JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Hongxing Chen,Renquan Wang,Jun Li,Chang Liu,Xiaojiao Yang,Ying Liu
The combination of high coercivity and resistivity is a strong requirement for permanent magnets to resist thermal demagnetization under complex operating conditions. However, this still remains a challenge for conventional strategies, which always sacrifice the maximum energy product as the coercivity or resistivity increases. In this work, we report a unique strategy of introducing only 0.1 wt% of insulating nano-diamonds (NDs) into the hot-deformed Nd-Fe-B magnets to significantly and simultaneously improve both magnetic properties ( H ci , B r , (BH) max and H k / H cj ) and resistivity. In particular, the coercivity increased by 60% from 746 to 1193 kA/m. Further microstructure observations indicate that this exceptional effect stems from NDs can effectively inhibit the formation of coarse grains and optimize the distribution of Nd-rich phases, ensuring a strong pinning effect to enhance hard magnetic performance. Meanwhile, the presence of additional grain boundaries and NDs can also lead to higher resistivity by preventing the movement of free electrons. Our work provides a distinctive strategy for interface modification with excellent comprehensive performance in permanent magnets.
研究领域:
材料科学
·
磁学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Wang Jiang,Xin Meng,Weiguang Gong,Chenyang Li,Yichen Xu,Longjie Jiao,Pu Du,Zhong Xin
In this study, branched poly(lactic acid) (PLA) was synthesized through melt blending, which was blended with linear PLA (L-PLA) to enhance the crystallization. Nonisothermal and isothermal crystallization studies demonstrated that nucleated PLA exhibited a crystallization temperature and melt crystallinity of 119.0 °C and 48.0%, respectively, at the highest degree of entanglement of branched PLA (B-PLA). Following a simple annealing treatment, the Vicat softening temperature (VST) and heat deflection temperature (HDT) of nucleated PLA reached 157.2 and 94.3 °C, respectively. The presence of dipole interactions among molecular chain segments during the initial stages of nucleation was revealed via in situ infrared spectroscopy, which facilitated the adsorption of L-PLA onto B-PLA, thereby allowing branched segments to serve as nucleation sites for L-PLA. This comprehensive analysis elucidated the influence of B-PLA on the crystallization behavior of L-PLA and established a correlation between its degree of entanglement and nucleation efficacy. It could be concluded that nucleated PLA retains its biodegradability while demonstrating improved crystallization and heat resistance.
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
RSC Advances
·
2015
·Vol. 5
·期 89
·72691-72698
·
IF 3.84
Yang Wang,Zhu Wang,Piming Ma,Huiyu Bai,Weifu Dong,Yi Xie,Mingqing Chen
Poly(vinyl alcohol)/melanin nanocomposites with improved tensile strength, Young's modulus and heat distortion temperature (HDT) were prepared by using simple aqueous solution mixing. When incorporated into PVA with low content (0.5–2 wt%), melanin nanoparticles dramatically enhanced the mechanical properties of PVA. With addition of 2 wt% melanin, the nanocomposites exhibited a tensile strength (σ) of 155 MPa and a Young's modulus (E) of 2.95 GPa, which were much higher than these of neat PVA. HDT was enhanced from 56.5 °C to 100 °C. TEM indicated that melanin nanoparticles were uniformly dispersed in PVA without aggregation. The strong hydrogen bonding between the –OH (or –NH–) of melanin and –OH of PVA confirmed by FTIR, which played a key factor to prevent the aggregation of nanoparticles in PVA matrix and made a contribution to the high performance of PVA.
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
Journal of Materials Research and Technology-JMR&T
·
2023
·
IF 6.4
Hanjing Zhu,Meng Zhou,Ke Jing,Baohong Tian,Yi Zhang,Xu Li,Yunzhang Li,Xianhua Zheng,Heng Li,Zipeng Ma,Yong Liu,Alex A. Volinsky,Jin Zou
The 0.5Y 2 O 3 /Al 2 O 3 -Cu/30Mo3SiC and 0.3GO-0.5Y 2 O 3 /Al 2 O 3 -Cu/30Mo3SiC composites were fabricated by fast hot press sintering. Hot compression tests of the composites were carried out using the Gleeble-1500 simulator at 0.001–10 s −1 strain rates and 650–950 °C deformation temperatures. The effects of doped reduced graphene oxide (rGO) on the hot deformation behavior and microstructure of 0.5Y 2 O 3 /Al 2 O 3 -Cu/30Mo3SiC composites were investigated. Trace of molybdenum carbide (MoC) layers/nanoparticles formed in-situ at the rGO-Cu/Mo interface, which is beneficial to the interfacial bonding of the composite. The enhanced flow stress and activation energy of hot deformation is attributed to the addition of the rGO. The activation energy of the composites was improved by 11% with the addition of rGO. The dislocation density and texture orientation ratio decrease at higher deformation temperatures.
