Different concentrations of multiwall carbon nanotubes (MWCNT) and carboxyl functionalized MWCNT (MWCNT-COOH) were added to a high melt strength polypropylene (HMS-PP) to produce foams with high dielectric constants, using azodicarbonamide (AZO) as blowing agent. The AZO foaming behavior and the crystallization, thermal properties, steady state and oscillatory shear rheological properties of the nanocomposites were analyzed by polarized light optical microscopy (PLOM), differential scanning calorimetry (DSC), thermogravimetry analyses (TGA) and parallel plate rheometry. The morphology, the dielectric and dynamic mechanical properties (DMTA) of the foams were also studied by scanning electron microscopy (SEM), impedance spectroscopy and bending method, respectively. A decrease in crystallite size and an increase in the HMS-PP overall crystallinity promoted by the presence of both types of MWCNTs was observed, as well as an increase in the crystallization temperatures. From these results and from the analyses of the rheological properties, it was possible to predict that the 5 wt.% MWCNT foam would have the lowest bubble growth rate, the 1.5 wt.% MWCNT-COOH the highest, while the 3 wt.% MWCNT-COOH composition would have the slowest bubble stability (and consequently the highest cellular density) and the 1.5 wt.% MWCNT-COOH the fastest. Also, it was possible to predict that only the 5 wt.% MWCNT-COOH foam would have a percolated and electrically conductive structure. All these predictions were confirmed by the resultant morphology and impedance spectroscopy results. The highest mechanical damping was displayed by the 3 wt.% MWCNT-COOH foam, while the lowest by the 5 wt.% MWCNT-COOH foam. Regarding the dielectric properties, the 1.5 wt% MWCNT-COOH foam was found to be the most suitable to be used as a capacitor material; this foam was also the less dense of all the samples.

使用偶氮二甲酰胺（AZO）作为发泡剂，将不同浓度的多壁碳纳米管（MWCNT）和羧基官能化MWCNT（MWCNT-COOH）添加到高熔体强度聚丙烯（HMS-PP）中，以生产具有高介电常数的泡沫。通过偏光光学显微镜（PLOM），差示扫描量热法（DSC），热重分析（TGA）和平行板流变法分析了纳米复合材料的AZO发泡行为以及结晶，热性能，稳态和振荡剪切流变性能。还分别通过扫描电子显微镜（SEM），阻抗谱和弯曲法研究了泡沫的形态，介电和动态力学性能（DMTA）。观察到两种类型的MWCNT的存在促进了晶粒尺寸的减小和HMS-PP总体结晶度的增加，以及结晶温度的升高。从这些结果和流变性质的分析，可以预测5wt。％的MWCNT泡沫将具有最低的气泡增长率，1.5wt。％的MWCNT-COOH最高，而3wt。％ MWCNT-COOH组合物将具有最慢的气泡稳定性（并因此具有最高的泡孔密度），并且具有1.5wt。％的MWCNT-COOH最快。而且，可以预测只有5重量％的MWCNT-COOH泡沫将具有渗透的和导电的结构。所有这些预测都由所得的形态和阻抗谱结果证实。3重量％MWCNT-COOH泡沫显示出最高的机械阻尼，而5重量％MWCNT-COOH泡沫显示出最低的机械阻尼。关于介电性能，发现1.5重量％的MWCNT-COOH泡沫最适合用作电容器材料。这种泡沫在所有样品中密度也较小。