A Novel Branched Phosphorus-Containing Flame Retardant

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A novel branched phosphorus-containing flame retardant: Synthesis and its application into poly (butylene terephthalate) Lijin Duan, Hongyu Yang, Yongqian Shi, Yanbei Hou, Yulu Zhu, Zhou Gui, and Yuan Hu Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.6b02428 • Publication Date (Web): 05 Sep 2016 Downloaded from http://pubs.acs.org on September 10, 2016

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Industrial & Engineering Chemistry Research

A novel branched phosphorus-containing flame retardant: Synthesis and its application into poly (butylene terephthalate) Lijin Duan a, Hongyu Yang b,Yongqian Shi a, Yanbei Hou a, Yulu Zhu a, Zhou Gui a*, Yuan Hu a*

a

State Key Laboratory of Fire Science, University of Science and Technology of

China, 96 Jinzhai Road, Hefei, Anhui 230026, P. R. China b

College of Materials Science and Engineering, Chongqing University, 174

Shazhengjie, Shapingba, Chongqing 400044, P. R. China

∗

Corresponding Author: Zhou Gui, Tel.: +86-551-63601288; Fax: +86-551-3601669;

E-mail: [email protected]

∗ Corresponding Author: Yuan Hu, Tel/fax: +86-551-3601664; E-mail: [email protected]

1 ACS Paragon Plus Environment


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Abstract A novel branched phosphorus-containing flame retardant, CEPO was successfully synthesized by a simple aqueous reaction of carboxyethyl-phenyl hypophosphorous acid and tris-(hydroxymethyl) phosphine oxide. Combining with ammonium polyphosphate, CEPO was applied into poly (butylene terephthalate) to fabricate the composites. The results indicated that both peak heat release rate and total heat release were reduced significantly. Moreover, the higher weight proportion of CEPO to ammonium polyphosphate, the higher flame retardant efficiency was. And high limiting oxygen index values and UL-94 vertical burning test ratings were realized. Thermogravimetric analysis-Fourier transform infrared spectra detected the existence of PH3, which helps to understand the flame-retardant mechanism in the gas phase. The composites formed much residue during the combustion, which is helpful to retard the heat flow as scanning electronic microscope photos indicate. Keywords: Phosphorus-containing; branched; flame-retardant mechanism; poly (butylene terephthalate)


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1. Introduction Among five kinds of typical engineering plastics, poly (butylene terephthalate) (PBT) is receiving more and more attention due to its good mechanical, chemical, electrical and thermal properties. PBT has been widely applied in electric devices, appliances and automotive industry, etc.1-7 As a promising engineering polymer with excellent properties, the consumption of PBT has been a good trend in recent years.8-12 In addition to the industrial and electric applications, PBT co-polymers have been utilized in the biomedical area.13,14

However, PBT itself has a big problem and faces challenges in applications. It is well known that PBT is quite easily ignited and flammable with heavy dripping, and its peak of heat release rate increases to 1967 kW/m2, which is quite dangerous15 and thus suffers from many restrictions for the growing requirements on fire safety of related materials. To solve this problem, many efforts have been made. Previous work indicated that aluminium diethylphosphinate (DAHPi) was the most-often used filler which served as the main flame retardant and worked with other assistant additives such as Fe2O3, Al2O3, melamine polyphosphate (MPP), melamine cyanurate (MCA) etc.16-20 Also, aluminum hypophosphite (AHPi) has attracted much attention, for example, Yang et al.21 studied the synergistic effect among AHPi, MPP and MCA in PBT matrix, and found that the addition decreased the heat release rate (HRR) obviously and caused a remarkable decrease in combustible gases, and particularly, a 20 wt.% addition was able to achieve high LOI and to reach UL-94 V-0 rating. As a common and industrialized flame retardant, ammonium polyphosphate (APP) has also been investigated extensively. Balabanovich6 reported the addition of APP and OP (2methyl-1, 2-oxaphospholan-5-one 2-oxide) into PBT, and explained why APP can



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facilitate the composition process of the matrix and how they retarded the flame. Considering the weakness of APP, Yang22 prepared the two kinds of microencapsulated APP, and found that the microencapsulation rendered APP much higher flame retardant efficiency. In addition, copolymerization is adopted to endow PBT with flame-retardancy, where 9, 10-dihydro-9-oxa-10-phospha-phenanthrene-10oxide (DOPO) and its derivates are often applied.23-26 However, only DAHPi is effective enough15 in industrial level for PBT. The research on flame-retardancy of PBT is not relatively sufficient compared with that of other polymers.

