Understanding the effects of high temperature and thermal cycles on the mechanical properties of expanded polystyrene (EPS) foam is critical for its use in sandwich panels. This paper presents an experimental investigation of these effects in typical environmental conditions that exist in construction applications. A total of 117 small specimens were cut from metal-faced sandwich panels with EPS core and were exposed to different numbers of thermal cycles and/or sustained high temperatures. The specimens were then loaded under compression, tension, and four-point bending for evaluating the degradation of the mechanical properties of the foam. The thermal cycles reflect typical surface temperature during daily summer conditions, with a period of 24 h each and with a temperature varying between 24°C to 80°C. The results show that the modulus of elasticity of EPS foam in compression reduced by about 38% after exposure to thermal cycles for 45 days, whereas the tensile and shear moduli reduced by about 5.7% and 13.8%, respectively. Exposure to sustained high temperature after thermal cycles led to larger degradation of the elastic and shear moduli in the range of 38%–50%. These degradations can lead to early failures in applications that rely on the EPS foam as a structural component like in insulating sandwich panels.

了解高温和热循环对发泡聚苯乙烯 (EPS) 泡沫机械性能的影响对于将其用于夹芯板至关重要。本文介绍了在建筑应用中存在的典型环境条件下对这些影响的实验研究。共有 117 个小样本从带有 EPS 芯的金属面夹层板上切下，并暴露于不同数量的热循环和/或持续高温。然后在压缩、拉伸和四点弯曲下加载样品，以评估泡沫机械性能的退化。热循环反映了夏季日常条件下的典型地表温度，每个周期为 24 小时，温度在 24°C 至 80°C 之间变化。结果表明，EPS泡沫的压缩弹性模量在暴露于热循环45天后降低了约38%，而拉伸模量和剪切模量分别降低了约5.7%和13.8%。在热循环后暴露于持续高温导致弹性和剪切模量在 38%–50% 范围内的更大退化。这些退化可能导致依赖 EPS 泡沫作为结构部件的应用（如绝缘夹芯板）中的早期故障。