Preparation, Thermal Degradation, and Fire Behaviors of Intumescent

Article pubs.acs.org/IECR

Preparation, Thermal Degradation, and Fire Behaviors of Intumescent Flame Retardant Polypropylene with a Charring Agent Containing Pentaerythritol and Triazine Rong Yang, Binbin Ma, Hui Zhao, and Jinchun Li* School of Materials Science and Engineering and Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu, P. R. China S Supporting Information *

ABSTRACT: A macromolecular charring agent named as PEPADC was synthesized by using cyanuric chloride, 2,6,7trioxa-l-phosphabicyclo[2.2.2]octane-4-methanol (PEPA), and diethylenetriamine and used to prepare intumescent flame retardant polypropylene (IFR-PP) containing ammonium polyphosphate (APP). The effect of flame retardant compound on thermal degradation, flame retardancy, and fire behavior properties of a IFR-PP system has been investigated. The results suggested that the max thermal degradation temperature (Tmax) as well as char residue at 700 °C increased with IFR loading. The highest LOI value of IFRPP is 35.5, while the IFR loading is 30 wt % and the weight ratio of APP to PEPADC is 4:1. Meanwhile, the IFR-PPs can pass UL-94 V-0 when the weight ratio of APP to PEPADC is between 1:2 and 5:1. Cone calorimetry results indicated that IFR-PPs exhibited much lower heat release rate (HRR), total heat release (THR), specific extinction area (SEA), and total smoke production (TSP) than the neat PP. intumescent flame retardant has been investigated.11−14 However, there are some drawbacks of the first generation IFR system, such as a relative high loading, low water resistance, and low thermal stability. To solve these problems, there are two main ways to improve the efficiency of the flame retardant. One is modification of the acid source, such as microencapsulation at the surface,15−17 and incorporating amine compounds into APP.18,19 The other is the synthesis of a more efficient charring agent which may be compounded with APP to obtain a more efficient flame retardant system. In that case, two types of high-efficiency charring agents have been designed and synthesized, including polyol phosphate compounds20,21 and triazine derivatives.22,23 In the 1960s, a novel caged bicyclic phosphate, 2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane-4-methanol (PEPA), was synthesized.24 This compound was used as a charring agent to prepare flame-retardant PP in the 1980s.20 Since then, a series of charring agents based on PEPA, which have high phosphorus content, good thermal stability, and water resistance, have been synthesized.5,25−29 Recently, polymeric charring agents that contain a triazine ring structure have gained extensive attention because of their good thermal stability, excellent charring, and blowing effects in intumescent flame retardants.30−34 Since both PEPA derivatives

1. INTRODUCTION Polypropylene (PP) has been widely used in various industrial fields such as automobile, electrical and electronic, packing, and construction because of its good mechanical properties, low cost, heat resistance, and transparency. Because of a large number of methyl groups, PP itself is easy to ignite with a rather fast fire spread speed, thus it is very important to enhance the flame retardance of PP. Generally, the common and effective way to reduce flammability of polymeric materials is adding flame retardants (FR). For PP, there are three main types of flame retardants, halogen-containing flame retardants, such as decabromodiphenyl ether, inorganic flame retardants, such as aluminum hydroxide, and intumescent flame retardants. During the past two decades, intumescent flame retardants (IFR) have been the focus of attention due to a relatively high flame-retardant efficiency at low loading, antidripping, lowsmoke formation, and low toxicity of releasing gases during burning.1−3 These flame retardants are widely used in polyolefins,4,5 epoxy resins,6,7 and polyurethanes.8,9 Generally speaking, an IFR system is commonly combined with an acid source as a carbonization agent, a charring agent, and a blowing agent. The IFR goes through a series of chemical reactions such as esterification, carbonization, expansion, and solidification to form an intumescent char layer, which can act as a barrier, and to protect the inside material from the heat and slow mass transfer.10 The first generation IFR system was ammonium polyphosphate (acid source)/pentaerythritol (charring agent)/ melamine (blowing agent). The mode of action of an © XXXX American Chemical Society

Received: January 19, 2016 Revised: March 20, 2016 Accepted: April 15, 2016

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DOI: 10.1021/acs.iecr.6b00204 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

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Industrial & Engineering Chemistry Research

