Effects of acid diffusibility and affinity to cellulose on strength loss of polycarboxylic acid crosslinked fabrics

Carbohydrate Polymers 144 (2016) 282–288

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Carbohydrate Polymers journal homepage: www.elsevier.com/locate/carbpol

Effects of acid diffusibility and affinity to cellulose on strength loss of polycarboxylic acid crosslinked fabrics Bolin Ji a,b , Cunyi Zhao b , Kelu Yan a,c,∗ , Gang Sun b,∗ a b c

College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, PR China Division of Textiles and Clothing, University of California, Davis, CA 95616, USA National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, Shanghai 201620, PR China

a r t i c l e

i n f o

Article history: Received 19 November 2015 Received in revised form 22 January 2016 Accepted 11 February 2016 Available online 26 February 2016 Keywords: Molecular size Diffusibility Affinity Anti-wrinkle Strength loss Chemical compounds studied in this article: Succinic acid (PubChem CID: 1110) Dichloroacetic acid (PubChem CID: 6597) Benzophenone-3,3 ,4,4 -tetracarboxylic dianhydride (PubChem CID: 75498) 1,2,3,4-Butanetetracarboxylic acid (PubChem CID: 15560) Sodium hypophosphite monohydrate (PubChem CID: 23708894) 2,4,6-Trihydroxybenzoic acid monohydrate (PubChem CID: 2723793) 3,4-Dihydroxybenzoic acid (PubChem CID: 72) Bromophenol blue (PubChem CID: 8272) Collodion (PubChem CID: 44135439)

a b s t r a c t 1,2,3,4-Butanetetracarboxylic acid (BTCA) imparts good anti-wrinkle property to cotton fabrics and results in significant strength loss due to cross-linking and acid degradation of cellulose simultaneously. However, benzophenone-3,3 ,4,4 - tetracarboxylic acid (BPTCA), an aromatic acid, crosslinks cellulose effectively but causes less strength loss to the products under similar conditions. The difference in damages to cellulose fibers was analyzed by using diffusibility and corresponding affinity of the acids to cellulose fibers, which were estimated by their molecular sizes and Hansen solubility parameters (HSP). Both experimental results and theoretical speculations revealed consistent agreement, indicating that smaller acid molecules could diffuse into cellulose fiber more rapidly and deeply, resulting in more acid degradation. Besides, the aliphatic acid such as BTCA has higher molecular affinity than BPTCA to cellulose, causing additional more degradation of cellulose. Both factors are potential reasons of the observed more severe tensile strength loss of the BTCA treated cotton fabrics. © 2016 Elsevier Ltd. All rights reserved.

1. Introduction Esterification of polycarboxylic acids with cellulose can form cross-linking bridges between celluloses and can be applied in antiwrinkle finishing of cotton fabrics (Welch, 1988; Yang, 2001). It has been proved that 1,2,3,4-butanetetracarboxylic acid (BTCA), an model aliphatic polycarboxylic acid, reacts with cellulose by first formation of its intermediate anhydrides (Yang and Wang, 1996) and then esterification of the anhydrides with cellulose. The roles

∗ Corresponding authors. E-mail addresses: [email protected] (K. Yan), [email protected] (G. Sun). http://dx.doi.org/10.1016/j.carbpol.2016.02.036 0144-8617/© 2016 Elsevier Ltd. All rights reserved.

of catalysts in the reactions were also clarified in the previous studies (Ji, Qi, Yan, & Sun, 2015; Ji, Tang, Yan, & Sun, 2015; Peng, Yang, & Wang, 2012; Yang, 2001). However, the severe strength loss of the treated fabrics is a main hurdle to its practical application. There are two major reasons accounting for the strength loss in the crosslinked cellulose by polycarboxylic acids: ester cross-linking between acid and cellulose and acidic degradation of cellulose macromolecules (Kang, Yang, Wei, & Lickfield, 1998). In our previous studies, the catalytic actions of alkaline salt catalysts were investigated in details (Ji, Qi et al., 2015; Ji, Tang et al., 2015). Results indicated that large alkaline metal ion accelerates the formation of anhydrides by BTCA, and catalyst anion assists the esterification between anhydrides and cellulose. On the other side,