Recently, hyperbranched polymers have received considerable attention in the field of flame-retardancy, among which hyperbranched polysiloxans27-30 are most-frequently reported and discussed due to their facile preparation and high efficiency, while branched polyphosphate acrylates31-33, as well as polyurethane acrylates34,35, have been widely used in flame-rtardant UV-curable coatings because of their chemical activities and satisfactory effectiveness. In addition, triazine-based hyperbranched polymers36-38, often serving as char agents, attract increasing concerns currently. For instance, Wen et al39,40 have systematically investigated several triazine-based hyperbrabched polymers on the thermal stability and flame-retardancy of polypropylene. Besides, the synergistic effect with other additives on flameretardancy, especially ammonium polyphosphates,41,42 has also been reported and achieved good results.

In this work, a novel branched phosphorus-containing flame retardant was synthesized, as presented in Figure 1. Then as-synthesized flame retardant was combined with APP to prepare PBT composites. Briefly, we created a phosphorus-


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containing system with different oxidation states, where APP contains phosphorus of higher oxidation state, while CEPO lower oxidation state. Such a system, we believe, will bring better results and a similar one has been investigated before.43 The novel flame retardant was characterized. Furthermore, the thermal and combustible properties of the PBT composites were evaluated by thermogravimetric analysis (TGA) and cone calorimetry testing, respectively. The mechanisms for properties improvement were also discussed.

2. Experiments 2.1 Raw Materials Poly (butylene terephthalate) (PBT1100-211M, 27 g/10min) was obtained from Jiangsu Changchun Chemicals (Jiangsu, China); high molecular weight (n>1000) ammonium polyphosphate (APP) was provided by Shandong Shian Chemicals (Shandong, China); carboxyethyl-phenyl hypophosphorous acid (CEPPA) was purchased from XQ Flame Retardant Science and Technology (Shandong, China); tris-(hydroxymethyl) phosphine oxide (THPO) was supplied by Hubei Harmonious Technology Co., Ltd (Hubei, China). 2.2 Synthesis of novel branched phosphorus-containing flame retardant The novel flame retardant (CEPO) was synthesized by the esterification of CEPPA and THPO, with a set value 3/2 in mole ratio to keep their functional groups equal, in the aqueous solution at 180 °C with N2 flux and under a strong stirring for at least 8 h. After that, the flask was vacuumized for another 2 h to remove the water left. The product was poured out and cooled down, and CEPO was finally obtained and used without further purification. The chemical structure and synthetic process of CEPO are depicted in Figure 1. 2.3 Preparation of PBT composites



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PBT and APP were dried in the air-circulated oven under 100 °C for 1 h before using. All samples were compounded by a two-rotor mixer at a speed of 80 rpm and under a temperature range of 230-240 °C for 10 min, and then molded into a regular shape and size (100 × 100 × 3 mm3) by a hot-pressing for further use. The formulas of the PBT composites were listed in Table 1. 2.4 Characterization Fourier transform infrared (FTIR) spectrum of the sample was obtained by a Nicolet 6700 spectrometer (4 cm-1, Nicolet Instrument Company, USA) with at least 16 scans.

1

H nuclear magnetic resonance (1H NMR) measurement was performed by an

AVANCE 400 Bruker spectrometer, with dimethyl sulfoxide-d6 or D2O as the solvent.

Limiting oxygen index (LOI) test was carried out by an HC-2 oxygen index meter (Jiangning Analysis Instrument Company, China) according to ASTM D2863. The sample size is 100 * 6 *3 mm3.

The vertical combustion test was carried out by a CFZ-2-type instrument (Jiangning Analysis Instrument Company, China) according to UL-94 test ASTM D3801-2010. The specimens used were 127 × 12.7 × 3 mm3.

Cone calorimetry testing was accomplished by a JCZ-2 type instrument (Jiangning Analysis Instrument Company, China) under 35 kW/m2 using 100 × 100 × 3 mm3 specimens, according to ISO 5660-1.


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TGA was performed using a Q5000 IR thermal analyzer under N2 (air) atmosphere with the flow of 50 mL/min. About 5-10 mg specimens were heated from room temperature to 800 °C at a linear rate of 20 °C/min.

The TG-IR coupling is the combination of a Q5000 IR thermal analyzer and a Nicolet 6700 spectrometer, which have been used in the TGA and IR tests respectively. The specimen was heated under N2 atmosphere (50 mL/min), form room temperature to 800 °C at a linear heating rate of 20 °C/min.