(Japan) instrument at a heating rate of 10 °C min−1 from ambient to 700 °C under flowing nitrogen (60 mL min−1). The morphologies of the residues were observed by a Carl Zeiss (SUPRA 55) SEM instrument. UL-94 vertical burning tests were determined with a vertical burning test instrument (CZF2-type) (Jiangning, China) according to ASTM D3801 with sheet dimensions of 130.0 × 13.0 × 3.2 mm3. LOI tests were carried out with a JF-3 oxygen index meter (Jiangning, China) according to the standard of ASTM D 2863-97 with the threedimensional size of 130.0 × 6.5 × 3.2 mm3. The cone calorimetry was carried out by an FTT cone calorimeter, according to the standard of ISO 5660-1. The samples with the three-dimensional size of 100.0 × 100.0 × 3.0 mm3 were irradiated at an external heat flux of 35 kW/m2. Raman spectroscopy measurement was carried out with a DXR laser Raman spectrometer (Thermo scientific) using a 780 nm helium−neon laser line at room temperature.

and triazine derivatives have an excellent charring effect in intumescent flame retardants, the effect of a charring agent containing PEPA and the triazine structure is worthy of investigation. In the work reported here, a novel macromolecule charring agent containing PEPA, triazine rings, and diethylenetriamine groups has been designed and synthesized. The chemical structure and thermal properties of the charring agent were characterized by NMR, FTIR, elemental analysis, ICP-AES, and TGA. The optimum balance between APP and the charring agent, as well as the thermal degradation behavior and fire behavior of IFR-PP systems, was investigated in detail.

2. EXPERIMENTAL SECTION 2.1. Materials. PP was supplied by Sinopec Beijing Yanshan Company Ltd. (T30s, MI = 3.0 g 1 min−1). APP was kindly provided by ShiFang ChangFeng Chemical Co., Ltd. (Sichuan China). PEPA was purchased from Shanghai D&R Fine Chemical Co., Ltd. (Shanghai China). Cyanuric chloride and diethylenetriamine were purchased from Aladdin Industrial Corporation (Shanghai China). 2.2. Preparation of Flame-Retardant PP. APP and the charring agent (PEPADC) (see Scheme 1) were dried at

3. RESULTS AND DISCUSSION 3.1. Thermal Stability Property. Figure 1 shows the TGA and DTG curves of neat PP and IFR-PPs; related data are

Scheme 1. Chemical Structure of PEPADC

reduced pressure and 80 °C for 8 h before blending. Then, flame-retardant PP was prepared, by using an internal mixer (Changzhou Suyan Science and Technology Co., Ltd. China SU-70C) at 190 °C with a rotation speed of 20 r min−1 for 5 min. The detailed formulations of the IFR-PPs are listed in Table 1. 2.3. Characterization. Thermogravimetric analysis data for PP and IFR-PPs were obtained using a NSK TG/DTA6300 Figure 1. TGA (a) and DTG (b) curves of PP and IFR-PPs in nitrogen.

Table 1. Composition of IFR-PPs samples

PP

APP

PEPADC

PP PP1 PP2 PP3 PP4 PP5 PP6 PP7 PP8

100 70 70 70 70 70 70 70 70

0 30 0 10 15 20 22.5 24 25

0 0 30 20 15 10 7.5 6 5

APP:PEPADC

summarized in Table 2. For PP, there is only one single degradation process with the initial thermal degradation (T5 wt %) and maximum loss (Tmax) temperatures at 381.0 °C and 447.0 °C, respectively. Compared to neat PP, IFR-PPs show two- or three-step degradation processes. IFR-PPs have lower T5 wt % because of relatively lower thermal stability of APP and PEPADC (Figure S2). The T5 wt % of IFR-PPs increases with an increase in content of APP. While the additive of APP is higher than PEPADC, the T5 wt % of IFR-PPs are

1:2 1:1 2:1 3:1 4:1 5:1 B


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Industrial & Engineering Chemistry Research Table 2. TG and DTG Data of PP and IFR-PPs under N2 Atmosphere char residues (%) samples PP PP1 PP2 PP3 PP4 PP5 PP6 PP7 PP8

