Zn-doped carbon microspheres as synergist in intumescent flame-retardant thermoplastic polyurethane composites: Mechanism of char residues layer regulation. (June 2022)

• Record Type: Journal Article
• Authors: Piao, Junxiu; Lai, Yongxing; Ren, Jinyong; Wang, Yaofei; Feng, Tingting; Wang, Yaxuan; Liu, Wei; Dong, Huixin; Chen, Wenjiao; Jiao, Chuanmei; Chen, Xilei
• Is Part Of: Composites communications. Volume 32(2022)
• Publication Date: 2022-06
• Subjects: Carbon microspheres -- Thermoplastic polyurethane -- Fire safety -- Flame-retardant mechanism
• DOI: 10.1016/j.coco.2022.101173
• Languages: English
• ISSNs: 2452-2139

Abstract

Abstract: Despite thermoplastic polyurethane (TPU)/ammonium polyphosphate (APP) being an excellent intumescent flame-retardant TPU composite (IFR-TPU), it is still not a "fire-safety" TPU composite. In this work, the Zn-doped carbon microspheres (CMSs-Zn) were prepared and added into the TPU/APP composite as a synergist to fabricate an IFR-TPU composite with excellent fire safety performance (TPU/CMSs-Zn). Cone calorimeter tests exhibited the peak heat release rate (pHRR), total heat release (THR), peak smoke production rate (pSPR), total smoke release (TSR) of TPU/CMSs-Zn composites were decreased by 65.4 %, 50.7 %, 65.3 %, and 63.4 % respectively. Moreover, the smoke density tests showed that the luminous flux (LF) of TPU/CMSs-Zn increased from 1.4 % to 40.1 %. In addition, the investigation of the flame-retardant mechanism for TPU/CMSs-Zn revealed that CMSs-Zn amplifies the role of APP in condensed phase by participating in char formation and catalysis effect, thus forming a dense protective char residues layer. The char residues layer regulation mechanism can provide a novel strategy for facilitating fire-safety TPU composite. Graphical abstract: Image 1 Highlights: A significant defect in the fire safety of traditional IFR-TPU composites is observed. As a synergist, the Zn-doped carbon microspheres (CMSs-Zn) were fabricated via a convenient process. The addition of CMSs-Zn has realized the unification of TPU flame retardant, smoke suppression, and toxicity reduction. A novel mechanism of char residues layer regulation for IFR-TPU composites has been proposed.