Poly Ester Imide Research Articles

Recovery of high-grade copper from waste polyester imide enameled wires by pyrolysis and ultrasonic treatment

Recovery of high-grade copper from waste enameled wires can effectively alleviate the shortage of copper resources. In this paper, the evolution of pyrolytic products during pyrolysis of waste polyester imide enameled wires was analyzed and the thermal decomposition mechanism was presented. A technology consisting pyrolysis and ultrasonic was proposed to achieve deep decarbonization. The results showed that the pyrolysis process was mainly divided into two stages. Below 500 °C, polyester imide was first depolymerized into large monomer, and then pyrolytic oil containing ketones, imides, amines and aromatic compounds was generated by random fracture (three main ways) and free radical reactions. With increase of temperature, the free radical reactions of small molecules to produce carbon and pyrolytic gas were dominant. The decarbonization efficiency reached 99.99% and the high-grade copper was obtained under the optimal conditions. This study provided the theoretical basis for recycling high-grade copper from waste enameled wires.

Study on Flame Retardancy of Enamelled Wires Using a Cone Calorimeter

The flame-retardancy of enamelled wires was studied by using a cone calorimeter. The characteristic parameters including time to ignition, heat release rate, total smoke release and so on, were obtained. The effect of heat radiation flux on the flame retardancy was analyzed. The results show that the flame retardancy of enamelled wires is related to the content of different components in the composite insulation layer. Polyimide enamelled wires have good flame retardant performance, followed by corona resistant wire with filler, and ordinary polyamide imide composite polyester imide enamelled wire has poor flame retardant performance. In conclusion, the heat release rate measured by cone calorimeter can be used for evaluate the flame retardancy of enamelled wires and provide a reference for the development and application of flame retardant enamelled wires.

Thermal and Electrical Characterization of Polyester Resins Suitable for Electric Motor Insulation

This paper undertakes the thermal and electrical characterization of three commercial unsaturated polyester imide resins (UPIR) to identify which among them could better perform the insulation function of electric motors (high-power induction motors fed by pulse-wide modulation (PWM) inverters). The process foreseen for the motor insulation using these resins is Vacuum Pressure Impregnation (VPI). The resin formulations were specially selected because they are one-component systems; hence, before the VPI process, they do not require mixing steps with external hardeners to activate the curing process. Furthermore, they are characterized by low viscosity and a thermal class higher than 180 °C and are Volatile Organic Compound (VOC)-free. Thermal investigations using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) techniques prove their excellent thermal resistance up to 320 °C. Moreover, impedance spectroscopy in the frequency range of 100 Hz-1 MHz was analyzed to compare the electromagnetic performance of the considered formulations. They manifest an electrical conductivity starting from 10-10 S/m, a relative permittivity around 3, and a loss tangent value lower than 0.02, which appears almost stable in the analyzed frequency range. These values confirm their usefulness as impregnating resins in secondary insulation material applications.

Comparative Studies of the Dielectric Properties of Polyester Imide Composite Membranes Containing Hydrophilic and Hydrophobic Mesoporous Silica Particles.

In this paper, comparative studies of hydrophilic and hydrophobic mesoporous silica particles (MSPs) on the dielectric properties of their derivative polyester imide (PEI) composite membranes were investigated. A series of hydrophilic and hydrophobic MSPs were synthesized with the base-catalyzed sol-gel process of TEOS, MTMS, and APTES at a distinctive feeding ratio with a non-surfactant template of D-(-)-Fructose as the pore-forming agent. Subsequently, the MSPs were blended with the diamine of APAB, followed by introducing the dianhydride of TAHQ with mechanical stirring for 24 h. The obtained viscous solution was subsequently coated onto a copper foil, 36 μm in thickness, followed by performing thermal imidization at specifically programmed heating. The dielectric constant of the prepared membranes was found to show an obvious trend: PEI containing hydrophilic MSPs > PEI > PEI containing hydrophobic MSPs. Moreover, the higher the loading of hydrophilic MSPs, the higher the value of the dielectric constant and loss tangent. On the contrary, the higher the loading of hydrophobic MSPs, the lower the value of the dielectric constant with an almost unchanged loss tangent.

