To prepare epoxy resin-based composites with excellent comprehensive properties, this study synthesized dendritic nanosilica (DSiO₂) via a dual-template method and applied them to modify epoxy resin (EP). The relationship between structure and property of the composites was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption-desorption tests. The results indicate that after modification with the silane coupling agent Z-6040, DSiO₂ exhibits excellent dispersibility in epoxy resin. As the mass fraction of DSiO₂ increases from 0 to 0.9%, the onset curing temperature of the composite decreases from 160.7℃ to 111.3, and the peak temperature decreases from 196.3℃ to 159.6℃; the tensile strength increases from 24.2 MPa to 53.6 MPa, the elongation at break increases from 10.5% to 13.5%, and the Rockwell hardness increases from 85.1 to 91.5. Compared with the unmodified EP, the DSiO₂/EP composites exhibit significantly increased storage modulus, a glass transition temperature (T_g) that shifts toward higher temperature, and enhanced thermal stability.

To investigate the effects of different accelerators and their dosage on the pre-curing and cured properties of epoxy resin/anhydride systems (EP/MTHPA), this study employed three accelerators—DMP-30, N,N-dimethylaniline, and N,N-dimethylbenzylamine—to prepare EP/MTHPA cured products at different curing agent dosages. The pre-curing behavior of the resin system and the mechanical properties, thermal stability, and electrical properties of the cured materials were studied. The results show that when the accelerator dosage is 0.75 g, the viscosity variation of the resin system is more suitable for production process control. Among them, the EP/MTHPA/DMP-30 system exhibits excellent comprehensive performance, with the lowest polymerization activation energy of 74.58 kJ/mol, a heat deflection temperature reaching 123.40℃, a flexural modulus, flexural strength, and impact strength of 123.6 MPa, 2.9 GPa, and 14.8 kJ/m², respectively, and a volume resistivity of 9.6×10¹⁶ Ω·cm.

This study aims to clarify the effects of the crystallization characteristics of domestically washed polypropylene resin and the casting process on the microstructure of cast films and the comprehensive properties of biaxially oriented polypropylene (BOPP) films. Using domestically washed polypropylene resin as the research object, the effects of crystallization characteristics of the domestic resin and casting process on the regulation of the cast film microstructure and the resulting effects on the comprehensive properties of BOPP films were systematically investigated by means of characterization techniques such as polarizing optical microscopy (POM) and wide-angle X-ray diffractometry (WAXD). The results show that the domestic resin can form β-crystals of relatively small size during slow cooling. Increasing the chill roll temperature can increase the crystallinity, β-crystal content, and spherulite size of the cast film, while the β-crystals on the cast film surface directly influence the size and distribution morphology of the crater rings on the surface of the domestic BOPP film. The comprehensive properties of the domestic BOPP film have approached those of imported products of the same specification.

To improve the dielectric properties of polypropylene (PP), different mass fractions of β-nucleating agent and nano-montmorillonite (MMT) were added into a PP matrix in this paper to construct various ternary composite systems β-MMT-PP, and the synergistic effect of the two on the microstructure and dielectric properties of PP was investigated. The modified PP materials were characterized by means of X-ray diffractometry (XRD), differential scanning calorimetry (DSC), polarizing optical microscopy, pulsed electro-acoustic (PEA) method, conduction current, and DC breakdown tests. The results indicate that the addition of an appropriate amount of β-nucleating agent and MMT can effectively improve the microstructure of PP. When the mass fractions of β-nucleating agent and MMT are 0.5% and 1.0%, the β-crystal content and crystallinity in the composite system reach their peak values of 84.01% and 55.4%, respectively. With the addition of β-nucleating agent and MMT, both the space charge injection threshold field strength and the breakdown strength of PP are improved, reaching maximum values of 19.73 kV/mm and 94.99 kV/mm, respectively. An appropriate amount of β-nucleating agent can induce the transformation from α-crystal form to β-crystal form and refine the spherulites, thereby better improving the dielectric properties of the material.

