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Tomiak F, Zitzmann M, Drummer D. A Multi-Material Flame-Retarding System Based on Expandable Graphite for Glass-Fiber-Reinforced PA6. Polymers (Basel) 2023; 15:4100. [PMID: 37896344 PMCID: PMC10610593 DOI: 10.3390/polym15204100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/02/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023] Open
Abstract
A synergistic multi-material flame retardant system based on expandable graphite (EG), aluminum diethylphosphinate (AlPi), melamine polyphosphate (MPP), and montmorillonite (MMT) has been studied in glass-fiber-reinforced polyamide 6 (PA6). Analytical evaluations and fire performances were evaluated using coupled thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR) as well as cone calorimetry, UL-94 fire testing, and limiting oxygen index (LOI). A combination of EG/AlPi/MPP/MMT has been shown to provide superior flame-retarding properties when integrated at 20 wt.% into glass-fiber-reinforced PA6 (25 wt.%), achieving UL-94 V0 classification and an oxygen index of 32%. Strong residue formation resulted in low heat development overall, with a peak heat release rate (pHRR) of 103 kW/m2, a maximum of average heat release rate (MAHRE) of 33 kW/m2, and deficient total smoke production (TSP) of 3.8 m2. Particularly remarkable was the structural stability of the char residue. The char residue could easily withstand an areal weight of 35 g/cm2, showing no visible deformation.
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Affiliation(s)
- Florian Tomiak
- Institute of Polymer Technology, Friedrich-Alexander-University Erlangen-Nürmberg, Am Weichselgarten 10, 91058 Erlangen, Germany; (M.Z.)
- Bavarian Polymer Institute, Friedrich-Alexander-University Erlangen-Nürnberg, Dr. Mack Strasse 77, 90762 Fuerth, Germany
| | - Melanie Zitzmann
- Institute of Polymer Technology, Friedrich-Alexander-University Erlangen-Nürmberg, Am Weichselgarten 10, 91058 Erlangen, Germany; (M.Z.)
- Bavarian Polymer Institute, Friedrich-Alexander-University Erlangen-Nürnberg, Dr. Mack Strasse 77, 90762 Fuerth, Germany
| | - Dietmar Drummer
- Institute of Polymer Technology, Friedrich-Alexander-University Erlangen-Nürmberg, Am Weichselgarten 10, 91058 Erlangen, Germany; (M.Z.)
- Bavarian Polymer Institute, Friedrich-Alexander-University Erlangen-Nürnberg, Dr. Mack Strasse 77, 90762 Fuerth, Germany
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Fabrication of Rigid Isocyanate-Based Polyimide Foam Achieved Excellent Use Safety via Synergy between Expandable Graphite and Phosphorus-Containing Polyol. Polymers (Basel) 2023; 15:polym15061381. [PMID: 36987162 PMCID: PMC10052713 DOI: 10.3390/polym15061381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 03/12/2023] Open
Abstract
For the advantages of low cost, excellent thermal insulation, and sound absorption properties, the rigid isocyanate-based polyimide foam (RPIF) presents great application prospects as a building insulation material. However, its inflammability and the accompanying toxic fumes create huge safety hazard. In this paper, reactive phosphate-containing polyol (PPCP) is synthesized and employed with expandable graphite (EG) to obtain RPIF with excellent use safety. EG can be considered as an ideal partner for PPCP to weaken the drawbacks in toxic fume release. Limiting oxygen index (LOI), cone calorimeter test (CCT), and toxic gas results show that the combination of PPCP and EG can synergistically enhance flame retardancy and the use safety of RPIF owing to the unique structure of a dense char layer possessing a flame barrier and toxic gas adsorption effects. When EG and PPCP are simultaneously applied to the RPIF system, the higher EG dosage will bring higher positive synergistic effects in the use safety of RPIF. The most preferred ratio of EG and PPCP is 2:1 (RPIF-10-5) in this study; RPIF-10-5 shows the highest LOI, low CCT results and specific optical density of smoke, and low HCN concentration. This design and the findings are of great significance to improving the application of RPIF.
