The synergism effect of montmorillonite on the intumescent flame retardant thermoplastic polyurethane composites prepared by selective laser sintering

• Published in: Polymer composites Vol. 43; no. 9; pp. 5863 - 5876
• Main Authors: Li, Jianshuo, Wu, Wei, Hu, Huanbo, Rui, Zhengguo, Zhao, Tianyu, Zhang, Xiyun
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.09.2022; Blackwell Publishing Ltd
• Subjects: Composite materials; Crystallization; Dispersion; Fillers; Fire protection; Fire resistance; Flame retardants; Fourier transforms; Infrared lasers; Infrared spectroscopy; intumescent flame retardant; Laser sintering; Montmorillonite; Polyurethane resins; Raman spectroscopy; Rapid prototyping; selective laser sintering; Sintering (powder metallurgy); Sodium; Spectrum analysis; Structural analysis; synergism effect; Thermal stability; Thermodynamic properties; thermoplastic polyurethane; Three dimensional printing; Urethane thermoplastic elastomers
• ISSN: 0272-8397; 1548-0569
• DOI: 10.1002/pc.26621

Selective Laser Sintering (SLS) is a powder‐based 3D printing technology. It offers a new means of fabricating complex modules with special properties, such as mechanical, flame retardant, electrical and thermal properties. In this paper, the effect of an intumescent flame retardant (IFR) and montmorillonite (MMT) on the fire resistance of thermoplastic polyurethane (TPU) was investigated. TPU composites powders were prepared by mixing with a two‐step method and can be effectively applied to SLS. Morphology characters exhibited that the fillers disperse well in the TPU powder. The structure analysis and hydrophilia analysis of sodium montmorillonite (Na‐MMT) and organically modified montmorillonite (OMMT) demonstrates the different compatibility in TPU, which reflects diverse flame retardant behavior. With 22% IFR and 3% OMMT fillers, the LOI of TPU composites increased from 17.2% to 28% and subsequently a UL‐94 V‐0 ranking was obtained. In the CCT results, the formula of 22% IFR and 3% OMMT showed the lowest heat release and smoke production. The study also explored the effects of flame retardant fillers on the thermal stability of TPU composites and melting and crystallization behaviors in SLS processing. In addition, the char residues after heating were analyzed via scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy and laser Raman spectroscopy. The results demonstrate that the composites have favorable flame retardant properties, thermal stability, char forming performance, and SLS process properties. The TPU composites prepared via SLS in this study demonstrated extensive potential in fire protection materials. In this paper, an intumescent flame retardant TPU composite was prepared by selective laser sintering: a powder‐based 3D printing technology. The TPU composites exhibit good flame retardancy and char‐forming properties, the LOI was increased to 28% and achieved UL‐94 V‐0 rating because of the synergism effect by IFR and OMMT. The TPU composites have good application prospects in manufacturing complex parts with good flame retardancy.