Scanning electric microscope (SEM,) photos were obtained by a cold field emission electron microscope (JSM-6700F, resolution: 1.0 nm (15 kV)) under different magnifications.

3. Results and discussion 3.1 Structure and thermal property characterization of CEPO It can be observed from Figure 2 that all IR characteristic peaks have appeared. At 3403 and 3060 cm-1 are assigned to –OH from THPO and C-H stretching vibration in aromatic structure44 from CEPPA, respectively. Peaks at 2925 and 1436 cm-1 correspond to–CH2–. The peak located at 1749 cm-1 appears, associated with C=O from O=C-O-R, which is a direct evidence of esterification. The peak at 1234 cm-1 belongs to C-O-R of O=C-O-R, further confirming the existence of the esterification. The characteristic peak of P=O45 is found at 1048 cm-1and the peak at 1159 cm-1 indicates the existence of P-O-C. As can be seen from Figure 3, combined with characteristic peaks of CEPPA and THPO, the strongest signal of CEPO belongs to the solvent DMSO-d6 (2.5 ppm), with the characteristic peak of the reference compound tetramethylsilane (TMS) located at 0 ppm.

The signals at 7.73 and 7.75



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ppm are attributed to benzene ring. And the signals at ca. 3.92 and 4.42 ppm are assigned to O=P–CH2-O-P=O and O=P–CH2-O-C=O, respectively, evolved from different esterification routes. -CH2-CH2- structure from CEPPA section gives the signals at 2.04 and 2.46 ppm. Therefore, the analysis above indicates that the CEPO was successfully synthesized. The thermal property of CEPO was investigated by TGA both under N2 and air atmosphere (Figure 4). It can be seen that there is little change for the decomposition process of CEPO under different atmospheres. It has almost no change before the temperature reaches 250 °C.

However, the thermal decomposition begins and

accelerates when the temperature surpasses 250 °C, and maximum weight loss rate occurs especially in the range of 300-350 °C. A very small amount of residue (approximately 3 wt%) is left at the temperature of 700 °C. The thermal stability of CEPO is suitable for processing of PBT under the experimental condition (230240 °C) and appropriate for flame-retardancy because it can work before the matrix decomposes (degradation temperature of PBT: 350 °C). 3.2 Thermal Stability of PBT composites As shown in Figure 5, PBT has a high thermal stability and the primary thermal degradation occurs in 350~400 °C, while the flame-retardant composites exhibit lower thermal stability. The composites decompose slowly in the range of ca. 250– 350 °C, which can be explained by the release of NH3 from APP.26,46 In the range of 350–380 °C, the composites decompose sharply as PBT performs and almost have no further change under higher temperatures. Actually, APP itself has a relatively high thermal decomposition temperature (ca. 280 °C),47,48 and the release of even a small amount of NH3 is noticeable enough for polyesters. 4 wt% residue is obtained for PBT, which is similar with the reported work.15,49,50 For the composites, however, much


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more residues remain and increase with increasing proportion of APP, which indicates that APP retards the flame mainly in the condensed phase, and on the other hand CEPO works principally in the gas phase. 3.3 Flammability of PBT composites Data from the LOI and UL-94 tests are recorded in Table 2. The composites added with 30 wt% fillers achieve the highest LOI and reach UL-94 V-0 rating. When the addition decreases to 25 wt%, the LOI is still no less than 32%, and a V-1 or even V-0 rating can be obtained. When the content of flame retardants is further decreased to 20 wt%, the melt dripping behavior appears (except of PBT-10%CEPO-10%APP), and the value of LOI decreases below 30% (PBT-15%CEPO-5%APP) for the first time. It is noted that only when the weight ratio of CEPO to APP is 50/50, the composite can achieve UL-94 V-1 rating. Moreover, the equal proportion between the two flame retardants also obtains the best flame retardancy. As given in Table 3, PBT has a high PHRR of ca. 1200 kW/m2 and the THR is 53.1 MJ/m2. With addition of flame retardants, both PHRR and THR decrease greatly, indicating that the flame retardants are efficient in retarding combustion. The higher proportion of CEPO would cause lower values of PHRR under the same content, which is also demonstrated in Figure 6. As expected and proved preliminarily, the cone calorimetry testing results further confirm that CEPO would be more prone to work in gas phase. It’s noticeable that the composites have similar HRR-Time curves at the equal loading of flame retardants: the 30 wt%-added composites have two separated peaks, where the first one is originated from the high addition of APP, and the second peak should be explained as the destruction of carbon layers formed by the influence of APP. In the case of the composites containing 20 wt% flame retardants, HRR is indeed higher, and the second peak disappears, because a small amount of APP is not enough to form the



