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Advances in Flame Retardant Polymeric Materials

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A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Applications".

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 41799

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Special Issue Editors

Dr. Jelena Vasiljević

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Guest Editor

Faculty of Natural Sciences and Engineering, University of Ljubljana, Ljubljana, Slovenia
Interests: sol-gel coatings; dispersion coatings; flame retardants; flame retardant polymers; thermal stability; flammability; polymer composites; polymer nanocomposites; water and oil repellency; multifunctionality; antimicrobial activity; functional protective textiles; textile finishing; surface modification
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Dr. Ivan Jerman

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Co-Guest Editor

Assistant Professor, Department of Material Chemistry, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
Interests: synthesis of polyhedral oligomeric silsesquioxane; sol-gel thin films; modification of pigments; spectrally selective paint coatings; high solar absorptivity coatings for concentrated solar power; textile finishing; flame retardant polymers; surface treatments; nanocoatings; electrochromic materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue of Polymers aims to broaden and deepen the scientific and technological knowledge with the most recent advances in the preparation, performance, and application of flame-retardant polymeric materials with respect to the concept of long-term environmental, economic, and social sustainability.

Flame-retardant natural and synthetic polymeric materials play a crucial role in building the fire-safe urban world. At the same time, the demand for minimizing potential health and environmental impacts requires considering the toxicology, safety, and circularity parameters at the beginning of the design process of flame-retardant systems. This drives development of new flame retardants and flame-retardant materials, ensuring that fire safety is not compromised at the expense of the targeted sustainability. In that respect, an interdisciplinary approach for the development of flame-retardant systems with improved persistent, bioaccumulative, and toxic profiles, lowered heat and smoke release, and reduced smoke toxicity is of high importance.

We invite the research community to contribute to this Special Issue by submitting comprehensive reviews or original research articles. The topics of interest include but are not limited to:

· Flame-retardant co-monomers and co-polymers;

· New polymeric flame retardants and their application;

· Flame-retardant polymers by reactive extrusion;

· Multi-component flame-retardant systems;

· Bio-based flame retardants and their application;

· Flame-retardant composites;

· Nano-dispersed flame-retardant systems;

· Flame-retardant systems for surface treatments and coatings;

· Flame-retardant systems for film- and fiber-forming polymers;

· Fundamentals of thermal stability, heat transfer, smoke release, and flame-retardant mechanisms;

· Flame retardancy of recycled polymers;

· Assessment of the toxicity of combustion products;

· Assessment of the migration/leaching of flame retardant from polymer;

· Assessment of the physical/chemical recyclability of flame-retardant polymer;

· Assessment of the biodegradation of flame-retardant polymer;

· Life cycle analysis (LCA) of flame-retardant polymeric materials;

· Structure modelling of flame-retardant molecules.

Dr. Jelena Vasiljević
Prof. Dr. Ivan Jerman
Guest Editors

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.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

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

flame retardants
additives
composites
nanocomposites
coatings
films
fibers
adhesives
foams
polymerization
reactive extrusion
synergism
flame-retardant mechanism
thermal stability
heat transfer
smoke release
recycling
toxicity
migration
leaching
biodegradation
life cycle analysis

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Published Papers (12 papers)

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Research

Jump to: Review

14 pages, 3809 KiB

Open AccessArticle

Suppression of Smoldering of Calcium Alginate Flame-Retardant Paper by Flame-Retardant Polyamide-66