Analysis of Influence of Insulating Resin Paint Film on Enameled Wire Properties Based on Molecular Simulation

As one of the varieties of magnet wire, the enameled wire has excellent mechanical properties, heat resistance, ageing resistance, dimensional stability and chemical stability. This is one of the keys affecting the development of the electrical industry, especially the development of new motors. Different varieties of enameled wire insulating varnishes have advantages and disadvantages, in addition to their general properties. In order to improve the service life and reliability of the electrical coil of the motor, it is necessary to select the appropriate enameled wire reasonably according to different purposes. Molecular simulation technology can play a guiding role in the relationship between the molecular structure and properties of resins, help to understand the microscopic mechanism, shorten the experimental period, improve efficiency and save costs. In this paper, based on density functional theory (DFT) and molecular dynamics (MD), the microscopic properties of four insulating resins, polyamide–imide (PAI), polyester (PET), polyesterimide (PEI), and polyimide (PI), were studied. We also studied the influence mechanism of the insulating resin microstructure on the macroscopic properties of enameled wires, including adhesion, insulating properties and flexibility. The calculation results show that the polyester insulating enameled wire paint has good insulation performance and flexibility, the polyamide–imide paint has the best adhesion, and the polyimide insulating paint has very reliable insulation performance and flexibility. The performance research in this paper lays a foundation for the preparation of insulating resin coatings with better comprehensive properties. The performance research in this paper lays a foundation for preparing insulating resin paint with excellent comprehensive performance.

Performance Analysis Based on Thermal Aging Tests of Sol-Gel and Polymer Insulated Wires by Enameling and Extrusion Technology

This research activity aims to evaluate electrical insulation system (EIS) intended for electrical machine winding wires. The evaluation is based on mechanical, thermal, and electrical properties tests following international standards for enameled wires. Dielectric parameters such as dissipation factor, partial discharge inception voltage (PDIV), parallel capacitance, and parallel resistance behavior of different insulator configurations on twisted-pair samples are observed during thermal aging tests. Those configurations are formed of different combinations of dielectric layers based on conventional polymers (polyester-imide (PEI), polyamide-imide (PAI), polyimide (PI)) used as coating wires. A study using two mineral varnishes (silica-based) obtained by the sol-gel process integrated on these classical enamels an outer layer of extrusion of thermoplastic polymer with and without mineral fillers. Given the high consummation of energy and the use of unsustainable materials involving the production of wires, the principal interest of this work is to exploit new configurations of coating wire produced, with less environmental impact than conventional ones. This work investigates the impact of filled resins on the performance of insulating samples and the influence of the use of sol-gel solutions (mineral varnishes) on the insulated wire to increase the thermal class.

Influence of Nanoparticles on the Dielectric Response of a Single Component Resin Based on Polyesterimide.

The influence of various types of nanoparticle fillers with the same diameter of 20 nm were separately incorporated into a single component impregnating resin based on a polyesterimide (PEI) matrix and its subsequent changes in complex relative permittivity were studied. In this paper, nanoparticles of AlO and ZnO were dispersed into PEI (with 0.5 and 1 wt.%) to prepare nanocomposite polymer. Dielectric frequency spectroscopy was used to measure the dependence of the real and imaginary parts of complex relative permittivity within the frequency range of 1 mHz to 1 MHz at a temperature range from +20 °C to +120 °C. The presence of weight concentration of nanoparticles in the PEI resin has an impact on the segmental dynamics of the polymer chain and changed the charge distribution in the given system. The changes detected in the H NMR spectra confirm that dispersed nanoparticles in PEI lead to the formation of loose structures, which results in higher polymer chain mobility. A shift of the local relaxation peaks, corresponding to the -relaxation process, and higher mobility of the polymer chains in the spectra of imaginary permittivity of the investigated nanocomposites was observed.

The Thermal Properties and Degradability of Chiral Polyester-Imides Based on Several l/d-Amino Acids.

Eight kinds of chiral diacid monomers were prepared with amino acids with different side groups or configurations. Polyester-imides (PEIs) were synthesized from these diacid monomers and diphenol monomers through polycondensation reaction, and the performances and properties were compared with the chiral polyamide-imides (PAIs) previously synthesized by our work group. Their thermal properties were analyzed by thermo gravimetric analysis (TGA) and dynamic thermomechanical analysis (DMA), and it was found that the glass transition temperature (Tg) of PEI was mainly affected by the volume of side groups. Their degradability was studied through buffer degradation experiments, and the changes in their water contact angle, molecular weight, structure and appearance during the degradation process were characterized by contact angle tester, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). With degradation, the hydrophilicity of PEI was improved, and when amino acids with larger side groups or D configuration were introduced into the backbone of PEI, the degradability decreased.