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Vothi H, Kim C, Nguyen T, Lee J, Nguyen LAT, Suhr J. Thermal degradation and flame retardancy of nylon 6/aluminum methylmethoxy phosphonate composites. RSC Adv 2023; 13:5219-5227. [PMID: 36777944 PMCID: PMC9910282 DOI: 10.1039/d2ra07297a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/06/2023] [Indexed: 02/11/2023] Open
Abstract
An aluminum methylmethoxyphosphonate (AlPo)-based flame retardant (FR) was synthesized. Thermal degradation and flame retardancy of nylon 6 (PA6)/AlPo composites were examined and compared with PA6/commercial aluminum diethylphosphinate (AlPi) composites. The PA6/AlPo composite achieved a V-0 rating at 20 wt% loading during the UL-94 test, and it exhibited the formation of a charred layer that protected the polymer from burning and reduced the release of gases during the combustion of PA6. AlPo demonstrated exceptional performance in gaseous and condensed phases in the PA6 matrix, whereas AlPi only worked in the gaseous phase. The differences between the thermal degradation mechanisms and flame retardancies of AlPi and AlPo were investigated via Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and cone calorimetry. A suitable degradation mechanism was proposed to aid the development of flame retardants in the future.
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Affiliation(s)
- Hai Vothi
- Center for Composite Materials & Concurrent Design, Research & Business Foundation, Sungkyunkwan University Suwon 16419 Republic of Korea +84339949314.,University of Science Ho Chi Minh City Vietnam.,Vietnam National University Ho Chi Minh City Vietnam
| | - Chowon Kim
- Department of Polymer Science and Engineering, Sungkyunkwan University Suwon 16419 Republic of Korea +821077087847
| | - TanBinh Nguyen
- Department of Polymer Science and Engineering, Sungkyunkwan University Suwon 16419 Republic of Korea +821077087847
| | - Jinwoo Lee
- Department of Polymer Science and Engineering, Sungkyunkwan University Suwon 16419 Republic of Korea +821077087847
| | - Lan-Anh T. Nguyen
- Department of Energy Science, Sungkyunkwan UniversitySuwon16419Republic of Korea
| | - Jonghwan Suhr
- Department of Polymer Science and Engineering, Sungkyunkwan University Suwon 16419 Republic of Korea +821077087847.,Department of Mechanical Engineering, Sungkyunkwan University Suwon 16419 Republic of Korea
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Li J, Qian L, Xi W, Qiu Y, Tang W, Li S. Alloying synergistic flame retardant effect improving fire resistance and mechanical properties of polyamide 6. J Appl Polym Sci 2022. [DOI: 10.1002/app.53226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Junxiao Li
- College of Chemistry and Materials Engineering Beijing Technology and Business University Beijing China
- Petroleum and Chemical Industry Engineering Laboratory of Non‐halogen Flame Retardants for Polymers Beijing China
- China Light Industry Engineering Technology Research Center of Advanced Flame Retardants Beijing China
| | - Lijun Qian
- College of Chemistry and Materials Engineering Beijing Technology and Business University Beijing China
- Petroleum and Chemical Industry Engineering Laboratory of Non‐halogen Flame Retardants for Polymers Beijing China
- China Light Industry Engineering Technology Research Center of Advanced Flame Retardants Beijing China
| | - Wang Xi
- College of Chemistry and Materials Engineering Beijing Technology and Business University Beijing China
- Petroleum and Chemical Industry Engineering Laboratory of Non‐halogen Flame Retardants for Polymers Beijing China
- China Light Industry Engineering Technology Research Center of Advanced Flame Retardants Beijing China
| | - Yong Qiu
- College of Chemistry and Materials Engineering Beijing Technology and Business University Beijing China
- Petroleum and Chemical Industry Engineering Laboratory of Non‐halogen Flame Retardants for Polymers Beijing China
- China Light Industry Engineering Technology Research Center of Advanced Flame Retardants Beijing China
| | - Wei Tang
- College of Chemistry and Materials Engineering Beijing Technology and Business University Beijing China
- Petroleum and Chemical Industry Engineering Laboratory of Non‐halogen Flame Retardants for Polymers Beijing China
- China Light Industry Engineering Technology Research Center of Advanced Flame Retardants Beijing China
| | - Shanzhe Li
- College of Chemistry and Materials Engineering Beijing Technology and Business University Beijing China
- Petroleum and Chemical Industry Engineering Laboratory of Non‐halogen Flame Retardants for Polymers Beijing China
- China Light Industry Engineering Technology Research Center of Advanced Flame Retardants Beijing China
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Xiang YL, Huang SH, Hu QH, Wang QY, Zhao MQ, Jiang YC, Chen X, Lin J, Zhou QH. Zwitterionic meso-silica/polypeptide hybrid nanoparticles for efficient azithromycin delivery and photodynamic therapy for synergistic treatment of drug-resistant bacterial infection. Int J Biol Macromol 2022; 219:597-610. [PMID: 35952811 DOI: 10.1016/j.ijbiomac.2022.08.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 07/22/2022] [Accepted: 08/05/2022] [Indexed: 12/21/2022]
