Herein, radar-absorbing polymethacrylimide (RAPMI) foam was prepared using the particle foaming method. Nineteen samples were prepared based on different ratios and absorbent types, and their microstructural characteristics were analyzed and compared. Their dielectric constant and loss tangent were measured at 2–18 GHz, and the electromagnetic (EM) characteristics were analyzed. Subsequently, their mechanical properties were tested. The effect mechanism of the absorbents on the EM and mechanical behavior was analyzed, and the experimental data were compared. Finally, a laminated foam was designed. Results show that the samples can achieve 90% bandwidth effective absorption (reflection loss ≤ −10 dB) at 33.6-mm thickness and 18.6%, 32.4%, 62.5%, 62.9%, 35.7%, and 51.9% maximum increases in compressive strength, compressive modulus, tensile strength, tensile modulus, shear strength, and shear modulus, respectively, compared with particle polymethacrylimide (PMI) foam. The designed laminated foam can theoretically achieve full-band effective absorption at a minimum thickness of 15.3 mm. The preparation of RAPMI foam is simple and inexpensive, and this research strengthens the engineering application of PMI foam in cutting-edge fields, such as military and aerospace. It provides an important reference for researchers, technicians, and engineers in the fields of absorbing materials, polymers, and composites.

中文翻译：

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碳材料增强聚甲基丙烯酰亚胺泡沫的机械性能和雷达吸收能力：制备、比较和设计

采用颗粒发泡法制备了吸波聚甲基丙烯酰亚胺（RAPMI）泡沫。根据不同配比和吸附剂类型制备了19个样品，并对其微观结构特征进行了分析和比较。在 2-18 GHz 下测量了它们的介电常数和损耗角正切，并分析了电磁 (EM) 特性。随后，测试了它们的机械性能。分析了吸收剂对电磁和力学行为的影响机理，并对实验数据进行了比较。最后，设计了层压泡沫。结果表明，样品在33.6毫米厚度下可实现90%带宽有效吸收（反射损耗≤−10 dB），抗压强度最大增加18.6%、32.4%、62.5%、62.9%、35.7%和51.9%，分别与颗粒聚甲基丙烯酰亚胺 (PMI) 泡沫相比，压缩模量、拉伸强度、拉伸模量、剪切强度和剪切模量。设计的层压泡沫理论上可以在最小厚度15.3毫米的情况下实现全频段有效吸收。RAPMI泡沫制备简单、成本低廉，本研究加强了PMI泡沫在军事、航空航天等前沿领域的工程应用。为吸波材料、聚合物和复合材料领域的研究人员、技术人员和工程师提供了重要参考。