T5 wt % (°C) 381.0 335.7 303.4 327.0 354.7 352.6 350.7 356.7 368.3

Tmax1 (°C) 440.1 461.8 464.7 474.8 473.5 472.0 470.0 471.4 471.4

Tmax2 (°C)

rate of Tmax (wt %/min) 28.9 16.0 19.6 17.6 18.7 23.1 22.3 21.9 22.6

587.4

539.8 546.6 549.4 550.1

nearly the same around 350 °C. In the first step, intumescence flame retardants decompose and form an intumescence char layer. Furthermore, PP of IFR-PPs starts to decompose, while the temperature is higher than 450 °C. However, the Tmax of IFR-PPs is higher than neat PP due to the intumescence char which can act as a barrier between pyrolysis products and heat. While the temperature increases to 500 °C, there are no residues for neat PP. However, the char residues of IFR-PPs are increased first and then keep nearly the same with increasing APP content of flame retardant compounds, and the IFR-PP with the highest APP content reaches char residues at 500 °C of 20.8 wt %. IFR-PPs with higher APP content decompose further, while the temperature is higher than 500 °C. There are two reasons for the decomposition of the IFR-PP at higher temperature. For one thing, there is a major decomposition of APP, while the temperature is higher than 500 °C. For another, the PP that was covered by the intumescence char layer has been decomposed during high temperature for a long time. Figure 2 shows the DTA traces of IFR-PPs during TGA tests. The first endothermic peak at 165 °C belongs to the melting

500 °C

600 °C

700 °C

0 22.5 7.4 11.8 16.4 17.9 19.6 19.4 20.8

0 12.9 5.6 10.2 13.7 11.4 10.5 12.3 11.4

0 6.0 4.7 9.7 11.7 9.2 8.7 10.4 9.6

Table 3. LOI and UL-94 Test Results of PP and IFR-PPs UL-94 (3.2 mm) samples PP PP1 PP2 PP3 PP4 PP5 PP6 PP7 PP8

LOI (%) 18 22 21 28 32 34 34.5 35.5 34

rating

dripping

N.R. N.R. N.R. V-0 V-0 V-0 V-0 V-0 V-0

yes yes yes no no no no no no

the LOI value of PP is 18 due to its aliphatic chain structure. While added individually 30 wt % APP or PEPADC, the LOI values increased and reached 21 and 22 which is still rather low and shows no flame retardancy effect. However, the LOI values of IFR-PPs increased dramatically with compounding APP and PEPADC. It increased first and then decreased with increasing the amount of APP. The highest LOI value reaches 35.5 when the ratio of APP:PEPADC is 4:1. Apparently, PP blended individually with one additive shows no rating in the UL-94 test owing to their low LOI values. However, IFR-PPs can pass the UL-94 V-0 rating when the ratio of APP and PEPDAC is from 1:2 to 5:1. It indicated that there is a synergistic effect between APP and PEPDAC, and the optimal ratio of APP:PEPADC is 4:1. Cone Calorimeter Test. The cone calorimetry is one of the most useful bench-scale tests and has been widely used by fire safety researchers and engineers, because it could simulate a real-world fire situation.35 To further evaluate the flammability of the IFR-PPs, the samples of PP, PP3, PP4, and PP7 were selected to do the cone calorimeter test. As can be seen from Table 4, the TTI of IFR-PP is shorter than that of pure PP, which should be attributed to the difference in the melt flow behavior between PP and IFR-PP.36 For one thing, pure PP needs more energy to melt, and its initial thermal degradation temperature is higher than IFR-PP. For another, the flame retardant compound decomposes and forms a solid-like intumescent layer which makes the surface get hotter more quickly due to its getting closer to the cone heater. Figure 3 shows the heat release rate curves of PP and IFRPPs. It is noticeable that PP shows only a one-step process. After ignition, PP burned very quickly with a sharp peak heat release rate (860.6 kW/m2). When adding 30 wt % flame retardant compounds, IFR-PPs show two- or three-step processes with much lower PHRR and longer combustion

Figure 2. DTA traces of IFR-PPs.