Abstract
The treatment of drug-resistant bacterial infections attributed to the overuse of antibiotics still remains a serious challenge globally. Herein, zwitterionic charge switchable meso-silica/polypeptide hybrid nanoparticles (MSPNs) were prepared for the synergistic chemo-photodynamic therapy in the treatment of drug-resistant bacterial infections. Subsequently, azithromycin (AZT) and methylene blue (MB) were loaded in the MSPNs to form the combined chemo-photodynamic therapeutic nanoparticles (MSPNs-AZT/MB) for the treatment of methicillin-resistant Staphylococcus aureus (MRSA). Remarkably, the as-prepared MSPNs-AZT/MB exhibited a negative surface charge of -5.2 mV at physiological pH while switching into positive surface charge of 24.7 mv in an acidic environment, leading to enhanced binding with bacterial surface. The lipase-triggered AZT release up to 77.9 % was achieved, and the loaded MB demonstrated efficient singlet oxygen (1O2) generation for photodynamic therapy. The in vitro experimental results displayed an excellent antibacterial effect against MRSA in both planktonic and biofilm phenotypes. Additionally, the as-prepared MSPNs-AZT/MB exhibited synergistic and enhanced antibacterial infection effect up to 94 % comparing to monotherapy in a mice model. Considering the above advantages, the as-prepared combined chemo-photodynamic therapeutic nanoparticles showed promising biocompatibility and clinical potential for the efficient therapy of drug-resistant bacteria.
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Affiliation(s)
- Ya-Li Xiang
- Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, First Ring Road, 4th Section No.16, Chengdu, Sichuan 610041, China
| | - Shuang-Hui Huang
- Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, First Ring Road, 4th Section No.16, Chengdu, Sichuan 610041, China
| | - Qiu-Hui Hu
- Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, First Ring Road, 4th Section No.16, Chengdu, Sichuan 610041, China
| | - Qiu-Yue Wang
- Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, First Ring Road, 4th Section No.16, Chengdu, Sichuan 610041, China
| | - Mei-Qi Zhao
- Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, First Ring Road, 4th Section No.16, Chengdu, Sichuan 610041, China
| | - Yu-Chen Jiang
- Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, First Ring Road, 4th Section No.16, Chengdu, Sichuan 610041, China
| | - Xiao Chen
- Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, First Ring Road, 4th Section No.16, Chengdu, Sichuan 610041, China
| | - Juan Lin
- School of Biomedical Sciences and Technology, Chengdu Medical College, Xindu Road No.783, Chengdu, Sichuan 610500, China.
| | - Qing-Han Zhou
- Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, First Ring Road, 4th Section No.16, Chengdu, Sichuan 610041, China; Key Laboratory of General Chemistry of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, Chengdu 610041, China.
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Tomiak F, Drummer D. The Impact of β-Radiation Crosslinking on Flammability Properties of PA6 Modified by Commercially Available Flame-Retardant Additives. Polymers (Basel) 2022; 14:polym14153168. [PMID: 35956684 PMCID: PMC9371137 DOI: 10.3390/polym14153168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/19/2022] [Accepted: 07/28/2022] [Indexed: 02/01/2023] Open
Abstract
A comparative study was conducted investigating the influence of β-radiation crosslinking (β-RC) on the fire behavior of flame retardant-modified polyamide 6 (PA6). In order to provide a comprehensive overview, a variety of commercially available flame-retardant additives were investigated, exhibiting different flame retarding actions such as delusion, char formation, intumescence and flame poisoning. This study focused on the identification of differences in the influence of β-RC on fire behavior. Coupled thermal gravimetrical analysis (TGA) and Fourier transformation infrared spectroscopy (FTIR) were used to conduct changes within the decomposition processes. Dynamic thermal analysis (DTA) was used to identify structural stability limits and fire testing was conducted using the limiting oxygen index (LOI), vertical UL-94 and cone calorimeter testing. Crosslinking was found to substantially change the fire behavior observed, whereas the observed phenomena were exclusively physical for the given formulations studied: warpage, char residue destruction and anti-dripping. Despite these phenomena being observed for all β-RC formulations, the impact on fire resistivity properties were found to be very different. However, the overall fire protection properties measured in UL-94 fire tests were found to deteriorate for β-RC formulations. Only β-RC formulations based on PA6/EG were found to achieve a UL-94 V0 classification.
