Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends

The foamed structure of recycled polyethylene-terephthalate (rPET) is a promising solution for industrial applications; however, the remedy for its inherent melt-dripping property is still a challenging topic. In our research, we were able to improve the flame retardancy of the endothermic–exothermi...

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Main Authors: Veronika Anna Szabó, Sándor Kálmán Jakab, András Kovács, Tamara Zsuzsanna Böcz, Gábor Dogossy
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Crystals
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Online Access:https://www.mdpi.com/2073-4352/15/1/80
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author Veronika Anna Szabó
Sándor Kálmán Jakab
András Kovács
Tamara Zsuzsanna Böcz
Gábor Dogossy
author_facet Veronika Anna Szabó
Sándor Kálmán Jakab
András Kovács
Tamara Zsuzsanna Böcz
Gábor Dogossy
author_sort Veronika Anna Szabó
collection DOAJ
description The foamed structure of recycled polyethylene-terephthalate (rPET) is a promising solution for industrial applications; however, the remedy for its inherent melt-dripping property is still a challenging topic. In our research, we were able to improve the flame retardancy of the endothermic–exothermic hybrid rPET foam by adding a different mixture of flame retardants to the formula. Three different kinds of halogen-free flame retardant agents were used: ammonium polyphosphate-based Exolit AP 422 (AP), organic aluminum phosphate in the form of Exolit OP 1240 (OP), and Budit 342 containing melamine polyphosphate (MPP). The hybrid flame retardant mixture, by combining the swelling and charring mechanism, increased the flame retardancy of the samples. The sample made with 15 phr OP and 5 phr MPP displayed outstanding performance, where five samples were capable of self-extinguishing in 5 s, while only slightly decreasing the tensile and flexural strength properties and simultaneously increasing the Young and flexural modulus compared to the reference sample. The addition of MPP reduced the porosity in many cases, while preventing cell coalescence. Our results prove that the hybrid flame retardant agent frameworks efficiently increase the flame retardancy of rPET foams, facilitating their application in industrial sectors such as the aerospace, packaging, renewable energy, and automotive industries to realize sustainability goals. The utilization of halogen-free flame retardants is beneficial for better air quality, reducing toxic gas and smoke emissions.
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spelling doaj-art-b9e0f0f21b5a4c0c8c465f4bbc425d252025-01-24T13:28:14ZengMDPI AGCrystals2073-43522025-01-011518010.3390/cryst15010080Use of Hybrid Flame Retardants in Chemically Foamed rPET BlendsVeronika Anna Szabó0Sándor Kálmán Jakab1András Kovács2Tamara Zsuzsanna Böcz3Gábor Dogossy4Department of Materials Science and Engineering, Audi Hungaria Faculty of Vehicle Engineering, Széchenyi István University, Egyetem tér 1, H-9026 Győr, HungaryDepartment of Materials Science and Engineering, Audi Hungaria Faculty of Vehicle Engineering, Széchenyi István University, Egyetem tér 1, H-9026 Győr, HungaryInstitute of Materials Engineering, University of Pannonia, P.O. Box 158, H-8201 Veszprém, HungaryDepartment of Social Studies and Sociology, Apáczai Csere János Faculty of Humanities, Education and Social Sciences, Széchenyi István University, Liszt Ferenc u. 42., H-9022 Győr, HungaryDepartment of Vehicle Manufacturing and Engineering, Audi Hungária Faculty of Vehicle Engineering, Széchenyi István University, Egyetem tér 1, H-9026 Győr, HungaryThe foamed structure of recycled polyethylene-terephthalate (rPET) is a promising solution for industrial applications; however, the remedy for its inherent melt-dripping property is still a challenging topic. In our research, we were able to improve the flame retardancy of the endothermic–exothermic hybrid rPET foam by adding a different mixture of flame retardants to the formula. Three different kinds of halogen-free flame retardant agents were used: ammonium polyphosphate-based Exolit AP 422 (AP), organic aluminum phosphate in the form of Exolit OP 1240 (OP), and Budit 342 containing melamine polyphosphate (MPP). The hybrid flame retardant mixture, by combining the swelling and charring mechanism, increased the flame retardancy of the samples. The sample made with 15 phr OP and 5 phr MPP displayed outstanding performance, where five samples were capable of self-extinguishing in 5 s, while only slightly decreasing the tensile and flexural strength properties and simultaneously increasing the Young and flexural modulus compared to the reference sample. The addition of MPP reduced the porosity in many cases, while preventing cell coalescence. Our results prove that the hybrid flame retardant agent frameworks efficiently increase the flame retardancy of rPET foams, facilitating their application in industrial sectors such as the aerospace, packaging, renewable energy, and automotive industries to realize sustainability goals. The utilization of halogen-free flame retardants is beneficial for better air quality, reducing toxic gas and smoke emissions.https://www.mdpi.com/2073-4352/15/1/80PET bottle recyclinghybrid flame retardancyhalogen-free flame retardancy
spellingShingle Veronika Anna Szabó
Sándor Kálmán Jakab
András Kovács
Tamara Zsuzsanna Böcz
Gábor Dogossy
Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends
Crystals
PET bottle recycling
hybrid flame retardancy
halogen-free flame retardancy
title Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends
title_full Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends
title_fullStr Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends
title_full_unstemmed Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends
title_short Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends
title_sort use of hybrid flame retardants in chemically foamed rpet blends
topic PET bottle recycling
hybrid flame retardancy
halogen-free flame retardancy
url https://www.mdpi.com/2073-4352/15/1/80
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