point of PP. It shows an additional endothermic peak around 370 °C for IFR-PPs which coordinate to the decomposition of intumescence flame retardants. The biggest endothermic peak comes out at 470 °C due to the decomposition of PP. It indicated that PEPADC formed an intumescence char layer before the thermal degradation of the PP matrix, which can delay the decomposition of the inside matrix and improve the flame retardance of PP. 3.2. Fire Behaviors. LOI and UL-94 Test. LOI and UL-94 measures are convenient and useful tools and are widely used to evaluate the flame retardancy of materials. As shown in Table 3, C


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Industrial & Engineering Chemistry Research Table 4. Cone Calorimetry Results for PP and IFR-PPs sample

TTI (s)

PHRR (kW/m2)

av-HRR (kW/m2)

THR (MJ/m2)

av-SEA (m2/kg)

TSP (m2)

residues (wt %)

PP PP3 PP4 PP7

47 32 31 35

860.6 166.8 136.5 257.6

222.8 76.2 67.1 56.5

110.3 108.2 81.0 80.8

6711 4129 2623 1888

154.6 96.5 59.9 42.6

3.3 14.5 16.7 29.1

Figure 3. Comparison of heat release rate (HRR) curves of PP and IFR-PPs.

time. For PP3, PP4, and PP7, the values of PHRR are 166.8, 136.5, and 257.6 kW/m2, respectively. The first PHRR (PHRR1) appears at 45 s, because the charring agent PEPADC decomposes and forms an unstable char. In that case, the second PHRR (PHRR2) of PP3 and PP7 appears at around 250 s, and the effective intumescent char layers are formed which can stop both the mass and the heat transferring from the materials; therefore, the HRR values decrease. As combustion goes on, the defective char bursts and releases trapped volatiles, thus it shows a third PHRR (PHRR3) at around 400−600 s. Besides the above-mentioned intumescent flame retardant materials fire behavior, there are different fire behaviors for each IFR-PP. PP3 shows a relatively lower HRR before 700 s and the highest HRR in the later combustion stage. PP4 shows almost constant HRR from 300 to 600 s and then decreases until extinguishing. The HRR value of PP7 is the highest among the three IFR-PPs; however, it decreases significantly and keeps the lowest HRR after char formation. To better understand these differences, the digital photos of PP and IFR-PPs after the cone calorimeter test are shown in Figure 4. It is notable that PP shows no residue after the cone test; however, a large amount of an intumescent char layer was formed for IFR-PPs. For PP3 and PP4, the surfaces of the char layer were cracked with many vesicular pores. However, the intumescent char layer of PP7 was continuous and complete after the combustion. Generally, the continuous and dense intumescent char layer can provide a better barrier effect and protect the inside materials from further burning. In the early stage of combustion, PP3 formed the char layer quickly because of more charring agent content; however; this char layer was not very stable, and it would be cracked under high temperature for a long time. For PP4, the blowing agent released gas fast, while the formed char layer was not stable. Therefore, the char layer burst not only by higher air pressure from inside but also higher temperature due to the expanded char layer being closer to the cone heater. In fact, the char layer expanded too high and

Figure 4. Digital photographs of PP (a), PP3 (b), PP4 (c), and PP7 (d) after the cone calorimeter test.

hit the cone heater during the test. For PP7, the speed of char formation was not as fast as PP3 or PP4 due to the relatively lower PEPADC content which brings up the influence of both sides on fire behavior. On the negative side, the heat release rate would be higher due to the gradual formation of char which is the result of the highest HRR of PP7 among the IFRPPs. On the positive side, once the continuous and dense char layer formed after a totally carbonization, the HRR reduced significantly, and it would not burst under high temperature for a long time. That is why the LOI value of PP7 is the highest. Figure 5 shows the THR curves of PP and IFR-PPs. It can be seen that THR values of PP decreased obviously with flame retardants. When the combustion time lasted for 700 s, the THR of PP4 and PP7 are almost the same; however, the THR D


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Figure 7. Comparison of SPR curves of PP and IFR-PPs.

