Study on properties of cotton fabric incorporated with diammonium phosphate flame retardant through cyclodextrin and 1,2,3,4-butane tetracarboxylic acid binding system

Abstract

The chemical and physical structure of cyclodextrin makes it attractive for use in flame retardant finishing for improving the functional properties and durability of the finished fabric. The suitability of cyclodextrins for grafting using viable techniques that could be reproduced was studied. The flame retardant diammonium phosphate was applied on cyclodextrin-grafted cotton fabric and grafted cum bonded with 1,2,3,4-butane tetracarboxylic acid fabric. The modified monochlorotriazinyl-β-cyclodextrin gives more percentage of grafting (2.7%) under normal processing conditions used for cotton fabric. The effect of treatments like cyclodextrin grafting and 1,2,3,4-butane tetracarboxylic acid treatment on grafted fabric were analysed for diammonium phosphate flame retardant finishing. The whiteness and loss of strength caused by the cyclodextrin grafting was within acceptable limits and the hand value alteration was very less. The flammability behaviour and durability after 1, 5, 10, 20 and 40 washing cycles were determined. The results reveal that the flame retardant property of cyclodextrin treatment enhances the durability of the fabric from non-durable to semi-durable, whereas the diammonium phosphate treatment on 1,2,3,4-butane tetracarboxylic acid/cyclodextrin-grafted fabric changes the flame retardant from non-durable to durable. The evolution of gases during the burning of untreated and treated samples was analysed and the results show that the cyclodextrin-grafted fabric masks the evolving gases to some extent during burning and also that there was less release of formaldehyde in grafted samples compared with ungrafted diammonium phosphate finished sample.

Keywords

Cyclodextrin 1 2 3 4-butane tetracarboxylic acid diammonium phosphate grafting binding inclusion complex flame retardant

Introduction

Cotton fabric is extremely suitability as a wearing material due to its unique characteristics. However, its flame retardant (FR) property is not good compared with that of fibres like wool and nomex. Textiles differ widely in construction (knitted, woven and nonwoven) and in the chemical nature of fibres. As a result, the flammability of textiles varies noticeably from very flammable to intrinsically FR textiles. In fire accidents involving children, clothing worn by children may ignite, resulting in a very high rate of deaths one of every four or disfiguring burns, especially with ignition of nightwear [1]. The flame spread rate of textiles after ignition is dependent mainly on fabric density and usually lighter fabrics are dangerous than heavier ones [2].

On the other hand, the FR finishing causes reduction in strength, yellowing, undue stiffness, formaldehyde release, loss of flame retardancy during the laundering process and evolving of toxic gases due to pyrolysis [3]. It has been observed that by modifying the cellulosic fibre through coating or bonding with binding agent, these properties of the finished fabric may improve. Application of 1,2,3,4-butane tetracarboxylic acid (BTCA) on cotton/nomex was studied using hydroxy functional organophosphorous oligomer [4]. Blanchard and Garves [5] investigated the applicability of phosphorus-based polycarboxylic acids (PCA) as FR agents for cotton and blends.

The new textile auxiliary cyclodextrin (CD) was found to be suitable in various applications in textile finishing to improve the durability of the fabric and enhance its slow release property. The ability of CD to serve as a host in the formation of solid or liquid phases of compounds by formation of inclusion complex with a large variety of compounds through host–guest complex formation, as shown in (Figure 1), is widely used in various finishes [6].

Figure 1.

Host–guest chemistry through inclusion complex formation.

Previously, researchers used CD for a variety of end uses such as for its aroma and for drug release; subsequently, modification of cotton fabric was performed effectively through coating, grafting or bonding with binding agents for improving the functional properties of the finished fabric, especially indoor and outdoor fabrics [7 –15]. The use of monochlorotriazinyl-β-cyclodextrin (MCT-β-CD) for producing covalent bonding mechanism for dyeability has been studied previously [16]. The covalent bond formation between MCT-β-CD and –OH group of cellulose is shown in Figure 2.

Figure 2.

Covalent bonding mechanism of MCT-β-CD with –OH group of cellulose.

This new type of modification of cotton fabric through cyclodextrin treatment and bonding with BTCA may be a permanent property to the treated material and these chemicals gets assembled on the cotton fabric as shown in Figure 3.

