Inorganic particles polymer coat wear, heat storage composite variable height!

I. Background

ultra thin film capacitor having charge and discharge rate, high pressure, low-cost and lightweight advantages, plays an important role in modern electrical and electronic fields. Commercial biaxially oriented polypropylene film (BOPP) as is currently the most commonly used flexible energy storage material having an excellent storage efficiency at ordinary temperature, but when the ambient temperature is higher than 100 ° C, its electrical properties under high electric field significantly reduce the occurrence and storage efficiency. From the energy dissipation mechanism is concerned, for the linear dielectric leakage current is generated under a high electric field is an important way of energy loss. For this reason, some studies have high insulating inorganic particles into the polymer matrix, to reduce the leak current density of the composite, to improve its breakdown and storage properties. But the introduction of inorganic particles often results in excessive agglomeration and surface defects such as energy, based on this, work on surface modified inorganic particles emerging in recent years. Most researchers mainly use an interfacial modifier silane coupling agent or dopamine to reduce the surface energy of the inorganic particles to improve its dispersibility, but these small molecules simply by interfacial modifier to improve its dispersibility, often With little success.

Second, studies

Recently, , Tsinghua He Jinliang Professor , Professor Li Qifu In TF Polymer high heat-yl The dielectric storage areas made significant progress . In this study, the first of magnesia (MgO) nanoparticles and silane coupling agent to react, to achieve aminated nanoparticles. The nanoparticles aminated maleic anhydride grafted polypropylene (PP-g-MAH) to react to form a PP-g-MAH / MgO composites. The PP-g-MAH / MgO composite formed blended with PP PP / PP-g-MAH / MgO composites. PP-g-MAH as a \”bridge\” between the PP polymer and inorganic particles MgO, not only the leakage current can be suppressed by providing a deep well, the dielectric constant and increase the polarity element. In particular, the energy density PP-MAH-MgO nanocomposite at 120 oC of 1.66 J / cm3, the η> 90% of the energy density even when the ratio of pure PP 80 ℃ (i.e. 1.39 J / cm3) 19%. This result shows that by modifying the interface, PP nanocomposite films can be improved operating temperatureHigh 120 ℃. The work \”Interface-modulated nanocomposites based on polypropylene for high-temperature energy storage\” was published in the top international academic journals Energy Energy Storage Materials. 无机粒子穿上高分子外衣,变身高耐热储能复合材料!

III. Highlights herein:

  1. On the use of polymer-based interfacial modifier to enhance interfacial polarization and high temperature storage performance of inorganic nanoparticles.
  2. to explain the mechanism of regulation of modified inorganic particles with a surface charge decay interfacial effects.

Fourth, the research results discussed ideas and specific

Preparation of nanoparticles having different interface design and corresponding polymer nanocomposites 无机粒子穿上高分子外衣,变身高耐热储能复合材料!
Figure 1 and characterization. (A) APTES-MgO and PP-MAH-MgO prepared schematic nanoparticles. (B) untreated MgO, (c) APTES-MgO, and (d) TEM image of PP-MAH-MgO nanoparticles. Containing 3 wt% (e) untreated MgO, (f) APTES-MgO, and (g) Polymer PP-MAH-MgO nano nanoparticles cross-sectional SEM image of the composite material.

MgO nanoparticles aminated silane coupling agent in the process (the APTES), the amino group of the MgO nanoparticles condensation reaction with an amino ester group of the PP-g-MAH, both coupling through chemical bond, in order to obtain as PP-g-MAH shell MgO / PP-g-MAH conjugate, wherein the shell thickness of 10 nm. The above-described conjugates blended with polypropylene, since the compatibility between PP-g-MAH and high PP matrix, such that nanoparticles can be dispersed in the MgO PP group homogeneous mass. When designing a composite high storage system performance at such high temperatures, firstly, a surface modifying agent with the polymer matrix must have a high degree of compatibility with high thermal stability and to avoid the formation of defects at the interface. Second, the nanoparticles should have a high dielectric constant and a smaller electric field distortion due toPP is a low dielectric constant leak current under high temperature conditions susceptible to distortion of electric field is increased. Third, should be introduced through the surface features of the deep well, to inhibit conduction loss.

