Poly Amide-imide Research Articles

Dual-bionic, fluffy, and flame resistant polyamide-imide ultrafine fibers for high-temperature air filtration

Particulate matter (PM) pollution has been acknowledged as a serious health hazard globally, calling for thermo-stable air filtration materials to remove particles from high-temperature emission sources. However, the commercial filter media suffer from large fiber diameter and compact assembling architecture, resulting in the difficulty in achieving a balance between filtration efficiency and pressure drop. Herein, a dual-bionic strategy is proposed to prepare high-performance polyamide-imide (PAI) fibrous assemblies for the application in high-temperature air filtration. Inspired by the fact that Masson Pine shows attractive capability of particle retention, PAI fibers with biomimetic groove structure are constructed via asynchronous phase separation principle, meanwhile showing fluffy assembling architecture via humidity-induced electrospinning technology. Furthermore, the stiff cellulose networks within loofah sponges, which contributes to robust mechanical property, inspired us to construct semi-interpenetrating polymer network (semi-IPN) structure within PAI fibers. Benefitting from the hierarchical structure and intrinsic flame resistant property, the resulting PAI ultrafine fibers present distinct characteristics of high specific surface area (25.97 m2/g) and high porosity (90.44 %), contributing to a high PM2.5 filtration efficiency (98 % at severe pollution), a low pressure drop (only 46.35 Pa), and satisfying long serving time at 220℃. The successful fabrication of PAI filter media brings new insights for designing next-generation thermo-stable air filters.

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.

Synthesis and interfacial interaction of Ag2S quantum dots for enhancing the tribological behaviors of PTFE-based lubricating coatings

The small size and strong interfacial interaction are the key factor and challenge for quantum dots to play their reinforcing role as promising fillers of solid lubricating coatings. Herein, the minuscule Ag2S quantum dots (FQDs) of 1.71 nm with high dispersibility were synthesized via thermal decomposition of the precursor under the disturbance of polyamide-imide (PAI) molecules, and their interaction was investigated. Then the optimization of the mechanical and tribological properties of the polytetrafluoroethylene-based lubricating coatings depending on interfacial interaction was conducted, and their enhancement mechanisms were discussed. The results indicated that the PAI molecules were chemically adsorbed to the surface of the Ag2S FQDs and the interfacial interaction was improved based on the in-situ coordination reaction between the carboxyl group and Ag ions. The micro-hardness and wear life were thus increased by 45.70 % and 395.24 % compared with the original coating. Enhancing mechanical strength, inhibiting the frictional reaction of substrate and promoting the formation of sp2 carbon-based tribofilm were the crucial effects of Ag2S FQDs to improve the coating performance in terms of protection against friction and wear. The smaller size and strong interfacial interaction of Ag2S FQDs promoted the structural integrity and continuity of carbon-based tribofilm.

Preparationof self‐emulsifying waterborne polyamide‐imide sizing for carbon fiber and improvement on mechanical performances of carbon fiber reinforced thermoplastic polymer

AbstractRecently, Carbon fiber reinforced thermoplastic polymer (CFRTP) has been widely used in automotive, aviation, and aerospace. However, the traditional epoxy Carbon fiber (CF) sizing for thermosetting composites was unsuitable for high‐performance CFRTP due to the high‐molding temperatures and incompatibility between them. Herein, a novel semi‐aromatic polyamide‐imide (PAI) backbone structure with multi‐ethoxy pendant groups was designed and synthesized via click‐reaction and solvent‐free polymerization. Waterborne PAI sizing was prepared via self‐emulsifying without surfactants. CF/PEEK (polyether‐ether‐ketone) and CF/PEI (polyether‐imide) composites were manufactured. Results showed that novel PAI had excellent thermal stability and solubility, PAI sizing was stable after 6‐month‐storage. Mechanical performances and hydrothermal aging resistance of composites were improved. Compared with commercial‐sized CF (eCF)/PEI, the flexural strength of sCF/PEI increased by 35.2% to 753.47 MPa, and retention rates of them with aging also increased. Noted, mechanisms of interface enhancement were revealed by quantum chemical calculations, ππ stacking and hydrogen bonding between PAI and PEI, PEEK was found.