Figure 3.

Assembling of CD and BTCA on the cotton fabric.

The temporary FR diammonium phosphate (DAP) is used in the industry for cellulosic material and it causes problems such as loss of strength and whiteness, changes in hand values, reduction in durability and evolution of hazardous gases during burning. After reviewing previously published literature and analysing the problems, we decided to introduce CD and/or BTCA bonding into DAP finishing such that the functional property may undergo a change.

In this study, the suitability of CD was studied among four categories for effective grafting, namely α, β, γ and modified CD; it was found that use of MCT-β-CD was effective for grafting under normal processing conditions used for cotton. DAP was applied on CD-grafted fabric and BTCA/CD-grafted fabric to analyse the various factors. It was found that the durability of flame retardancy was increased for BTCA/CD/DAP combination fabric compared with CD/DAP-treated sample due to the formation of covalent bonding and cross-linking [17]. This new type of modification of CD and bonding is a permanent property to the treated material.

Materials and methods

Materials

To perform CD grafting on 100% cotton fabric, grey plain-woven fabric was purchased from Venkateswara Textiles (Erode, TN, India).This was pretreated as per industrial practices after which it weighed 140 gm and its cloth cover (Kc) was 19.8. In order to find out the suitability of CDs for grafting, three different types of CDs were selected namely α, β and γ and the β-CDs were modified into monochloro triazinyl compounds.All these CDs were supplied along with auxiliaries by Alchemy solutions (Cochin, India) as LR grade. The PCA, BTCA, was also tried as a binding agent along with sodium hypophosphate as catalyst to study its effect on CD-grafted FR cotton fabric. The temporary FR DAP (P₂O₅, 53%; NH₃, 25%; N, 20.8%) was used along with urea to produce the FR finishing on pretreated fabric, CD-grafted sample, BTCA-bound sample and BTCA/CD-grafted sample. The DAP, BTCA and urea were supplied by National Scientific (Erode, TN, India) as LR grade.

Methods

Preparation of MCT-β-CD

MCT-β-CD was prepared by condensation process wherein the cyanuric chloride was condensed with CD in an aqueous medium at 0–5℃ in the presence of sodium hydroxide to give 4-chloro-6-hydroxy-s-triazin-2-yl-β-cyclodextrin sodium salt with a degree of substitution of active Cl, 0.4. This product is a reactive derivative and can be covalently fixed on cellulose. This modified CD can be applied by standard methods like reactive dyeing due to the resemblance in reactive dye structure.

Grafting of CD on cotton

The grafting of cotton fabric with different CDs, namely α, β, γ and modified β-cyclodextrin, was carried out by optimizing the variables such as temperature, concentration, pH, time and material to liquor ratio for producing a higher grafting yield. The grafting percentage is calculated from the difference in weight between the fabrics before and after grafting, and the following equation was used to calculate the grafting percentage

Percentage of grafting (G) = \frac{(W_{2} - W_{1})}{W_{1}} \times 100

(1)

where W₁ is the weight of fabric before grafting and W₂ is the weight of fabric after grafting.

The reproducibility of the grafting was checked using triplicate method.

In order to compare the effect of CD grafting for FR finishing, various treatments were done on CD-grafted/ungrafted samples, as shown in Table 1. The binding agent and DAP were applied using two bowl padding mangles with 90% expression and curing was done at 160℃ for 2 min.

Table 1.

Details of differently treated samples.

Sample code	Description
S1	Control sample (untreated)
S2	BTCA treatment on ungrafted sample
S3	MCT-β-CD-grafted sample
S4	DAP treatment on ungrafted sample
S5	BTCA treatment on MCT-β-CD-grafted sample
S6	BTCA and DAP treatment on ungrafted sample
S7	DAP treatment on MCT-β-CD-grafted sample
S8	BTCA and DAP treatment on MCT-β-CD-grafted sample

MCT-β-CD: monochlorotriazinyl-β-cyclodextrin; BTCA: 1,2,3,4-butane tetracarboxylic acid; DAP: diammonium phosphate.

Various tests and analyses were carried out to find out the effect of CD treatment on flammability and other properties. The FR behaviour of differently treated samples towards washing was determined as per AATCC 124 test method for 1, 5, 10, 20 and 40 washing cycles.