FIG 2 PP and PP nanocomposite (a) 20 oC dielectric and at (b) 120 oC versus frequency. When the 1 kHz, (c) the dielectric constant and (d) a dissipation factor change with temperature.

select OF PP-g-MAH as the inorganic particles interfacial modifier, because of its strong polar anhydride group can enhance the dielectric response of the composite material. The dielectric constant of PP / PP-g-MAH / MgO MgO composites after the PP-g-MAH-modified form was increased from 2.22 (neat PP) to 2.47. This is mainly due to the polar group-coated surface MgO accompanying the nanoparticles more uniformly dispersed in the PP matrix, and a larger area formed interfacial polarization. As the temperature increases, the dielectric constant of PP / PP-g-MAH / MgO composites can maintain a relatively stable state. Instead, only the particle surface of the MgO composites grafted silicone coupling agent, its poor dielectric heat stability. Meanwhile, the nanocomposite containing PP-g-MAH / MgO nanoparticles exhibit relatively pure PP even lower temperatures and loss factor at low frequencies. This means that PP / PP-g-MAH / MgO nanocomposites conduction losses is suppressed, indicating that the interface modifier PP-g-MAH stability plays an important role for the composite dielectric heat.

Figure 3. The local charge trap characterized by Kelvin probe force microscope level distribution. (A) un-MgO / PP and morphology of the scanning line (b) PP-MAH-MgO nanocomposite. (C) un-MgO / PP and (d) PP-MAH-MgO nanocomposite line scan profile on a temporal change the surface potential. (E) un-MgO / PP and the surface potential (f) PP-MAH-MgO nanocomposite nanoparticle / polymer interface is attenuated. (G) the surface potential attenuation curve obtained by the local region of the interface trap charge level distribution.

In order to obtain direct evidence of the presence of deep traps in the interface region modified, nanometer spatial resolution using a Kelvin probe force significantlyMicromirrors (KPFM) interface to detect the surface potential attenuation. On the first thin film sample morphology obtained frozen sections to locate the position of the nanoparticle. Then select the center position of the nanoparticles through the charging and implemented ISPD measurement. Obviously, the surface charge of PP-MAH-MgO / PP nanocomposite attenuated forms other than untreated MgO / PP nanocomposite, especially much slower in interface charge traps at the interface than the un-MgO / PP, which interface charge traps showed PP-MAH-MgO / PP interface charge traps than in untreated MgO / PP is much deeper.

FIG. 4. PP PP and high temperature storage properties of nanocomposites. (A) pure PP and PP-MAH-MgO nanocomposites 120 oC, PE curve at 400 MV / m; (b) charge-discharge efficiency and energy density at 120 oC; (c) 80 oC and 120 oC when the charging and discharging efficiency is the maximum energy density of 90% or more is obtained; the cycle at (d) 200 MV / m and 120 ° C charge and discharge performance.

To characterize the properties at high temperature storage, the measurement temperature was set to 120 oC (the temperature exceeds BOPP film commercially maximum operating temperature (i.e. 105 oC)). Results As expected, when the electric field exceeds 198 MV / m, the original η PP dropped below 90%, down to 62% at 400 MV / m, due to the modification of the interface nanoparticle / polymer inhibit electrical conductivity. At high temperature and high electric field, PP-MAH-MgO nanocomposite exhibits the highest storage density and storage efficiency. It is noted that when the 120 oC (i.e. 1.66 J / cm3), PP-MAH-MgO nanocomposite η> 90% of the energy density even when the ratio of pure PP 80 oC (i.e. 1.39 J / cm3) 19%. This result shows that by modifying the interface, PP nanocomposite films can be raised to the operating temperature of 120 oC. Further, 50,000 successive charge-discharge cycle, PP-MAH-MgO / PP nanocomposite signs were not observed in energy density and storage efficiency decreases, good charge-discharge cycle characteristics may be attributed to nanocomposite increase resistivity.

V. Study Summary

In this work, the interface regulator polymer nanocomposites improve high temperature storage properties. SEM and TEM demonstrated PP-MAH-MgO nano particles having a good compatibility and dispersibility in the PP matrix. PP / PP-MAH-MgO nanocomposite having stable dielectric properties, and improve its breakdown strength at high temperatures. Moreover, charge-discharge efficiency, energy density and cycle stability and other properties of PP / PP-MAH-MgO nanocomposites have significantly improved. References: Interface-modulated nanocomposites based on polypropylene for high-temperature energy storage Energy Storage Materials, 28 (2020) 255-263 DOI:.. 10.1016 / j.ensm.2020.03.017 Link:. Https: // www.