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covered layers. It’s easy to understand that the time to ignition is greatly prolonged due to the release of NH3 from APP and some phosphorus-containing derivates from CEPO upon irradiation, as the NH3 can’t support combustion and will dilute the oxygen, at the same time phosphorus-containing derivates can act as the free radical scavengers.51 Digital photos of the residue are presented in Figure 7, and the

corresponding results are well accordant with the results obtained from Figure 6. It can be concluded that combination of APP and CEPO is beneficial to the improvement in flame retardancy. A further investigation on the char residue is in the “Flame-retardant mechanisms.” 3.4 Flame-retardant mechanisms TG-IR curves are presented in Figure 8, absorption peaks of the pyrolysis products of PBT have no apparent change in the temperatures range of 250–390 °C, with carbon dioxide at 2348 cm-1, esters at 1738 cm-1 and hydrocarbon structures at 1478 cm-1. For the flame-retarded composite, however, the peak at ca. 3072 cm-1 attributed to carboxyls is much more stronger while the peak of CO2 is quite weak compared with those of PBT. And the peaks becomes more complicated that all the characteristic peaks belonging to esters, hydrocarbons or benzene structures, have left their traces among the wavenumber below 1750 cm-1. The flame-retardant composite has a new peak located at 2320 cm-1, which is contributed to PH3 evolved from the flame retardants. The results indicate that the flame-retardant composite becomes harder to burn completely. Further, it also helps to understand the flame-retardant mechanism in the gas phase, since PH3 can act as a radical scavenger and easily to get oxidized to capture radicals.51 Figure 9 depicts the digital photos of char residues of flameretardant composites. It can be found that under same addition content, relatively high content of CEPO would help form more compact residue. It is very clear that PBT-


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10%CEPO-20%APP and PBT-15%CEPO-15%APP form porous structure which can be

caused by the release of NH3 and strong degradation, while residue of PBT-20%CEPO10%APP is compact and non-porous. It is indicated that the former would be less

efficient in retarding flame and heat while the latter would be more effective. The result is quite in consistence with that from the cone calorimetry testing.

4. Conclusions A novel branched phosphorus-containing flame retardant (CEPO) was synthesized by a simple aqueous reaction and well defined by IR spectroscopy and 1H NMR tests. CEPO was combined with APP to fabricate PBT composites. Under a 30 wt% addition with different ratios, the composites achieved a UL-94 V-0 rating and their LOI was no less than 34%. The addition of flame retardants reduced the PHRR and THR significantly, and a higher proportion of CEPO resulted in a higher flameretardant efficiency. The existence of PH3 was testified by TG-IR, which helps to understand the gas phase mechanism. An appropriate weight ratio of CEPO to APP (2:1) will lead to formation of a compact non-porous char residue, which has an obvious effect in hindering heat flow.

Acknowledgement The work was financially supported by the National Natural Science Foundation of China (No. 51036007), the National Basic Research Program of China (973 Program) (2012CB719701) and China Postdoctoral Science Foundation (2012M521246).

References (1)

Zhang, S. D.; Tan, L. C.; Liang, J. Z.; Huang, H. X.; Jiang, G. Relationship

between structure and properties of reprocessed glass fiber reinforced flame retardant poly(butylene terephthalate). Polym. Degrad. Stabil. 2014, 105, 140-149. 11 ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(2)

Fung, C. P. Fibre orientation of fibre-reinforced PBT composites in injection

moulding. Plast. Rubber. Compos. 2004, 33, 170-176. (3)

Shen, H. B.; Nutt, S.; Hull, D. Direct observation and measurement of fiber

architecture in short fiber-polymer composite foam through micro-CT imaging. Compos. Sci. Technol. 2004, 64, 2113-2120. (4)

Chisholm, B. J.; Fong, P. M.; Zimmer, J. G.; Hendrix, R. Properties of class-

filled thermoplastic polyesters. J. Appl. Polym. Sci. 1999, 74, 889-899. (5)

