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Enhanced smoke/toxicity suppression of intumescent flame retardant thermoplastic polyurethane composites with the addition of graphene

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Abstract

High flame retardancy with significant suppression of toxic smoke and melt-dripping are challenging issues associated with flame-retardant thermoplastic polyurethane (TPU). To address these issues, in this work, graphene (Gr) was used as an effective two-dimensional smoke-toxicity suppressant with loadings less than 1 wt%, in combination with two efficient intumescent flame retardant (IFR) systems reported in our previous works. The IFRs were consisted of ammonium polyphosphate, pentaerythritol (PER), and melamine polyphosphate (MPP) with MPP:PER ratios of 10:1 (IFR1) and 1:1 (IFR2). Cone calorimeter test (CCT) results showed outstanding flame retardancy and excellent toxic smoke suppression in TPU/IFR1/0.75%Gr sample with reduced peak heat release rate (PHRR) by 85.3%, peak smoke production rate (PSPR) by 92.1%, and peak carbon monoxide production (PCOP) by 91.3% compared with neat TPU. TPU/IFR2/0.5%Gr sample exhibited a similar trend, with the PHRR, PSPR, and PCOP reduced by 66.8%, 62.5%, and 64.0%, respectively, with good anti-dripping property. The barrier function of graphene had a significant influence on reducing total smoke released in TPU/IFR1/0.75%Gr and TPU/IFR2/0.5%Gr samples by 82.1% and 34.3%, respectively, compared with their related TPU/IFRs composites. TPU nanocomposites reached a UL-94 V-0 rating and LOI of more than 29%. TGA results indicated improved char-forming, and FESEM depicted the graphitized integrated char structures. Mechanical performance of TPU/IFR2/0.5%Gr exhibited an enhanced ductility compared with the neat TPU. The possible flame retardancy mechanism was proposed based on the data obtained from the CCT, TGA, and EDS elemental analysis.

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Abbreviations

APP:

Ammonium polyphosphate

CCT:

Cone calorimeter test

EDS:

Energy-dispersive X-ray analysis

FESEM:

Field emission scanning electron microscope

FPI:

Fire performance index

FGI:

Fire growth index

Gr:

Graphene

IFR:

Intumescent flame retardant

LOI:

Limiting oxygen index

MPP:

Melamin polyphosphate

PCOP:

Peak carbon monoxide production

PER:

Pentaerytritol

PHRR:

Peak heat release rate

PSPR:

Peak smoke production rate

SF:

Smoke factor

TGA:

Thermal gravimetric analysis

THR:

Total heat release

TPU:

Thermoplastic polyurethane

TSR:

Total smoke release

TTI:

Time to ignition

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Acknowledgements

The authors would like to acknowledge the use of the facilities and technical assistance of the staffs of the Fire Engineering Department of Road, Housing & Urban Development Research Center (BHRC), Iran. We also wish to thank the use of the facilities and technical assistance of the staffs of the Department of Plastic of Iran Polymer and Petrochemical Institute (IPPI), Iran. We also acknowledge Iran University of Science and Technology (IUST) for partial support for the completion of this work.

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Authors and Affiliations

  1. Research Laboratory of Green Organic Synthesis and Polymers, Department of Chemistry, Iran University of Science and Technology, Tehran, 16846‑13114, Iran

    Leila Taghi-Akbari & Mohammad Reza Naimi-Jamal

  2. Department of Polymer Processing, Iran Polymer and Petrochemical Institute (IPPI), Tehran, 14965-115, Iran

    Shervin Ahmadi

  3. Fire Engineering Department, Road, Housing & Urban Development Research Center (BHRC), Tehran, 14965-115, Iran

    Saeed Bakhtiyari

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  1. Leila Taghi-Akbari
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  2. Mohammad Reza Naimi-Jamal
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Correspondence to Mohammad Reza Naimi-Jamal.

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Taghi-Akbari, L., Naimi-Jamal, M.R., Ahmadi, S. et al. Enhanced smoke/toxicity suppression of intumescent flame retardant thermoplastic polyurethane composites with the addition of graphene. Iran Polym J (2024). https://doi.org/10.1007/s13726-024-01303-y

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