by Kai Xu, Xing Tian, Ying Cao, Yaqi He, Yanzhi Xia and Fengyu Quan

Polymers 2021, 13(3), 430; https://doi.org/10.3390/polym13030430 - 29 Jan 2021

Cited by 13 | Viewed by 2340

Abstract

Calcium alginate (Ca-Alg) fibers are renewable fibers obtained from the ocean with essential flame retardancy, which have recently been applied as components of flame-retardant paper. However, the application of Ca-Alg fibers is limited because of their tendency to smolder. Therefore, composites papers were fabricated by blending using flame-retardant polyamide-66 (FR-PA), with a 5 wt% content of phosphorous flame retardant, which will form molten carbon during combustion. When the FR-PA content is 30% of the composite paper, FR-PA forms a compact carbon layer on the surface of the Ca-Alg fibers during combustion, which isolates the mass/heat transfer and effectively suppresses the smoldering of Ca-Alg. This consists of a condensed flame retardant mechanism. Furthermore, the combustion and thermal degradation behavior of paper were analyzed by cone calorimetry (CONE), TG and TG-IR. Ca-Alg in the composite paper decomposed and released CO₂ before ignition, which delayed the ignition time. Simultaneously, the FR-PA contained in the composite paper effectively inhibited the combustion of volatile combustibles in the gas phase. Overall, FR-PA and Ca-Alg improve the thermal stability of the composite paper in different temperature regions under air atmosphere. Ca-Alg reduces the formation of aromatic products and NH₃ in the composite paper under N₂ atmosphere. Ca-Alg-based paper with excellent flame retardancy was successfully prepared. Full article

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

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14 pages, 3695 KiB

Open AccessArticle

Effect of the B:Zn:H₂O Molar Ratio on the Properties of Poly(Vinyl Acetate) and Zinc Borate-Based Intumescent Coating Materials Exposed to a Quasi-Real Cellulosic Fire

by Jakub Łopiński, Beata Schmidt, Yongping Bai and Krzysztof Kowalczyk

Polymers 2020, 12(11), 2542; https://doi.org/10.3390/polym12112542 - 30 Oct 2020

Cited by 3 | Viewed by 1901

Abstract

In order to investigate an influence of the B:Zn:H₂O molar ratio on the fire protection efficiency of poly(vinyl acetate)-based thermoplastic intumescent coating materials (ICs), systems containing ammonium polyphosphate, melamine, pentaerythritol and different types of zinc borates (ZBs) were tested in a vertical position in quasi-real fire conditions. 3ZnO·2B₂O₃·6H₂O (ZB6), 2ZnO·3B₂O₃·3.5H₂O (ZB3.5) or 3ZnO·2B₂O₃ (ZB0) were added in amounts of 1–10 wt. parts/100 wt. parts of the other coating components mixture. Char formation processes and thermal insulation features were investigated using an open-flame furnace heated according to the cellulosic fire curve. Thermogravimetric features (DTG), chemical structures (FTIR) and mechanical strength of the ICs and the chars were analyzed as well. It was revealed that the type and dose of the ZBs significantly affect thermal insulation time (TIT) (up to 450 °C of a steel substrate) and sagging (SI) of the fire-heated coatings as well as the compressive strength of the created chars. The highest TIT value (+89%) was noted for the sample with 2.5 wt. parts of ZB3.5 while the lowest SI (−65%) was observed for the coatings containing 10 wt. parts of the hydrated borates (i.e., ZB3.5 or ZB6). The best mechanical strength was registered for the sample filled with the anhydrous modifier (3 wt. parts of ZB0). The presented results show that the ICs with the proper ZBs can be used for effective fire protection of vertically positioned steel elements. Full article

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

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16 pages, 6249 KiB

Open AccessArticle

Flame-Retardant Mechanism and Mechanical Properties of Wet-Spun Poly(acrylonitrile-co-vinylidene chloride) Fibers with Antimony Trioxide and Zinc Hydroxystannate

by Ji Su Kim, Ji Eun Song, Daeyoung Lim, Heejoon Ahn and Wonyoung Jeong

Polymers 2020, 12(11), 2442; https://doi.org/10.3390/polym12112442 - 22 Oct 2020

Cited by 8 | Viewed by 2681

Abstract

To produce flame retardant poly(acrylonitrile-co-vinylidene chloride) (PANVDC) fibers with limiting oxygen index (LOI) values above 28%, flame retardants are added to fibers. Because antimony trioxide (ATO) used widely for PANVDC is suspected as a carcinogen, non-toxic zinc hydroxystannate (ZHS) could be the alternative for reduction of ATO usage. Moreover, a flame retardant efficiency of the combination of ATO with ZHS could be expected because it was reported that ATO resists flame in the gas phase, whereas ZHS reacts in the condensed phase. Therefore, this study discussed the flame retardant mechanisms of ATO and ZHS in PANVDC, and evaluated the efficiency of the combination. PANVDC fibers with ATO and ZHS in 15 phr were produced by wet spinning. When ZHS was added, a more cyclized structure was detected (e.g., 1-methylnaphthalene) through pyrolysis−gas chromatography-mass spectrometry (Py-GC/MS). As a result of SEM-EDX analysis, Sb and Cl hardly remained in char layers of PANVDC-ATO; meanwhile, Zn, Sn, and Cl remained in that of PANVDC-ZHS. This implied that SbCl₃ from reaction of ATO and HCl reacts in the gas phase, whereas ZnCl₂ and SnCl₂ from ZHS and HCl promotes the cyclization reaction of PANVDC in the condensed phase. The LOI values of PANVDC, PANVDC-ATO, and PANVDC-ZHS were 26.4%, 29.0%, and 33.5%, respectively. This suggests that ZHS is a highly effective for PANVDC. Meanwhile, the LOI of PANVDC containing ATO-ZHS mixture is 31.0%. The combination of ATO and ZHS exhibited no efficiency. The addition of ATO and ZHS slightly reduced the tenacities of the fibers, respectively, 3.11 and 3.75 from 4.42 g/den. Full article