Figure 5. Comparison of total heat release (THR) curves of PP and IFR-PPs.

of PP3 still increased with a relatively low gradient which is the result from the unstable intumescent char layer of PP3. Figure 6

Figure 8. Comparison of TSP curves of PP and IFR-PPs.

parameters of PP7 are less than a third of neat PP, indicating that the flame retardant compound of APP and PEPADC can efficiently decrease fire gas toxicity of PP, and the values of avSEA and TSP of PP7 are the lowest, indicating that an appropriate ratio of the flame retardant compound can play an effective role in improving the flame retardancy of IFR-PP systems. Figure 9 and Figure 10 show the CO2 and CO production of PP and IFR-PPs. In the stage of flame initiation and early development, the formation of CO is leading due to the incomplete combustion of pyrolysis volatile at the relatively low

Figure 6. Comparison of mass loss curves of PP and IFR-PPs.

shows the mass loss of PP and IFR-PP, which is in accordance with the THR behavior during cone calorimetry. For PP4, there is an abnormal phenomenon of mass loss that is the mass increased from 500 to 800 s, which is due to the intumescent char layer being too high and hitting the cone heater, so that the data calculation is no longer correct. At the end of burning, there are 3.3%, 14.5%, 16.7%, and 29.1% of residue chars left, respectively, for neat PP, PP3, PP4, and PP7. The PP7 shows significantly higher residue chars, which indicates that the char layer of PP7 is more dense and stable to prevent both the mass and the heat from transferring.37 Besides heat release, smoke density and toxicity have been the focus of attention due to the increasing interest in fire and consumer safety. It is generally accepted that smoke production rate and toxicity are the principal causes of death during a fire. In that case, the smoke and gas release behaviors of neat PP and IFR-PPs during the cone calorimeter test were investigated too. Figure 7 and Figure 8 show the smoke production rate (SPR) and total smoke production (TSP) curves of neat PP and IFR-PPs. The average specific extinction area (av-SEA) which represents the smoke density decreased greatly with a flame retardant compound as well as SPR TSP. Further, the total smoke production of PP decreases with an increase of APP content of the compound; the av-SEA, SPR, and TSP

Figure 9. Comparison of CO2 product curves of PP and IFR-PPs. E


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Figure 10. Comparison of CO product curves of PP and IFR-PPs.

temperature. As the fire develops, the higher temperature tends to form CO2.38 IFR-PPs show much lower peaks of CO and CO2 productions than that of neat PP. The form of CO2P curves are the same as each HRR curve since the formation of CO2 is one of the main exothermic reactions. However, there is something different about COP of IFR-PPs. First of all, the total COP of IFR-PPs are higher than that of neat PP which results from the incomplete combustion of the flame-retardant materials. The COP of PP3 and PP4 keep increasing after the formation of the intumescent char layer which is attributed to the incomplete combustion induced by the defective char layer. However, the COP of PP7 decreases as long as the formation of the effective char layer which indicated that the char layer of PP7 is continuous and dense. Combined with the analysis of fire behaviors of IFR-PPs, there is a synergestic effect and an optimum balance between APP and PEPADC. The appropriate proportion of the flame retardant compound can effectively improve the flame retardancy of IFR-PP. In this case, IFR-PP shows the best flame retardancy, while APP:PEPADC is 4:1. Figure 11 presents the SEM microphotographs of the char residues of PP3, PP4, and PP7 after the LOI test. For PP3, the char layer was smooth, and there were a few microholes on the surface; and there were a few microholes and some bubbles on the surface of PP4. However, there were a lot of bubbles on the char layer of PP7 due to more blowing agent of PP7. The char layer of PP7 was continuous and compact, and there were no microholes on the surface. It indicated that the char layer of IFR-PPs is more stable with a higher additive of APP, which can provide a barrier between IFR-PPs and heat, thus protect the inside materials. Raman spectroscopy is a powerful tool to analyze carbonaceous materials due to its high sensitivity to the degree of structural disorder.39,40 To further investigate the structure of char residues, the Raman spectra of the char residues of IFRPPs were tested. Figure 12 shows Raman spectra of residual char of IFR-PPs which were fitted into 2 Gaussian bands between 1300 and 1600 cm−1 with software Origin 9.0. The structural organization of the char can be estimated by a ratio of the intensity of the D and G bands (ID/IG), where ID and IG are the integrated intensities of the D and G bands, respectively.41,42 Basically, the higher the ratio of ID/IG, the better structure the char is. According to Figure 12, the ID/IG ratio of IFR-PPs increases from 2.64 to 7.64 with the increase content of APP in the flame retardant compound indicating the smaller in-plane microcrystalline size and the most thermally stable

Figure 11. Scanning electron micrographs of the surfaces of char residues PP3 (a), PP4 (b), and PP7 (c) after the LOI test.

char structure of PP7. The ID/IG ratio of IFR-PPs increases significantly, while the APP/PEPADC ratio of the flame retardant compound is from 1:2 to 3:1; however, the increase of the ID/IG ratio becomes gentle with more additive of APP. This indicated that the content of APP is enough to catalyze the charring agent to stable char, while APP is two times higher than PEPADC.

