查找使用阿拉丁产品的科研文献

Modified Metal-Doped Fe-Al Catalysts for H2-Rich Syngas Production from Microwave-Assisted Gasification of HDPE Plastic

Jingmo Zhou,Chaoyue Liu,Wenke Zhao,Faizan Ahmad,Yaning Zhang

This study pioneers the application of metal-doped Fe-Al as multifunctional redox catalysts for tunable syngas production from plastics via a microwave-assisted process (CLG). We rationally designed a series of redox catalysts (Ni, Ca, Ce, Sr, Co) to unlock efficient H2-rich syngas production from (high-density polyethylene) HDPE. A class of metal-doping (Ni, Ca, Ce, Sr, and Co) Fe-Al redox catalysts was engineered, with Ni-doped Fe-Al (Ni-Fe-Al) exhibiting the excellent H2-rich syngas production (75.32 mmol/gHDPE syngas, 47.09 mmol/gHDPE H2). This is attributed to the improved redox activity, which facilitates efficient lattice oxygen transfer and catalytic reforming reactions, alongside improved microwave absorption and a porous structure that promotes reactant access. This strategic material design, coupled with process parameter optimization (800 W, redox catalyst/plastic = 2.0), developed a highly efficient HDPE-to-syngas conversion system. The process produced a high-quality syngas (90.03% H2+ CO, H2/CO ratio = 2.27) with a rapid heating rate (233.0 °C/min) and minimal energy input (3.52 kWh/molgas). This work provides not just an effective upcycling route for plastics, but a fundamental blueprint for designing advanced redox catalysts to unlock the full potential of microwave-CLG.

Hierarchical structure of MWCNT reinforced semicrystalline HDPE composites: A contrast matching study by neutron and X-ray scattering

Dong Liu,Xueyu Li,Hongtao Song,Pucheng Wang,Jie Chen,Qiang Tian,Liangwei Sun,Liang Chen,Bo Chen,Jian Gong,Guangai Sun

Combining neutron and X-ray scattering (SANS, SAXS, and WAXD) as the contrast matching probes, the hierarchical structures of the multi-wall carbon nanotubes/high density polyethylene (MWCNTs/HDPE) composites (0.1–2.0 wt%) have been studied. SANS measurement avoided the correlation peak associated to the semicrystalline nature of HDPE from SAXS, and the passible scattering from the stretch induced voids. Benefitting from SANS data, the power law ( α ) taking the flexible cylinder suggested that whole MWCNTs in the unstretched composites follow a self-avoiding random walk ( α  ≈ 1.67). SANS data suggest a hollow flexible cylinder structure with outer and inner diameters (core-shell-like cross section) of the scatterers as ca. 12.6 nm and 4.1 nm, while the Kuhn length is about 43.0 nm. Tensile test displayed improved mechanical properties. Interestingly, the Hermans orientation parameter ( f ) of HDPE crystals ( f c ) in the stretched composites are around a plateau ca. 0.96 initially, while decreased remarkably to 0.776 when the fraction is further increased to 2.0 wt%. f obtained by SANS showed a similar tendency (decreased from 0.756 to 0.572). Combining all the results along with differential scanning calorimetry (DSC) measurement, a mechanism of adhered crystals on the surface of MWCNTs and a reinforcement model are proposed.

Preparation and properties of HDPE/MVQ thermoplastic vulcanizate with low-temperature-resistant super toughness and shape memory properties

Yuan Ma,Jiafeng Meng,Lin Xia

Facile Fabrication of N-Methyl-D-Glucamine Grafted HDPE Particle as Adsorbent for Boron Removal from Aqueous Solution

Ji Fu Du,Zhen Dong,Xin Yang,Long Zhao

Glycidyl methacrylate (GMA) was grafted onto the surface of HDPE particles by radiation grafting and emulsion graft copolymerization. And subsequent ring-opening reaction of expoxy groups in poly-GMA graft chains with N-methylglucamine (NMG) was conducted to synthesis the boron adsorbent. The synthesis condition (radiation dose and NMG concentration) was optimized and characterized by IR and SEM. Adsorption behaviors of the boron adsorbent for boron removal presented that adsorption kinetics was well described by pseudo-second-order kinetic mode. The adsorption isothermal was well fitted with both Langmuir and Freundlich isotherm models. The adsorption capacity for boron reached 15.63 mg/g at optimal pH 8. Dynamic experiment revealed that boron could be efficiently adsorbed by the boron adsorbent and fully desorbed using 13 BV of 1 mol/L HCl.