Physical properties

The weight of fabric was measured according to ASTM D3776-96 and reported in grams per square meter. The crease recovery angles (CRA) were determined according to ISO 2313:1972 test method and reported in degrees (°). Tensile strength testing of samples was determined by using Grab method, as per ISO 13934-2-1999 test method.

Aesthetic properties

The whiteness index was measured with the help of spectrophotometer using Premier colorscan software, according to AATCC 110-2000 test method. The flexural rigidity was tested by using KES-FB2-AUTO-A Pure bending tester and surface roughness was tested using KES-FB4-AUTO-A surface performance tester.

Morphological and chemical analyses

The surface morphological structures of samples were identified using a Cold Field Emission scanning electron microscope (Hitachi S-4700 FE-SEM). Fourier transform infrared analysis was performed on a Bio-Rad FTS-40 FTIR spectrophotometer.

Flammability and thermogravimetry analysis testing

Limiting oxygen index (LOI) is a method to determine the minimum oxygen concentration in an oxygen/nitrogen mixture that will sustain the flame. It is a convenient, reproducible and inexpensive way of determining the tendency of a material to sustain flame. LOI testing was carried out according to ASTM 2863 test method and reported in percentage (%). Vertical flammability test was conducted according to ISO 6940: 2004 test method and the char length and status of burning were reported in order to analyse the FR behaviour.Thermal analysis of the samples was done using thermogravimetry analyzer (TGA V5.1 A DUPONT 2000 model). For every 10% weight loss, the decomposition temperature was measured and analysed accordingly.

Performance testing

The evolution of smoke gas was analysed for differently treated samples to determine the maximum concentration during the test period for CO, CO₂, HCl, HCN, HF, HBr, SO₂ and NOX. The maximum concentration has been reported in parts per million (ppm), as per ASTM E 800 test method.

The formaldehyde releasing behaviour was determined according to ISO 14184-1:1998 test method and the formaldehyde releasing behaviour for differently treated samples was compared.

Results and discussion

The grafting yield of different CD was analysed using various parameters. The grafting yield increased linearly with increase in CD concentration but beyond 1.6%, the grafting yield was limited and further increase plays no significant role.

Figure 4 shows that α-CD and modified β-cyclodextrin give maximum grafting yield than do the other types under normal conditions (α, 2.7%; β, 0.3%; γ, 0.3% and MCT-β-CD, 2.7%). The maximum percentage of grafting was achieved using modified CD under normal processing conditions of cotton fabric (concentration 1.6%; pH, 11; MLR, 1:10; temperature, 90℃ and time, 40 min); this modified CD is analogous to those of reactive dyes and that may be the reason for higher grafting yield under normal conditions used for cotton.

Figure 4.

Percentage of grafting under optimised condition.

The experimental results presented in Figures 5 –9 indicate that there is a remarkable effect on the physical properties of the treated samples. In Figure 4, the reduction in the tensile strength of the fabrics (S2, S5, S6 and S8) is the result of cross-linking of cellulose molecules [18]. However, samples S4 and S7 also lose their strength due to the two factors: acid-catalysed cellulose depolymerisation and cross-linking [19]. The grafted sample shows only negligible fabric strength loss. The maximum strength loss of about 12% takes place in cross-linked sample and FR sample.

Figure 5.

Tensile strength of differently treated samples.

Figure 6.

Whiteness of differently treated samples.

Figure 7.

Crease recovery angle of differently treated samples.

Figure 8.

Flexural rigidity of differently treated samples.

Figure 9.

Surface roughness of differently treated samples.

Observing lower strength loss values in cross-linked fabrics is in accordance with the study by Xu and Li [20], who have used a cross-linking model to explain the reasons for the strength loss values as the formation of intermolecular and intramolecular cross-links reduces the possibility of equalizing the stress distribution that causes a reduction in the capacity to withstand load.

In Figure 6, the CD-grafted sample (S3) shows less changes in whiteness after grafting but samples S6 and S8 show maximum whiteness loss of about 11% and 12%, respectively; this reduction in whiteness is due to the presence of hydroxyl group, which is able to form >C = C< structure by dehydration during a curing process [21,22]. The reduction in whiteness took place as expected for the DAP-treated sample and BTCA-treated samples.

