Hybrid composites with low flammability based on renewable calcium alginate and nano-calcium borate were fabricated using an in situ method through a simple, eco-friendly vacuum drying process. The composites were characterized by X-ray diffractometry (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The combustion behavior and flammability of the composites were assessed by using the limiting oxygen index (LOI) and cone calorimetry (CONE) tests. The composites showed excellent thermal stability and achieved nonflammability with an LOI higher than 60. Pyrolysis was investigated using pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS) and the results showed that fewer sorts of cracking products were produced from the hybrid composites compared with the calcium alginate. A possible thermal degradation mechanism of composites was proposed based on the experimental data. The combined results indicate that the calcium borate had a nano-effect, accumulating more freely in the hybrid composites and contributing significantly to both the solid phase and gas phase, resulting in an efficient improvement in the flame retardancy of the composites. Our study provides a novel material with promising potentiality for flame retardant applications. This is an open access article distributed under the which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Hybrid composites based on renewable calcium alginate and nano-calcium borate have been fabricated to successfully create a new material for flame retardant applications, using an eco-friendly vacuum drying process, according to a study by Zhenhui Liu, Xihui Zhao, Lei Zhang and Qun Li from the College of Chemistry and Chemical Engineering, and Zichao Li from Qingdao University, both based at the College of Life Sciences in China. The composites showed excellent thermal stability, achieving non-flammability with a limited oxygen index over 60.