In situ prepared polyamide 6/DOPO-derivative nanocomposite for melt-spinning of flame retardant textile filaments. (August 2019)

• Record Type: Journal Article
• Authors: Vasiljević, Jelena; Čolović, Marija; Jerman, Ivan; Simončič, Barbara; Demšar, Andrej; Samaki, Younes; Šobak, Matic; Šest, Ervin; Golja, Barbara; Leskovšek, Mirjam; Bukošek, Vili; Medved, Jožef; Barbalini, Marco; Malucelli, Giulio; Bolka, Silvester
• Is Part Of: Polymer degradation and stability. Volume 166(2019)
• Page Start: 50
• Page End: 59
• Publication Date: 2019-08
• Subjects: Polyamide 6 -- DOPO derivative -- Flame retardant -- In situ polymerization -- Melt-spinning -- Nanocomposite filament yarns; Polymers -- Deterioration -- Periodicals; Stabilizing agents -- Periodicals; Polymères -- Dégradation -- Périodiques; Stabilisants -- Périodiques; 668.9
• DOI: 10.1016/j.polymdegradstab.2019.05.011
• Languages: English
• ISSNs: 0141-3910

Abstract

Abstract: A novel flame retardant polyamide 6 (PA6)/bridged 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-derivative (PHED) nanocomposite textile filament yarns were developed. The scalable production approach includes in situ water-catalyzed ring-opening polymerization of ε -caprolactam in the presence of the flame retardant PHED followed by melt-spinning of nanocomposite filament yarns and production of knitted fabrics. The specific chemical structure of the PHED additive enabled its excellent miscibility with molten ε-caprolactam and the uninterrupted polymerization of ε -caprolactam. The produced PA6/PHED nanocomposite was characterized by the preserved molecular structure of the polyamide 6 and uniformly distributed nano-dispersed FR at concentrations of 10 and 15 wt %. The PA6/PHED nanocomposite structure was successfully preserved after the melt-spinning processing. The PA6 nanocomposite filament yarns at the applied 15 wt %. loading of PHED showed (a) increased thermo-oxidative stability compared to neat PA6 up to 500 °C, with a 43% higher residue at 500 °C and (b) self-extinguishment of fiber strand and knitted samples within 1 s in standard vertical flame spread tests (ASTM D6413), followed by the significant reduction of the melt-dripping and the melt-drop flammability. Additionally, 1.2 mm-tick PA6/PHED bar samples achieved a V0 rating in UL94 vertical burning test at the applied 10 wt % concentration of PHED. This innovative and scalable approach could pave the way for the production of new-generation nanocomposite PA6 filament yarns with self-extinguishing properties at the macro-scale, which would be highly beneficial for increasing fire safety, whilst maintaining the use of a DOPO derivative at the minimum level. Graphical abstract: A new scalable approach is established to produce the first-ever polyamide 6/DOPO-derivative nanocomposite filament yarns and knitted fabrics with superior flame retardancy and self-extinguishing properties. The in situ approach for the incorporation of the organophosphorus additive of specific chemical structure in the PA6 matrix guarantees its uniform distribution and nanodispersion as well as the successful melt-spinning of textile filaments with highly effective flame retardancy, whilst maintaining the use of a DOPO-derivative at the minimum level. Image 1 Highlights: Flame retardant PA6/PHED nanocomposite was produced by in situ polymerization approach. Textile filament yarns were successfully melt-spun from produced nanocomposites. PHED increased thermo-oxidative stability of PA6 up to 500 °C, with 43% higher residue at 500 °C. Self-extinction within 1 s for PA6/PHED fiber strand and knitted fabric was achieved in vertical flame spread tests (ASTM D6413). UL94 V-0 rating was achieved for 1.2 mm-tick PA6/PHED bar samples with 10 wt % of PHED.