Levchik, S. V.; Bright, D. A.; Alessio, G. R.; Dashevsky, S. Synergistic action

between aryl phosphates and phenolic resin in PBT. Polym. Degrad. Stabil. 2002, 77, 267-272. (6)

Balabanovich, A. I.; Balabanovich, A. M.; Engelmann, J. Intumescence in

poly(butylene terephthalate): the effect of 2-methyl-1,2-oxaphospholan-5-one 2-oxide and ammonium polyphosphate. Polym. Int. 2003, 52, 1309-1314. (7)

Gao, F.; Tong, L. F.; Fang, Z. P. Effect of a novel phosphorous-nitrogen

containing intumescent flame retardant on the fire retardancy and the thermal behaviour of poly(butylene terephthalate). Polym. Degrad. Stabil. 2006, 91, 12951299. (8)

Polybutylene terephthalate (PBT). Kunststoffe International 2007, 97, 86-8.

(9)

Bienmuller, M.; Wanders, M. Polybutylene terephthalate (PBT). Kunststoffe

International 2008, 98, 101-5. (10)

Eibeck, P.; Anderlik, R. Polybutylene Terephthalate (PBT). Kunststoffe

International 2010, 100, 104-6. (11)

Bienmuller, M.; Wanders, M. Polybutylene Terephthalate (PBT). Kunststoffe

International 2011, 101, 48-51.


Page 12 of 28

Page 13 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(12)

Bernnat, A.; Eibeck, P.; Dirlenbach, J. Polybutylene Terephthalate (PBT).

Kunststoffe International 2013, 103, 67-70. (13)

Moroni, L.; Licht, R.; de Boer, J.; de Wijn, J. R.; van Blitterswijk, C. A. Fiber

diameter and texture of electrospun PEOT/PBT scaffolds influence human mesenchymal stem cell proliferation and morphology, and the release of incorporated compounds. Biomaterials 2006, 27, 4911-4922. (14)

Malda, J.; Woodfield, T. B. F.; van der Vloodt, F.; Kooy, F. K.; Martens, D. E.;

Tramper, J.; van Blitterswijk, C. A.; Riesle, J. The effect of PEGT/PBT scaffold architecture on oxygen gradients in tissue engineered cartilaginous constructs. Biomaterials 2004, 25, 5773-5780. (15)

Brehme, S.; Schartel, B.; Goebbels, J.; Fischer, O.; Pospiech, D.; Bykov, Y.;

Doring, M. Phosphorus polyester versus aluminium phosphinate in poly(butylene terephthalate) (PBT): Flame retardancy performance and mechanisms. Polym. Degrad. Stabil. 2011, 96, 875-884. (16)

Gallo, E.; Braun, U.; Schartel, B.; Russo, P.; Acierno, D. Halogen-free flame

retarded poly(butylene terephthalate) (PBT) using metal oxides/PBT nanocomposites in combination with aluminium phosphinate. Polym. Degrad. Stabil. 2009, 94, 12451253. (17)

Han, X.; Zhao, J. Q.; Liu, S. M.; Yuan, Y. C. Flame retardancy mechanism of

poly(butylene terephthalate)/aluminum diethylphosphinate composites with an epoxyfunctional polysiloxane. RSC Adv. 2014, 4, 16551-16560. (18)

Gallo, E.; Schartel, B.; Braun, U.; Russo, P.; Acierno, D. Fire retardant

synergisms between nanometric Fe2O3 and aluminum phosphinate in poly(butylene terephthalate). Polym. Advan. Technol. 2011, 22, 2382-2391.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(19)

Braun, U.; Schartel, B. Flame retardancy mechanisms of aluminium

phosphinate in combination with melamine cyanurate in glass-fibre-reinforced poly(1,4-butylene terephthalate). Macromol. Mater. Eng. 2008, 293, 206-217. (20)

Bakirtzis, D.; Ramani, A.; Delichatsios, M. A.; Zhang, J. Structure of the

condensed phase and char of fire-retarded PBT nanocomposites by TGA/ATR in N-2. Fire Safety J. 2009, 44, 1023-1029. (21)

Yang, W.; Song, L.; Hu, Y.; Lu, H. D.; Yuen, R. K. K. Investigations of

Thermal Degradation Behavior and Fire Performance of Halogen-Free Flame Retardant Poly(1,4-butylene terephthalate) Composites. J. Appl. Polym. Sci. 2011, 122, 1480-1488. (22)

Yang, W.; Lu, H. D.; Tai, Q. L.; Qiao, Z. H.; Hu, Y.; Song, L.; Yuen, R. K. K.