4. CONCLUSION In this paper, a novel macromolecule charring agent (PEPADC) containing both PEPA and triazine rings groups has been designed and synthesized. Its chemical structure was confirmed by NMR, FTIR, ICP, and elemental analysis. F


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The onset decomposition temperature of IFR-PPs was lower than PP due to the lower decomposition temperature of the flame retardant compound. However, the maximum mass loss temperature of the IFR-PPs is higher than PP. The fire behaviors of PP are improved by the addition of APP and PEPADC. The LOI value of the IFR-PP can reach to 35.5, while the ratio of APP to PEPADC is 4:1. Moreover, IFR-PPs can pass UL-94 V-0 rating, while the weight ratio of APP to PEPADC is from 1:2 to 5:1. Cone calorimeter results indicate that not only the HRR and THR but also the SEA, TSP, COP, and CO2P of PP decrease significantly by adding a flame retardant consisting of APP and PEPADC. The DTA, SEM, and Raman results demonstrate that the flame retardant compound decomposed first and formed the compact char layer with a fine microstructure which can act as a barrier between PP and heat and protect the inside matrix. Furthermore, the char layer becomes denser with higher APP addition.

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ASSOCIATED CONTENT

* Supporting Information S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.iecr.6b00204. Preparation, FTIR, solid-state 13C NMR, elemental analysis, ICP, TGA results of PEPADC (PDF)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Corresponding author address: School of Materials Science and Engineering, Changzhou University, Changzhou 213000, Jiangsu, China. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (51473024). REFERENCES

(1) Horacek, H.; Grabner, P. Advantages of flame retardants based on nitrogen compounds. Polym. Degrad. Stab. 1996, 54, 205. (2) Horacek, H.; Pieh, S. The importance of intumescent systems for fire protection of plastic materials. Polym. Int. 2000, 49, 1106. (3) Bourbigot, S.; Le Bras, M.; Duquesne, S.; Rochery, M. Recent advances for intumescent polymers. Macromol. Mater. Eng. 2004, 289, 499. (4) Xie, R.; Qu, B. Expandable graphite systems for halogen-free flame-retarding of polyolefins. I. Flammability characterization and synergistic effect. J. Appl. Polym. Sci. 2001, 80, 1181. (5) Xie, F.; Wang, Y. Z.; Yang, B.; Liu, Y. A novel intumescent flameretardant polyethylene system. Macromol. Mater. Eng. 2006, 291, 247. (6) Gérard, C.; Fontaine, G.; Bellayer, S.; Bourbigot, S. Reaction to fire of an intumescent epoxy resin: Protection mechanisms and synergy. Polym. Degrad. Stab. 2012, 97, 1366. (7) Wang, J. S.; Liu, Y.; Zhao, H. B.; Liu, J.; Wang, D. Y.; Song, Y. P.; Wang, Y. Z. Metal compound-enhanced flame retardancy of intumescent epoxy resins containing ammonium polyphosphate. Polym. Degrad. Stab. 2009, 94, 625. (8) Toldy, A.; Harakály, G.; Szolnoki, B.; Zimonyi, E.; Marosi, G. Flame retardancy of thermoplastics polyurethanes. Polym. Degrad. Stab. 2012, 97, 2524. (9) Usta, N. Investigation of fire behavior of rigid polyurethane foams containing fly ash and intumescent flame retardant by using a cone calorimeter. J. Appl. Polym. Sci. 2012, 124, 3372.

Figure 12. Raman spectra of char residues for IFR-PPs.

