Polymer composites can be applied to a variety of applications due to their ability to change material properties. This study suggests that blended m-aramid and polyurethane (PU) produces microporous structures in the form of thin-film. Changes in physico-chemical properties may have contributed to improved heat resistance properties. 2.5 wt% of plasticizer and DMAc were added to change the properties of the m-aramid/PU. After a brief wash, 0.08mm m-aramid/PU in thin-film form was prepared. Scanning electron microscopy (SEM) and PMI capillary flow porometer showed the pore formation, size and distribution according to blending and coagulation bath condition, while T-g and peak shift using thermomechanical analyzer (TMA) and FT-IR observed the excellent blendability of m-aramid/PU without phase separation. The initial decomposition temperature (IDT) and T-m (melting temperature) showed higher thermal properties than pure PU. The heat resistance property of PU itself was improved with increasing m-aramid components. (C) 2018 Elsevier Ltd. All rights reserved.