Supramolecular-Wrapped α-Zirconium Phosphate Nanohybrid for Fire Safety and Reduced Toxic Emissions of Thermoplastic Polyurethane

Abstract

In the current study, a facile approach is introduced to enhance the flame retardancy of thermoplastic polyurethane (TPU) using a supramolecular-wrapped α-zirconium phosphate nanohybrid (CPP@ZrP). The CPP@ZrP nanohybrid was successfully synthesized by enveloping a phytic acid-doped polypyrrole shell and linking it to cobalt ions via the multivalent anions of phytic acid. The CPP@ZrP nanohybrid exhibited relatively uniform dispersion within the TPU matrix, leading to strong interface between TPU and CPP@ZrP and hence high mechanical and flame-retarding properties. The strength of TPU increased by 37% with 850% elongation at break at 5.0 wt % CPP@ZrP. Similarly, adding CPP@ZrP into TPU substantially reduced the peak heat release rate by 41.8%, peak smoke production rate by 25.8%, and total CO production by 32.9%. The average effective heat of combustion from the TPU/CPP@ZrP composite was reduced by 25% which confirms the reduction in flammable volatile substances. The experimental measurements and morphology of char residuals reveal that the CPP@ZrP nanohybrid reduces the flame retardancy of TPU in the gas and condensed phases via reacting with the flammable volatiles and preventing heat transfer to the flames. The study introduces a facile approach to designing a metallic-organic–inorganic hybrid flame retardant, CPP@ZrP, with high efficacy in reducing fire risks and mitigating smoke toxicity in polymers.

A high-performance, sensitive, low-cost LIG/PDMS strain sensor for impact damage monitoring and localization in composite structures

“…Conversely, piezoelectric sensors face challenges in interpreting information from signals due to the dispersive and multimodal characteristics of guided waves. Recently, the rapid development of nanomaterials is expected to solve this challenge [5][6][7][8][9]. Flexible sensors that can withstand large deformation have appeared, which can meet the requirements of monitoring large strain ranges and complex structure profiles [8,[10][11][12][13].…”