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

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20 pages, 10603 KiB

Open AccessArticle

The Toxicological Testing and Thermal Decomposition of Drive and Transport Belts Made of Thermoplastic Multilayer Polymer Materials

by Piotr Krawiec, Łukasz Warguła, Daniel Małozięć, Piotr Kaczmarzyk, Anna Dziechciarz and Dorota Czarnecka-Komorowska

Polymers 2020, 12(10), 2232; https://doi.org/10.3390/polym12102232 - 28 Sep 2020

Cited by 23 | Viewed by 3270

Abstract

The article presents the potential impact of flat drive and transport belts on people’s safety during a fire. The analysis distinguished belts made of classically used fabric–rubber composite materials reinforced with cord and currently used multilayer polymer composites. Moreover, the products’ multilayers during the thermal decomposition and combustion can be a source of emissions for unpredictable and toxic substances with different concentrations and compositions. In the evaluation of the compared belts, a testing methodology was used to determine the toxicometric indicators (W_LC50SM) on the basis of which it was possible to determine the toxicity of thermal decomposition and combustion products in agreement with the standards in force in several countries of the EU and Russia. The analysis was carried out on the basis of the registration of emissions of chemical compounds during the thermal decomposition and combustion of polymer materials at three different temperatures. Moreover, the degradation kinetics of the polymeric belts by using the thermogravimetric (TGA) technique was evaluated. Test results have shown that products of thermal decomposition resulting from the neoprene (NE22), leder leder (LL2), thermoplastic connection (TC), and extra high top cower (XH) belts can be characterized as moderately toxic or toxic. Their toxicity significantly increases with the increasing temperature of thermal decomposition or combustion, especially above 450 °C. The results showed that the belts made of several layers of polyamide can be considered the least toxic in fire conditions. The TGA results showed that NBR/PA/PA/NBR belt made with two layers of polyamide and the acrylonitrile–butadiene rubber has the highest thermal stability in comparison to other belts. Full article

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

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23 pages, 5183 KiB

Open AccessArticle

Enhanced Biodegradation/Photodegradation of Organophosphorus Fire Retardant Using an Integrated Method of Modified Pharmacophore Model with Molecular Dynamics and Polarizable Continuum Model

by Jiawen Yang, Qing Li and Yu Li

Polymers 2020, 12(8), 1672; https://doi.org/10.3390/polym12081672 - 27 Jul 2020

Cited by 12 | Viewed by 2991

Abstract

A comprehensive 3D-quantitative structure–activity relationship (QSAR) pharmacophore model was constructed using the values of comprehensive biodegradation/photodegradation effects of 17 organophosphorus flame retardants (OPFRs) evaluated by a normalization method to modify OPFRs with high biodegradation/photodegradation, taking tris(chloro-isopropyl) phosphate (TCPP), tris(2-chloroethyl) phosphate (TCEP) and tris(1-chloro-2-propyl) phosphate (TCIPP)—which occur frequently in the environment, and are the most difficult to degrade as target molecules. OPFR-derivative molecules TCPP–OH shows the highest improvement in biodegradation and photodegradation (55.48% and 46.37%, respectively). On simulating the biodegradation path and photodegradation path, it is found that the energy barrier of TCPP–OH for phosphate bond cleavage is reduced by 15.73% and 52.52% compared to TCPP after modification, respectively. Finally, in order to further significantly improve its biodegradability and photodegradation, the efficiency enhancement in the biodegradation and photodegradation of TCPP–OH are analyzed under the simulated environment by molecular dynamics and polarizable continuum model, respectively. The results of molecular dynamics show that the biodegradation efficiency of the TCPP–OH increased by 75.52% compared to TCPP. The UV spectral transition energy (4.07 eV) of TCPP–OH under the influence of hydrogen peroxide solvation effect is 44.23% lower than the actual transition energy (7.29 eV) of TCPP. Full article

