High flame retardant performance of SiO2-TiO2 sol coated on polyester/cotton fabrics

 VNU Journal of Science: Natural Sciences and Technology, Vol. 37, No. 1 (2021) 11-18 
 Original Article 
 High flame retardant performance of SiO2-TiO2 sol coated on 
 polyester/cotton fabrics 
 Pham Thi Thu Trang1,2, Le Ha Giang1, Nguyen Ba Manh1, Trinh Duc Cong1, Ngo 
 Trinh Tung1 and Vu Anh Tuan1,2.* 
 1Institute of Chemistry, Vietnam Academy of Science and Technology. 
 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam. 
 2Graduate University of Science and Technology, Vietnam Academy of Science and Technology. 
 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam. 
 Received 10 November 2020 
 Revised 12 January 2021; Accepted 2 February 2021 
 Abstract: SiO2 and TiO2 sols were successfully synthesized by using sodium silicate and titanium 
 chloride as Si and Ti sources. SiO2-TiO2 sol coated polyester/cotton fabric was fabricated by deep-
 coating method and using SiO2, TiO2 sols as coating materials. SiO2-TiO2 coated fabric were 
 characterized by XRD, FTIR, TGA, SEM and EDX. From SEM image, it showed the SiO2, TiO2 
 particles of 20-30 nm which well deposited on fabric surface. TGA result revealed the significant 
 improvement of thermal resistance and stability of SiO2-TiO2 coated fabric as compared to those 
 of uncoated fabric. Flame retardant performance of SiO2-TiO2 coated fabrics was much better than 
 that of uncoated fabric. Thus, SiO2-TiO2 coated fabric SiO2-TiO2 content of 26wt% showed the 
 UL-94 classification of V-0 and LOI value of 30.3 were obtained. Moreover, mechanical property 
 (tear strength) of SiO2-TiO2 coated fabrics were also improved. 
 Keywords: nano silica, titanium dioxide, polyester/cotton fabrics, flame retardant 
1. Introduction* and ventilation of cotton yarn with high 
 strength of polyester [1,2]. However, polyester / 
 Polyester/cotton fabric is a blend of cotton fabric is flammable and it cannot be used 
polyester and cotton and it is widely used in the as flame retardancy materials. Therefore, many 
textile industry. The quality of blended fabric is efforts on flame retardancy improvements have 
improved by the combination of the comfort been devoted [3,4]. Materials of coating can be 
 of organic or inorganic nature. Halogen-based 
________ 
* flame retardants materials have been shown to 
 Corresponding author. be one of the most effective materials to reduce 
 Email address: vuanhtuan.vast@gmail.com 
 the risk of fire, but the downside is the release 
 https://doi.org/10.25073/2588-1140/vnunst.5167 of toxic and corrosive gases during combustion 
 11 
12 P.T.T. Trang et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 37, No. 1 (2021) 11-18 
[5,6]. Phosphorus and nitrogen based materials 85%, Merck company), ion exchange 
are preferably chosen as flame retardants (AMBERLITETM IR 120 from Down Chemical 
because of their eco-friendly by-products, low company), H2O2 (31 wt% from Aldrich 
toxicity. However, their poor flame retardant company), NH4OH (30 wt% from Sigma 
performance and low thermal stability were company). Polyester/cotton fabric (trade mark- 
noted [7,8]. Flame retardants of inorganic Lacoste, 35% polyester-65 %cotton, 115 g/cm2) 
nature such as nanosilica, nano alumino-silica, is provided by the textile Dong Xuan-Vietnam 
nano clay are often used to cover the fabric company. 
surface to create an insulating and fireproof 
protective layer and simultaneously, the 2.1. Synthesis of silica sol 
physico-mechanical properties can be 
 Silica sol was synthesized by ion exchange 
improved. Among inorganic flame retardants, 
 method using Amberlite as ion exchange resin 
nano silica and nano titanium dioxide have 
 and sodium silicate (liquid glass) as source of 
received a great interest because these materials 
 silicon [11]. 
