A novel phenylethynyl-terminated siloxane-containing ortho-hydroxy polyimide (O-SPI) was synthesized and physically blended with thermoplastic polyimide (PI) to enhance both the thermal and mechanical properties of polyimide, addressing the growing demand for high-performance materials in harsh environments. The blend underwent conversion to semi-Interpenetrating Polymer Networks ( semi-IPNs) and benzoxazole structures through thermal curing of reactive phenylethynyl groups and thermal rearrangement of ortho-hydroxy imide units. The trends in thermal and mechanical properties were investigated in relation to the chemical structures and varying mass fraction of O-SPI. The covalent incorporation of semi-IPNs and rigid benzoxazole structures restrict segmental motion while the backbone linkage confers the toughness of the blends. These synergistic effects insure the cured blends with high glass transition temperatures (472.51°C) and tensile strength (117.81 MPa) simultaneously, demonstrating their potential for applications in challenging conditions.

Bisphenol A-based phthalonitrile resin was synthesized by nucleophilic substitution reaction from bisphenol A and 4-nitrophthalonitrile, and then the obtained resin was cured with sulfaguanidine as a novel curing agent. The curing characteristics, kinetics, thermal stability and dynamic mechanical property were studied by standard thermal analysis techniques including DSC, TGA, and DMA. The peak temperature of exothermic peak ( Tp) and apparent activation energy ( Ea) of sulfaguanidine cured phthalonitrile resin were 263.20°C and 76.6 kJ·mol−1 respectively, much lower than those of traditional aromatic diamine cured resin. Moreover, the resin cured by sulfaguanidine showed excellent thermomechanical properties and thermal stability. The glass transition temperature ( Tg) was 284.8°C, the initial thermal decomposition temperature ( Td,5%) was 439.6°C, and the char yield at 800°C was 62.1% in nitrogen atmosphere. To sum up, organic guanidine cured phthalonitrile resin exhibits excellent curing characteristics (low Tp and Ea) and high thermal properties, which provides a promising approach to preparing phthalonitrile resin with high comprehensive performance.

The development of epoxy resin (EP) with simultaneous enhancements in flame retardancy, mechanical performance, and low dielectric properties represents a significant and complex challenge. In this study, halloysite nanotubes (HNTs) were modified with melamine amino tris-methylene phosphonate (MA) to produce MA-modified HNTs (HMA), which were then integrated into EP to form EP/HMA composites. The incorporation of 1 wt% HMA significantly enhanced the flame retardancy (limit oxygen index up to 29.7%, UL-94 V-0 rating), reduced peak heat release rate by 23.4%, decreased total heat release by 11.9%, reduced total smoke production by 18.4%, and improved mechanical properties (tensile strength by 17.0%, impact strength by 61.0%) compared to pure EP. Additionally, EP/HMA showed a low dielectric constant (3.16) and a dielectric loss (0.019) at 1 GHz. This research presents a versatile strategy for creating multifunctional EP composites with high potential for applications in microelectronics, electronic packaging, and other relevant fields.

Traditional thermally conductive materials are gradually losing their advantages as the electronics industry develops rapidly. Polymers are in urgent need of a material with high thermal conductivity, stable structure, good mechanical properties and oxidation resistance, which makes hexagonal boron nitride (h-BN) an excellent heat transfer filler for polymer composites. Boron nitride nanosheets (BNNS) are monolayers of hexagonal boron nitride, and theoretical studies have shown that BNNS have a higher thermal conductivity than h-BN (up to 400 Wm−1K−1, in-plane). This paper provides a comprehensive review of various methods for preparing BNNS, including mechanical exfoliation, liquid phase sonication exfoliation and chemical vapor deposition (CVD). In addition, various factors affecting the thermal conductivity of BNNS, including grain boundary, grain size and defects, are also discussed. Then, the influence of BNNS as filler on the thermal conductivity of the polymer was further discussed. Finally, this paper summarizes the existing BNNS applications and lists the application scenarios of BNNS in various fields. The purpose of this review is to summarize the previous work and put forward the prospect and future development direction of preparing high thermal conductivity BNNS-included polymer composites, so as to stimulate the research and improvement of new preparation methods for BNNS and promote its practical application as heat transfer materials.

Two series of novel poly(ester-amide-imide)s (PEsAIs) with pendant phthalimide side group were synthesized by copolymerization of phthalimide-hydroquinone bis(trimellitate anhydride) (PI-TAHQ), p-phthaloyl chloride (TPC) and other fluorinated monomers using the two-step method. These PEsAIs had glass transition temperatures ( Tgs) in the range of 228 °C–296°C and coefficients of thermal expansion (CTEs) of 18–55 ppm·K−1. These films had good mechanical properties with tensile modulus of 3.7–5.7 GPa, tensile strengths of 92–153 MPa and elongations at break of 2.2%–8.3%. All films displayed good transparency with transmittances at 400 nm (T400nm) of 43%–79% and transmittances at 850 nm (T850nm) exceeding 89%, and these PEsAIs were amorphous. Especially, PEsAI-d-60 presented the best comprehensive performance with Tg of 296°C, low CTE of 18 ppm·K−1 and high transmittance (T400nm of 79%, T850nm of 91%), which exhibited the potential of this novel poly(ester-amide-imide) containing pendant phthalimide substituent in optical transparent materials.

