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Recent Advances in Flame Retardant Polymeric Materials

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: 31 May 2024 | Viewed by 11049

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Special Issue Editor

Dr. Chao Ma

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Guest Editor

College of Emergency Management, Nanjing Tech University, Nanjing 210009, China
Interests: flame retardant; synthesis; organophosphorus compound; polymer; fire safe material; flame retardant mechanism

Special Issue Information

Dear Colleagues,

Polymeric materials are widely used in every corner of our modern life. Even though various merits are characterized by polymers, most of them are combustible due to the nature of high contents of C and H elements. With the increasing concern of fire hazards and more and more strict laws and regulations, flame retardant polymeric materials have found their rapid development in recent decades. Nowadays, except for some specific halogen-containing flame retardants banned, researchers generally focus on flame retardants containing phosphorus, nitrogen, silicon, boron, etc. When superior flame retardancy is achieved by polymeric materials, better other properties like thermal, mechanical, dielectric, electromagnetic shielding, electrochemistry properties are also desired to obtain polymers with good comprehensive performances. Furthermore, fire-safe polymeric nanocomposites are prepared always with low loading and property enhancement.

This Special Issue is designed to gather scientific papers about recent advances in flame retardant polymeric materials. Contributions are invited on all themes, including but not limited to the synthesis of new flame retardants, polymers with excellent flame retardancy, multifunctional flame retardant polymers, study of flame retardant mechanisms and flame retardant polymeric nanocomposites. Full papers, short communications and review articles presenting and discussing the most recent trends in these areas are welcomed.

Dr. Chao Ma
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

polymeric materials
flame retardants
synthesis
multifunctionality
mechanisms
nanocomposites

Published Papers (6 papers)

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Research

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20 pages, 5133 KiB

Open AccessArticle

Flammability of Thick but Thermally Thin Materials including Bio-Based Materials

by Rodolphe Sonnier, Loïc Dumazert, Arnaud Regazzi, Lily Deborde and Christophe Lanos

Molecules 2023, 28(13), 5175; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28135175 - 03 Jul 2023

Cited by 2 | Viewed by 1074

Abstract

The fire reaction of various types of flammable lightweight materials is investigated using a cone calorimeter. The influences of parameters such as sample density, sample mass, effective heat of combustion and heat flux on the mass loss after exposition are discussed. Interpretations of the hemp fibers’ tests results lead us to propose a phenomenological model able to calculate the peak of heat release rate (pHRR) of such thermally thin materials, with or without flame retardant. A database gathering the whole results of tests performed on a large set of materials including fibers, bio-resources panels, bio-based concretes and fabrics is used to validate the proposed model. Interestingly, the model is found to be relevant also for denser wood specimens. The model is based on the distinction of the contributions of the exposed top layer and the deeper layer to the combustion. Indeed, in such materials, the heat conduction is limited (either by the intrinsic properties of the material or by the formation of an insulating char) and therefore the pHRR only depends on a limited volume of materials directly absorbing the heat flux from the radiant cone. Accuracy and limitations of the model are discussed. Full article

(This article belongs to the Special Issue Recent Advances in Flame Retardant Polymeric Materials)

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18 pages, 3282 KiB

Open AccessArticle

Phosphasilazanes as Inhibitors for Respirable Fiber Fragments Formed during Burning of Carbon-Fiber-Reinforced Epoxy Resins

by Philipp Kukla, Lara Greiner, Sebastian Eibl, Manfred Döring and Frank Schönberger

Molecules 2023, 28(4), 1804; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28041804 - 14 Feb 2023

Viewed by 1663

Abstract

Carbon-fiber-reinforced polymer composites (CFRPs) exhibit additional hazards during and after burning due to respirable fragments of thermo-oxidatively decomposed carbon fibers. In this study, various phosphasilazanes are incorporated into the RTM 6 epoxy matrix of a CFRP to investigate their flame-retarding and fiber-protective properties via cone calorimetry. Residual carbon fibers are analyzed using SEM and EDX regarding their diameter and elemental composition of deposits. The decomposition process of phosphasilazanes is characterized by DIP-MS and infrared spectroscopy of char. Flame-retardant efficiency and mode of action are correlated with the chemical structure of the individual phosphasilazane and compared for neat resin and composite samples. Phosphasilazanes mainly acting in the condensed phase show beneficial fiber-protective and flame-retardant properties. Those with additional gas phase activity are less efficient. The phosphasilazanes degrade thermally via scission of the Si-N bond. The distribution and agglomeration of deposited particles, formed during the fire, influence the residual fiber diameters. Continuous layers show the best combination of flame retardancy and fiber protection, as observed for N-dimethylvinylsilyl-amidophosphorus diphenylester. Full article