研究领域:
材料科学
·
力学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER ENGINEERING AND SCIENCE
·
2024
·Vol. 64
·期 6
·2724-2735
·
IF 3.2
Weihua Ye,Yanchao Yuan,Xing Liu,Shumei Liu,Jianqing Zhao
Polyamide 6 (PA6) is a widely used thermoplastic engineering polymer, and the toughening modification for PA6 is always a main research topic. Meanwhile, the rigidity and heat resistance of PA6 usually deteriorate. To address this conflict, an epoxy compound (EGDE-GA) was designed and synthesized and used to modify PA6 by dynamic vulcanization in twin-screw extruder. EGDE-GA is a linear molecule with a flexible molecular structure, which is favorable to toughening of PA6, and epoxy groups of EGDE-GA can form local cross-linked structure to improve the rigidity and retain the heat resistance of PA6. At the loading of 20 wt% of EGDE-GA, the modified PA6 (PA6/EGDE-GA 20) exhibited very high elongation at break and notched impact strength, which were increased by 413% and 520%, respectively, compared to those of PA6. The tensile strength was 61.4 MPa, which was higher than that of PA6. The heat deflection temperature remained almost unchanged. The results showed that the modified polymers may possess the high toughness without sacrificing the original rigidity by building the local crosslinked structure using dynamic vulcanization. The findings provide a feasible method for reusing and upcycling PA6 and other polymers with higher value and wider use in the industry. Highlights The polyamide 6 (PA6) is toughened via dynamic vulcanization. The toughness of modified PA6 is increased by 520% compared with pure PA6. The toughened PA6 exhibits higher tensile strength than that of pure PA6. The toughened PA6 maintains its rigidity and heat resistance.
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
CHINESE JOURNAL OF POLYMER SCIENCE
·
2024
·
IF 4.1
Zhu Qing-Li,Cheng Han-Lei,Liu Wei-Xuan,Xiao Yin-Bin,Wu Xin-Lei,Breu Josef,Hong Wei,Wang Zhi-Jian,Zheng Qiang,Wu Zi-Liang
Achieving continuous motions typically requires dynamic external stimuli for cyclic deformation, or crafted geometries with intricate modules to form a self-regulated feedback loop upon static stimulation. It is still a grand challenge to realize self-sustained motion in soft robots subject to unchanging environment, without complex geometry or a control module. In this work, we report soft robots based on an anisotropic cylindrical hydrogel showing self-regulated, continuous rolling motions under constant light irradiation. The robots are animated by mirror-symmetry-breaking induced by photothermal strain gradient. The self-sustained motion is attributed to the fast and reversible deformation of the gel and the autonomous refresh of the irradiated region during the rolling motion. The hydrogel robots can reach a rolling speed of 1.27 mm·s −1 on a horizonal surface and even climb a ramp of 18° at a speed of 0.57 mm·s −1 in an aqueous environment. Furthermore, the hydrogel robots can overcome an obstacle, with rolling direction controllable through irradiation angle of the light and local irradiation on selective regions. This work suggests a facile strategy to develop hydrogel robots and may provide unforeseen inspirations for the design of self-regulated soft robots by using other intelligent materials.
研究领域:
软体机器人
·
智能材料
·
仿生学
✓ 已验证
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2016
·
IF 5.557
Zhu Xiong,Haibo Lin,Fu Liu,Xuemin Yu,Yunze Wang,Yi Wang
The permeability and thermal stability are crucial to the application of environmentally benign, sustainable and bio-based polylactide (PLA) membrane. In the present work, we introduce a bio-based pore forming agent β-cyclodextrin to enhance the permeability of PLA membrane. Furthermore, we improve the protein resistance and heat-deformation resistance via a surface crosslinking strategy. P(VP-VTES) copolymer was first synthesized and seeded on the surface of PLA membranes steadily through the swelling, hydrolysis and condensation. The physicochemical property of PLA membrane was characterized by XPS , FTIR and SEM. The hydrophilicity, pure water flux and BSA fouling resistance were evaluated respectively. The crystallization evolution of PLA membrane was investigated by DSC and XRD . It was found that the surface crosslinked P(VP-VTES) significantly improved the hydrophilicity, dry membrane flux recovery (~98%) and BSA resistance. Meanwhile, the surface crosslinking induced the crystallization of PLA membrane up to ~38% degree of crystallinity and withstood ~100 °C hydrothermal treatment without dimension deformation or filtration performance deterioration. This study suggests a simple but effective strategy to simultaneously enhance the fouling resistance and thermal stability, as well as the permeability of PLA membranes through the surface crosslinking and the pore forming agent β-cyclodextrin.