Flame retardancy mechanisms of poly(1,4-butylene terephthalate) containing microencapsulated ammonium polyphosphate and melamine cyanurate. Polym. Advan. Technol. 2011, 22, 2136-2144. (23)

Sablong, R.; Duchateau, R.; Koning, C. E.; Pospiech, D.; Korwitz, A.;

Komber, H.; Starke, S.; Haussler, L.; Jehnichen, D.; Landwehr, M. A. D. Incorporation of a flame retardancy enhancing phosphorus-containing diol into poly(butylene terephthalate) via solid state polycondensation: A comparative study. Polym. Degrad. Stabil. 2011, 96, 334-341. (24)

Brehme, S.; Köppl, T.; Schartel, B.; Fischer, O.; Altstädt, V.; Pospiech, D.;

Döring, M. Phosphorus Polyester - an Alternative to Low-Molecular-Weight Flame Retardants in Poly(Butylene Terephthalate)? Macromol. Chem. Physic. 2012, 213, 2386-2397. (25)

Koppl, T.; Brehme, S.; Pospiech, D.; Fischer, O.; Wolff-Fabris, F.; Altstaedt,

V.; Schartel, B.; Doring, M. Influence of polymeric flame retardants based on


Page 14 of 28

Page 15 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


phosphorus-containing polyesters on morphology and material characteristics of poly(butylene terephthalate). J. Appl. Polym. Sci. 2013, 128, 3315-3324. (26)

Fischer, O.; Pospiech, D.; Korwitz, A.; Sahre, K.; Haussler, L.; Friedel, P.;

Fischer, D.; Harnisch, C.; Bykov, Y.; Doring, M. Synthesis and properties of phosphorus polyesters with systematically altered phosphorus environment. Polym. Degrad. Stabil. 2011, 96, 2198-2208. (27)

Zhuo, D. X.; Gu, A. J.; Liang, G. Z.; Hu, J. T.; Yuan, L.; Chen, X. X. Flame

retardancy materials based on a novel fully end-capped hyperbranched polysiloxane and bismaleimide/diallylbisphenol A resin with simultaneously improved integrated performance. J. Mater. Chem. 2011, 21, 6584-6594. (28)

Zhuo, D. X.; Gu, A. J.; Liang, G. Z.; Hu, J. T.; Cao, L.; Yuan, L. Flame

retardancy and flame retarding mechanism of high performance hyperbranched polysiloxane modified bismaleimide/cyanate ester resin. Polym. Degrad. Stabil. 2011, 96, 505-514. (29)

Ye, J. H.; Liang, G. Z.; Gu, A. J.; Zhang, Z. Y.; Han, J. P.; Yuan, L. Novel

phosphorus-containing hyperbranched polysiloxane and its high performance flame retardant cyanate ester resins. Polym. Degrad. Stabil. 2013, 98, 597-608. (30)

Jia, P.; Liu, H. C.; Wang, Y. C.; Cai, X. F. A novel epoxy-functionalized

hyperbranched polysiloxane (HPSi) endowing methyl phenyl silicone resin (Si603)/epoxy systems with enhanced compatibility and fire retardancy performance. Rsc Adv. 2015, 5, 97413-97421. (31)

Wang, X. F.; Zhan, J.; Xing, W. Y.; Wang, X.; Song, L.; Qian, X. D.; Yu, B.;

Hu, Y. Flame Retardancy and Thermal Properties of Novel UV-Curable Epoxy Acrylate Coatings Modified by a Silicon-Bearing Hyperbranched Polyphosphonate Acrylate. Ind. Eng. Chem. Res. 2013, 52, 5548-5555.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(32)

Wang, H. L.; Xu, S. P.; Shi, W. F. Photopolymerization behaviors of

hyperbranched polyphosphonate acrylate and properties of the UV cured film. Prog. Org. Coat. 2009, 65, 417-424. (33)

Huang, Z. G.; Shi, W. F. UV curing behavior of hyperbranched polyphosphate

acrylate/di(hydroxylpropyl methacrylate) piperazine and properties of the cured film. Prog. Org. Coat. 2007, 59, 312-317. (34)

Zhu, S. W.; Shi, W. F. Flame retardant mechanism of hyperbranched

polyurethane acrylates used for UV curable flame retardant coatings. Polym. Degrad. Stabil. 2002, 75, 543-547. (35)