To address the problem that it is difficult for high-frequency and high-speed electronic packaging materials to exhibit both high thermal stability properties and low dielectric properties, a novel biobased benzoxazine (M-f) was synthesized from 4-vinylguaiacol and furfurylamine using both solvent and solvent-free methods, and then the benzoxazine monomer was chemically grafted onto polyphenylene oxide oligomer (SA9000) through free radical copolymerization to fabricate a series of IPN resins. The structure, thermal, and dielectric properties of all resins were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), dynamic thermo-mechanical analysis (DMA), and microwave network analyzer. The results demonstrate that both M-f and M-f/SA9000 IPN resins display relatively high glass transition temperatures (170-245℃), and high frequency low dielectric properties (dielectric constant<3, dielectric loss factor≤0.008) under 5 and 10 GHz, which is satisfied with the requirement of high frequency communications. In particular, the M-f and M-f/SA9000 IPN resins prepared via the solvent-free method exhibit superior high-frequency low dielectric properties compared with the corresponding samples fabricated by the solvent method. Therefore, the work provides a new strategy for the structural design and preparation method of high-performance electronic packaging biomaterials.

Inspired by the molecular architecture of liquid-crystalline polyester resins that exhibit inherently low dielectric loss at high frequency, we incorporated ester moieties and fluorinated substituents for reducing dielectric constant, into polyimide backbones to develop polyimides with good processability, high mechanical performance, and low-dielectric characteristics. Firstly, effect of the number of ester linkages per repeat unit, their connection topology, and their chemical identity (phenyl vs. naphthyl esters) on the dielectric properties, mechanical properties, thermal properties, and water absorption of polyimides were systematically explored. On this basis, -CF₃ pendent groups were subsequently introduced into ester-containing diamines to evaluate their influence on the dielectric, mechanical, and thermal properties of the resulting polyester-imides. The results demonstrate that the rigid and linear topology of ester-bearing monomers enhances the chain packing and crystallinity of polyimides, leading to a substantial reduction in dielectric loss of polyimides together with low water absorption, high tensile strength and excellent thermal properties. Concurrently, the incorporation of trifluoromethyl substituents does not disrupt the dense chain packing and crystallinity of polyester-imide chains, thereby preserving the low dielectric loss, low water absorption and high thermal properties of polyester-imides while further reducing the dielectric constant and improving mechanical robustness. These findings can provide theoretical guidance for the molecular design of high-performance polyimides with low dielectric constant and low dielectric loss for high-frequency applications.

In this study, tetramethylbisphenol A (TMBPA) was used as the bisphenol source, and a dihydroxy-terminated oligomeric polyphenylene ether resin (TMBPA-MPPO) was synthesized via monomer copolymerization. Further, through a nucleophilic substitution reaction, TMBPA-MPPO was end-capped with chloromethylstyrene (VBC) to prepare a crosslinkable polyphenylene ether resin MPPO-VBC. The product structure was characterized by FT-IR, and the dielectric properties, thermal properties, and moisture absorption of the cured product were systematically evaluated. The results show that MPPO-VBC has good curing activity, and after curing it exhibits excellent dielectric properties (dielectric constant is 2.60, dielectric loss factor is 0.004 5 at 1 MHz) and heat resistance (T_g=200℃). On this basis, MPPO-VBC was blended with triallyl isocyanurate (TAIC), coated onto glass fiber cloth, and a composite was prepared. Its dielectric loss factor further decreased to 0.001 4, the glass transition temperature increased to 221.4℃, and the tensile strength and flexural strength reached 212 MPa and 267 MPa, respectively, demonstrating application potential in high-frequency copper-clad laminates.