Intumescence flame retardants consisting of APP and PEPADC were blended with propylene and prepared IFR-PPs successfully. G


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Industrial & Engineering Chemistry Research (10) Lu, H.; Wilkie, C. A. Study on intumescent flame retarded polystyrene composites with improved flame retardancy. Polym. Degrad. Stab. 2010, 95, 2388. (11) Camino, G.; Grassie, N.; McNeill, I. Influence of the fire retardant, ammonium polyphosphate, on the thermal degradation of poly (methyl methacrylate). J. Polym. Sci., Polym. Chem. Ed. 1978, 16, 95. (12) Camino, G.; Costa, L.; Trossarelli, L.; Costanzi, F.; Pagliari, A. Study of the mechanism of intumescence in fire retardant polymers: part VI-mechanism of ester formation in ammonium polyphosphatepentaerythritol mixtures. Polym. Degrad. Stab. 1985, 12, 213. (13) Bertelli, G.; Marchetti, E.; Camino, G.; Costa, L.; Locatelli, R. Intumescent fire retardant systems: effect of fillers on char structure. Angew. Makromol. Chem. 1989, 172, 153. (14) Riva, A.; Camino, G.; Fomperie, L.; Amigouët, P. Fire retardant mechanism in intumescent ethylene vinyl acetate compositions. Polym. Degrad. Stab. 2003, 82, 341. (15) Bras, M. L.; Bugajny, M.; Lefebvre, J. M.; Bourbigot, S. Use of polyurethanes as char-forming agents in polypropylene intumescent formulations. Polym. Int. 2000, 49, 1115. (16) Liu, J. C.; Xu, M. J.; Lai, T.; Li, B. Effect of surface-modified ammonium polyphosphate with KH550 and silicon resin on the flame retardancy, water resistance, mechanical and thermal properties of intumescent flame retardant polypropylene. Ind. Eng. Chem. Res. 2015, 54, 9733. (17) Ni, J. X.; Song, L.; Hu, Y.; Zhang, P.; Xing, W. Y. Preparation and characterization of microencapsulated ammonium polyphosphate with polyurethane shell by in situ polymerization and its flame retardance in polyurethane. Polym. Adv. Technol. 2009, 20, 999. (18) Shao, Z. B.; Deng, C.; Tan, Y.; Chen, M. J.; Chen, L.; Wang, Y. Z. Flame retardation of polypropylene via a novel intumescent flame retardant: Ethylenediamine-modified ammonium polyphosphate. Polym. Degrad. Stab. 2014, 106, 88. (19) Tan, Y.; Shao, Z. B.; Chen, X. F.; Long, J. W.; Chen, L.; Wang, Y. Z. Novel multifunctional organic−inorganic hybrid curing agent with high flame-retardant efficiency for epoxy resin. ACS Appl. Mater. Interfaces 2015, 7, 17919. (20) Halpern, Y.; Mott, D. M.; Niswander, R. H. Fire retardancy of thermoplastic materials by intumescence. Ind. Eng. Chem. Prod. Res. Dev. 1984, 23, 233. (21) Chen, L.; Wang, Y. Z. A review on flame retardant technology in China. Part I: development of flame retardants. Polym. Adv. Technol. 2010, 21, 1. (22) Hu, X. P.; Li, W. Y.; Wang, Y. Z. Synthesis and characterization of a novel nitrogen-containing flame retardant. J. Appl. Polym. Sci. 2004, 94, 1556. (23) Li, B.; Xu, M. J. Effect of a novel charring-foaming agent on flame retardancy and thermal degradation of intumescent flame retardant polypropylene. Polym. Degrad. Stab. 2006, 91, 1380. (24) Verkade, J. G.; Reynolds, L. T. The synthesis of a novel ester of phosphorus and of arsenic. J. Org. Chem. 1960, 25, 663. (25) Li, X.; Ou, Y. X.; Zhang, Y. H.; Lian, D. J. Synthesis and structure of a novel caged bicyclic phosphate flame retardant. Chin. Chem. Lett. 2000, 11, 887. (26) Peng, H. Q.; Zhou, Q.; Wang, D. Y.; Chen, L.; Wang, Y. Z. A novel charring agent containing caged bicyclic phosphate and its application in intumescent flame retardant polypropylene systems. J. Ind. Eng. Chem. 2008, 14, 589. (27) Song, P. G.; Fang, Z. P.; Tong, L. F.; Xu, Z. B. Synthesis of a novel oligomeric intumescent flame retardant and its application in polypropylene. Polym. Eng. Sci. 2009, 49, 1326. (28) Gao, F.; Tong, L. F.; Fang, Z. P. Effect of a novel phosphorousnitrogen containing intumescent flame retardant on the fire retardancy and the thermal behavior of poly(butylenes terephthalate). Polym. Degrad. Stab. 2006, 91, 1295. (29) Song, P. A.; Fang, Z. P.; Tong, L. F.; Xu, Z. B. Synthesis of a novel oligomeric intumescent flame retardant and its application in polypropylene. Polym. Eng. Sci. 2009, 49, 1326.

