Phenolic resin microspheres surface-modified with sodium silicate for reducing fire hazard in TPU composites

In this article, a sodium silicate surface-modified phenolic resin microsphere (SSMPHM) was prepared to reduce the fire hazard of thermoplastic polyurethane (TPU). The characterization results demonstrated that sodium silicate was success-fully deposited on the surface of the phenolic resin microsphere (PHM). The results of the combustion test demonstrated that the introduction of SSMPHM remarkably reduced the fire hazard of thermoplastic polyurethane (TPU) composites (e.g.,similar to 66.0% and 77.0% decline in peak heat release rate (pHRR) and smoke factor (SF) at 4 wt% content (TPU/SSM-4)). At the same time, the peak value of COP reduced from 0.029 to 0.009 g s(-1) compared with TPU. The results of condensed phase analysis demonstrated that compared with TPU, the char residue layer of TPU/SSM-4 was relatively dense and continuous. In addition, mechanical perfor-mance tests showed that SSMPHM could make up for the loss of mechanical perfor-mance caused by PHM. The work provides new insights into modifying PHM for effectively reducing the fire hazard of TPU.