This paper reports that a novel polyimide dielectric composite with three-dimensional (3D) thermally conductive networks and enhanced breakdown strength was firstly fabricated by filling with ...core-double-shell structured F-BA fillers. The F-BA particles were composed of nano-sized boron nitride (nBN) and polydopamine-coated spherical alumina (PDA@Al
2
O
3
). Moreover, to ameliorate interfacial compatibility between F-BA fillers and PI matrix as well as restrain phonons scattering during propagation, 1,6-Diisocyanatohexane (HDI) was innovatively used as “bridge agent” to connect and functionalize nBN and PDA@Al
2
O
3
particles to generate core-double-shell structure. The results revealed that breakdown strength of PI dielectric composite with 25 wt % F-BA fillers was increased to 146.3 MV·m
−1
, showing an increment of 68.5% in comparison with that of pure PI. Furthermore, the thermal conductivity of F-BA/PI composite with 25 wt % F-BA fillers increases to 6.41 W/m·K of in-plane direction and 1.01 W/m·K of through-plane direction, respectively, which shows 36 and 6 times higher than polyimide of 0.18 W/m·K. For dielectric properties of F-BA/PI composite, the dielectric constant and loss are less than 3.5 and 0.02, respectively. Considering these properties, the prepared PI dielectric composite shows potential application in high-performance electronic devices.
Polymer dielectrics with excellent energy storage performance at high temperature are urgently needed in advanced applications, such as hybrid electric vehicles, smart grid and pulsed power sources. ...Polyetherimide (PEI), which is supposed to be the most promising candidate among polymer dielectric materials, displays a limitation for high‐temperature polymer dielectrics owing to the rapidly decreasing discharged energy density (Ud) and charge‐discharge efficiency (η). Herein, a novel PEI with cross‐linked networks was firstly prepared by utilising 2,4,6‐Triaminopyrimidine (TAP) as a cross‐linker. The results showed that the breakdown strength of the cross‐linked PEI (c‐PEI) with 2 wt% TAP increased to 399.4 MV/m, showing an increment of 23.3% in comparison with non‐cross‐linked PEI. Additionally, owing to the restrained polarisation loss and relaxation loss by cross‐linked networks, the dielectric loss of c‐PEI dielectric gradually decreased with the increasing content of TAP. Of particular significance was the c‐PEI dielectrics exhibiting improved Ud and η at high temperature. The maximum Ud of c‐PEI with 2 wt% TAP was 2.53 J/cm3 at 150°C, which was 24.8% higher than non‐cross‐linked PEI (2.11 J/cm3 at 150°C). This research provides an innovative strategy to achieve novel PEI dielectrics with improved Ud and η at high temperature.
Heavy metal wastewater pollution has become an ecological challenge worldwide. This study reports the development of a novel poly (6-acryloylamino-N-hydroxyhexanamide) (PAHHA) resin for effective ...adsorption of heavy metal ions, including Cu2+, Pb2+ and Ni2+. The chelating resin was synthesized by the grafting reaction between 6-amino-N-hydroxyhexanamide and polyacrylic resin, thus containing the hydroxamate and acylamino groups. The batch adsorption experiments revealed that the PAHHA resin exhibited an excellent adsorption performance for Cu2+, Pb2+ and Ni2+. The maximum adsorption capacities of Cu2+, Pb2+ and Ni2+ were determined to be 238.59, 232.48 and 115.77 mg·g−1, respectively. Based on the adsorption kinetics, the pseudo-second-order kinetic model was noted to fit well for all metal ions. The metal ion concentration as a function of the equilibrium adsorption capacity fitted well with the Langmuir isotherm, thus indicating the single layer adsorption process. The adsorption mechanism was investigated by using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS) and adsorption isotherms. It was revealed that the PAHHA resin possessed multiple active sites, including –CONHOH, –CONH– and –COOH, which could strongly adsorb the metal ions. Specifically, the –CONHOH group displayed a high affinity by forming a stable five-membered ring with heavy metal ions. Overall, the developed resin exhibits advantages such as simple synthesis, inexpensive raw material and good recyclability, along with high adsorption ability, thus providing a new approach for efficiently treating wastewater contaminated with heavy metal ions.
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•Hydroxamate and acylamino were introduced to prepare PAHHA, subsequently applied for the heavy metal ion adsorption.•PAHHA resin possessed multiple active sites that can be strongly bind with the metal ions.•PAHHA resin achieved an excellent adsorption capacity for Cu2+, Pb2+ and Ni2+.•PAHHA resin presented the effective stability and good regeneration property.
