Cross-Linked and Rigid Polyimide Composite Foams with Prominent Fire Resistant, Thermal Insulating, and Wave-Transparent Properties

Li, Jianwei; Lin, Jun; Wang, Yugen; Chu, Wei; Liu, Fei; Wang, Bin

doi:10.1021/acsapm.2c00931

Cited by 19 publications

(6 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This can be attributed to the ultrahigh melting point of PPTA molecules, which the PPTA molecules decompose before melting. As the low dielectric constant/loss, excellent mechanical properties, and high thermal stability are all important factors that need to be considered for evaluating a dielectric material, the nanoporous ANF aerogel films exhibit superior comprehensive performance, which outperforms the vast majority of dielectric materials (Figure e). − …”

Section: Resultsmentioning

confidence: 99%

Ambient Drying Route to Aramid Nanofiber Aerogels with High Mechanical Properties for Low-k Dielectrics

Liu

Robertson

Qiang

et al. 2022

ACS Appl. Polym. Mater.

View full text Add to dashboard Cite

Polymeric aerogels with low dielectric constant (low-k) are an important material solution for applications in high-frequency terminal electronic devices. However, most aerogels are prepared using high-cost supercritical drying or freeze-drying methods and typically exhibit poor mechanical properties and low thermal stability, which limits their use in practical applications. Here, we report the fabrication of aerogels with layered structure and hierarchical nanopores based on aramid nanofibers (ANFs), using a vacuum-assisted filtration method followed by low-cost ambient drying. The porosity of the ANF aerogels can be controlled from 38 to 79% by rationally selecting solvents with different surface tension for solvent exchange, tuning the affinity between solvents and ANF skeletons as well as controlling the solvent evaporation rate during the ambient drying process. The ANF aerogels have an ultralow and tunable dielectric constant as low as 1.56 while exhibiting a low dielectric loss between 0.0040 to 0.0055 at 1 MHz. The advantageous low-k property can be preserved at high temperatures up to 300 °C, and an inherent flame retardancy is achieved due to the rigid and all-aromatic backbone structure of poly(p-phenylene terephthalamide). Moreover, the nanoporous ANF layers with relatively lower porosity compared with the overall porosity of the aerogel provide strong mechanical strength and modulus, while the presence of larger nanopores from the interspacing of ANF layers ensures a high porosity for the entire aerogel, which endows the aerogel film with superior tensile strength and modulus compared with their conventional counterparts containing homogeneous porous structures. Collectively, these ANF aerogels exhibit low-k, outstanding mechanical properties, high thermal stability, and inherent flame retardancy, enabling them to become very promising next-generation dielectric materials.

show abstract

Section: Resultsmentioning

confidence: 99%

Ambient Drying Route to Aramid Nanofiber Aerogels with High Mechanical Properties for Low-k Dielectrics

Liu

Robertson

Qiang

et al. 2022

ACS Appl. Polym. Mater.

View full text Add to dashboard Cite

show abstract

“…Under the protection of nitrogen atmosphere, the appropriate amount of anhydrous ethanol was firstly added into a three-neck flask that was immersed in an oil bath at 70 • C. Then, BTDA (32.22 g, 0.1 mol) and ring-opening catalyst 2-MI (0.03 g) were added under continuous mechanical stirring and cool reflux for 2 h to obtain 3, 3 , 4, 4 -benzophenone tetracarboxylic acid diester (BTDE), until the solution gradually changed from white to light yellow. At this time, equimolar diamine ODA, MDA, MPD, DDS, or PDA was added for further stirring for 2 h, and then silicone oil AK8805 (0.5 mL) was added to as a surfactant for Polymers 2023, 15, 2609 4 of 18 20 min to obtain five different polyester ammonium salt (PEAS) precursor solutions. After the reaction was completed, the resulting PEAS powders were obtained through rotary evaporation.…”