are environmentally friendly, non-toxic and 
 The process of synthesizing sol silica 
highly effective in slowing or resisting fire [9-
 consists of the following steps: Step 1: 
12]. El-Shafei et al. [13] modified the fabric 
 Dissolution of sodium silicate in distilled water. 
with nano TiO sol gel from titanium 
 2 Step 2: Na+ ion exchange by using ion 
isopropoxide and the fire resistance of the TiO 
 2 exchange resin (AMBERLITETM IR 120). Step 
modified fabric is significantly improved (LOI 
 3: Adjusting pH value of 8.5-9.0 by KOH 
increased from 17.4% to 23%). Fei et al. [14] 
 addition to form the Si(OH) slurry. Step 4: 
modified fabric with nano silica synthesized 4
 Stirring the mixture until to get the 
from TEOS and the significant enhance of 
 homogeneous sols. 
flame retardancy (LOI value from 19.0 to 23.0) 
is reported. Liu et al. [15] reported that fabric 2.2. Synthesis of titanium dioxide sol 
coated with silica nano by using the sources of 
organic silicon TEOS and trimethylsilane and Titanium dioxide sol was synthesized by 
showed that the thermal stability was using titanium tetrachloride (TiCl4) as Ti soured 
considerably imp ... 0 - 
 o
19]. In the XRD patterns of SiO2-TiO2 coated 200 C), weight loss of 10 wt% was observed. 
14 P.T.T. Trang et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 37, No. 1 (2021) 11-18 
 SEM images of polyester/cotton fabric and 
 SiO2-TiO2 coated fabric (S7) were given in 
 figure 4. In figure 4A, polyester/cotton fabric 
 Fig. 2: FTIR spectra of polyester/cotton fabric (a) 
 and SiO2-TiO2 coated fabric (b-e) 
This weight loss is due to the water desorption. 
At the second stage (250 - 350 oC), weight loss 
of 50 wt% is noted. This is due to the partial 
decomposition of fabric. At the third stage (350 
- 500 oC), weight loss was 38 wt%. The weight 
loss in this region is due to the further 
decomposition of fabrics. As seen in the 
derivative thermogravimetry of polyester/cotton 
fabric (Fig 3B), the decomposition occurred at 
 o o
Tmax of 330 - 430 C and 480 C. The behavior 
of weight loss for SiO2-TiO2 coated fabrics was 
different from that of polyester/cotton fabric. 
Thus, in the temperature range from 50 oC to 
300 oC, weight loss of 1.5-2% was observed. In Fig. 3: Weight loss (A) and derivative 
the range from 350 oC to 550 oC, weight loss of thermogravimetry (B) of polyester/cotton fabric and 
 SiO2-TiO2 coated fabric 
SiO2-TiO2 coated fabric (S1-S7) was 65 wt%, 50 
wt%, 41 wt% and 38 wt%, respectively. From showed the heterogeneous structure with 
this result, it clearly indicated that SiO2-TiO2 the pore system consisted of large pore (100 -
coating reduced the weight loss of fabric. Thus, 150 nm), medium pore (50-60 nm) and small 
SiO2-TiO2 coated fabric (7 coating times) 
 pore (20 -30 nm). In the SEM image of SiO2-
showed the weight loss of 38% which was 2.5 TiO coated fabric (figure 4B), it can be seen 
times less than that of polyester/cotton fabric 2
 SiO2, TiO2 particles of 30-40 nm size which 
(98 wt%). Moreover, the decomposition of filled up the pore system of polyester/cotton 
SiO2-TiO2 coated fabrics needed higher fabric and simultaneously covered the fabric 
temperature (see fig 3B). surface. 
3.2. Morphology and chemical composition EDX spectra of polyester/cotton fabric and 
 SiO2-TiO2 coated fabric-S7 were presented in 
 figure 5 and elemental composition was given 
 in table 1. 