Synthesis of a Novel Phosphorous-Nitrogen Based Charring Agent and Its Application in Flame-retardant HDPE/IFR Composites

Junlei Chen,Jihui Wang,Aiqing Ni,Hongda Chen,Penglong Shen

In this work, a novel phosphorous–nitrogen based charring agent named poly(1,3-diaminopropane-1,3,5-triazine-o-bicyclic pentaerythritol phosphate) (PDTBP) was synthesized and used to improve the flame retardancy of high-density polyethylene (HDPE) together with ammonium polyphosphate (APP). The results of Fourier transform infrared spectroscopy (FTIR) and13C solid-state nuclear magnetic resonance (NMR) showed that PDTBP was successfully synthesized. Compared with the traditional intumescent flame retardant (IFR) system contained APP and pentaerythritol (PER), the novel IFR system (APP/PDTBP, weight ratio of 2:1) could significantly promote the flame retardancy, water resistance, and thermal stability of HDPE. The HDPE/APP/PDTBP composites (PE3) could achieve a UL-94 V-0 rating with LOI value of 30.8%, and had a lower migration percentage (2.2%). However, the HDPE/APP/PER composites (PE5) had the highest migration percentage (4.7%), lower LOI value of 23.9%, and could only achieve a UL-94 V-1 rating. Besides, the peak of heat release rate (PHRR), total heat release (THR), and fire hazard value of PE3 were markedly decreased compared to PE5. PE3 had higher tensile strength and flexural strength of 16.27 ± 0.42 MPa and 32.03 ± 0.59 MPa, respectively. Furthermore, the possible flame-retardant mechanism of the APP/PDTBP IFR system indicated that compact and continuous intumescent char layer would be formed during burning, thus inhibiting the degradation of substrate material and improving the thermal stability of HDPE.Keywords:intumescent flame retardant;polyethylene composites;mechanical properties;thermal properties;flame retardancy mechanism

RETRACTED: The Effect of Intrinsic Mechanical Properties on Reducing the Friction-Induced Ripples of Hard-Filler-Modified HDPE

Chuanbo Liu,Chengqing Yuan,Shutian Liu

Ripple deformations induced by friction on polymeric materials have negative effects on the entire stability of operating machineries. These deformations are formed as a response to contacting mechanics, caused by the intrinsic mechanical properties. High-density polyethylene (HDPE) with varying silicon nitride (Si3N4) contents is used to investigate different ripple deformation responses by conducting single-asperity scratch tests. The relationship between the intrinsic mechanical properties and the ripple deformations caused by filler modifications is analyzed in this paper. The results show the coupling of the inherent mechanical properties, and the stick-slip motion of HDPE creates ripple deformations during scratching. The addition of the Si3N4filler changes the frictional response; the filler weakens the ripples and almost smoothens the scratch, particularly at 4 wt.%, but the continued increase in the Si3N4content produces noticeable ripples and fluctuations. These notable differences can be attributed to the yield and post-yield responses; the high yield stress and strain-hardening at 4 wt.% provide good friction resistance and stress distribution, thus a smooth scratch is observed. In contrast, increasing the filler content weakens both the yield and post-yield responses, leading to deformation. The results herein reveal the mechanism behind the initial ripple deformation, thus providing fundamental insights into universally derived friction-induced ripples.

High-value utilization method of digital printing waste paper fibers-Co-blending filled HDPE composites and performance improvement

Xiaolin Zhang,Jingjing Di,Long Xu,Jinyan Lv,Jingting Duan,Xiaofeng Zhu,Xin Li,Xiangfeng Bo

Due to accelerated modernization, urban environmental waste is being generated at an exponential rate, and paper is one of the largest solid wastes. Among them, digital printing waste paper has remarkable fiber quality and purity, making it a superior renewable fiber resource. However, the printing method and ink/toner used in the digital printing process are different from traditional printing methods, and the waste paper is relatively difficult to deink, resulting in the traditional waste paper utilization industry (recycled paper) is not given much attention and becomes low-value waste paper. How to realize the resourcefulness and high-value and efficient utilization of digital printing waste paper fiber (DPWF) is a real problem that needs attention in the field of renewable resources. In this paper, DPWF was used in the field of melt blending filled thermoplastic resin composites to avoid the waste paper deinking process while improving various properties of the material. It is shown that the best mechanical properties of the composites are achieved at 35% DPWF content. At the same time, coupling agent was used to further improve the properties of the composites in response to the interfacial incompatibility between fiber and resin. The best modification effect was achieved when the coupling agent was added at 3%, at which time the interfacial, water absorption, crystallization and thermal properties of the composites were improved, among which vinyltrimethoxysilane (A171) and γ-methacryloxypropyltrimethoxysilane (KH570) had significant effects.

