our results showed that the shape-memory composites could memorize 3 temporary shapes, as revealed by the presence of broad melting transition peaks in the differential scanning calorimetry curves. In the trans-1,4-polyisoprene/LDPE/HDPE composites, the cross-linked network and the crystallization of the LDPE and HDPE portions can serve as fixed domains, and all crystallizations can act as reversible domains. We proposed a schematic diagram to explain the vital role of the cross-linked network and the crystallization in the shape-memory process.
研究领域:
高分子材料科学
·
生物医学工程
·
智能材料
·
功能高分子
·
热响应材料
✓ 已验证
DOI
高影响因子
POLYMERS & POLYMER COMPOSITES
·
2020
·
IF 1.023
Yuru Wang,He Ren,Yibin Yan,Shuyan He,Shuang Wu,Qian Zhao
The effects of four hindered phenolic antioxidants in the short-term heat-oxygen stability of High-Density Polyethylene (HDPE) was evaluated by the Melt Flow Rate (MFR) and Oxidation Induction Time (OIT) analyses. The results showed that Irganox 1330 and Irganox 1010 had more excellent processing property and oxidation resistance behavior in HDPE than Irganox 1024 and Irganox 3114. The OIT values of HDPE with Irganox 1330 and Irganox 1010 were up to 97.25 min and 89.73 min respectively. The long-term accelerated heat-oxygen stability tests of HDPE containing hindered phenolic antioxidants were carried out at 110°C in deionized water pressurized with pure oxygen at a pressure of 10 MPa. The characterization of the long-term heat-oxygen stability was performed by Fourier Transform Infrared (FTIR), Differential Scanning Calorimetry (DSC) and tensile testing. However, the results exhibited that the aging resistance of HDPE containing Irganox 1010 was inferior to that of HDPE containing Irganox 1024 and Irganox 3114, which is quite contrary to their short-term effect on HDPE stabilization. It may be speculated that the ester groups of Irganox 1010 undergo hydrolysis during the long-term heat-oxygen stability tests, leading to the formation of 3-(3,5-ditert-butyl-4-hydroxy-phenyl) propanoic acid and pentaerythritol.
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）