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.

Design, fabrication, and physicochemical characterization of polyamideimide membranes containing ZIF-8 and CMS particles for potential gas separation applications

The development of hybrid membrane materials with excellent permeance and selectivity applied for gas separation has been the focus of world attention. However, the development of membranes with efficient separation performance remains a great challenge.The ZIF-8 nanocrystals were prepared by a precipitation reaction with Zinc metal cluster and 2-methylimidazole, whereas the carbon molecular sieves (CMS) were synthesized by pyrolysis of polyamideimide (PAI) polymer. The successful formation of ZIF-8 nanocrystals was evident from the rhombic octahedron shape, and EDX confirms the presence of Zn metal cluster and methylimidazole linker. The ZIF-8 and CMS nanoparticles incorporated PAI membranes were prepared using the phase inversion technique with varying loading wt.% of 1, 2, and 3%. PAI/ZIF-8 and PAI/CMS membranes cross-sectional morphology confirmed that synthesized nanoparticles were well embedded through the PAI membrane. The PAI/ZIF-8 (3 %) membrane, thin dense skin top layer, and well-defined honeycomb porous substructure were observed. It was noticed that the PAI/ZIF-8 (1 wt%) membrane had shown endurance for ultimate strain up to 8.25 % which is comparatively higher than the PAI/CMS membranes. However, both the ZIF-8 and CMS membranes had shown a decrease in the mechanical stability at the higher filler loading of 3 wt% which could be due to the increased brittleness due to the aggregation of filler particles at the higher loading. Thus, the inclusion of ZIF-8 and CMS particles in the PAI matrix positively altered the physicochemical properties of the resulting hybrid membranes, which could help them achieve remarkable gas permeance and selectivity.

Design of Customized Pnuematic Wheel

The modern wheel of a car is defined as a circular section intended to rotate the axle bear. To meet market demand, original equipment manufacturers use the latest technology to design and manufacture wheels. Advanced technology that assists in the production of wheel rims is computer aided design (CAD) software and software analysis. In this paper we have used CAD and analytics software to the best of their ability. Wheel modeling was done using SOLIDWORKS and was submitted to ANSYS for analysis work. The ANSYS system is used to reproduce various strengths, component weight tracking and to validate and review results. The solution mode in the ANSYS system calculates bending times, pressures, and shifts in their relationships without manual intervention, reducing the relative time and scientific calculation strategy by the person. The dry analysis work of the ANSYS was performed by considering the Polyamide Imide material with different geometry (suggestions 1, 2, 3, 4, 5, 6) and their related functionality have been observed respectively. In this outcome paper Proposition 6 met the requirement and suggested prototyping. Keywords: ANSYS, SOLIDWORKS, Stress Analysis,

Polyetherimide for Magnet Wire Applications

<div class="section abstract"><div class="htmlview paragraph">Magnet wire is composed of a conducting core and thin layer of electrical insulation. Copper (Cu) is typically used as conducting core, and various polymers such as polyamideimide, polyimide, and polyesterimide are used for electrical insulation. The role of the magnet wire is related to the interchange between electrical and mechanical energy for energy transformation application such as transformers, motors, generators etc. Currently, the electric vehicles (EV) industry is growing rapidly and demands on related components are therefore increasing. Compared to the combustion engine, EV needs more electrical power with higher voltages or higher currents, which can increase probability of electrical discharge. The degradation of the insulation layer can occur by polymer bond breakage due to electrical stresses under partial discharge. To keep high performance under higher voltage, insulating polymers should have high heat and chemical resistance as well as low water absorption. In addition, the adhesion between the insulating polymer and Cu should be sufficient to prevent crack issues. As an incumbent solution, polyamideimide (PAI) and polyimide (PI) is being used for this application in a varnish form. However, PAI absorbs moisture in humid environments or when immersed in water (up to 5% weight), which can cause reliability issues [<span class="xref">1</span>]. PI shows very poor adhesion strength with the conducting core due to its stiffness and low surface energy [<span class="xref">2</span>, <span class="xref">3</span>], which can cause reliability problems for magnet wires [<span class="xref">4</span>]. Therefore, there are strong demands to solve such issues like improvements in dielectric strength, water resistance, and high heat resistance. In this report, we will share the results of excellent flexibility, adhesion, and electrical performance of polyetherimide (PEI, ULTEM™ resin) based varnish as a high voltage insulation material.</div></div>