研究领域:
材料科学
·
环境工程
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
POLYMER ENGINEERING AND SCIENCE
·
2024
·
IF 3.2
Honglin Li,Wanjun Liu,Zhize Chen
An efficient and scalable method to prepare oligolactic acid stereocomplex microplates (SC-OLA-MPs) is developed. Oligolactic acid was firstly synthesized via the melt polycondensation of lactic acid. Then, the oligo ( L -lactic acid) and oligo ( D -lactic acid) were crystallized with a mixture of dichloromethane and acetone, and consequently the stereocomplex microparticles were obtained in the form of circular microplates with a diameter of approximately 2 μm. As an eco-friendly nucleating agent, SC-OLA-MPs were introduced into poly ( L -lactic acid) (PLLA) via melt blending. The nonisothermal and isothermal crystallization of the SC-OLA-MPs/PLLA composites were investigated, and the crystal morphology and heterogeneous nucleation phenomena during the isothermal crystallization process were photographed with POM. SC-OLA-MPs show excellent nucleating effects on PLLA crystallization. With the incorporation of 10% SC-OLA-MPs, the crystallization half-time of the SC-OLA-MPs/PLLA composite decreased from 7.18 to 0.45 min at 100°C, compared to the neat PLLA. Through a short-time molding procedure, the thermal deformation temperature of PLLA is improved by the addition of SC-OLA-MPs. Highlights Polylactic acid stereocomplex microplates were fabricated by solution crystallization. This method is easy and scalable. This microplate is an effective nucleating agent for PLLA.
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
Journal of Composites Science
·
2024
·Vol. 8
·期 10
·436
·
IF 3
Shujun Han,Yuexin Qi,Xi Ren,Changxu Yang,Zhibin He,Zhenzhong Wang,Duanyi Li,Jingang Liu
Thermoplastic polyimide (PI) matrixes, including PI-a (cc-34ODA) and PI-b (ct-34ODA) were prepared via the hot-pressing procedures of the resins derived from the 3,4′-oxydianiline (34ODA) and two alicyclic dianhydrides of 1S,2R,4S,5R-hydrogenated pyromellitic dianhydride (ccHPMDA) and 1R,2S,4S,5R-hydrogenated pyromellitic dianhydride (ctHPMDA), respectively. The resins exhibited thermoplastic features with good formability at higher temperatures. The afforded semi-alicyclic PI sheets exhibited enhanced properties in comparison to commercially available, wholly aromatic thermoplastic PIs, such as PI-ref1, which are derived from 3,3′,4,4′-oxydiphthalic anhydride (ODPA) and 4,4′-oxydianiline (44ODA), as well as PI-ref2, which is based on pyromellitic dianhydride (PMDA) and 4,4′-bis(3-aminophenoxy)biphenyl (mBAPB). In addition, the developed PI sheets exhibited high heat deflection temperatures (HDT) of 267.4 °C for PI-a and 268.6 °C for PI-b. There values were significantly higher when compared with those of PI-ref1 (Ratem®YS20, HDT: 239.0 °C), PI-ref2 (Aurum®PL450C, HDT: 238.0 °C), PI-ref3 (Ultem®1000, HDT: 206.0 °C), PI-ref4 (Therplim®TO65, HDT: 180.0 °C), and PI-ref5 based on phthalic anhydride-terminated fluorinated PIs (HDT: 215.0 °C). In terms of mechanical properties, the current PI sheets showed superior flexural properties among the polymers with the flexural strength of 189.0 ± 11.7 MPa (PI-a) and 200.5 ± 4.2 MPa (PI-b), respectively. In addition, the PI sheets exhibited comparable compression properties, inferior impact strength, and tensile properties compared with the referenced PI counterparts. Basically, the PI-b sheet showed better comprehensive properties than those of the stereoisomeric PI-a analog.