(30) Hu, X. P.; Guo, Y. Y.; Chen, L.; Wang, X. L.; Li, L. J.; Wang, Y. Z. A novel polymeric intumescent flame retardant: synthesis, thermal degradation mechanism and application in ABS copolymer. Polym. Degrad. Stab. 2012, 97, 1772. (31) Feng, C. M.; Zhang, Y.; Liu, S. W.; Chi, Z. G.; Xu, J. R. Synthesis of novel triazine charring agent and its effect in intumescent flameretardant polypropylene. J. Appl. Polym. Sci. 2012, 123, 3208. (32) Mahapatra, S. S.; Karak, N. s-Triazine containing flame retardant hyperbranched polyamines: synthesis, characterization and properties evaluation. Polym. Degrad. Stab. 2007, 92, 947. (33) Dai, J. F.; Li, B. Synthesis, thermal degradation, and flame retardance of novel triazine ring-containing macromolecules for intumescent flame retardant polypropylene. J. Appl. Polym. Sci. 2010, 116, 2157. (34) Lai, X.; Tang, S.; Li, H.; Zeng, X. Flame-retardant mechanism of a novel polymeric intumescent flame retardant containing caged bicyclic phosphate for polypropylene. Polym. Degrad. Stab. 2015, 113, 22. (35) Yang, R.; Chen, L.; Zhang, W. Q.; Chen, H. B.; Wang, Y. Z. In situ reinforced and flame-retarded polycarbonate by a novel phosphorus-containing thermotropic liquid crystalline copolyester. Polymer 2011, 52, 4150. (36) Wang, D. Y.; Liu, Y.; Wang, Y. Z.; Artiles, C. P.; Hull, T. R.; Price, D. Fire retardancy of a reactively extruded intumescent flame retardant polyethylene system enhanced by metal chelates. Polym. Degrad. Stab. 2007, 92, 1592. (37) Liu, Y.; Zhao, J.; Deng, C. L.; Chen, L.; Wang, D. Y.; Wang, Y. Z. Flame-retardant effect of sepiolite on an intumescent flameretardant polypropylene system. Ind. Eng. Chem. Res. 2011, 50 (4), 2047−2054. (38) Biswas, B.; Kandola, B. K.; Horrocks, A. R.; Price, D. A quantitative study of carbon monoxide and carbon dioxide evolution during thermal degradation of flame retarded epoxy resins. Polym. Degrad. Stab. 2007, 92, 765. (39) Sadezky, A.; Muckenhuber, H.; Grothe, H.; Niessner, R.; Pöschl, U. Raman microspectroscopy of soot and related carbonaceous materials: spectral analysis and structural information. Carbon 2005, 43, 1731. (40) Le Bras, M.; Bourbigot, S.; Le Tallec, Y.; Laureyns, J. Synergy in intumescence application to β-cyclodextrin carbonisation agent in intumescent additives for fire retardant polyethylene formulations. Polym. Degrad. Stab. 1997, 56, 11. (41) Bourbigot, S.; Le Bras, M.; Delobel, R.; Decressain, R.; Amoureux, J. P. Synergistic effect of zeolite in an intumescence process: study of the carbonaceous structures using solid-state NMR. J. Chem. Soc., Faraday Trans. 1996, 92, 149. (42) Zhao, H. B.; Liu, B. W.; Wang, X. L.; Chen, L.; Wang, X. L.; Wang, Y. Z. A flame-retardant-free and thermo-cross-linkable copolyester: Flame-retardant and anti-dripping mode of action. Polymer 2014, 55, 2394.

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