Stability of Graphene Oxide Composite Membranes in an Aqueous Environment from a Molecular Point of View

We used molecular dynamics to investigate the stability of graphene oxide (GO) layers supported on three polymeric materials, namely a polyvinylidene fluoride (PVDF), a pristine and a crosslinked polyamide–imide (PAI and PAI-cr). The membrane configurations consisted of a few layers of GO nanosheets stacked over the specified polymeric supports and submerged in water. We monitored the position, the tilt angle, and the radial distribution function of the individual GO nanosheets in respect to the plane of the supports. We showed that the outermost GO nanosheets were more distorted than those attached directly on the supports. The greatest distortion was observed for the GO nanosheets of the PVDF-supported system. Next, we recorded the density profiles of the water molecules across the distance from the layers to the polymer and discussed the hydrogen bonds between water hydrogens and the oxygen atoms of the GO functional groups.

Study on the tribological properties of Si3N4/polyamide-imide composites

Si3N4 whiskers were modified with triethoxysilane as a means to improve the interfacial interaction with a poly-amide imide (PAI). The Si3N4/PAI composites were prepared by in-situ polymerization as an approach to improve the friction behavior and mechanical properties in order to meet the performance needs of electrical transformers and motors in harsh environments. 4,4′-diamino diphenyl ether, m-phenylenediamine, triethylamine, trimellitic anhydride chloride, and Si3N4 whiskers were used to manufacture Si3N4/PAI composite, which was then characterized for friction and mechanical behavior. The research showed that the addition of Si3N4 whiskers improved the mechanical properties and friction properties of PAI. When the whisker content was 10 wt%, the tensile strength of the composite was 137.5 MPa, which is 15% higher than pure PAI, and the wear rate was 0.69 × 10-8 g/N·m, which is 57% lower than pure PAI, and the friction coefficient was 0.47, which was an increase of 9%. In aerospace, machinery, and transportation applications, these materials may have better performance due to their improved combination of properties.

Lead titanate nanowires/polyamide-imide piezoelectric nanocomposites for high-temperature energy harvesting

With an increasing demand for self-powered microelectronics to be used in scientific tasks and exploration missions in extreme environments, the implementation of piezoelectric energy harvesting at high temperature is an important research focus for renewable energy sources. Piezoelectric composites made from piezoelectric ceramic fillers and polymer matrices combine high electromechanical coupling with flexibility, resulting in a versatile candidate for energy harvesting. In this research, a nanocomposite formed by lead titanate nanowires (PbTiO3 NWs) and a polyamide-imide (PAI) matrix is developed and shown to have an excellent piezoelectric response at high temperatures. By in situ measurements of the piezoelectric g31 and d31 coefficients of the nanocomposite films with different PbTiO3 NW weight fractions in the temperature range 25–250 °C, the dependence of temperature and filler concentration on the piezoelectric properties are fully characterized. In addition, the effect of NW alignment on piezoelectric properties through direct ink writing is also studied. Finally, a bending-mode energy harvester made from this nanocomposite is demonstrated to generate a maximum power density of 33 μW·m−2 at resonance and a power density of 20 μW·m−2 under low-frequency random excitation at 200 °C, while keeping a long operating life of at least 100 h. In conclusion, this work provides a new solution for high-temperature energy harvesting from low-frequency random vibrations using PbTiO3/PAI nanocomposites.