Cu/Ni-bearing wastewater contamination has recently been a challenge for the environmental protection worldwide. Herein, a novel poly(2-acrylamide-pentanedihydroxamic acid) (PAPDA) resin containing ...–CONHOH and –COOH groups was prepared and applied to effectively remove Cu2+ and Ni2+ from heavy metal wastewater. The batch adsorption experiments revealed that the maximum adsorption capacities of PAPDA resin for Cu2+ and Ni2+ were 436.08 and 195.05 mg·g−1, respectively, which were 10.20 and 9.45 times higher than that of polyacrylic resin. Specifically, the adsorption kinetics and thermodynamics of PAPDA were respectively consistent with the pseudo-second-order kinetic model and the Langmuir isotherm model, indicating that the adsorption is a single-layer chemisorption process. Besides, the adsorption mechanism was investigated by SEM, XRD, FT-IR, XPS, DFT calculations, suggesting that the PAPDA resin possessing abundant active sites could effectively adsorb the heavy metal ions. Noticeably, the –CONHOH groups represented the strong affinity towards Cu2+ and Ni2+ by forming stable five-membered rings. In addition, column experiments were conducted to study the practical adsorption process of PAPDA resin to heavy metal ions. Overall, the results proved that the novel PAPDA resin as a green and highly efficient adsorbent has a promising potential for the treatment of heavy metals-containing wastewater.
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•Novel acylamino dihydroxamic acid chelating resin (PAPDA) is designed and prepared.•PAPDA resin possessed multiple active sites that can be bound with the metal ions.•PAPDA resin achieved an excellent adsorption capacity for Cu2+and Ni2+.•PAPDA resin exhibited the faster adsorption rate for Cu2+ than that of Ni2+.•PAPDA resin presented effective stability and good regeneration property.
Dielectric polymer‐based composites with high breakdown strengths and thermal conductivities have attracted considerable attention when applied in electronic devices. In this study, a novel ...poly(m‐phenyleneisophthalamide) (PMIA) dielectric nanocomposite is successfully fabricated by introducing functionalized hexagonal boron nitride nanosheet (fBNNS) fillers. Due to effective functionalization of hexagonal boron nitride nanosheets (BNNSs), fBNNSs fillers are homogeneously dispersed in the PMIA matrix. The breakdown strength and thermal conductivity of PMIA/fBNNSs dielectric nanocomposite are investigated. Research results indicate that the breakdown strength of fBNNSs‐12 reaches 105.6 MV m−1, which is 1.34 times that of pure PMIA. Moreover, owing to high thermal conductivity of fBNNSs, the thermal conductivities of fBNNSs‐12 are observably increased to 8.06 W m−1 K of in‐plane direction and 0.84 W m−1 K of through‐plane direction, respectively. Considering these properties, the manufactured PMIA/fBNNSs dielectric nanocomposites show potential applications in field of electronics.
Boron nitride nanosheets are first fabricated adopting an ultrasonic‐assisted solvent method, and then functionalized with octadecyl isocyanate. Novel poly(m‐phenyleneisophthalamide) (PMIA) dielectric composites are prepared by adding functionalized boron nitride nanosheets (fBNNSs) into the PMIA matrix. The dielectric property, breakdown strength, and thermal conductivity of manufactured PMIA dielectric composite are discussed.
A new class of recyclable and high-performance thermosets from comb-shaped aromatic polyamides with pendent furan groups, which was prepared from a newly designed furan-containing diacid by ...high-temperature polycondensation in solution was reported. 1H nuclear magnetic resonance (1H NMR), fourier transform infrared spectroscope (FT-IR) and gel permeation chromatography demonstrated the chemical structure of target polyamides, while gelation test, 1H NMR and FT-IR characterizations revealed the capability of these polyamides to be reversibly crosslinked by bismaleimide via Diels-Alder reaction. The use of polyamides with high molecular weight and high content of regular pendent furan groups as precursor permitted the tailoring of mechanical properties of the resultant thermosets in a broad range by simply adjusting the ratio of furan to bismaleimide. In addition, the thermally reversible cross-linking by Diels-Alder reaction allowed the repeated recycling of cross-linked polyamide with reasonable recovery in mechanical properties.
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•A newly designed diacid has been prepared for aromatic polyamides with pendent furan groups.•The furanic polyamides with good processibility were produced in an industrial friendly pathway.•Cross-linking of furanic polyamides via Diels-Alder reaction yielded thermally recyclable thermosets.•Mechanical properties of the thermosets can be tailored by adjusting the ratio of furan to maleimide groups.