Acidic Polyester Imides as Thermally Stable Binder Polymers for Negative-Tone Black Photoresist

Polyimides are well-known for their high chemical inertness and thermal stability. However, it is usually challenging to synthesize UV-curable polyimides since the imidization reaction requires such harsh conditions that acrylate type double bonds cannot withstand. In this work, synthetic methods are developed to obtain polyester-imide type binder polymers with high thermal stability, high compatibility with the other components of the black photoresist, and fine photolithographic patterning property for the negative-tone black photoresist. The syntheses of diimide-diacid or diimide-diol intermediates for the polyesterification with dianhydride gave polyester imides which meets this requirement. The photolithographic tests have shown that the patterning of the micron-sized PDL of the organic light emitting diode (OLED) panel could be obtained. This work will interest the researchers working on the design and optimization of thermally stable binder polymers.

Detection of Ageing Effect in Polyesterimide by Terahertz Time-Domain Spectroscopy

The ageing and degradation of polyesterimide (PESI) may threat the safe operation of the electrical equipment. Due to the lack of effective experimental methods, the ageing mechanism is still under debate. In this article, we employ differential scanning calorimetry and terahertz time-domain spectroscopy (THz-TDS) at variable temperatures to investigate the glass transition temperature and molecular dynamics of PESI. Ageing sample with a duration of 30 days was prepared to study the influence of hygrothermal ageing. Three peaks emerge in both absorption spectra and dielectric spectrum of ageing sample at the range of 0.2–2.25 THz. We investigate the temperature dependence of dielectric loss for both samples. Four temperature regimes and three crossover temperatures are extracted according to the slope of fitting curves. We find that the ageing treatment has different effect on the molecular dynamics in each temperature range. This indicates the evolution of ageing at various space scales. We believe that THz-TDS has immediate application potential in the detection of ageing degree and service-life evaluation.

Electric conductivity, aging and chemical degradation of polyesterimide resins used in the impregnation of rotating machines

This work aims to investigate the electrical properties of both thermally aged and nonaged, commercially available impregnating varnish based on polyester-imide (PEI). The physical, thermal and dielectric properties of a virgin resin are initially investigated using Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Broadband Dielectric Spectroscopy (BDS) in order to quantify the behavior of the virgin PEI network. The second step consists in measuring and comparing the dielectric properties and the DC conductivity of virgin and thermally aged varnishes. The aged varnish was subjected to thermal aging at 240 °C for 4 weeks in an oxidative atmosphere. The results show large variations in both the real (e′) and the imaginary (e″) parts of the complex permittivity and in the DC conductivity (σ DC ) of the resin after aging. These results reveal an increase in these values at temperatures below 70 °C, which are close to the glass transition temperature (T g ) of the material. Above 70 °C, they show opposite trends, with a marked important decrease in the electrical properties of aged resin. The thermal treatment seems improve the resin insulation properties for high measurement temperatures (> 70 °C). The changes that occur in charge carrier density and mobility could partly explain these variations, which are related to network changes. Therefore, Fourier Transform Infrared spectroscopy (FTIR) measurements are performed in order to understand the chemical and structural changes caused by the thermo-oxidation.

Synthesis and properties of polyester imides based on 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3ʹ,4,4ʹ-tetracarboxylic acid dianhydride

Evidence for the Higgs boson, for which the Nobel Prize in physics was awarded in 2013, was discovered by the European Organization for Nuclear Research (CERN) in 2012, using the Large Hadron Collider (LHC). PIXEO BP-S exhibited superior resistance to both radiation and cryogenics and this polymer played a crucial role in the operation of the LHC, thus contributing to the Higgs boson discovery. Herein, we report the synthesis and characterization of various polyester imides for a cryogenic and radiation-resistant polyimide adhesive tape. These polyester imides (3) were synthesized from 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3ʹ,4,4ʹ-tetracarboxylic acid anhydride (ESDA) and various diamines (1a–1l). All polymers showed high solubility in various solvents, especially 3a, which was synthesized from ESDA and 4,4ʹ-bis(3-aminophenoxy)diphenyl sulfone and dissolved even in ether solvents such as dioxane and dioxolane. Dynamic mechanical analysis and X-ray diffraction studies indicated that the excluded volume of the polyester imides had a length of 150 A, and that this volume affected the thermoplastic properties and solubilities of the polymers. The degree of imidization of 3a dissolved in dimethyl sulfoxide was examined by 1H-Nuclear magnetic resonance(NMR) imaging utilizing a 15N-enriched amine model compound in conjunction with 1H–15N heteronuclear single quantum coherence 2-dimensional NMR and was found to be 99.5%. PIXEO BP-S tape used for Large Hadron Collider and its chemical structure.