 P.T.T. Trang et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 37, No. 1 (2021) 11-18 15
 concentration of SiO2-TiO2 solution (10 wt% 
 SiO2 and 2 wt% TiO2) was used. This can be 
 explained on the basis of the competition 
 between SiO2 and TiO2 particles since 
 concentration of SiO2 was 5 times higher than 
 that of TiO2 which promoted much more SiO2 
 deposition on fabric surface than TiO2 
 deposition. 
 (B) 
 Fig. 4: SEM image (A) polyester/cotton fabric and 
 (B) SiO2-TiO2 coated fabric (S7) 
 As given in Table 1, C content decreased 
 Fig. 5: EDX spectra of polyester/cotton fabric (A) 
with increasing SiO2-TiO2 coating times while and SiO -TiO coated fabric-S (B) 
O, Si and Ti content increased with increasing 2 2 7
SiO2-TiO2 coating times (S1-S7). Thus, C Table 1: Elemental composition of polyester/cotton 
content decreased from 51.06 wt% to 20.45 fabric and SiO2-TiO2 coated fabrics 
wt%, respectively. O content of S1, S3, S5 and 
S7 samples was 28.38%, 33.41%, 38.7% and 
45.97 wt%, respectively. N content of S1, S3, S5 
and S7 samples was 14.12%, 12,42%, 10.09% 
and 7.58%. Si content of S1, S3, S5 and S7 
samples was 5.34%, 11.06%, 18.72% and 
23.99%, respectively. Ti content of S1, S3, S5 
and S7 sample was 1.01%, 1.35%, 1.64% and 
2.01 wt%, respectively. Interestingly, the ratio 
of Si/Ti increased with increasing SiO2-TiO2 
coating times. Normally, this ratio Si/Ti should 3.3. Flame retardancy and mechanical property 
maintain unchanged since the same 
16 P.T.T. Trang et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 37, No. 1 (2021) 11-18 
 UL-94 classification and limiting oxygen fabric and SiO2-TiO2 coated fabric was shown 
index (LOI) of polyester/cotton fabric and SiO2- in table 3. 
TiO2 coated fabric were listed in the table 2 
 Table 3: Tear strength of polyester/cotton fabric 
 Table 2: UL-94 classification and limiting oxygen SiO2-TiO2 coated fabrics 
index (LOI) of polyester/cotton fabric and SiO2-TiO2 
 coated fabrics Sample Tear strength 
 (N/mm) 
 Sample UL - 94 LOI 
 (%) Polyester/cotton fabric 39.37 
 Polyester/cotton fabric V-2 17.5 
 SiO2-TiO2 coated fabric (S1) 41.22 
 SiO2-TiO2 coated fabrics (S1) V-2 19.0 
 SiO2-TiO2 coated fabric (S3) 43.35 
 SiO2-TiO2 coated fabrics (S3) V-1 23.6 
 SiO2-TiO2 coated fabric (S5) 45.27 
 SiO2-TiO2 coated fabrics (S5) V-1 25.2 
 SiO2-TiO2 coated fabrics (S7) V-0 30.3 SiO2-TiO2 coated fabric (S7) 37.56 
 As seen in table 2, polyester/cotton fabric As seen in table 3, the increase of tear 
and SiO2-TiO2 coated fabric-S1 had the UL-94 strength from 39.37 (polyester/cotton fabric) to 
of V-2 which did not satisfy the quality 
 45.26 N/mm (SiO2-TiO2 coated fabric-S5) was 
requirement for flame retardant materials. SiO2-
 observed. Further SiO2-TiO2 coating (SiO2-
TiO2 coated fabrics (S3 and S5) showed UL-94 
 TiO2 coated fabric-S7) leaded to decrease the 
classification of V-1 which satisfied the quality tear strength (37.56 N/mm). This can be 
requirement for flame retardant materials. SiO2-
 explained by the fact that SiO2-TiO2 coated 
TiO2 coated fabric-S7 reached the best quality 
 fabric with high loading, SiO2 and TiO2 
requirement for flame retardant materials (UL- particles tended to the agglomeration, making 
94 classification of V-0). Polyester/cotton 
 SiO2-TiO2 coated fabric become more fragile 
fabric showed the LOI value of 17.5 while the and consequently decreased the tear strength. 