Zhu, S. W.; Shi, W. F. Synthesis and photopolymerization of hyperbranched

polyurethane acrylates applied to UV curable flame retardant coatings. Polym. Int. 2002, 51, 223-227. (36)

Mahapatra, S. S.; Karak, N. Hyperbranched aromatic Polyamines with s-

triazine rings. J. Appl. Polym. Sci. 2007, 106, 95-102. (37)

Mahapatra, S. S.; Karak, N. s-Triazine containing flame retardant

hyperbranched polyamines: Synthesis, characterization and properties evaluation. Polym. Degrad. Stabil. 2007, 92, 947-955. (38)

Borah, J.; Karak, N. Blends of triazine-based hyperbranched polyether with

LDPE and plasticized PVC. J. Appl. Polym. Sci. 2007, 104, 648-654. (39)

Wen, P. Y.; Wang, X. F.; Xing, W. Y.; Peng, X. M.; Yu, B.; Shi, Y. Q.; Tang,

G.; Song, L.; Hu, Y.; Yuen, R. K. K. Synthesis of a Novel Triazine-Based Hyperbranched Char Foaming Agent and the Study of Its Enhancement on Flame Retardancy and Thermal Stability of Polypropylene. Ind. Eng. Chem. Res. 2013, 52, 17015-17022.


Page 16 of 28

Page 17 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(40)

Wen, P. Y.; Wang, X. F.; Wang, B. B.; Yuan, B. H.; Zhou, K. Q.; Song, L.;

Hu, Y. A.; Yuen, R. K. K. One-pot synthesis of a novel s-triazine-based hyperbranched charring foaming agent and its enhancement on flame retardancy and water resistance of polypropylene. Polym. Degrad. Stabil. 2014, 110, 165-174. (41)

Ke, C. H.; Li, J.; Fang, K. Y.; Zhu, Q. L.; Zhu, J.; Yan, Q.; Wang, Y. Z.

Synergistic effect between a novel hyperbranched charring agent and ammonium polyphosphate on the flame retardant and anti-dripping properties of polylactide. Polym. Degrad. Stabil. 2010, 95, 763-770. (42)

Li, J.; Ke, C. H.; Xu, L.; Wang, Y. Z. Synergistic effect between a

hyperbranched charring agent and ammonium polyphosphate on the intumescent flame retardance of acrylonitrile-butadiene-styrene polymer. Polym. Degrad. Stabil. 2012, 97, 1107-1113. (43)

Yang, H. Y.; Song, L.; Tai, Q. L.; Wang, X.; Yu, B.; Yuan, Y.; Hu, Y.; Yuen,

R. K. K. Comparative study on the flame retarded efficiency of melamine phosphate, melamine phosphite and melamine hypophosphite on poly(butylene succinate) composites. Polym. Degrad. Stabil. 2014, 105, 248-256. (44)

Yang, H.; Song, L.; Tai, Q.; Wang, X.; Yu, B.; Yuan, Y.; Hu, Y.; Yuen, R. K.

K. Comparative study on the flame retarded efficiency of melamine phosphate, melamine phosphite and melamine hypophosphite on poly(butylene succinate) composites. Polym. Degrad. Stabil. 2014, 105, 248-256. (45)

Yang, H. Y.; Wang, X.; Yuan, H. X.; Song, L.; Hu, Y.; Yuen, R. K. K. Fire

performance and mechanical properties of phenolic foams modified by phosphoruscontaining polyethers. J. Polym. Res. 2012, 19.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(46)

Page 18 of 28

Wang, L. S.; Kang, H. B.; Wang, S. B.; Liu, Y.; Wang, R. Solubilities,

thermostabilities and flame retardance behaviour of phosphorus-containing flame retardants and copolymers. Fluid Phase Equilibr. 2007, 258, 99-107. (47)

Balabanovich, A. I. The effect of ammonium polyphosphate on the

combustion and thermal decomposition behavior of poly(butylene terephthalate). J. Fire Sci. 2003, 21, 285-298. (48)

Qin, Z. L.; Li, D. H.; Li, Q.; Yang, R. J. Effect of nano-aluminum hydroxide

on mechanical properties, flame retardancy and combustion behavior of intumescent flame retarded polypropylene. Mater. Design. 2016, 89, 988-995. (49)

Yan, H. W.; Wei, J. L.; Yin, B.; Yang, M. B. Effect of the surface

modification of ammonium polyphosphate on the structure and property of melamineformaldehyde resin microencapsulated ammonium polyphosphate and polypropylene flame retardant composites. Polym. Bull. 2015, 72, 2725-2737. (50)