The formation of ester cross-links between cellulosic chains imparts crease resistance in cotton fabrics [23]. The CRA of the samples considerably increased for fabrics S2, S5 and S8 by about 11% due to the formation cross-linking by BTCA with the hydroxyl group of cellulose [24]. This observation is in tune with the findings of Welch and Peters [25] and Yang et al. [26] stating that the presence of hydroxyl groups hinders the cross-linking ability.

The hand value of the samples was measured in terms of flexural rigidity and surface roughness, as shown in Figures 8 and 9. The results reveal that the hand value of the CD-grafted sample (S3) was not affected but the FR finished sample’s roughness increase about 13%, which shows that the FR finished sample becomes little stiff. The results prove that CD treatment is not affecting the hand value of the treated sample.

Flammability and thermogravimetry analysis of the samples

Table 2 shows the LOI value of differently treated samples. The control cotton fabric (S1) does not have flame retardancy property and the LOI value lies as 17.5%. After treating the fabric with MCT-β-CD, the LOI values slightly increased since the CD act as carbon source and as charring agent [27]. In the result, it is observed that the LOI value of fabric S8 was the maximum compared with that of the DAP-alone finished sample (S4). The increasing FR behaviour is attributed to the combination of CD with acid resource DAP and/or blowing agent BTCA that exhibited outstanding char-forming ability. The FR-finished sample shows more LOI value before washing and it decreases beyond increasing the washing cycles due to non-permanency in nature [28]. However, the retention of flame retardance on the fabric is increased by forming a cross-linking with PCA [29]. The huge difference (67.5%) between the samples (S4 and S8) shows the retention of FR on the fabric even after 40 washing cycles. The difference in LOI value and retaining capacity may be explained as follows.

Table 2.

LOI of differently treated samples.

Sample code	LOI (%) value of samples after number of washing cycles
Sample code	0	1	5	10	20	40
S1	17.5	17.5	17	17	17	17
S2	18	18	18	17.5	17.5	17.5
S3	19	19	19	18.5	18.5	18.5
S4	32	31	28.5	25	22.5	18.5
S5	19	19	19	19	18.5	18.5
S6	33	31	31	30.5	26	24
S7	34	33	32	31	30	28
S8	35	35	35	34	33	31

LOI: limiting oxygen index.

The phosphorylation of –OH group of cotton/CD in sample 8 has caused intumescent formulations containing three active ingredients: (a)acid source (e.g. phosphate from DAP), (b) carbonization compound (e.g. starch derivative-CD) and (c) a blowing agent (bonding agent-BTCA). BTCA is able to esterify the hydroxyl groups of both cellulose and CD; however, cross-linked network is formed among BTCA/CD/DAP on cellulose.

The char length and burning time test results reveal the flame retardancy behaviour of differently treated samples, as shown in Tables 3 and 4, respectively. As discussed for the LOI value, the burning characteristics also differ among samples S1 to S8 due to the difference in the nature of flammability. The results whose status was observed as ‘completely burned’ denote that the fabric does not have flame retardancy and the CD-treated sample along with DAP (S7) and cross-linked sample along with DAP (S6) showed the status of suppressed combustion even after 40 washing cycles; But the sample (S8) shows excellent FR property due to the intumescent formulations among CD/DAP/BTCA.

Table 3.

Char length of differently treated samples.

Sample code	Char length (mm) after number of washing cycles
Sample code	0	1	5	10	20	40
S1	CB	CB	CB	CB	CB	CB
S2	CB	CB	CB	CB	CB	CB
S3	CB	CB	CB	CB	CB	CB
S4	46	48	53	63	79	90
S5	CB	CB	CB	CB	CB	CB
S6	45	48	49	54	56	72
S7	44	42	44	46	48	48
S8	44	44	46	46	47	49

CB: completely burned.

Table 4.

Burning time of differently treated samples.

Sample code	Time of burning (s) after number of washing cycles
Sample code	0	1	5	10	20	40
S1	23(CB)	23(CB)	22(CB)	22(CB)	21(CB)	21(CB)
S2	27(CB)	27(CB)	26(CB)	24(CB)	24(CB)	23(CB)
S3	24(CB)	23(CB)	24(CB)	22(CB)	23(CB)	22(CB)
S4	875(FR)	868(FR)	870(FR)	356(FR)	162(FR)	32(FR)
S5	26(CB)	26(CB)	25(CB)	25(CB)	26(CB)	26(CB)
S6	890(FR)	891(FR)	878(FR)	852(SC)	181(SC)	88(SC)
S7	879(FR)	875(FR)	871(FR)	860(FR)	452(SC)	235(SC)
S8	891(FR)	888(FR)	883(FR)	871(FR)	652(FR)	431(FR)

CB: continue burning; SC: slow and suppressed combustion; FR: flame retardant.

