Abstract
Aiming at achieving polyamide 6 with enhanced flame retardancy and maintained mechanical properties, halloysite nanotubes (HNT) and bisphenol-A bis(diphenyl phosphate) (BDP) flame retardant were introduced to prepare PA6/HNT/BDP flame retardant nanocomposites. Efficient loading of BDP inside the HNT lumen was demonstrated. Qualitative and quantitative characterization of BDP-loaded HNT revealed that BDP was mainly encapsulated inside the central lumen of halloysite and also located in the small pores on the outer surface of HNT. The use of only BDP (up to 4 wt%) or HNT (up to 10 wt%) cannot improve the UL-94 of the PA6 to reach V-0 classification. By combining use of HNT and BDP, the nanocomposites achieved V-0 rating with significant suppression in peak heat release rate and total heat release from cone calorimeter. The negative effect of BDP on strength and rigidity of PA6 composites was obviously minimized by encapsulating some portions of BDP in the nanotube. As a result, the tensile strength and thermal stability of the PA6 retained without loss of stiffness. During burning process, the BDP in the bulk polymer performed its function in the early period of the process, whereas the BDP inside the nanotube possessed a prolonged release for flame retardation at the later stage of combustion.
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References
Zong R, Hu Y, Liu N, Li S, Liao G (2007) Investigation of thermal degradation and flammability of polyamide-6 and polyamide-6 nanocomposites. J Appl Polym Sci 104:2297–2303
Levchik GF, Levchik SV, Lesnikovich AI (1996) Mechanisms of action in flame retardant reinforced nylon 6. Polym Degrad Stab 54:361–363
Marney DCO, Russell LJ, Wu DY, Nguyen T, Cramm D, Rigopoulos N et al (2008) The suitability of halloysite nanotubes as a fire retardant for nylon 6. Polym Degrad Stab 93:1971–1978
Li Q, Li B, Zhang S, Lin M (2012) Investigation on effects of aluminum and magnesium hypophosphites on flame retardancy and thermal degradation of polyamide 6. J Appl Polym Sci 125:1782–1789
Chen J, Lui S, Jiang Z, Zhao J (2012) Flame retardancy, smoke suppression effect and mechanism of aryl phosphates in combination with magnesium hydroxide in polyamide 6. J Wuhan Univ Technol Mater Sci Ed 27:916–923
Morgan AB, Wilkie CA (2014) The non-halogenated flame retardant handbook. Wiley, New York
Fu Y, Zhao D, Yao P, Wang W, Zhang L, Lvov Y (2015) Highly aging-resistant elastomers doped with antioxidant-loaded clay nanotubes. ACS Appl Mater Interfaces 7:8156–8165
Zhong B, Lin J, Liu M, Jia Z, Luo Y, Jia D et al (2017) Preparation of halloysite nanotubes loaded antioxidant and its antioxidative behaviour in natural rubber. Polym Degrad Stab 141:19–25
Massaro M, Riela S, Guernelli S, Parisi F, Lazzara G, Baschieri A et al (2016) A synergic nanoantioxidant based on covalently modified halloysite–trolox nanotubes with intra-lumen loaded quercetin. J Mater Chem B 4:2229–2241
Falcón JM, Sawczen T, Aoki IV (2015) Dodecylamine-loaded halloysite nanocontainers for active anticorrosion coatings. Front Mater. https://doi.org/10.3389/fmats.2015.00069
Fakhrullin RF, Tursunbayeva A, Portnov VS, Lvov YM (2014) Ceramic nanotubes for polymer composites with stable anticorrosion properties. Crystallogr Rep 59:1107–1113
Tohidi S, Ghaee A, Barzin J (2016) Preparation and characterization of poly(lactic-co-glycolic acid)/chitosan electrospun membrane containing amoxicillin-loaded halloysite nanoclay. Polym Adv Technol 27:1020–1028
Kurczewska J, Pecyna P, Ratajczak M, Gajęcka M, Schroeder G (2017) Halloysite nanotubes as carriers of vancomycin in alginate-based wound dressing. Saudi Pharm J 25:911–920
Biddeci G, Cavallaro G, Di FB, Lazzara G, Massaro M, Milioto S et al (2016) Halloysite nanotubes loaded with peppermint essential oil as filler for functional biopolymer film. Carbohydr Polym 52:548–557
Rizzo C, Arrigo R, D’Anna F, Blasi FD, Dintcheva NT, Lazzara G et al (2017) Hybrid supramolecular gels of Fmoc-F/halloysite nanotubes: systems for sustained release of camptothecin. J Mater Chem B 5:3217–3229
Massaro M, Riela S, Cavallaro G, Colletti CG, Milioto S, Noto R et al (2016) Ecocompatible halloysite/cucurbit[8]uril hybrid as efficient nanosponge for pollutants removal. ChemistrySelect 1:1773–1779
Massaro M, Colletti CG, Lazzara G, Guernelli S, Noto R, Riela S (2017) Synthesis and characterization of halloysite–cyclodextrin nanosponges for enhanced dyes adsorption. ACS Sustain Chem Eng 5:3346–3352
Breen C, D’Mello N, Yarwood J (2002) The thermal stability of mixed phenylphosphonic acid/water intercalates of kaolin and halloysite. A TG–EGA and VT-DRIFTS study. J Mater Chem 12:273–278