LOI value of SiO2-TiO2 coated fabrics was 19.0 
(for S1), 23.6 (for S3), 25.2 (for S5) and 30.3 (for 
S7), respectively. It is well known that O2 4. Conclusions 
content in the air is ca. 19 % (v/v). Therefore, 
polyester/cotton fabric is easily burned in air. From the obtained results, some conclusions 
 could be drawn: SiO2 and TiO2 sols were 
SiO2-TiO2 coated fabrics (S3, S5) with LOI 
value of 23.6-25.2 are slowly burned in air. successfully synthesized by using sodium 
 silicate and titanium chloride as Si and Ti 
SiO2-TiO2 coated fabric (S7) showed the highest 
LOI value of 30.3 which is unburnable under sources. SiO2-TiO2 sol polyester/cotton fabric 
 was fabricated by deep coating method and 
flame. Thus, the SiO2 and TiO2 nanoparticles 
with the size of 30-50 nm were covered on the using SiO2-TiO2 sol as coating materials. SiO2-
surface of the polyester/cotton fabric to help TiO2 coated fabrics with different SiO2-TiO2 
prevent contact between flame and combustible content were made by repeating the coating 
components (polyester/cotton fabric). times. Polyester/cotton fabric and SiO2-TiO2 
 Mechanical property of polyester/cotton coated fabrics were characterized by XRD, 
 FTIR, TGA, SEM and EDX. From SEM result, 
fabric and SiO2-TiO2 coated fabrics 
 One of the most important physico- it showed that SiO2, TiO2 particles of 20-30 nm 
mechanical properties of fabric is the tear filled up the pore system of fabric and well 
strength. Tear strength of polyester/cotton deposited on fabric surface. From TGA analysis 
 of the samples, it revealed the significant 
 P.T.T. Trang et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 37, No. 1 (2021) 11-18 17
improvement of thermal resistance and stability (2001) 1–17. https://doi.org/10.1016/S0048-
 9697(01)00852-X 
of SiO2-TiO2 coated fabrics. 
 Flame retardancy and mechanical property [7] Q. Tang, B. Wang, G. Tang, Y. Shi, X. Qian, B. 
 Yu, L. Song, Y. Hu, Preparation of 
(tear strength) of polyester/cotton fabric and microcapsulated ammonium polyphosphate 
SiO2-TiO2 coated fabric were tested and pentaerythritol with glycidyl methacrylate, butyl 
evaluated. The SiO2-TiO2 coated fabric (7 methacrylate and their synergistic flame-
coating times, Si-Ti content of 26 wt%) showed retardancy for ethylene vinyl acetate copolymer, 
the highest flame retardancy performance. Polym. Adv. Technol. 25 (2014) 73–82. 
Thus, UL-94 classification of V-0 and LOI https://doi.org/10.1002/pat.3207 
 [8] F. Carosio, J. Alongi, G. Malucelli, Layer by 
value of 30.3 were obtained. Additionally, Layer ammonium polyphosphate-based coating 
mechanical property (tear strength) of SiO2- for flame retardancy of polyester-cotton blends, 
TiO2 coated fabrics was also improved. Carbohydr. Polym. 88 (2012) 1460–1469. 
 https://doi.org/10.1016/j.carbpol.2012.02.049 
 [9] L. Yan, Z. Xu, X. Wang, Influence of nano-silica 
Acknowledgement on the flame retardancy and smoke suppression 
 properties of transparent intumescent fire-
 Authors thank the Vietnam Academy of Science retardant coatings, Progress in Organic Coatings, 
and Technology- VAST for financial support 112 (2017) 1460–1469. https://doi.org/10.1016/ 
(TĐPCCC.03/18-20 and VHH.2020.2.01). j.porgcoat.2017.07.017 
 [10] H. Zhan, J. Lu, H. Yang, H. Yang, J. Lang and Q. 