(This article belongs to the Special Issue Recent Advances in Flame Retardant Polymeric Materials)

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23 pages, 7196 KiB

Open AccessArticle

A Systematic Investigation on the Influence of Intumescent Flame Retardants on the Properties of Ethylene Vinyl Acetate (EVA)/Liner Low Density Polyethylene (LLDPE) Blends

by Eid M. Alosime and Ahmed A. Basfar

Molecules 2023, 28(3), 1023; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28031023 - 19 Jan 2023

Cited by 4 | Viewed by 1683

Abstract

Because of their high filler loadings, commercial-grade clean flame-retardant materials have unstable mechanical properties. To address this issue, intumescent polymers can be used to develop clean flame retardants with very low levels of smoke and toxicity generation. An intumescent flame retardant (IFR) system composed of red phosphorus (RP), zinc borate (ZB), and a terpolymer of ethylene, butyl acrylate, and maleic anhydride (EBM) was used to prepare EVA (ethylene-vinyl acetate) and EVA/LLDPE (linear low-density polyethylene) composites; their mechanical and flammability properties were systematically investigated. The limiting oxygen index (LOI) of the EVA/LLDPE (as base material) composite containing RP and ZB mixed with nonhalogenated flame retardant, mainly magnesium hydroxide (MH) and coadditives, including processing aids and thermal stabilizers, was established. RP was found to have little effect on the tensile properties of EVA/LLDPE 118W/120 phr flame-retardant (MH + RP) composites. There was a minute difference in the effective trend of RP between tensile strength and elongation at break. Following the addition of ZB, the elongation at break of the composites gradually decreased with increasing RP content and then leveled off when the RP content was over 10 phr. Mechanical properties (elongation at break and tensile strength) can be best maintained at below 10 phr content of RP. The mechanical properties decreased with lower amounts of EBM content. In addition, flame retardancy increased when the EBM content decreased. The findings further revealed that MH and RP have poor compatibility, yielding poor mechanical properties. The LOI greatly increased with RP content, even though the total content of flame retardants (main + intumescent flame retardant) was the same in all formulations. Only over 5 phr RP content formulations passed V-0 of the UL-94 test. When under 5 phr, the RP content formulations did not pass V-0 of the UL-94 test. Full article

(This article belongs to the Special Issue Recent Advances in Flame Retardant Polymeric Materials)

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24 pages, 7356 KiB

Open AccessArticle

Influence of Phosphorus Structures and Their Oxidation States on Flame-Retardant Properties of Polyhydroxyurethanes

by Maxinne Denis, Guilhem Coste, Rodolphe Sonnier, Sylvain Caillol and Claire Negrell

Molecules 2023, 28(2), 611; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28020611 - 06 Jan 2023

Cited by 2 | Viewed by 2183

Abstract

This article focuses on the synthesis of polyhydroxyurethane (PHU) materials containing novel phosphorus flame retardants (FR). Four different phosphorus compounds were grafted onto cyclic carbonate: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), diethyl phosphite (DEP), diphenyl phosphite (DPP) and dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (BPPO). Thus, three novel phosphorus reactive cyclic carbonates which have never been reported so far were synthetized. Phosphorus FR containing PHU materials were characterized by FTIR to evidence the total conversion of the cyclic carbonate. Moreover, the gel contents up to 80% confirmed the formation of the polymer network. Then, the thermal stability and the flame-retardant properties were investigated by thermogravimetric analyses, cone calorimeter and pyrolysis combustion flow calorimeter. The mode of action of phosphorus compounds, depending on the oxidation state, was especially highlighted. Phosphonate (+III) provided better action in a condensed phase than phosphinate thanks to a more efficient char formation. Among phosphonates, differences were observed in terms of char-formation rate and expansion. DEP provided the best flame-retardant properties, with a reduction of 76% of pHRR with 2 wt% of phosphorus in cone calorimeter analysis. Therefore, this article highlighted the different modes of action of phosphorus flame retardants, depending on the oxidation state of phosphorus, in PHU materials. Full article