Towards One-Pot Synthesis of Trimodal HDPE/UHMWPE In-Reactor Blends by CrOx/VOx/CpCr/SiO2 Tri-Metallic Catalysts

Shiyang Wang,Lijia Ding,Ruotong Chen,Yang Yang,Jianhao Guo,Xiaofeng Xue,Ning Zhao,Yibin Zhan,Tiedong Xie,Boping Liu,Yulong Jin

Trimetallic catalysis provides a potential route for the one-pot production of multimodal PE with balanced mechanical and processing properties. Herein, a series of CrO x /VO x /CpCr/SiO 2 trimetallic catalysts are constructed by grafting CrCp 2 onto a CrO x /VO x /SiO 2 with tunable CrCp 2 loadings and benchmarked against mono- and bimetallic catalysts. FT-IR spectroscopy confirmed successful CrCp 2 immobilization, and the catalyst containing 0.25 wt% CrCp 2 exhibited the highest productivity. Owing to the distinct H 2 sensitivities of the three active sites, both molecular weight (MW) and molecular weight distribution (MWD) can be efficiently regulated through CrCp 2 loading and H 2 partial pressure, enabling the synthesis of tri- or broad-modal PE in a single reactor. Compared with unimodal PE of comparable MW, the trimodal PE exhibited lower melt viscosity and an improved stiffness-toughness balance.

Developing CrOx/VOx/Ind2ZrCl2/Silica/TiBA tri-metallic catalysts for controllable synthesis of trimodal UHMWPE/HDPE in-reactor blends

Shiyang Wang,Liting Wei,Xinglong Zhao,Lantian Li,Yuxin Gao,Shuang Chen,Yang Yang,Boping Liu,Yulong Jin

A series of mono-, bi- and tri-metallic catalysts including Ind 2 ZrCl 2 /silica, CrO x /VO x /silica and CrO x /VO x /Ind 2 ZrCl 2 /silica were synthesized for C 2 H 4 polymerization in this work. The results show that conventional cocatalyst TiBA could hardly activate Ind 2 ZrCl 2 /silica. However, under the assistance of the surface species over CrO x /VO x /silica, traces of TiBA (Al/metal ＜15, molar ratio) endowed the Zr species with moderate activity. The combined results of XPS, FTIR-pyridine-adsorption and DRS Uv–vis show that the Lewis acidic Cr and V sites could interact with Ind 2 ZrCl 2 and improve the electronic deficiency of Zr center, which is possible to promote zirconocene activation, though direct Si-O-Zr linkage was non-negligible, and redox between Cr(VI)/V(V) and zirconocene existed. The Zr species were responsible for ultra-high molecular weight polyethylene (UHMWPE) synthesis, and the relative content of UHMWPE fractions could be controllably regulated by polymerization temperature, partial pressure of hydrogen and the loading amount of Zr. Generally, these tri-metallic catalysts CrO x /VO x /Ind 2 ZrCl 2 /silica could synthesize trimodal HDPE/UHMWPE in-reactor blends with very broad molecular weight distribution. Meanwhile, owing to the excellent copolymerization ability of zirconcene, preferential distribution of the short chain branches along the ultra-high molecular weight (MW) chains for C 2 H 4 /1-hexene trimodal copolymers was achieved. The rheological results show that the fractions with extreme MW difference in the trimodal polyethylene (PE) exhibited excellent miscibility, and its superiority in processing and mechanical properties over the monomodal PE with similar MW was verified by rheological, tensile and impact tests.