This study reports that a novel high-temperature poly (m-phenyleneisophthalamide) (PMIA) composite with enhanced dielectric constant and thermal conductivity was prepared by filling with BaTiO3 ...nanowires–carbon nanotubes (BTCNs) fillers. Due to effective functionalization of BaTiO3 nanowires (BTNWs) and multi-wall carbon nanotubes (MWCNTs), the fabricated BTCNs fillers were homogeneously dispersed in PMIA matrix. The consequence displays that the dielectric constant of PMIA composite with 15 wt % BTNWs fillers increases to 27.6 at 103 Hz, which is about nine times higher than that of pure PMIA. Moreover, owing to the high thermal conductivity of MWCNTs, the thermal conductivity of PMIA with 15 wt% BTNWs fillers increases to 1.01 W/(mK). The enhanced thermal conductivity is beneficial for BTCNs/PMIA composite to dissipate the generated heat by dielectric loss. Considering these merits, this research would provide new methods and ideas for preparation of high-temperature dielectric polymer composites and reducing the internal thermal effect.
This study reports that a novel high-temperature poly (m-phenyleneisophthalamide) (PMIA) composite with enhanced dielectric constant and thermal conductivity was prepared by filling with BaTiO
3
...nanowires–carbon nanotubes (BTCNs) fillers. Due to effective functionalization of BaTiO
3
nanowires (BTNWs) and multi-wall carbon nanotubes (MWCNTs), the fabricated BTCNs fillers were homogeneously dispersed in PMIA matrix. The consequence displays that the dielectric constant of PMIA composite with 15 wt % BTNWs fillers increases to 27.6 at 10
3
Hz, which is about nine times higher than that of pure PMIA. Moreover, owing to the high thermal conductivity of MWCNTs, the thermal conductivity of PMIA with 15 wt% BTNWs fillers increases to 1.01 W/(mK). The enhanced thermal conductivity is beneficial for BTCNs/PMIA composite to dissipate the generated heat by dielectric loss. Considering these merits, this research would provide new methods and ideas for preparation of high-temperature dielectric polymer composites and reducing the internal thermal effect.
This paper reports that a novel polyimide dielectric composite with three-dimensional (3D) thermally conductive networks and enhanced breakdown strength was firstly fabricated by filling with ...core-double-shell structured F-BA fillers. The F-BA particles were composed of nano-sized boron nitride (nBN) and polydopamine-coated spherical alumina (PDA@Al.sub.2O.sub.3). Moreover, to ameliorate interfacial compatibility between F-BA fillers and PI matrix as well as restrain phonons scattering during propagation, 1,6-Diisocyanatohexane (HDI) was innovatively used as "bridge agent" to connect and functionalize nBN and PDA@Al.sub.2O.sub.3 particles to generate core-double-shell structure. The results revealed that breakdown strength of PI dielectric composite with 25 wt % F-BA fillers was increased to 146.3 MV·m.sup.-1, showing an increment of 68.5% in comparison with that of pure PI. Furthermore, the thermal conductivity of F-BA/PI composite with 25 wt % F-BA fillers increases to 6.41 W/m·K of in-plane direction and 1.01 W/m·K of through-plane direction, respectively, which shows 36 and 6 times higher than polyimide of 0.18 W/m·K. For dielectric properties of F-BA/PI composite, the dielectric constant and loss are less than 3.5 and 0.02, respectively. Considering these properties, the prepared PI dielectric composite shows potential application in high-performance electronic devices.
Alien Hand syndrome (AHS) is characterized in most patients by seemingly purposeful, involuntary movements of the extremities. It is not well known among physicians on account of its diverse clinical ...manifestations.
We present a 57-year-old Chinese man who could not stop or turn himself around as he involuntarily and uncontrollably walked forward, which had happened frequently in the month prior to treatment. He had been a heavy drinker for thirty years before the onset of the disease, with an alcohol intake of 600 to 800 ml/day.
History of alcohol intake and the brain magnetic resonance imaging findings indicated a diagnosis of Marchiafava-Bignami disease. The patient was additionally diagnosed with Alien Hand Syndrome according to his clinical symptoms.
The patient was treated with high doses of vitamin B for 1 month.
The patient's abnormal behaviors never appeared during the treatment, and no instance of recurrence was observed during the 6 months of follow-up.
The clinical manifestation of AHS is non-specific. Only by considering its diverse manifestation can doctors better understand the disease and achieve early intervention.
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