Surge‐Resistant Nanocomposite Enameled Wire Using Silica Nanoparticles with Binary Chemical Compositions on the Surface

We developed polyesterimide (PEI) nanocomposite enameled wires using surface‐modified silica nanoparticles with binary chemical compositions on the surface. The modification was done using silanes assisted by ultrasound, which facilitated high density modification. Two different trimethoxysilanes were chosen for the modification on the basis of resemblance of chemical compositions on the silica surface to PEI varnish. The surface‐modified silica was well dispersed in PEI varnish, which was confirmed by optical observation and viscosity measurement. The glass transition temperature of the silica‐PEI nanocomposite increased with the silica content. The silica‐dispersed PEI varnish was then used for enameled wire fabrication. The silica‐PEI nanocomposite enameled wire exhibited a much longer lifetime compared to that of neat PEI enameled wire in partial discharge conditions.

Ground-wall insulation system analysis combining advanced imaging techniques and numerical simulation

High resolution X-ray computed tomography is used to reconstruct the interior of a sample of an insulation system based on mica-paper tapes impregnated with polyester imide resin that is used in ground-wall insulation of a.c. motor – and generator – windings rated 11kV and above. The tomographic volume is post-processed to identify the presence of minute voids, air-bubbles and very low-density zones that can bring-on partial discharges and material deterioration critical for the operative life of the rotating machines. The tomographic volume is segmented into different materials and a computational mesh is built on it. The electrostatic field is simulated under suitable boundary conditions at the copper conductors and at the ground side. The numerical model allows predicting the maximum intensity of the electric field in critical zones and spotting points above the 2.2kV/mm threshold, as derived from experimental partial discharge inception voltage carried out on the coil, yielding an indirect pre-evaluation of the insulating material that can guide the improvement of the manufacturing process (i.e. impregnation taping).

Fotoindukowane wlasciwosci poliestroimidow zawierajacych ugrupowania azobenzowe

A series of polyesterimides (PEI) containing photochromic azobenzene groups substituted with either F atom or NO 2 , CH 3 or OCF 3 ligands, were presented. They were obtained from various diesterdianhydrides and two amines: 1,3-phenylenediamine or 2,4-diamino-4'-fluoroazobenzene (Scheme B and C). PEI products show good solubility in some typical organic solvents and high glass transition temperature (141-212 °C). Elemental analysis, FTIR, 1 H NMR and UV-VIS methods have confirmed the chemical structure of the products obtained. Their thermal stability was also determined (by TGA). PEI products showed reversible photoisomerization trans-cis-trans in NMP solutions while exposed to non-polarized light (Hg lamp, λ = 365 nm) (Fig. 1, Scheme A). Exposure to polarized light (laser Ar + , λ = 488 nm) caused reorientation of the azobenzene groups what led to induction of optical anisotropy in the initially isotropic polymers. Photoinduced optical anisotropy in PEI films was examined by calculation of the value of dichroism generated (Fig. 3 and 4). The value of photoinduced dichroism (D) were in the range of 0.12-0.26. Photoinduced properties of the polymers were considered dependently on their chemical structure i.e. the kind of substituent in the azobenzene group and on the part of these groups in a polymer unit. The polymers with nitric substituent showed the biggest D values. However, no effect of introduction of the next azobenzene group to PEI mer was observed. Preliminary investigations of ability of selected polymeric films to formation of holographic networks (laser Ar + , λ = 514.5 nm) were carried out. It was found that this phenomenon was reversible (Fig. 6).

Carbon/polyesterimide thick-film resistive composites – Experimental characterization and theoretical analysis of physicochemical, electrical and stability properties

This paper describes carbon/polyesterimide thick-film resistive composites. Polyesterimide (PEI) resin with high thermal durability served as an insulative matrix whereas medium structure carbon black (MSCB), blend of MSCB and graphite (G), and high structure carbon black (HSCB) have been used as an active phase. Chosen physicochemical investigations, electrical measurements (dependence of sheet resistance, hot temperature coefficient of resistance and 1/ f noise on kind and content of conductive filler and curing temperature) and various stability tests have been used for complete description of MSCB/PEI, (MSCB + G)/PEI and HSCB/PEI thick-film resistor series. Electrical properties have been analyzed based on continuum percolation model completed by Balberg concepts connected with excluded volume and assumption of power distribution of distances between conductive grains embedded in polyesterimide.

