Preparation and Deterioration of Fireproof Polymer Composite Sheet for Elastomeric Seismic‐Protection Isolators for Buildings in Use

Deterioration of fireproof polymer composite sheets equipped to elastomeric seismic‐protection isolators for buildings in use was investigated by various instrumental analyses after chemical treatments. The fireproof polymer composite sheet was prepared from polyisobutylene, various flame retardants, plasticizers, and so forth. Heat release tests with a cone calorimeter, fire resistance tests, and horizontal displacement tests were carried out for the fireproof polymer composite sheets. Furthermore, the fireproof polymer composite sheet after practical use was characterized in the present study. The sheet was found to have discolored during a regular inspection conducted in 14th year after the construction of elastomeric seismic‐protection isolators for buildings, which was immersed in rainwater collected in the pit for approximately 24 months. Rainwater‐unimmersed fireproof polymer composite sheets and the unused one were adopted as controls. Foamability, fire resistance, and heat insulating effect were significantly deteriorated after immersing into the rainwater. The deterioration of the foamability, fire resistance, and heat insulating effect was precisely investigated by Fourier transform infrared spectroscopy (FT‐IR), gas chromatograph–mass spectrometry (GC–MS), X‐ray diffraction (XRD) measurement, and electron beam microanalysis (EPMA) after extracting the rainwater‐immersed, rainwater‐unimmersed, and unused fireproof polymer composite sheets with methanol. Polyalcohol, pentaerythritol, and mineral oil as plasticizers were found to be leached from the fireproof polymer composite sheet by immersing in rainwater. The removal of pentaerythritol was also related to the deterioration of the foamability, fire resistance, and heat insulating effect since it played an important role as a forming agent.