Nevertheless, the thermal stability of the differently treated samples was highly evidenced with the help of TGA analysis (Figure 10). The FR behaviour of cotton fabrics can be evaluated through the degradation nature of control and treated samples using thermogravimetry technique [30,31]. The control sample (S1) and β-CD-grafted sample (S2) lose weight drastically due to evaporation of moisture and after 350℃, decomposition starts. Nevertheless, the weight of the FR-finished sample (S3) decreases gradually at 280℃ and when heated above 400℃, the weight loss is minimum compared with the control sample.

Figure 10.

TGA: 1, control sample; 2, MCT-β-CD-grafted sample; 3, FR finshed sample; 4, cross-linked and inclusion compound formed sample.

The thermogravimetry graph reveals that the cross-linking and grafting onto cotton fabric followed by treatment with FR chemical (S4) increases the thermal stability of the fabric and hence imparts flame-retarding property.

The gases evolved during burning (Figure 11) and formaldehyde release (Table 5) of the differently treated samples were analysed and the result showed that the gas emitting level is more in the case of FR samples due to the combustible gases generated during burning [31]. The compounds that evolved such as CO, CO₂, HCl, HCN, HF, HBr, SO₂, NOX and HCHO were determined quantitatively for the differently treated samples and the results showed that the CD-inclusion compound formed samples (S7 and S8) emitted less amount of evolving gases and formaldehyde since CD is capable of masking the evolving gases. Due to this peculiar character of CD, the release of formaldehyde and emission of gases during burning were reduced, minimising their adverse effect on the environment. The free and released formaldehyde is high for samples S4 and S6 due to the presence of N-methylol groups in the FR. The results shown for the fabric treated with CD (S7) or with a combination of BTCA (S8) are in the same range, around 198 ppm, as was expected since CD has masking behaviour and BTCA has no influence on the formaldehyde releasing nature. The remaining samples (S1 to S3 and S5) did not show any detectable range of HCHO release behaviour.

Figure 11.

Determination of evolving of gases in differently treated samples.

Table 5.

Determination of HCHO release in differently treated samples.

Sample code	HCHO release (ppm)
S1	<30
S2	<30
S3	<30
S4	233
S5	<30
S6	230
S7	198
S8	199

Fourier transform infrared (FTIR) spectroscopic studies were made to confirm the cross-linking reaction and inclusion formation. FTIR analysis spectrum (Figure 12) of control fabric (S1) shows peaks at 3300 cm⁻¹ (intermolecular H-bonding), 2900 cm⁻¹ (CH₂ str.), 1840 cm⁻¹ (CH₂ bending) and 985 cm⁻¹ (anti-symmetric bridge C–O–C). β-CD-grafted cotton fabric (S2) produces a broad peak between 2800 and 3200 cm⁻¹ that is characteristic of –OH stretching of cellulose and –OH in-plane bending is shifted from 1450–1400 cm⁻¹ to 900–1000 cm⁻¹ since the –OH group of cellulose is linked with CD.FR cotton fabric (S3) shows peaks due to >C = O (980–1100⁻¹) and –N–H (1500–1956 cm⁻¹) and this is evident in the formation of ester groups as described by Huang et al. [32].

Figure 12.

FTIR analysis of the samples: 1, control sample; 2, MCT-β-CD-grafted sample; 3, FR finished sample; 4, cross-linked and inclusion compound formed sample.

Figure 13.

SEM analysis of the samples at 500 × 1, control sample; 2, MCT-β-CD-grafted sample; 3, FR finished sample; 4, cross-linked and inclusion compound formed sample.