 Zhang, Synergistic Flame-Retardant Mechanism 
References of Dicyclohexenyl Aluminum Hypophosphite and 
 Nano-Silica, Polymers, Published: 11 (7) (2019) 
[1] M. Leistner, A.A. Abu-Odeh, S.C. Rohmer, J.C. 1211. https://doi.org/10.1177/0892705717738287 
 Grunlan, Water-based chitosan/ melamine [11] L. Qomariyah, F.N. Sasmita, H.R. Novaldi, W. 
 polyphosphate multilayer nanocoating that Widiyastuti, Winardi, Preparation of Stable 
 extinguishes fire on polyester-cotton fabric, Colloidal Silica with Controlled Size Nano 
 Carbohydr. Polym. 130 (2015) 227–232. https://d Spheres from Sodium Silicate Solution, Materials 
 oi.org/10.1016/j.carbpol.2015.05.005 Science and Engineering, 395 (2018) 012017. 
[2] Y. Pan, L. Liu, X. Wang, L. Song, Y. Hu, https://doi.org/10.1088/1757-899X/395/1/012017 
 Hypophosphorous acid cross-linked layerby-layer [12] T. Kashiwagi, J.W. Gilman, K.M. Butler, R.H. 
 assembly of green polyelectrolytes on polyester- Harris. Flame retardant mechanism of silica 
 cotton blend fabrics for durable flame-retardant gel/silica, Article in Fire and Materials, 24 (6) 
 treatment, Carbohydr. Polym. 201 (2018) 1–8. (2000) 277-289. https://doi.org/10.1002/1099101 
 https://doi.org/10.1016/j.carbpol.2018.08.044 8(200011/12)24:63.0.CO;2-A 
[3] M.M. Abd EI-Hady, A. Farouk, S. Sharaf, Flame [13] A. El-Shafei, M. ElShemy, A. Abou-Okeil. Eco-
 retardancy and UV protection of cotton based friendly finishing agent for cotton fabrics to 
 fabrics using nano ZnO and polycarboxylic acids, improve flame retardant and antibacterial 
 Carbohydr. Polym. 92 (2013) 400–406. https://doi properties, Carbohydrate Polymers, 118(2015) 
 .org/10.1016/j.carbpol.2012.08.085 83–90. https://doi.org/10.1016/j.carbpol.2014.11 
[4] H. Yang, C.Q. Yang, Durable flame retardant .007 
 finishing of the nylon/cotton blend fabric using a [14] D.D. Fan, F. You, Y. Zhang, Z. Huang, Flame 
 hydroxyl-functional organophosphorus oligomer, retardant effects of fabrics finished by hybrid 
 Polym. Degrad. Stab. 88 (2005) 363–370. nano-micro silica-based Sols, Procedia 
 https://doi.org/10.1016/j.polymdegradstab.2004.1 Engineering, 211 (2018) 160–168. https://doi.org 
 1.013 /10.1016/j.proeng.2017.12.124 
[5] J. Legler, A. Brouwer, Are brominated flame [15] C. Liu, T. Xing, B. Wei, G. Chen, Synergistic 
 retardants endocrine disruptors? Environ. Int. 29 Effects and Mechanism of Modified Silica Sol 
 (2003) 879–885. https://doi.org/10.1016/S0160- Flame Retardant Systems on Silk Fabric, 
 4120(03)00104-1. Materials, 11 (2018) 1842. https://doi.org/10.3 
[6] F. Rahman, K.H. Langford, M.D. Scrimshaw, 390/ma11101842 
 J.N. Lester, Polybrominated diphenyl ether [16] N. Sasirekha, B. Rajesh, Y.W. Chen, Synthesis of 
 (PBDE) flame retardants, Sci. Total Environ. 275 
 TiO2 sol in a neutral solution using TiCl4 as a 