Strengthening mechanism of in-situ synthesized Cu2S nanoparticles on tribological performance of polyamide-imide bonded solid lubricating coatings

Cuprous sulfide (Cu2S) nanoparticles were in-situ synthesized in Polyamide-imide (PAI) bonded solid lubricating coatings to improve the tribological performance of PAI lubricating coatings. To reveal the strengthening mechanism of in-situ synthesized Cu2S nanoparticles on tribological performance of PAI lubricating coatings, hydrothermal synthesized Cu2S (noted as HS-Cu2S) nanoparticles were also prepared as a comparison. The experimental result indicated that in-situ synthesized Cu2S nanoparticles can more conspicuously promote the tribological performance of PAI lubricating coatings than HS-Cu2S nanoparticles. The possible reason was attributed to that in-situ synthesized Cu2S nanoparticles generated interfacial interactions with bonded resin PAI during the high-temperature curing process of composite coatings. As a result, the dispersion performance of in-situ synthesized Cu2S nanoparticles was effectively promoted in PAI lubricating coatings, and simultaneously, the bonding strength between Cu2S nanoparticles and bonded resin was also stimulated. What's more, a continuous organic-inorganic composite tribo-film was in-situ formed on the surface of the counterpart steel ball during the friction process. Therefore, direct abrasion between counterpart steel ball and composite coatings was restrained, and tribological performance of the composite coatings was significantly promoted.

Polyamideimide dielectric with montmorillonite nanosheets coating for high-temperature energy storage

To meet the ever-increasing demand for electric power storage and conversion under harsh environment, polymer dielectrics, as the functional component in electrostatic capacitors, are required to serve at high temperatures. However, it is challenging to maintain favorable electrical insulation in polymer dielectrics with the temperature rise because of the high conduction loss at elevated temperature, which will lead to reduced breakdown strength, energy density, and service life. Here, a versatile surface engineering method is presented to enhance the high-temperature electrical insulation and energy storage performance of polymer dielectric via dip-coating montmorillonite (MMT) nanosheets. At 150 °C, a significantly enhanced breakdown strength of 551MV/m is achieved in a MMT coated polyamideimide (PAI) with optimized coating thickness and MMT content, resulting in a high energy density of 2.9 J cm−3 and a charge-discharge efficiency >80% that outperform existing high-temperature polymers and polyimide-based composites. Finite element simulation demonstrates that this superior performance is attributed to the anisotropic electrical properties of MMT nanosheets, which not only blocks charges injected from electrodes but also regulates the transport of charges to dissipate along the in-plane direction. This work offers a versatile and scalable approach for enabling high-temperature electrostatic energy storage and high-temperature insulation of a wide range of polymer dielectrics.

Perovskite Solar Cells on Polymer‐Coated Smooth and Rough Steel Substrates

Fabricating efficient perovskite solar cells on steel substrates could enable easy building integration of this photovoltaic technology. Herein, an n–i–p perovskite solar cell is developed on steel substrates for top illumination. The optimized stack uses a Ti bottom electrode, covered with an indium tin oxide (ITO) interlayer and a SnO2 electron transport layer passivated by [6,6]‐phenyl‐C61‐butyric acid. The active layer is a triple‐cation perovskite. A thermally evaporated tris(4‐carbazoyl‐9‐ylphenyl)amine)/MoO3 bilayer acts as hole transport layer. The transparent top contact consists of ITO with a MgF2 antireflective coating. Optical analysis shows small parasitic absorption and reflectance losses for this stack, which provides 15.9% power conversion efficiency when fabricated on glass. On steel, covered with a polyamide imide planarization coating to moderate the surface roughness (R p), the highest efficiency is 15.2% for high‐gloss steel (R p ≈ 200 nm), 14.9% for battery steel (R p ≈ 500 nm), 14.2% for packaging steel (R p ≈ 1500 nm), and 13.8% for construction steel (R p ≈ 2500 nm). While the short‐circuit current density and open‐circuit voltage are invariant, the fill factor decreases with increasing R p due to increasing series resistance and decreasing shunt resistance. The yield of working devices remain high, also for the roughest substrates.