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Affiliation(s)
- Florian Tomiak
- Institute of Polymer Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Am Weichselgarten 10, 91058 Erlangen, Germany;
- Bavarian Polymer Institute, Friedrich-Alexander-Universität Erlangen-Nürnberg, Dr. Mack Strasse 77, 90762 Fuerth, Germany
- Correspondence:
| | - Dietmar Drummer
- Institute of Polymer Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Am Weichselgarten 10, 91058 Erlangen, Germany;
- Bavarian Polymer Institute, Friedrich-Alexander-Universität Erlangen-Nürnberg, Dr. Mack Strasse 77, 90762 Fuerth, Germany
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Marset D, Fages E, Gonga E, Ivorra-Martinez J, Sánchez-Nacher L, Quiles-Carrillo L. Development and Characterization of High Environmentally Friendly Composites of Bio-Based Polyamide 1010 with Enhanced Fire Retardancy Properties by Expandable Graphite. Polymers (Basel) 2022; 14:polym14091843. [PMID: 35567012 PMCID: PMC9103054 DOI: 10.3390/polym14091843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 12/04/2022] Open
Abstract
Bio-based polyamide 1010 was melt-compounded with different percentages (2.5 to 10.0 wt.%) of expandable graphite (EGr) as an environmentally friendly solution to improve the flame retardancy properties. The mechanical, morphological, thermal and fire retardancy properties (among others) are analysed. The novelty of the article lies in the use of fully removable polyamide. The effect of the incorporation of EGr in the properties of this polymer was analysed and characterised. The incorporation of EGr into the PA1010 matrix led to very promising results. Mechanically, the EGr provided increased stiffness and a tensile strength up to 7.5 wt.%, verifying good mechanical performance. The DMTA results also show how the incorporation of EGr in the PA1010 matrix clearly increases the stiffness of the composites over the entire temperature range analysed. In terms of physical properties, water absorption of PA1010 was reduced particularly in the 10% EGr, which reduces the water absorption of PA1010 by 20%. In terms of flame retardant properties, with the incorporation of EGr, a significant reduction in the heat release rate (HRR) values as the concentration of the additive increases and a reduction in the maximum peak heat release rate (pHRR) can be observed for all compounds. In particular, it goes from 934 kW/m2 for neat polyamide to a value of 374 kW/m2 with 10% EGr. Finally, an improvement in the UL-94 rating of the 7.5 and 10% EGr composites was also observed, going from V-2 in the PA to V-1 in these composites.
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Affiliation(s)
- David Marset
- Textile Industry Research Association (AITEX), Plaza Emilio Sala 1, 03801 Alcoy, Spain; (D.M.); (E.F.); (E.G.)
| | - Eduardo Fages
- Textile Industry Research Association (AITEX), Plaza Emilio Sala 1, 03801 Alcoy, Spain; (D.M.); (E.F.); (E.G.)
| | - Eloi Gonga
- Textile Industry Research Association (AITEX), Plaza Emilio Sala 1, 03801 Alcoy, Spain; (D.M.); (E.F.); (E.G.)
| | - Juan Ivorra-Martinez
- Technological Institute of Materials (ITM), Universitat Politècnica de València (UPV), Plaza Ferrándiz y Carbonell 1, 03801 Alcoy, Spain; (L.S.-N.); (L.Q.-C.)
- Correspondence: ; Tel.: +34-966-528-433
| | - Lourdes Sánchez-Nacher
- Technological Institute of Materials (ITM), Universitat Politècnica de València (UPV), Plaza Ferrándiz y Carbonell 1, 03801 Alcoy, Spain; (L.S.-N.); (L.Q.-C.)
| | - Luis Quiles-Carrillo
- Technological Institute of Materials (ITM), Universitat Politècnica de València (UPV), Plaza Ferrándiz y Carbonell 1, 03801 Alcoy, Spain; (L.S.-N.); (L.Q.-C.)