A bio-based compatibilizer (ESO-g-S-HPG) to improve the compatibility and mechanical properties of CaCO3/HDPE composites

Hua Zhou,Liangdong Ye,Shanrong Li,Ziwei Li,Zhouqiao Wei,Zhiyi Huang,Shaorong Lu,Dongming Chen,Zuocai Zhang,Yuqi Li

Compatibilizers allow for the combination of two materials with vastly different polarities. The dosage of most compatibilizers must be more than 5 wt% to be effective—an expensive high dosage level that changes polymer composite properties. Thus, in this study, renewable resource epoxidized soybean oil (ESO) was used as the raw material to synthesize the end-hydroxyl group bio-based compatibilizer ESO-g-S-HPG. The experimental results revealed that composites prepared with ESO-g-S-HPG had better mechanical properties (i.e., tensile strength , impact strength , and energy storage modulus) than those prepared with a commercially available compatibilizer (TA 1618). The addition of 1 wt% of ESO-g-S-HPG significantly enhanced the interfacial compatibility between the HDPE and CaCO 3 , making it a good candidate for application in the field of HDPE composite filling and reinforcement, as evidenced by the minimal voids revealed by the scanning electron microscopy results. The molecular dynamics simulation results revealed that hyperbranched compatibilizers can eliminate filler aggregation and enhanced filler-matrix interaction, yielding effects that are better than those of linear compatibilizers. The compatibilizer proposed here can be a useful material for the fabrication of the next generation of composites applied in diverse industrial fields.

Synthesis of multifunctional double long chain tricyclic borate coupling agents and their effect on the properties of GCC/HDPE composites

Bo Wang,Maosheng Wan,Li Hua,Feiqing Rao,Jialin Liang,Zejie Zhao,Chunquan Li

HDPE has attracted significant attention owing to its outstanding corrosion resistance, ease of processing, and cost effectiveness. Nevertheless, it has low toughness and is prone to aging, which results in a decline in mechanical properties and restricts its application in special fields. Using diethanolamine, boric acid, phenol, 2,4,6 -trichloro- 1,3,5 -triazine and long chain primary amines as raw materials, a series of multifunctional double chain tricyclic borate coupling agents 8a-f with novel structures were designed and synthesized. The structure of the target compounds was characterized by FT-IR and 1 H NMR. Thermal analysis showed that the double long chain tricyclic coupling agents had high thermal stability and the thermal decomposition temperature was as high as 270 °C. The oil absorption value of GCC powder treated with compound 8f decreased from 30.4  g/100 g– 13.6  g/100 g, and the contact angle increased from 0° to 135.4° . Compared with the unmodified composite, the mechanical properties of the modified GCC/HDPE composite were significantly enhanced, and its impact strength, tensile strength and bending strength were increased by 48.7  %, 48.6  % and 58.2  %, respectively. After 1000  h of UV aging, the tensile strength of the modified composite decreased by only 0.6  %, and there was no yellowing phenomenon, indicating that it has excellent aging resistance. This study provides a reference strategy for the development of functional coupling agents and high-performance composite materials.

Dynamic structure transformation of char precursors during co-pyrolysis of coal and HDPE by using ReaxFF MD simulation and experiments

Wei Feng,Mo Zheng,Jin Bai,Xianxian Zhang,Chuang Wu,Zhenxing Guo,Lingxue Kong,Zongqing Bai,Wen Li

Understanding the effects of co-pyrolysis synergies between low-rank coal and high-density polyethylene (HDPE) on the carbon structure evolution in char and the relationship between char structure and chemical bonds evolution is very needed. A combination of ReaxFF MD and experimental approaches provides an opportunity for fully understanding the dynamic profiles of char structures and coking trends during co-pyrolysis process of coal and HDPE. In this work, consistent conclusions were obtained from fixed-bed experiments and ReaxFF MD simulations in product distribution during both individual coal pyrolysis and co-pyrolysis at different temperatures. The ReaxFF MD simulation results reveal that adding HDPE partially inhibited the coking process of coal char. The RDF results indicated higher order degree and aromaticity exist in coal/HDPE(7:3)-Char when compared to those in coal-Char, which agrees well with the findings from XRD and FTIR approaches. By analyzing the evolution of C=C, C=O, C-O, C( sp 2 )-C( sp 3 ), C( sp 3 )-C( sp 3 ) and C( sp 2 )-H bonds in C 40 + fragments during secondary simulations of co-pyrolytic char, it was observed that the structural order and aromaticity of co-pyrolytic char increase with temperature, and the oxygen-containing bonds are the initial recombination sites for char formation. These findings provide rich theoretical information to complement the understanding of char structure in co-fed systems and the interaction between coal and HDPE blend.