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

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14 pages, 11699 KiB

Open AccessEditor’s ChoiceArticle

Poly (vinyl alcohol)/β-Cyclodextrin Composite Fiber with Good Flame Retardant and Super-Smoke Suppression Properties

by Cheng-Yuan Xing, Shi-Lin Zeng, Shi-Kai Qi, Meng-Jin Jiang, Long Xu, Li Chen, Sheng Zhang and Bang-Jing Li

Polymers 2020, 12(5), 1078; https://doi.org/10.3390/polym12051078 - 08 May 2020

Cited by 15 | Viewed by 3575

Abstract

Fibers with good flame retardant (FR) and smoke suppression performances are highly desirable for the purpose of eliminating fire hazard. This study developed a novel FR fiber by wet-spinning poly (vinyl alcohol)/β-cyclodextrin (PVA/βCD) composite fiber and crosslinking it with hexamethylene diisocyanate (HDI). βCDs showed good compatibility with PVA matrix, and the resulting PVA/CD/HDI fibers showed mechanical strength at the same level as natural cotton fiber. The PVA/CD/HDI fibers also showed excellent flame retardance (the LOI value of PVA/CD/HDI could reach 41.7%, and their peak of heat release (PHRR) could be reduced by up to 77.7% by neat PVA), and super-smoke suppression (the value of total smoke production (TSP) was only 28.6% compared to PVA). These dramatic reductions of fire hazard were ascribed to the char formation of βCD and crosslinking structure of PVA/CD/HDI, which formed a compact char layer during combustion, thus preventing heat transmission and smoke release. Full article

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

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15 pages, 12996 KiB

Open AccessArticle

Phytic Acid and Biochar: An Effective All Bio-Sourced Flame Retardant Formulation for Cotton Fabrics

by Marco Barbalini, Mattia Bartoli, Alberto Tagliaferro and Giulio Malucelli

Polymers 2020, 12(4), 811; https://doi.org/10.3390/polym12040811 - 04 Apr 2020

Cited by 53 | Viewed by 4141

Abstract

Flame retardant systems based on bio-sourced products combine quite high fire performances with the low environmental impact related to their synthesis and exploitation. In this context, this work describes a new all bio-sourced flame retardant system designed and applied to cotton fabrics. In particular, it consists of phytic acid (PA), a phosphorus-based naturally occurring molecule extracted from different plant tissues, in combination with biochar (BC), a carbon-rich solid product obtained from the thermo-chemical conversion of biomasses in an oxygen-limited environment. PA and BC were mixed together at a 1:1 weight ratio in an aqueous medium, and applied to cotton at different loadings. As revealed by flammability and forced combustion tests, this bio-sourced system was able to provide significant improvements in flame retardance of cotton, even limiting the final dry add-on on the treated fabrics at 8 wt.% only. The so-treated fabrics were capable to achieve self-extinction in both horizontal and vertical flame spread tests; besides, they did not ignite under the exposure to 35 kW/m² irradiative heat flux. Conversely, the proposed flame retardant treatment did not show a high washing fastness, though the washed flame retarded fabrics still exhibited a better flame retardant behavior than untreated cotton. Full article

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

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18 pages, 4629 KiB

Open AccessArticle

Effect of Different Flame-Retardant Bridged DOPO Derivatives on Properties of in Situ Produced Fiber-Forming Polyamide 6

by Jelena Vasiljević, Marija Čolović, Nataša Čelan Korošin, Matic Šobak, Žiga Štirn and Ivan Jerman