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
ACS Applied Polymer Materials
·
2024
·
IF 4.4
Danqing Song,Jin He,Qiqi Xie,Xuedong Lv,Yi Liu,Liuchun Zheng
Polyurethane (PU) is conventionally synthesized via the isocyanate route, which has been widely reported to be hazardous to the environment and humans. Consequently, there is an urgent need to develop an environmentally friendly method for the preparation of nonisocyanate polyurethanes (NIPUs). Herein, a green nonisocyanate synthetic route to polyurethane, originating from dimethyl carbonate, 1,6-hexanediamine, 1,6-hexanediol, and rigid biobased isosorbide is introduced to enhance the mechanical properties and heat deflection temperature of NIPUs. A series of biobased isosorbide nonisocyanate polycarbonate-based polyurethanes (ISPCUs) were synthesized by adjusting the isosorbide content in the hard segments. The results show that the rigid ring structure of isosorbide enhances the mechanical and thermal properties of PU. Notably, the melting point of ISPCUs increased from 93 to 119 °C, and the heat deflection temperature has been enhanced to 85 °C from 41 °C of NIPUs without isosorbide. The mechanical properties improved substantially, especially the tensile strength, which increased evidently from 18 MPa of PU to 65 MPa of ISPCUs. This work provides a method to synthesize biobased NIPUs with exceptional heat resistance and mechanical properties.
研究领域:
材料科学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2022
·
IF 9.224
Zecun Zhang,Xinyu Wan,Baomin Fan,Yuhong Ma,Biao Yang
Poor heat resistance and toughness put some limitations on the applications of poly(lactic acid), one of the most promising eco-friendly polymers. Herein, bimodal poly(l-lactic acid) (PLLA) was prepared by melt-blending high- and low- molecular-weight PLLAs, and the nonisothermal crystallization behavior, heat resistance, and mechanical properties of bimodal PLLA were investigated. Low-molecular-weight PLLA (L-PLLA) improves the crystallization capability of bimodal PLLA. The double melting behavior is reasonably explained by the melting–recrystallization mechanism. Octamethylenedicarboxylic dibenzoylhydrazide, a typical heterogeneous nucleating agent, significantly enhances the crystallization rate and crystallinity of PLLA. The maximum crystallinity of 100% L-PLLA is as high as 54.4%, and the heat deflection temperature (HDT) of the bimodal PLLA containing 95% L-PLLA is up to 151 °C, while the impact strength drops sharply to 17.2 kJ/m2 due to the large crystallite size. d-Sorbitol (DS) exhibits a completely different mechanism from heterogeneous nucleation, that is, a lower crystallization rate but elevated crystallinity and crystallization temperature. The DS-modified sample realizes an excellent balance between heat resistance (HDT up to 136 °C) and impact strength (47.9 kJ/m2) via a self-toughening effect by increasing the crystallinity and reducing the crystallite size.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
Polymers
·
2025
·Vol. 17
·期 4
·535
·
IF 4.9
Shunquan Liu,Run Zhang,Chenchao Fu,Tianshuo Zheng,Ping Xue
Due to excellent chemical resistance and impermeability, high-density polyethylene (HDPE) is widely used in petrochemical transportation, product packaging, sports equipment, and marine applications. Yet, with the wide variety of service environments, its mechanical and thermal properties do not meet the demand. In the present study, a compounding cross-linker comprising di-tert-butyl peroxide (DTBP) and triallyl isocyanurate (TAIC) is employed by combining with a two-step preparation process. High-quality cross-linking reactions are achieved for HDPE. In this study, the cross-linking of DTBP is first examined separately. A peak cross-linking degree of 74.7% is achieved, and there is a large improvement in thermal resistance and mechanical properties. Subsequently, the composite cross-linking system of DTBP and TAIC is investigated. The peak cross-linking degree is 82.1% (10% increase compared to DTBP). The peak heat deformation temperature is 80.1 °C (22% increase compared to DTBP). The peak impact strength is 104.73 kJ/m2(207% increase compared to neat HDPE). The flexural strength is 33.6 MPa (22% increase compared to neat HDPE). The results show that this cross-linking system further improves the cross-linking degree, heat resistance, and mechanical properties of HDPE, indicating its potential application in engineering materials for high performance.
研究领域:
材料科学
·
聚合物工程
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）