Epoxy resin/cyanate ester copolymer (EC) possesses the advantages of low dielectric constant and low dielectric loss, while the easy flammability of EC restricts its applications. The effect of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphazephenanthrene-10-oxide (DQ) and copper hydroxystannate (CuHS) on the flame retardancy, smoke suppression, mechanical properties and thermal decomposition behavior of EC was studied. The EC composite containing 7 wt% DQ and 3 wt% CuHS (EC/7DQ3CuHS) passed the UL-94 V0 rating with a limiting oxygen index of 32.0% The peak heat release rate and total heat release of EC/7DQ3CuHS fell by 41.9% and 35.0% respectively, compared with those of pure EC. The total smoke release of EC/7DQ3CuHS was reduced by 36.0% in comparison with that of the EC composite containing 10 wt% DQ. The tensile and impact strengths of the EC composite with 9 wt% DQ and 1 wt% CuHS increased by 16.9% and 19.2%, respectively in contrast with pure EC. The dielectric constant and dielectric loss of the EC composites maintained at relative low values. The as-prepared EC composites have application prospect in electronic packaging industry.

Reactive polyimide (PI) containing phenolic hydroxyl groups was prepared by the polymerization of 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane and mixed thiodiphthalic anhydride. A series of epoxy resin composites were obtained by adding reactive PI to N,N,N′,N′-tetraglycidyl-4,4′-diamino-diphenylmethane (TGDDM) epoxy resin in different proportions. The effect of PI content on curing behavior, thermal properties, and mechanical properties was carefully investigated. Even a small amount of PI addition improved the mechanical properties and heat resistance of the epoxy resin, particularly the fracture toughness. Among them, epoxy resin composites EP-PI-1.5 with the addition of 1.5 wt% PI showed the best mechanical properties, whose impact strength, fracture toughness, and tensile strength were increased by 114%, 59%, and 34%, respectively. The phase morphology was also investigated to illustrate the fracture mechanism by scanning electron microscope (SEM) characterization.

Polyimide (PI) aerogels with excellent properties have received a lot of attention, and the use of nanoparticles to improve the properties of aerogels has been investigated in the last few years. In this work, aminated functionalized MXene nanoparticles were successfully prepared as a cross-linking agent as well as an inorganic reinforcing phase, homogeneously embedded in PI aerogels, to synthesize a new PI composite aerogel. The results show that m-MXene can act as a cross-linking point to effectively maintain the network structure, which further improves the dimensional stability and compressive modulus. These PI composite aerogels have a high specific surface area, low density, low shrinkage and excellent mechanical properties.

The electromagnetic induction heating technology has the advantages of fast heating speed and cleanness, and can realize the rapid temperature curing of carbon fiber reinforced polymer (CFRP). In order to improve production efficiency and curing quality, a finite element model of induction heating CFRP was established, and the temperature field distribution and heating mechanism during induction heating of CFRP were analyzed. The correctness of the model and conclusion is verified by experiments. On this basis, the influence of current, diameter, frequency and distance on the heating rate is analyzed, and it is found that frequency has the greatest influence on the heating rate. In addition, the mathematical relationship between temperature field uniformity and entropy value is established, which provides a quantitative analysis method for the temperature field uniformity of induction heating CFRP. Through optimization analysis, it is obtained that for the CFRP mentioned in the article, the coil size is selected between 65 mm and 95 mm, and the spacing is between 3.5 mm and 6.5 mm, so that the temperature field has the best uniformity.

In this study, a novel bismaleimide monomer: Carbazole-Bismaleimide (Cz-BisMI) was introduced to the literature as a first. Cz-BisMI was synthesized by a catalytic cyclodehydration reaction of 3,6-bismalemic acid carbazole which is an intermediate product obtained by an imidization reaction of 3,6-diamino carbazole. Then, the chemical structure of Cz-BisMI was elucidated by FT-IR, 1H NMR, 13C NMR and LC-MS spectroscopies. The thermal properties of Cz-BisMI were investigated by DSC in comparison with a commercial bismaleimide monomer, 4,4-bismaleimidophenylmethane (DPM-BisMI). Cz-BisMI has a melting point of 192°C and also, the onset temperature of the exothermic curve was measured as 293°C. Furthermore, it was determined that Cz-BisMI has a 35.6 percent larger processing window than DPM-BisMI. The spin-coated films of Cz-BisMI showed a high refractive index in the range of 1.61 to 1.50 between 400 and 650 nm with good transparency of over 85%. On the other hand, a new poly(bismaleimide): P(Cz-BisMI)s containing carbazole units was prepared by the self-polymerization process of Cz-BisMI. P(Cz-BisMI)s showed a high thermal transition temperature of 356°C. In conclusion, Cz-BisMI is a viable choice as a bismaleimide monomer for the development of opto-electronic materials due to its enhanced optical properties and thermal behavior.