Qu, H.; Liu, X.; Xu, J.; Ma, H.; Jiao, Y.; Xie, J. Investigation on Thermal

Degradation

of

Poly(1,4-butylene

terephthalate)

Filled

with

Aluminum

Hypophosphite and Trimer by Thermogravimetric Analysis-Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis-Mass Spectrometry. Ind. Eng. Chem. Res. 2014, 53, 8476-8483. (51)

Yang, W.; Hu, Y.; Tai, Q. L.; Lu, H. D.; Song, L.; Yuen, R. K. K. Fire and

mechanical performance of nanoclay reinforced glass-fiber/PBT composites containing aluminum hypophosphite particles. Compos. Part a-Appl. S. 2011, 42, 794-800.


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Table Captions Table 1 Formulas of samples. Table 2 Data from the LOI and UL-94 tests. Table 3 Detailed data from the cone calorimetry testing.

Figure Captions Figure 1 Synthesis of CEPO. Figure 2 IR spectrum of CEPO. Figure 3 Chemical structures and corresponding 1H NMR spectra: (Ⅰ) CEPPA and its 1H NMR signals (a~e) with DMSO-d6 and TMS as the solvent and reference substance respectively, (Ⅱ) THPO and its 1H NMR signals (a,b) and (Ⅲ) CEPO and its 1H NMR signals (a~e) with DMSO-d6 as the solvent. Figure 4 TG and DTG curves of CEPO under N2 and air atmosphere. Figure 5 TGA curves of PBT composites. Figure 6 Cone calorimetry testing results of PBT and its composites. Figure 7 Digital photos of PBT (a, a-1) and its composites with different proportion addition of CEPO to APP (b, b-1 = 1:2; c, c-1 = 1:1; d, d-1 = 2:1) under 30 wt% after cone calorimetry testing. Figure 8 TG-IR curves at different temperatures of a) PBT and b) its composite with 30 wt% addition (CEPO: APP=2:1). Figure 9 SEM photos of PBT composites with different ratios of CEPO to APP after cone calorimetry testing (30 wt%).



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Tables Table 1 Number

PBT (wt%)

CEPO (wt%)

APP (wt%)

PBT

100

0

0

PBT-15%CEPO-15%APP

70

15

15

PBT-10%CEPO-20%APP

70

10

20

PBT-20%CEPO-10%APP

70

20

10

PBT-10%CEPO-15%APP

75

10

15

PBT-15%CEPO-10%APP

75

15

10

PBT-5%CEPO-15%APP

80

5

15

PBT-15%CEPO-5%APP

80

15

5

PBT-10%CEPO-10%APP

80

10

10

PBT-14%CEPO-7%APP

80

14

7


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Table 2

Number

UL-94

LOI (%)

t1/t2b(s/s)

Dripping a

PBT-10%CEPO-20%APP

34

1.05/1.10

N

V-0

PBT-15%CEPO-15%APP

36

0.88/1.14

N

V-0

PBT-20%CEPO-10%APP

34.5

0.95/2.23

N

V-0

PBT-10%CEPO-15%APP

32.5

0.94/1.09

N

V-0

PBT-15%CEPO-10%APP

32

10.00/7.00

N

V-1

PBT-5%CEPO-15%APP

30.5

12.00/3.00

Y

V-2

PBT-15%CEPO-5%APP

26.5

15.00/2.00

Y

V-2

PBT-10%CEPO-10%APP

31

10.00/5.00

N

V-1

Classification

a) Y means Yes; N means No. b) t1/t2 represents the burning time after the first and second 10 s flame

application respectively.



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Table 3 TTI/s

PHRR/(kW*m-2)

THR/(MJ*m-2)

TSR(m2/m2)

18

1173

53.1

-

PBT-15%CEPO-15%APP

-

179

39.8

147.9

PBT-20%CEPO-10%APP

41

157

32.3

90.3

PBT-10%CEPO-20%APP

58

187

31.6

96.6

PBT-10%CEPO-10%APP

33

311

31.7

51.7

PBT-14%CEPO-7%APP

32

254

29.5

-

Number PBT


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Figures

Figure 1



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Figure 2

Figure 3


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Figure 4

Figure 5



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Figure 6

Figure 7


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Figure 8

Figure 9



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For Table of Contents Only


Page 28 of 28

A Novel Branched Phosphorus-Containing Flame Retardant

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