Surface modification of imide containing polymers I: Catalytic groups

This paper describes basic studies of the surface modification of polyimide covered wires for insulation of electrical machines. Drain-off of the impregnating resin during production should be reduced by introduction of surface catalytic groups. 1H NMR kinetic analysis of aminolytic ring opening reaction of low molecular model compounds for polyimides showed very fast modification reactions. The catalytic effect of various functional groups on unsaturated polyester imide, acrylate and epoxy resins was investigated by DSC. Co(II)-catalysts and tertiary aliphatic amines proved highest activity for double bond containing systems and epoxy resins, respectively. Aminolytic treatment of Kapton ® slides was followed by ATR-IR spectroscopy. Plate–plate rheometer measurements of epoxy resins employing tertiary amine-treated Kapton ® slides proved significantly reduced gelling temperature.

Effect of Poly(esterimide)s as Compatibilizers on the Physical Properties of Poly(etherimide)/Thermotropic Liquid Crystalline Polymer in-situ Composites

This study investigates the compatibilizing effect of poly(esterimide) (PEsI) on the blend of poly(etherimide) (Ultem 1000; Ultem from General Electric Company) and thermotropic liquid crystalline polyesteramide (Vectra B950; Vectra B from Hoechst Celanese). Two types of polyesterimide (PEsI) were prepared as compatibilizers to improve the interfacial adhesion of incompatible Ultem and Vectra B. Poly(ethyleneterephthalate) (PET) based PEsI (EI10) and poly(butyleneterephthalate) (PBT) based PEsI (BI10) including 10 mol% of the imide are prepared. The binary Vectra B/PEsI and Ultem/PEsI blends were investigated in terms of thermal properties. This revealed that EI10 is more reactive (or compatible) with Vectra B, whereas BI10 is more compatible with Ultem. The effect of compatibilizer structures on the ternary Ultem/Vectra B/PEsI blends was also studied by thermal behavior, rheological properties, and mechanical properties. These results showed that BI10, more compatible with Ultem matrix, acts as a better compatibilizer in a ternary Ultem/Vectra B/PEsI blend system than EI10, more compatible with Vectra B phase. The optimum level of the compatibilzers turned out to be about 1–2 wt% for the blend systems.

Architecture and relevance of several strongly adhered biofilms over a polyester imide (PEI) surface

A microscopical study was undertaken to analyze the eventual fungi adhesion over a polyester imide surface in enameled copper wires. Scanning electron microscopy allowed to observe in these adhered biofilms, a high amount of pigments, hyphae and its enzymatic arsenal probably acting in the surface of the polymer. Due to the highly aromatic nature of this polyester and the residual phenol derivates still present in the reticulated polymer, an antifungal activity could be expected, but no significant changes were noted in fungal growing and in the adhesion process. Additionally, the wires showed completely failure in all insulation properties. The studies aimed to understand and evaluate the great fungi potential that could be explored in biodeterioration and biodegradation processes.

Conformational properties of macromolecules of heterocyclic polyester imides in dilute dichloroacetic acid solutions

Several series of polyester imides (PEIs) were prepared by melt polycondensation of trimellitimidobenzoic acid and acetylated, substituted hydroquinones as well as by solution polycondensation of corresponding dichlorides with hydroquinones. The influence of either phenyl- or tert-butyl substituents at the hydroquinone unit on the hydrodynamic (diffusion and viscometry) and optical [flow (FB) and electrical (EB) birefringence] properties of solutions of these PEIs were investigated. Independent methods for quantitative evaluation of the length of the statistical Kuhn segment A gave values of 14.5 nm (translational friction and electrical birefringence) and 12.0 nm (flow birefringence), respectively. The equilibrium rigidity of PEIs with phenyl and tert-butyl lateral substituents at the para-aromatic chain fragment was comparable. Conformational properties of the PEIs were analyzed, and the conjugation energies of the ester and amide groups for para-aromatic polyesters, PEIs, and structurally similar polyamidobenzoxazoles and polyamidobenzimidazoles were compared. The introduction of the phthalimide ring leads to a decrease of conjugation energy and deviation of the ester group from coplanarity. The Kuhn segment values obtained were useful for calculations of phase diagrams of semiflexible segmented block copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 12–24, 2004