The presence of specific peaks for a particular group in the finished cotton fabric confirms the formation of FR on the fibre. The fabric (4) bands at 2800 cm⁻¹ and 3300 cm⁻¹ caused due to inclusion of FR into β-CD and peaks between 1200 and 1606 cm⁻¹ characteristics of –OH bending, C–O stretching. The peak at 2245 cm⁻¹ corresponds to C–H stretching of CD. The stretching vibration (C = C) of aromatic moiety at 1606 cm⁻¹ proved the inclusion of FR into CD moiety. The band peak between 1200–1400 cm⁻¹ vibrations depicts for presence of phosphates as described by Ferraro & Krishnan [33].

Scanning electron micrographs are envisaged in a deposition of unevenly distributed particles through grafting, cross-linking and inclusion complex formation with FR on cotton fabric surface. The comparative SEM images of controlled sample and treated samples allow the visualization of presence of CD, FR and formed inclusion compound. The inclusion modifies the microscopic aspect of the treated samples. Thus, the inclusion complex and FR deposition combine chemically with the fibre to modify its intrinsic burning behaviour, as described by Chauhan et al. [34]. The comparative SEM images (Figure 13) of control sample (SEM 1) and CD-grafted sample (SEM 2), FR chemical-treated sample (SEM 3) and formed cross-linked and inclusion compound sample (SEM 4) allow the visualization of modified cellulosic fabrics. The inclusion modifies the microscopic aspect of the treated samples.

Conclusions

In this study, a viable method of grafting of MCT-β-CD compound on 100% cotton fabric was achieved. Its reproducibility was checked by triplicate method. Since the MCT-β-CD grafting conditions (1.6% concentration/90℃ /40 min/pH 11) bear a resemblance to normal processing conditions used for cotton fabric, this technique is not affecting the inherent characteristics of cotton fibre. The flammability, physical properties and aesthetic properties of differently treated fabrics (S1 to S8) were analysed and the results show that the newly formulated technique changes the hand value for acceptable quantity only. Ungrafted DAP-applied fabric (S4) exhibits effective flame retardancy up to 10 washing cycles but DAP applied on CD-grafted fabric (S7) showed durability up to 20 washing cycles. The BTCA treatment also influences the durability of DAP finish on CD-grafted fabric (S8) and it exhibits a better flame retardancy than fabric S7 and withstands up to 40 washing cycles. In this study, a semi-durable FR finishing was obtained through inclusion compound formation between CD and DAP (fabric S7) and the durable FR finishing was achieved with the help of BTCA on CD-grafted fabric using DAP (fabric S8), as confirmed using LOI testing and FTIR analysis. The changes of aesthetic value like whiteness, hand value and physical properties by the newly formulated technique are of negligible quantity only, when compared with regular FR finishing. The result reveals that the CD can be effectively used in FR finishing without affecting the hand and physical properties of the fabric. Nevertheless, the evolution of toxic gases during burning and the formaldehyde release in the FR-finished samples were minimised by CD treatment due to the masking behaviour of CD by its cavity. Hence, the grafting of MCT-β-CD is a novel, green route for the production of durable FR finish and it can be effectively used to produce multi-functional properties.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

References

Richard

Nazaré

Kandola

. The particular flammability hazards of nightwear. Fire Saf J 2004; 39(4): 259–276.

Hirschler

Piansay

. Survey of small-scale flame spread test results of modern fabrics. Fire Mater 2007; 31: 373–386.

Hardin

Hsieh

. The thermal conditions and pyrolysis products in flammability tests. Textile Chem Color 1985; 137: 41–46.

Yang

. Non-formaldehyde flame retardant finishing of the nomex/cotton blend fabric using a hydroxy-functional organophosphorus oligomer. JFire Sci 2007; 25(5): 425–446.

Blanchard

Graves

. Improving flame resistance of cotton/polyester fleece with phosphorous based polycarboxylic acids. AATCC Rev 2005; 5(5): 26–30.

Martel

Morcellet

Ruffin

. Capture and controlled release of fragrances by CD finished textiles. J Inclusion Phenom Macrocyclic Chem 2002; 44(1): 439–442.

Christine

Barker

Mischutin

. A flame retardant coating for textile application. J Ind Text 1977; 6: 182–188.

Mischutin

. Application of a clear flame retardant finish to fabrics. J Ind Text 1993; 22: 234–252.

George

Leitner

. New flame retardant - water repellent finish for tenting fabrics. J Ind. Text 1976; 6: 3–12.