The rapid development of 5G communication and millimeter-wave radar technology has imposed increasingly high requirements on the high-frequency performance of printed circuit boards (PCBs). Polytetrafluoroethylene (PTFE) stands out as a preferred material for microwave substrates due to its excellent dielectric properties, low water absorption, and outstanding chemical and thermal stability. This review categorized commercial products into five types based on their composite structures: woven glass fiber reinforced type, woven glass fiber reinforced-ceramic filled type, random short glass fiber reinforced type, random short glass fiber reinforced-ceramic filled type, and ceramic filled type, and discussed the representative products, key characteristics, fabrication processes, and technical advantages and disadvantages of each category. Furthermore, the paper provided a systematic overview of recent research progress on the effects of PTFE resin properties, filler type, content, morphology, and surface treatment on the performance of composite. PTFE-based composites are expected to maintain their dominant position in the millimeter-wave and even terahertz frequency bands for the foreseeable future. Looking ahead, breakthroughs in optimizing processing techniques, developing high-performance PTFE resins, innovating functional fillers, and conducting fundamental interface research are essential to narrow the performance gap with imported products and thereby advance China's microwave substrate materials industry.

To address the stringent requirements of 5G/6G high-frequency and high-speed communication technologies for printed circuit board (PCB) substrates, a polytetrafluoroethylene (PTFE)-filled modified bismaleimide-triazine (BT) resin/glass fiber (GF) composite was designed and fabricated in this study. The glass fiber fabric was surface-modified with silane coupling agent KH570 to enhance interfacial bonding, and low-dielectric PTFE filler was introduced into the glass fiber cloth pores via high-temperature and high-pressure lamination process. The influence mechanism of PTFE content on the comprehensive properties of the composite was systematically investigated. Results demonstrate that when the PTFE mass fraction is 5%, the composite achieves the optimal comprehensive performance. The dielectric constant and dielectric loss are 4.3 and 0.006 at 1 MHz, and 3.4 and 0.003 at 10 GHz, respectively. The glass transition temperature increases to 250℃ (approximately 25℃ higher than that of the pure BT system), and the residual char yield at 800℃ reaches 76.63% (an increase of about 17.55%). The flexural strength is maintained at 574.7 MPa, and the water contact angle increases to 86.5°. Mechanism analysis reveals that the introduction of PTFE significantly improve the high-frequency dielectric properties of the composite by reducing the polarization degree, filling pores to decrease interfacial polarization losses, and restricting the orientation movement of polar groups. Simultaneously, the high bond energy of C-F bonds endows the composite with enhanced thermal stability. However, the high coefficient of thermal expansion (CTE) of PTFE raises the CTE of composite to approximately 45×10^-6℃^-1, which requires further optimization. This material system achieves significant improvement in dielectric properties while maintaining the high heat resistance and good processability of BT resin, providing a cost-competitive substrate solution for mid-to-high frequency applications such as 5G millimeter-wave antennas and radio frequency front ends.

To address the bottleneck that thermal conductivity and dielectric properties are difficult to be synergistically enhanced for high-frequency and high-speed electronic packaging materials, silica (SiO₂) was modified via surface grafting with methylvinyldimethoxysilane. The modified SiO₂ (m-SiO₂) particles were incorporated into thermosetting polyphenylene ether (MPPO) through solution blending, and m-SiO₂/MPPO composites with low dielectric performance and high thermal conductivity were successfully prepared. The results demonstrate that the thermal conduction capability and thermal stability of the composites are remarkably improved, while its favorable dielectric properties are well maintained. At an m-SiO₂ mass fraction of 70%, the thermal conductivity of the composite reaches 1.18 W/(m·K), which is 4.92 times higher than that of neat MPPO. Moreover, the dielectric constant is 3.11 at 10 GHz, and the dielectric loss factor is 0.004 4. Thermogravimetric analysis reveals that the thermal decomposition temperatures (at 5% and 10% weight loss) of the composite under nitrogen atmosphere are increased by 224.1℃ and 181.4℃, respectively compared with neat MPPO. It is verified that m-SiO₂ can effectively inhibit the thermal degradation of polymer segments through bonding reaction with the resin matrix.