Ultraflexible polyamide-imide films with simultaneously improved thermal conductive and mechanical properties: Design of assembled well-oriented boron nitride nanosheets

The highly thermally conductive yet electrically insulating polymeric materials are exhibiting tremendous potential for thermal management materials. However, the practical application of these materials is restrained by the limited thermal conductivity (TC) and deterioration of mechanical properties. In this work, an ultraflexible polyamide-imide (PAI) film with a sandwich-like structure composed with assembled well-oriented functionalized boron nitride nanosheets (FBN) by facile layer-by-layer solution-coating strategy is constructed. The design of the layered structure and highly oriented arrangement of interconnected FBN (Herman's orientation parameter ƒ up to 0.847) endows the obtained PAI composite film with super-flexibility, ultrahigh in-plane thermal conductivity (λ//), superior thermal transfer capability (ΔTmax = 24.4 °C) and excellent electrical insulation performance. The PBP composite film reaches an ultrahigh λ//of 45.7 W m−1 K−1 with only 23 wt% FBN loading and exhibits a remarkable TC enhancement factor over 23 because of the more continuous phonon transfer networks that constructed by interconnected well-oriented FBN which could effectively suppress the phonon scattering. Furthermore, the mechanical properties of the layered composite film (PB4P) exhibit noteworthy enhancement compared with uniform PBN composite film, in which the tensile strength is increased by 110% and toughness enhancement is 329%. Meaningfully, our fabrication strategy has the advantage of simplicity and adaptability for commercial amplification. The composite film developed in this work provides a promising prospect for the thermal management system of modern power electronic devices.

Mixed Matrix Membranes Based on Torlon® and ZIF-8 for High-Temperature, Size-Selective Gas Separations.

Torlon® is a thermally and plasticization-resistant polyamide imide characterized by low gas permeability at room temperature. In this work, we aimed at improving the polymer performance in the thermally-enhanced He/CO2 and H2/CO2 separations, by compounding Torlon® with a highly permeable filler, ZIF-8, to fabricate Mixed Matrix Membranes (MMMs). The effect of filler loading, gas size, and temperature on the MMMs permeability, diffusivity, and selectivity was investigated. The He permeability increased by a factor of 3, while the He/CO2 selectivity decreased by a factor of 2, when adding 25 wt % of ZIF-8 at 65 °C to Torlon®; similar trends were observed for the case of H2. The MMMs permeability and size-selectivity were both enhanced by temperature. The behavior of MMMs is intermediate between the pure polymer and pure filler ones, and can be described with models for composites, indicating that such materials have a good polymer/filler adhesion and their performance could be tailored by acting on the formulation. The behavior observed is in line with previous investigations on MMMs based on glassy polymers and ZIF-8, in similar conditions, and indicates that ZIF-8 can be used as a polymer additive when the permeability is a controlling aspect, with a proper choice of loading and operative temperature.

Proton conducting membrane based on multifunctional interconnected copolymer containing 4,4′‐diaminodiphenylmethane‐aminoethyl piperazine with sulfonated polyethersulfone membrane for fuel cell application

AbstractThe facile fabrication of proton exchange membrane (PEM) by intermixing of aminoethylpiperazine monomer (AEP), diamino diphenylmethane (DDM) monomer, and AEP combine with varying compositions of DDM (2, 4, and 6 wt%) copolymer with sulfonated polyethersulfone (SPES) and polyamide‐imide (PAI) polymer matrix for fuel cell applications. The intermixing of AEP@DDM copolymer in the SPES/PAI matrix was confirmed by Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction spectroscopy (XRD) techniques. The physicochemical performance of fabricated PEM was analyzed by water uptake, ion exchange capacity (IEC), swelling ratio, thermal degradation, hydrolytic degradation, chemical and mechanical properties. The intermixing copolymer (AEP@DDM) has significantly suppressed the thermal and hydrolytic deterioration of the PEM. Furthermore, the PAI had noteworthy to improve the thermal and chemical stability of the membranes significantly. The proton conductivity of the SPES/PAI/AEP@DDM (6%) membrane was found to be 5.68 × 10−4 S cm−1 which is 104% higher than the pristine SPES membrane. Besides, the selectivity of SPES/PAI/DDM (6%) was also enhanced up to 80.34% compared to pristine SPES membrane. The inclusion of AEP@DDM in SPES/PAI enhanced the proton conductivity and contributed to the membrane structure's uniformity, as revealed from morphological studies. The AEP@DDM copolymer modification of SPES/PAI membrane has shown good stability, physicochemical property and can be considered as a promising membrane material for fuel cell application.