10.

Giraud

Bourbigot

Rochery

. Flame behavior of cotton coated with polyurethane containing microencapsulated flame retardant agent. J Ind Text 2001; 31: 11–26.

11.

Uppal

Bhat

Akato

. Flame retardant antibacterial cotton high-loft nonwoven fabrics. J Ind Text 2012; 41: 281–291.

12.

Handermann

. Flame resistant barriers for home furnishings. J Ind Text 2004; 33: 159–177.

13.

Dombrowski

. Flame retardants for textile coatings. J Ind Text 1996; 25: 224–238.

14.

Le Blanc

. Flame-retarding outdoor fabrics. J Ind Text 1980; 10: 60–67.

15.

Yang Cand Wu

. Combination of a hydroxyalkyl-functional organophorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: Part II. Formation of calcium salt during laundering and its suppression. Fire Mater 2003; 27: 239–251.

16.

Moldenhauer JP and Reuscher H. Textile finishing with MCT-beta-cyclodextrin. In: Torres Labandeira JJ and Vila-Jato JL (eds) Proceedings of the 9th international symposium on cyclodextrins, 31 May–3 June 1998, Santiago de Compostela, Spain. Dordrecht: Kluwer Academic Publishers, 1999, pp.161.

17.

Szejtli J, Zsadon B, Fenyvesi E, et al. Hungarian patent 181733, USA, 1980.

18.

Kang

Yang

Weir

. Mechanical strength of durable finished cotton fabric. Textile Res J 1998; 68(11): 865–870.

19.

Kang

Yang

Wei

. Mechanical strength of durable press finished cotton fabrics. Part I: Effects of acid degradation and crosslinking of cellulose by polycarboxylic acids. Text Res J 1998; 68(11): 865–870.

20.

. Crosslinking analysis of PCA durable press finishing of cotton fabrics and strength retention improvement. Text Res J 2000; 70(7): 588–592.

21.

Yang

. Fabric yellowing caused by citric acid as a crosslinking agent for cotton. Text Res J 1999; 69(9): 685–690.

22.

Andrews

Blanchard

Reinhardt

. Fabric whiteness retention in durable press finishing with citric acids. Text Chem Color 1993; 25: 52–54.

23.

Qiu

Yang

. Wrinkle recovery angle and wrinkle recovery appearance rating for durable press finished cotton fabric. AATCC Rev 2005; 5: 34–38.

24.

Hashem

Hauser

Smith

. Wrinkle recovery for cellulosic fabric by means of ionic crosslinking. Text Res J 2003; 73: 762–766.

25.

Welch

Peters

. Additives for improved whiteness and DP performance with citric acid finishing. Text Chem Color 2000; 32: 37–41.

26.

Yang

Jiang

. Non formaldehyde durable press finishing of cotton fabrics by combining citric acid with polymers of maleic acid. Text Res J 1998; 68(5): 457–464.

27.

Feng

Zhu

. An intumescent flame retardant system using β-cyclodextrin as a carbon source in polylactic acid (PLA). Polym Adv Technol 2011; 22(7): 1115–1122.

28.

Hendrix

DrakeGL Reeves

. Effects of temperature on oxygen index values. Text Res J 1971; 41(4): 360–360.

29.

Xiangdong

Zhou

Kun

Chen

Hui

. Synthesis and application of a formaldehyde-free flame retardant for bamboo viscose fabric. Text Res J 2014; 84(14): 1515–1527.

30.

Abidi

Hequet

Ethridge

. Thermogravimetry analysis of cotton fibers: Relationships with maturity and fineness. J Appl Polym Sci 2006; 103: 3476–3482.

31.

Dahiya

Rana

. Thermal degradation and morphological studies on cotton cellulose modified with various arylphorodichloridites. Polym Int 2004; 53: 995–1002.

32.

Huang

Hwang

Chen

. Application of mixed gel solution in the anti-wrinkle finishing on cotton fabrics. J Text Inst 2006; 98(2): 169–176.

33.

Ferraro

Krishnan

. Practical Fourier infrared spectroscopy, New York: Academic Press, 1990, pp. 203–203.

34.

Chauhan

Bhavsar

Bhagwat

. SEM studies of the chars of flame-retardant treated fabrics. Text Res J 1981; 51(7): 477–480.