Section: Synthesis Of Polyester Ammonium Precursor Powders and Prepar...mentioning

confidence: 99%

Preparation and Properties of High-Temperature-Resistant, Lightweight, Flexible Polyimide Foams with Different Diamine Structures

et al. 2023

View full text Add to dashboard Cite

Polyimide foam (PIF) is a rising star in high-end applications such as aerospace thermal insulation and military sound absorption. However, the basic rule on molecular backbone design and uniform pore formation of PIF still need to be explored. In this work, polyester ammonium salt (PEAS) precursor powders are synthesized between alcoholysis ester of 3, 3′, 4, 4′-benzophenone tetracarboxylic dianhydride (BTDE) and aromatic diamines with different chain flexibility and conformation symmetry. Then, a standard “stepwise heating” thermo-foaming approach is used to prepare PIF with comprehensive properties. A rational thermo-foaming program is designed based on in situ observation of pore formation during heating. The fabricated PIFs have uniform pore structure, and PIFBTDA-PDA shows the smallest size (147 μm) and narrow distribution. Interestingly, PIFBTDA-PDA also presents a balanced strain recovery rate (SR = 91%) and mechanical robustness (0.051 MPa at 25% strain) and its pore structure maintains regularity after 10 compression–recovery cycles, mainly due to high rigidity of the chains. Furthermore, all the PIFs possess lightweight feature (15–20 kg∙m−3), good heat resistance (Tg at 270–340 °C), thermal stability (T5% at 480–530 °C), thermal insulation properties (λ = 0.046–0.053 W∙m−1K−1 at 20 °C, λ = 0.078–0.089 W∙m−1K−1 at 200 °C), and excellent flame retardancy (LOI > 40%). The reported monomer-mediated pore-structure control strategy can provide guidelines for the preparation of high-performance PIF and its industrial applications.

show abstract

“…However, they cannot meet high-end engineering applications that require high-temperature thermal insulation due to their limitation in thermal stability. Therefore, it becomes paramount to develop foams that meet mechanical robustness and flexibility, excellent low-/high-temperature tolerance, and outstanding thermal insulation and radiation tolerance to suit the stringent requirements in the above-mentioned engineering areas. − …”

Section: Introductionmentioning

confidence: 99%

Lightweight, Radiation-Resistant, and Flexible Polyimide Foams with an Anisotropic Porous Structure for Efficient Thermal Insulation Applications

Luo

Wang

et al. 2023

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Flexible polyimide foams (PIFs) with an anisotropic porous structure were prepared by a facile strategy, possessing exceptional mechanical robustness and thermal insulation performances. A comparison of the foaming and rheological behavior, microstructure, and mechanical and thermal and radiation-resistant properties of copolymerized and blended PIFs was conducted. Besides, the formation mechanism of the anisotropic structure and its influence on the mechanical and thermal insulation properties were explored in depth. By reasonably regulating the molecular structure, melt viscosity, melt volatile content, and foaming temperature, a favorable microscopic morphology and structure can be achieved. PIFs with regular porous near-spherical appearance and aligned ellipsoidal strip structures exhibited anisotropic mechanical performance. Meanwhile, PIFs showed anisotropic thermal insulation behavior, which possessed a minimum thermal conductivity (λ) of 0.0314 W/m•K along the pore growth direction (i.e., vertical direction) and a λ as low as 0.0279 W/m•K in the horizontal direction. The anisotropic thermal conduction behavior endowed PIFs with intelligent thermal protection and infrared stealth performance. In addition, the PIFs presented an exceptional thermal stability and compressive strength retention rate after experiencing a radiation dose of 10027.5 kGy. Therefore, a facile strategy for rapid fabrication of PIFs that can be positioned for structural design, thermal insulation, and radiation-resistant applications in high-end engineering sectors was proposed.

show abstract

Cross-Linked and Rigid Polyimide Composite Foams with Prominent Fire Resistant, Thermal Insulating, and Wave-Transparent Properties

Cited by 19 publications

References 50 publications

Ambient Drying Route to Aramid Nanofiber Aerogels with High Mechanical Properties for Low-k Dielectrics

Ambient Drying Route to Aramid Nanofiber Aerogels with High Mechanical Properties for Low-k Dielectrics

Preparation and Properties of High-Temperature-Resistant, Lightweight, Flexible Polyimide Foams with Different Diamine Structures

Lightweight, Radiation-Resistant, and Flexible Polyimide Foams with an Anisotropic Porous Structure for Efficient Thermal Insulation Applications

Contact Info

Product

Resources

About