Exploration of pros and cons of polyetherimide solutions with varying concentrations as the sizing agents for graphite fibers in graphite fabric-PAEK composites

Some specialty polymers such as polyetheretherketone (PEEK), Polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyetherimide (PEI), polyamideimide (PAI), and polyimide (PI) are the ideal choices for developing high performance bidirectionally reinforced composites that would excel in specific strength performance. However, these polymer composites are extremely challenging from a processing point of view and have limited choices. Most of the time, a lot of compromises are to be made on the fiber-matrix wetting issues. The current research elaborated on a method to exploit two techniques together to opt for advantages from both. Polyetherimide (PEI) solutions of various concentrations/viscosities were used as sizing agents for the fibers so as to wet the cross-over points on graphite fabric and inter-tow filaments. It was expected that the PEI and PAEK would form a blend at the interface, although fiber would necessarily be covered with only PEI. It was also anticipated that there could be an optimum amount of PEI on the fibers’ surface for the best performance properties. Based on the in-depth studies on the performance properties, it was concluded that PEI solution in the range of 5–10 wt. % would lead to the best combination of performance properties. Compared to the classical method of developing PAEK-graphite fabric composites by film technique, the current method of combination of impregnation and film technique led to excellent results.

High-performance polyamide-imide films: Effect of functionalization degree of BN nanosheets

Chemical functionalization of boron nitride (BN) is necessary to improve the dispersion of the BN as well as interface compatibility within polymer matrix to enhance the properties of their composites. However, the degree of BN functionalization needs to be considered comprehensively to fully highlight the advantages. In the present work, a polyamide-imide (PAI) film with a parallel arrangement structure and designed functionalization of BN nanosheets by self-assembly technique is constructed. The design of optimum functionalization and defect control of the functionalized BN nanosheets (f-BNNSs) provides this flexible PAI/f-BNNSs composite film exhibits highly in-plane thermal conductivity, superior electrically insulating and improved mechanical properties. The thermal conductivity of the PAI/f-BNNSs film had an impressive improvement of 167%, from 5.06 W m−1 K−1 of PAI/BN film to 13.5 W m−1 K−1 of PAI/f-BNNSs film (PP1W3) at a low filler content of only 9 wt%. More importantly, systematic research was carried out in terms of the degree of functionalization, the quantities of defect of f-BNNSs and the performance of the composite films, which further revealed the mechanism of the thermal conductivity improvement of PAI/f-BNNSs composite films. This research provides significant guidance for the design of composite materials with excellent thermal conductivity based on the functionalization of low dimensional fillers, ensuring its application in the thermal management of high-power density electronic devices.

Synthesis and properties of transparent random and multi-block polyamide-imide films with high modulus and low CTE

Two new series of transparent polyamide-imides (PAIs) with high modulus and low coefficient of thermal expansion (CTE) were prepared by random or block copolymerization of 4,4′-biphthalic dianhydride (BPDA) and p-phthaloyl chloride (TPC) with 2,2′-bis(trifluoromethyl)benzidine (TFDB). These series of PAIs displayed low CTE of 16–42 ppm/K, good mechanical properties with high tensile modulus ranging from 4.9 to 6.6 GPa, tensile strengths of 112–170 MPa and elongations at break of 2.0–5.4%, as well as high transparency with transmittances at 500 nm (T500nm) of 84–87%, which was greatly affected by the feed ratio of monomer BPDA & TPC, and the block length caused by block polymerization. The block copolymer PAI-3-B1 presented the best comprehensive performance with high transparency (T500nm) of 87%, low CTE of 16 ppm/K and high tensile modulus of 6.1 GPa.