Effect of blowing agent content on the structure and flame‐retardant properties of rigid polyurethane foam/expanded graphite composites

Driven by global environmental issues, the development of green building materials has become an immediate focus. In this work, n‐pentane was used as an environmentally friendly blowing agent to prepare flame‐retardant rigid polyurethane foam (RPUF) with the addition of expandable graphite (EG) successfully, and the effect of n‐pentane content on flame retardancy and compressive properties of RPUF/EG composites was investigated through limit oxygen index (LOI), vertical burning test (UL‐94), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and compressive properties test. SEM results show that the content of EG and n‐pentane causes a change in the cell structure of RPUF. The change of the n‐pentane content has also an obvious effect on the thermal stability, flame retardancy, and specific compressive strength of RPUF/EG composites. In addition, the cell structure of RPUF matrix has an obvious influence on the distribution of EG in the composites, which indirectly affects the flame‐retardant efficiency of EG. This research explores the conditions for the application of environmentally friendly RPUF and expands its application prospects.