Mineral‐rubber composites based on phosphorylated butadiene rubber (PhBR), including pure expanded perlite (EP) and modified phosphorylated expanded perlite (PhEP) as fillers, have been developed. The process involved forming PhBR and its composites – EP/PhBR and PhEP/PhBR‐through the oxidative chlorophosphorylation (OxCh) reaction. An in‐depth comparative analysis was conducted on the thermal destruction of the PhBR matrix and the EP/PhBR, and PhEP/PhBR composites. The thermogravimetric (TG)/differential thermogravimetry (DTG) analyses revealed three stages of thermal degradation for the PhBR matrix and both composites, highlighting the notable effects of EP and PhEP in the second and third stages of the degradation process. In comparison, the PhEP/PhBR composite exhibited reduced weight loss, the highest integral procedural decomposition temperature (IPDT) value, and a lower Tmax on the DTG curve, compared with the EP/PhBR composite and the PhBR matrix. The mechanism of the thermal destruction reaction and the kinetic parameters Ea and A were calculated using the model‐fitting Coats‐Redfern method.This article is protected by copyright. All rights reserved