Hui Jing YH (2013) Internally modified halloysite nanotubes as inorganic nanocontainers for a flame retardant. Chem Lett 42:121–123
Marney DCO, Yang W, Russell LJ, Shen SZ, Nguyen T, Yuan Q et al (2012) Phosphorus intercalation of halloysite nanotubes for enhanced fire properties of polyamide 6. Polym Adv Technol 23:1564–1571
Joshi AR, Null R, Graham S, Abdullayev E, Mazurenko V, Lvov Y (2016) Enhanced flame retardancy of latex coating doped with clay nanotubes. J Coat Technol Res 13:535–541
Zheng T, Ni X (2016) Loading an organophosphorous flame retardant into halloysite nanotubes for modifying UV-curable epoxy resin. RSC Adv 6:57122–57130
Du M, Guo B, Jia D (2010) Newly emerging applications of halloysite nanotubes: a review. Polym Int 59:574–582
Isitman NA, Dogan M, Bayramli E, Kaynak C (2012) The role of nanoparticle geometry in flame retardancy of polylactide nanocomposites containing aluminium phosphinate. Polym Degrad Stab 97:1285–1296
Sun J, Gu X, Coquelle M, Bourbigot S, Duquesne S, Casetta M et al (2014) Effects of melamine polyphosphate and halloysite nanotubes on the flammability and thermal behavior of polyamide 6. Polym Adv Technol 25:1552–1559
Boonkongkaew M, Hornsby P, Sirisinha K (2017) Structural effect of secondary antioxidants on mechanical properties and stabilization efficiency of polyamide 6/halloysite nanotube composites during heat ageing. J Appl Polym Sci. https://doi.org/10.1002/app.45360
Yuan P, Southon PD, Liu Z, Green MER, Hook JM, Antill SJ et al (2008) Functionalization of halloysite clay nanotubes by grafting with γ-aminopropyltriethoxysilane. J Phys Chem C 112:15742–15751
Zhao W, Liu J, Zhang Y, Ban D (2015) Simple green synthesis of solid polymeric bisphenol A bis(diphenyl phosphate) and its flame retardancy in epoxy resins. RSC Adv 5:80415–80423
Yuan P, Tan D, Annabi-Bergaya F (2015) Properties and applications of halloysite nanotubes: recent research advances and future prospects. Appl Clay Sci 112–113:75–93
Rouquerol J, Avnir D, Fairbridge CW, Everett DH, Haynes JM, Pernicone N et al (1994) Recommendations for the characterization of porous solids (Technical Report). Pure Appl Chem 66:1739–1758
Liu M, Guo B, Du M, Cai X, Jia D (2007) Properties of halloysite nanotube–epoxy resin hybrids and the interfacial reactions in the systems. Nanotechnology 18:455703
Balabanovich AI (2004) Poly(butylene terephthalate) fire retarded by bisphenol A bis(diphenyl phosphate). J Anal Appl Pyrolysis 72:229–233
Tan D, Yuan P, Annabi-Bergaya F, Yu H, Liu D, Liu H et al (2013) Natural halloysite nanotubes as mesoporous carriers for the loading of ibuprofen. Microporous Mesoporous Mater 179:89–98
Yuan P, Southon PD, Liu Z, Kepert CJ (2012) Organosilane functionalization of halloysite nanotubes for enhanced loading and controlled release. Nanotechnology 23:375705
Zahidah KA, Kakooei S, Ismail MC, Raja PB (2017) Halloysite nanotubes as nanocontainer for smart coating application: a review. Prog Org Coat 111:175–185
Hu Y, Wang S, Ling Z, Zhuang Y, Chen Z, Fan W (2003) Preparation and combustion properties of flame retardant nylon 6/montmorillonite nanocomposite. Macromol Mater Eng 288:272–276
Laoutid F, Bonnaud L, Alexandre M, Lopez-Cuesta J-M, Dubois P (2009) New prospects in flame retardant polymer materials: from fundamentals to nanocomposites. Mater Sci Eng R Rep 63:100–125
Fina A, Camino G (2011) Ignition mechanisms in polymers and polymer nanocomposites. Polym Adv Technol 22:1147–1155
Lewin M (2011) Flame retarding polymer nanocomposites: synergism, cooperation, antagonism. Polym Degrad Stab 96:256–269
Dasari A, Yu Z-Z, Mai Y-W, Liu S (2007) Flame retardancy of highly filled polyamide 6/clay nanocomposites. Nanotechnology 18:445602
Samyn F, Bourbigot S, Jama C, Bellayer S (2008) Fire retardancy of polymer clay nanocomposites: is there an influence of the nanomorphology? Polym Degrad Stab 93:2019–2024
Acknowledgements
Financial support from the Thailand Research Fund through the Royal Golden Jubilee Ph.D. Program (Grant No. PHD 0145/2554) is gratefully acknowledged. The authors are thankful to the Exeter Advanced Technologies, University of Exeter (UK), and the Rubber Technology Research Centre (RTEC), Mahidol University (Thailand), for technical support. Sincere appreciation is extended to Prof. Peter Hornsby for helpful discussion.
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Boonkongkaew, M., Sirisinha, K. Halloysite nanotubes loaded with liquid organophosphate for enhanced flame retardancy and mechanical properties of polyamide 6. J Mater Sci 53, 10181–10193 (2018). https://doi.org/10.1007/s10853-018-2351-z
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DOI: https://doi.org/10.1007/s10853-018-2351-z