Polymers 2020, 12(3), 657; https://doi.org/10.3390/polym12030657 - 13 Mar 2020

Cited by 30 | Viewed by 5392

Abstract

The production of sustainable and effective flame retardant (FR) polyamide 6 (PA6) fibrous materials requires the establishment of a novel approach for the production of polyamide 6/FR nanodispersed systems. This research work explores the influence of three different flame-retardant bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivatives on the comprehensive properties of in situ produced PA6/FR systems. To this end, in situ water-catalyzed ring-opening polymerization of ε-caprolactam was conducted in the presence of three different bridged DOPO derivatives, e.g., one P−N bond phosphonamidate derivative and two P−C bond phosphinate derivatives. The selected bridged DOPO derivatives mainly act in the gas phase at the temperatures that relatively match the PA6 pyrolysis specifics. The effects of the FRs on the dispersion state, morphological, molecular, structural, melt-rheological, and thermal properties of the in situ synthesized PA6 were evaluated. The specific advantage of this approach is one-step production of PA6 with uniformly distributed nanodispersed FR, which was obtained in the case of all three applied FRs. However, the applied FRs differently interacted with monomer and polymer during the polymerization, which was reflected in the length of PA6 chains, crystalline structure, and melt-rheological properties. The applied FRs provided a comparable effect on the thermal stability of PA6 and stabilization of the PA6/FR systems above 450 °C in the oxygen-assisted pyrolysis. However, only with the specifically designed FR molecule were the comprehensive properties of the fiber-forming PA6 satisfied for the continuous conduction of the melt-spinning process. Full article

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

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18 pages, 4705 KiB

Open AccessArticle

Alkylation of Aromatic Compounds with Pentabromobenzyl Bromide and Tetrabromoxylene Dibromide as a New Route to High Molecular Weight Brominated Flame Retardants

by Mark Gelmont, Michael Yuzefovitch, David Yoffe, Eyal Eden and Sergei Levchik

Polymers 2020, 12(2), 352; https://doi.org/10.3390/polym12020352 - 06 Feb 2020

Cited by 7 | Viewed by 3016

Abstract

In the view of many national and international human health and environmental regulations, polymeric flame retardants are sustainable products. In this work, a series of high molecular weight and polymeric brominated flame retardants are synthesized by the alkylation of aromatic molecules or the alkylation of aromatic polymers with pentabromobenzyl bromide (PBBB) or tetrabromoxylylene dibromide (TBXDB). The flame retardants prepared via the alkylation of toluene or diphenylethane with PBBB were found to be not truly polymeric but had high M_w > 1400. However, the alkylation of the same aromatic molecules by a mixture of PBBB and TBXDP resulted in polymeric flame retardants with M_w > 130,000. Two other polymeric flame retardants were prepared by the alkylation of aromatic polymers (polyphenylene ether or polystyrene) with PBBB. It was found that the new flame retardants had a high bromine content of more than 68%. They showed high thermal stability with the onset of thermal decomposition above 360 °C and a maximum rate of weight loss at about 375–410 °C. The newly synthesized flame retardants were tested in different thermoplastics. Flame retardant efficiency and physical properties were comparable or better than the reference commercial flame retardants. Full article

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

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15 pages, 3997 KiB

Open AccessArticle

Flame-Retardant Performance of Transparent and Tensile-Strength-Enhanced Epoxy Resins

by Liang Li and Zaisheng Cai

Polymers 2020, 12(2), 317; https://doi.org/10.3390/polym12020317 - 04 Feb 2020

Cited by 24 | Viewed by 3477

Abstract

In this study, a flame-retardant additive with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) groups denoted DSD was successfully synthesized from DOPO, 4,4′-diaminodiphenyl sulfone (DDS), and salicylaldehyde. The chemical structure of DSD was characterized by FTIR–ATR, NMR, and elemental analysis. DSD was used as an amine curing agent, and the transparent, tensile strength-enhanced epoxy resins named EP–DSD were prepared via thermal curing reactions among the diglycidyl ether of bisphenol A (DGEBA), 4,4′-diaminodiphenylmethane (DDM), and DSD. The flame-retardancy of composites was studied by the limiting oxygen index (LOI) and UL-94 test. The LOI values of EP–DSD composites increased from 30.7% for a content of 3 wt % to 35.4% for a content of 9 wt %. When the content of DSD reached 6 wt %, a V-0 rating under the UL-94 vertical test was achieved. SEM photographs of char residues after the UL-94 test indicate that an intumescent and tight char layer with a porous structure inside was formed. The TGA results revealed that EP–DSD thermosets decomposed ahead of time. The graphitization degree of the residual chars was also investigated by laser Raman spectroscopy. The measurement of tensile strength at breaking point shows that the loading of DSD increases the tensile strength of epoxy thermosets. Py-GC/MS analysis shows the presence of phosphorus fragments released during EP–DSD thermal decomposition, which could act as free radical inhibitors in the gas phase. Owing to the promotion of the formation of intumescent and compact char residues in the condensed phase and nonflammable phosphorus fragments formed from the decomposition of DOPO groups, EP–DSD composites displayed obvious flame-retardancy. Full article