(This article belongs to the Special Issue Recent Advances in Flame Retardant Polymeric Materials)

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Graphical abstract

17 pages, 1874 KiB

Open AccessArticle

Apoptosis-Inducing Potential of Selected Bromophenolic Flame Retardants 2,4,6-Tribromophenol and Pentabromophenol in Human Peripheral Blood Mononuclear Cells

by Anna Barańska, Paulina Sicińska and Jaromir Michałowicz

Molecules 2022, 27(16), 5056; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27165056 - 09 Aug 2022

Cited by 4 | Viewed by 1582

Abstract

(1) Background: 2,4,6-Tribromophenol (2,4,6-TBP) and pentabromophenol (PBP) are utilized as brominated flame retardants (BFRs) in order to reduce the combustion of materials used in various utility products. The presence of 2,4,6-TBP and PBP has been reported in environmental samples as well as in inhaled air, dust, food, drinking water, and the human body. To date, there are limited data concerning the toxic action of 2,4,6-TBP and particularly PBP, and no study has been conducted to assess the apoptotic mechanism of action of these substances in human leukocytes. (2) Methods: PBMCs were isolated from leukocyte–platelet buffy coat and treated with tested substances in concentrations ranging from 0.01 to 50 µg/mL for 24 h. The apoptotic mechanism of action of the tested BFRs was assessed by the determination of phosphatidylserine exposure on the PBMCs surface, the evaluation of mitochondrial potential and cytosolic calcium ion levels, and the determination of caspase-8, -9, and -3 activation. Moreover, poly (ADP-ribose) polymerase-1 (PARP-1) cleavage, DNA fragmentation, and chromatin condensation were analyzed. (3) Results: 2,4,6-TBP and, more strongly, PBP induced apoptosis in PBMCs, changing all tested parameters. It was also found that the mitochondrial pathway was mainly involved in the apoptosis of PBMCs exposed to the studied compounds. (4) Conclusions: 2,4,6-TBP and PBP triggered apoptosis in human PBMCs, and some observed changes occurred at 2,4,6-TBP concentrations that were detected in humans occupationally exposed to this substance. Full article

(This article belongs to the Special Issue Recent Advances in Flame Retardant Polymeric Materials)

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Review

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19 pages, 3589 KiB

Open AccessReview

Layer-by-Layer Self-Assembly Coating for Multi-Functionalized Fabrics: A Scientometric Analysis in CiteSpace (2005–2021)

by Ying Pan, Li Fu, Jia Du, Dong Zhang, Ting Lü, Yan Zhang and Hongting Zhao

Molecules 2022, 27(19), 6767; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27196767 - 10 Oct 2022

Cited by 2 | Viewed by 2105

Abstract

Surface-engineered coatings have been increasingly applied to functionalize fabrics due to the ease of deposition of the coatings and their effectiveness in endowing the fabric with abundant properties. Among the surface modification methods, layer-by-layer (LbL) self-assembly has emerged as an important approach for creating multifunctional surfaces on fabrics. In this review, bibliometric analysis with the visualization analysis of LbL self-assembly coatings on fabrics was performed on publications extracted from the Web of Science (WOS) from 2005 to 2021 based on the CiteSpace software. The analysis results showed that research on LbL self-assembly coatings on fabrics has attracted much attention, and this technique has plentiful and flexible applications. Moreover, research on the LbL self-assembly method in the field of functionalization of fabrics has been summarized, which include flame retardant fabric, antibacterial fabric, ultraviolet resistant fabric, hydrophobic fabric and electromagnetic shielding fabric. It was found that the functionalization of the fabric has been changing from singularity to diversification. Based on the review, several future research directions can be proposed. The weatherability, comfort, cost and environmental friendliness should be considered when the multifunctional coatings are designed. Full article

(This article belongs to the Special Issue Recent Advances in Flame Retardant Polymeric Materials)

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