Flame-retardant bamboo fiber-based films for high-performance fire sensors

Natural polymers play a non-negligible role in the development of green and sustainable sensors. However, their poor flame retardancy and deficient thermal stability inevitably restrict their application in sensors for monitoring the fire full-process. In this work, a facile and eco-friendly method for the large-scale preparation of flexible films composed of bamboo fiber (BF), carboxymethyl cellulose (CC), and graphene (GN) by solution casting was put forward. Iron ions and phytic acid (PA) self-assemble on its surface, eventually resulting in a film (referred to as BCGP) that exhibits high strength and high flame retardancy. Specifically, the strength of the film reaches 3.92 MPa, and reliable strength still be ensured even after long-term soaking. Furthermore, the limiting oxygen index of the film is as high as 33 %, the vertical burning test attains the V-0 level. As a sensor, the film promptly triggers an alarm within 3.6 s of contact with flames, and its response remains sensitive even after repeated scorching. The temperature response encompasses a wide range of 50 to 200 °C, and the gauge factor is as high as 1572.