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Tomiak F, Schneider K, Schoeffel A, Rathberger K, Drummer D. Expandable Graphite as a Multifunctional Flame-Retarding Additive for Highly Filled Thermal Conductive Polymer Formulations. Polymers (Basel) 2022; 14:polym14081613. [PMID: 35458364 PMCID: PMC9031968 DOI: 10.3390/polym14081613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 11/29/2022] Open
Abstract
Expandable graphite (EG) and graphite (G) were assessed as multifunctional additives improving both flame retardancy and thermal conductivity in highly filled, thermal conductive polymeric materials based on polyamide 6 (PA6). Fire testing was conducted using modern UL-94, LOI and cone calorimeter test setups. It is demonstrated that thermal conductivity can significantly influence the time to ignition, although offering little fire resistance once ignited even in highly filled systems. Thus, for PA6 formulations containing solely 70 wt.% G, the peak heat release rate (pHRR) measured in cone calorimeter tests was 193 kW/m², whereas PA6 formulations containing 20 wt.% EG/50 wt.% G did not exhibit a measurable heat development. Particular attention was paid to effect separation between thermal conductivity and residue formation. Good thermal conductivity properties are proven to be particularly effective in test scenarios where the heat impact is comparatively low and the testing environment provides good heat dissipation and convective cooling possibilities. For candle-like ignition scenarios (e.g., LOI), filling levels of >50 wt.% (G or EG/G) are shown to be sufficient to suppress ignition exclusively by thermal conductivity. V0 classifications in UL-94 vertical burning tests were achieved for PA6 formulations containing ≥70 wt.% G, ≥25 wt.% EG and ≥20 wt.% EG/25 wt.% G.
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Affiliation(s)
- Florian Tomiak
- Institute of Polymer Technology, Friedrich-Alexander-University Erlangen-Nuremberg, Am Weichselgarten 10, 91058 Erlangen, Germany; (K.S.); (D.D.)
- Bavarian Polymer Institute, Friedrich-Alexander-University Erlangen-Nuremberg, Dr. Mack Strasse 77, 90762 Fuerth, Germany
- Correspondence:
| | - Kevin Schneider
- Institute of Polymer Technology, Friedrich-Alexander-University Erlangen-Nuremberg, Am Weichselgarten 10, 91058 Erlangen, Germany; (K.S.); (D.D.)
| | - Angelina Schoeffel
- Georg H. Luh GmbH, Schoene Aussicht 39, 65396 Walluf, Germany; (A.S.); (K.R.)
| | - Klaus Rathberger
- Georg H. Luh GmbH, Schoene Aussicht 39, 65396 Walluf, Germany; (A.S.); (K.R.)
| | - Dietmar Drummer
- Institute of Polymer Technology, Friedrich-Alexander-University Erlangen-Nuremberg, Am Weichselgarten 10, 91058 Erlangen, Germany; (K.S.); (D.D.)
- Bavarian Polymer Institute, Friedrich-Alexander-University Erlangen-Nuremberg, Dr. Mack Strasse 77, 90762 Fuerth, Germany
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Expandable Graphite, Aluminum Diethylphospinate and Melamine Polyphosphate as Flame Retarding System in Glass Fiber-Reinforced PA6. Polymers (Basel) 2022; 14:polym14061263. [PMID: 35335591 PMCID: PMC8951083 DOI: 10.3390/polym14061263] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 02/05/2023] Open
Abstract
A flame retardant system based on expandable graphite (EG), aluminum diethylphosphinate (AlPI) and melamine polyphosphate (MPP) was investigated in glass fiber- (GF) reinforced polyamide 6 (PA6). Burning characteristics were evaluated via cone calorimeter, limiting oxygen index (LOI) and UL-94 tests. Thermogravimetric analysis (TGA) and coupled Fourier transform infrared spectroscopy (FTIR) was used to investigate the decomposition process as well as flame retardant modes of actions. Specifically, in the cone calorimeter tests, formulations containing EG showed excellent flame retardant properties for non-reinforced and reinforced PA6. The best performance was achieved for 25 wt.% glass fiber-reinforced PA6 containing solely 20 wt.% EG, corresponding to a measured pHRR of 134 kW/m2 and a total smoke production of 1.2 m2. Higher glass fiber contents of 45 wt.% (30 vol.%) revealed a lower char volume, which was attributed to both the limited space available for expansion and the sheer-induced reduction in particle size during processing. All of the reinforced PA6 formulations only achieved V2 classifications, but this was at low filling degrees (10 wt.%) for both net EG or EG/AlPi/MPP combinations. For GF-reinforced PA6 containing EG/AlPi/MPP mixtures, a synergistic effect was found to improve the oxygen index up to 30.6%.
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