18 P.T.T. Trang et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 37, No. 1 (2021) 11-18 
 precursor and H2O2 as an oxidizing agent, Thin and a betulin-based copolymer, Cellulose, 25 
 Solid Films, 518 (2009) 43–48. https://doi.org (2018) 2115–2128. https://doi.org/10.1007/s105 
 /10.1016/j.tsf.2009.06.015 70-018-1695-5 
[17] K.B. Yazhinia and H.G. Prabu, Study on flame- [23] N. Lv, X. Wang, S. Pengab, L. Luo and R. Zhou, 
 retardant and UV-protection properties of cotton fabric Superhydrophobic/superoleophilic cotton-oil 
 functionalized with ppy–ZnO–CNT nanocomposite, absorbent: preparation and its application in 
 RSC Adv, 5 (2015) 49062-49069. https://doi.o oil/water separation, RSC Adv, 8 (2018) 30257-
 rg/10.1039/C5RA07487H 30264. https://doi.org/10.1039/C8RA05420G 
[18] I. Ahmada, C.W. Kan, Z. Yao, Photoactive cotton [24] S. Sun, T. Deng, H. Ding, Y. Chen, W. Chen, 
 fabric for UV protection and self-cleaning, RSC Preparation of nano-TiO2-Coated SiO2 
 Adv, 9 (2019) 18106-18114. https://doi.org/10. microsphere composite material and evaluation of 
 1039/C9RA02023C its self-cleaning property, Nanomaterials, 7(11) 
[19] Z. Zhaoa, J. Zhoua, T. Fana, L. Lia, Z. Liua, Y. (2017) 367. https://doi.org/10.3390/nano7110367 
 Liuab, M. Lu, An effective surface modification [25] H.A. Budiartia, R.N. Puspitasaria, A.M. Hattaa, 
 of polyester fabrics for improving the interfacial Sekartedjoa and Doty Dewi Risantia, Synthesis 
 deposition of polypyrrole layer, Materials and characterization of TiO2@SiO2 and 
 Chemistry and Physics, 203 (2018) 89-96. SiO2@TiO2 core-shell structure using lapindo 
 https://doi.org/10.1 mud extract via sol-gel method, Procedia 
 016/j.matchemphys.2017.09.062 Engineering, 170 (2017) 65 – 71. 
[20] M. Mohammadi, Mitra Dadvar, Bahram Dabir, https://doi.org/10.1016/j.proeng. 2017 .03.013 
 TiO2/SiO2 nanofluids as novel inhibitors for the [26] J. Sun, K. Xu, C. Shi, J. Ma, W. Li, X. Shen, 
 stability of asphaltene particles in crude oil: Influence of core/shell TiO2@SiO2 nanoparticles 
 Mechanistic understanding, screening, modeling, on cement hydration, Construction and Building 
 and optimization, Journal of Molecular Liquids, Materials, 156 (2017) 114-122. 
 238 (2017) 326-340. https://doi.org/10.1016/j. https://doi.org/10.101 
 molliq.2017.05.014 6/j.conbuildmat.2017.08.124 
[21] C. Chunga, M. Lee, E. Kyung Choe, [27] H. Zhang, X. Wang, N. Li, J. Xia, Q. Meng, J. 
 Characterization of cotton fabric scouring by FT-
 Ding, TiO2/graphene oxide nanocomposites for 
 IR ATR spectroscopy, Carbohydrate Polymers, photoreduction of heavy metal ions in reverse 
 58 (2004) 417–420. https://doi.org/10.1016/j.car osmosis concentrate, RSC Adv, 60 (2018) 34241-
 bpol.2004.08.005 34251. https://doi.org/10.1039/C8RA06681G 
[22] T. Huang, D. Li and M. Ek, Water repellency 
 improvement of cellulosic textile fibers by betulin