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

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16 pages, 5327 KiB

Open AccessArticle

Enhancement of Flame Retardancy of Colorless and Transparent Semi-Alicyclic Polyimide Film from Hydrogenated-BPDA and 4,4′-oxydianiline via the Incorporation of Phosphazene Oligomer

by Xiao Wu, Ganglan Jiang, Yan Zhang, Lin Wu, Yanjiang Jia, Yaoyao Tan, Jingang Liu and Xiumin Zhang

Polymers 2020, 12(1), 90; https://doi.org/10.3390/polym12010090 - 03 Jan 2020

Cited by 10 | Viewed by 3463

Abstract

Enhancement of flame retardancy of a colorless and transparent semi-alicyclic polyimide (PI) film was carried out by the incorporation of phosphazene (PPZ) flame retardant (FR). For this purpose, PI-1 matrix was first synthesized from hydrogenated 3,3′,4,4′-biphenyltetracarboxylic dianhydride (HBPDA) and 4,4′-oxydianiline (ODA). The soluble PI-1 resin was dissolved in N,N-dimethylacetamide (DMAc) to afford the PI-1 solution, which was then physically blended with PPZ FR with the loading amounts in the range of 0–25 wt.%. The PPZ FR exhibited good miscibility with the PI-1 matrix when its proportion was lower than 10 wt.% in the composite films. PI-3 composite film with the PPZ loading of 10 wt.% showed an optical transmittance of 75% at the wavelength of 450 nm with a thickness of 50 μm. More importantly, PI-3 exhibited a flame retardancy class of UL 94 VTM-0 and reduced total heat release (THR), heat release rate (HRR), smoke production rate (SPR), and rate of smoke release (RSR) values during combustion compared with the original PI-1 film. In addition, PI-3 film had a limiting oxygen index (LOI) of 30.9%, which is much higher than that of PI-1 matrix (LOI: 20.1%). Finally, incorporation of PPZ FR decreased the thermal stability of the PI films. The 10% weight loss temperature (T_10%) and the glass transition temperature (T_g) of the PI-3 film were 411.6 °C and 227.4 °C, respectively, which were lower than those of the PI-1 matrix (T_10%: 487.3 °C; T_g: 260.6 °C) Full article

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

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25 pages, 2124 KiB

Open AccessEditor’s ChoiceReview

The Potential for Bio-Sustainable Organobromine-Containing Flame Retardant Formulations for Textile Applications—A Review

by A Richard Horrocks

Polymers 2020, 12(9), 2160; https://doi.org/10.3390/polym12092160 - 22 Sep 2020

Cited by 29 | Viewed by 4478

Abstract

This review considers the challenge of developing sustainable organobromine flame retardants (BrFRs) and alternative synergists to the predominantly used antimony III oxide. Current BrFR efficiencies are reviewed for textile coatings and back-coatings with a focus on furnishing and similar fabrics covering underlying flammable fillings, such as flexible polyurethane foam. The difficulty of replacing them with non-halogen-containing systems is also reviewed with major disadvantages including their extreme specificity with regard to a given textile type and poor durability.The possibility of replacing currently used BrFRs for textiles structures that mimic naturally occurring organobromine-containing species is discussed, noting that of the nearly 2000 such species identified in both marine and terrestrial environments, a significant number are functionalised polybrominated diphenyl ethers, which form part of a series of little understood biosynthetic biodegradation cycles.The continued use of antimony III oxide as synergist and possible replacement by alternatives, such as the commercially available zinc stannates and the recently identified zinc tungstate, are discussed. Both are effective as synergists and smoke suppressants, but unlike Sb₂0₃, they have efficiencies dependent on BrFR chemistry and polymer matrix or textile structure. Furthermore, their effectiveness in textile coatings has yet to be more fully assessed.In conclusion, it is proposed that the future of sustainable BrFRs should be based on naturally occurring polybrominated structures developed in conjunction with non-toxic, smoke-suppressing synergists such as the zinc stannates or zinc tungstate, which have been carefully tailored for given polymeric and textile substrates. Full article

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

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