Syntactic foams are composite materials consisting in the association of hollow particles, called “microspheres” and a polymer matrix. The use of soft shell microspheres confers to the foam interesting properties but in return increases significantly its compressibility. Therefore, understanding and predicting the relationship between pressure and volume change is a crucial issue for the development of this type of material. The present study focuses on a high void fraction syntactic foam made with soft shell polymer microspheres embedded in a polyurethane matrix. Compression tests are performed using a capillary rheometer and a PVT accessory for the hydrostatic compression, and a more conventional apparatus for the confined compression. The experimental results are compared with De Pascalis’s pressure/volume model predictions, using Fok and Allwright’s model to determine the critical buckling pressure of the microspheres. The model proves to be fairly accurate at low pressure and high pressure, despite a notable deviation in the mid-pressure range. The influence of key model parameters such as microsphere size distribution and microsphere and matrix elastic properties is investigated. It is shown that the reinforcement of the matrix seems to be the only efficient way to limit the compressibility of such a syntactic foam.

句法泡沫是复合材料，由称为“微球”的空心颗粒和聚合物基质组成。软壳微球的使用赋予泡沫有趣的性质，但反过来显着增加了其可压缩性。因此，了解和预测压力与体积变化之间的关系是开发这类材料的关键问题。本研究的重点是由嵌入聚氨酯基质中的软壳聚合物微球制成的高空隙率复合泡沫塑料。使用毛细管流变仪和PVT附件进行静水压缩，以及使用更常规的密闭压缩设备进行压缩测试。将实验结果与De Pascalis的压力/体积模型预测进行了比较，使用Fok和Allwright模型确定微球的临界屈曲压力。尽管在中压范围内有明显的偏差，但该模型在低压和高压下都相当准确。研究了关键模型参数如微球尺寸分布以及微球和基体弹性性能的影响。结果表明，增强基质似乎是限制这种复合泡沫塑料可压缩性的唯一有效方法。