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pH value of finishing baths, which affects concentrations of corresponding acid anion and metal cation of the catalyst salt, shows important impact on both reactions of anhydride formation and esterification. Obviously, pH of the finishing bath will affect the strength loss of the treated fabrics by damaging cellulose. Yang et al. have investigated and identified the effects of pH and molecular flexibility of finishing reagents on the strength loss (Chen, Lickfield, & Yang, 2004; Kang et al., 1998; Yang, Wei, & Lickfield, 2000). Higher pH and larger molecular flexibility could be beneficial to strength retention of the treated fabrics. However, recent studies revealed that aromatic acids, such as benzophenone-3,3 ,4,4 -tetracarboxylic acid (BPTCA), could achieve the similar anti-wrinkle property on the fabrics but always cause lower tensile strength losses than aliphatic polycarboxylic acid does under similar conditions. Furthermore, aromatic acids are more acidic than aliphatic ones due to the chemical structural features under the same concentration in solutions. This disparity in damaging cellulose by the two types of acids is difficult to understand if only the impact of pH value is considered, but is worth of further investigation. One difference of the polycarboxylic acids lies at their molecular volumes or sizes, which could affect the diffusion of the chemicals into the cellulose fiber, one kind of polymers (Hansen and Hansen, 1988). Besides, both acids are dissolved in water, and are absorbed onto cotton fibers and finally diffuse into the fiber (Hou and Sun, 2013; Ji, Tang et al., 2015). Here, acids with great affinity to cellulose may diffuse rapidly into cellulose and also closely interfere with cellulose. Therefore, the interactions between the acids and cellulose should also have an impact on the strength loss of the treated fabrics, while the affinity of the acids with cellulose could be evaluated by analyzing their structural similarity. With the purpose of further understanding the reasons of mechanical strength loss of the anti-wrinkle fabrics treated by polycarboxylic acids, the effects of molecular volumes (MV) and Hansen solubility parameters (HSP) of the acids were investigated in this research. MV and HSP of acids were calculated by ChemDraw14.0 software to compare their diffusibility in the cellulose fibers and by HSPiP 4.1.07 software to compare their affinity to the cellulose, respectively. Besides, Fourier transform infrared (FTIR) spectroscopy was also used in the analysis of the relationship between wrinkle recovery angle and ester cross-linking. 2. Experiment 2.1. Materials Desized, scoured, and bleached pure cotton fabrics (#400) were obtained from Test Fabrics, Inc. (West Pittston, PA). Succinic acid (SUA), dichloroacetic acid (DCAA), benzophenone3,3 ,4,4 -tetracarboxylic dianhydride (BPTCD), sodium hypophosphite monohydrate (SHP) and glycerol were purchased from Sigma–Aldrich Co. (St Louis, USA). 1,2,3,4-Butanetetracarboxylic acid (BTCA), 2,4,6-trihydroxybenzoic acid monohydrate (2,4,6THBA, 95%), 3,4-dihydroxybenzoic acid (3,4-DHBA) and bromophenol blue were all purchased from Acros (New Jersey, USA). Sodium hydroxide (NaOH) was from EMD chemical Inc. (New Jersey, USA). Collodion (5%) was purchased from Electron Microscopy Sciences (Hatfield, USA). All chemicals were directly used as received. 2.2. Fabric treatment Fabrics were soaked in a solution of acid with or without catalyst and were padded twice with a wet pickup of ∼120%. The carboxyl concentrations were kept same for comparison, and catalyst was used at a 0.5 mole ratio to the amount of the acid. After being dried at 80 ◦ C for 5 min, they were cured at 160 ◦ C for 3 min. And then

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they were washed in tap water at the room temperature for 10 min to eliminate the residual finishing agents and catalysts. 2.3. Wrinkle recovery angle (WRA) and tensile strength retention (TSR) WRA and TSR of fabrics were measured according to the American Association of Textile Chemists and Colorists (AATCC) 66-1990 method and the American Society for Testing and Materials (ASTM) D 5035-06 method, respectively. WRA was measured by a wrinkle recovery tester (T.J. Edwards Inc., Boston, USA), and TSR was measured by an Instron 5566 instrument (Instron Corporation, MA, USA). For samples to be alkaline washed, treated fabrics were soaked in a 0.1 mol/L NaOH solution for 24 h at 50 ◦ C to completely destroy the cross-linking between acid and cellulose. 2.4. FTIR Before FTIR evaluation, treated fabrics were washed in a 0.1 mol/L NaOH solution for 4 min at room temperature, and dried at 80 ◦ C for 5 min. They were cut into powders, weighed accurately for 2.0 mg, and then mixed with 200.0 mg potassium bromide (KBr) to be pressed into a pellet. FTIR spectroscopy was measured by a Nicolet 6700 FTIR spectrometer (Thermo Electron Co., USA) in absorbance mode for all the samples in the range of 4000–400 cm−1 , and scan times and resolution were 64 and 4 cm−1 , respectively. Ester bond absorbance intensity at 1724 cm−1 (Yang, 1991; Yang, 1993a) was normalized against the absorbance intensity of 2900 cm−1 , due to the C H stretching vibration (Hou and Sun, 2013; Lam, Kan, & Yuen, 2011). 2.5. Optical microscopy Treated fabrics were cut by fiber slicing machine (Delarue Hyattsville, USA), and cross-section samples were put on the microscope slide with a drop of glycerol. And then a drop of bromophenol blue solution was dropped onto the sample. Samples were measured by a Motic microscope and the pictures were captured by a Dinoeye eyepiece camera AM-4023 (The Microscope Store, LLC, VA, USA) with a Dinocapture 2.0 software. 2.6. Molecular size by ChemDraw14.0 ChemDraw14.0 software was used to calculate the molecular volume (Álvarez and Aznar, 2008). Firstly, the molecules were processed by MM2 Minimize Energy program, and then by the Connolly solvent excluded volume program. The radius (r) of the acid was calculated based on V=

4 3

r 3

(1)

where V is the Connolly solvent excluded volume of an acid. 2.7. Hansen solubility parameters (HSP) (Hansen, 2007) HSP of various acids were calculated by HSPiP 4.1.07 software according to Y-MB method, and HSP of water or cellubiose were obtained from the database in the software. The distance between acid and water or cellulose was calculated based on 2

2

2 1/2

Ra = [4(ıD ) + (ıP ) + (ıH ) ]

(2)

where ıD is the energy from dispersion forces between molecules, ıP is the energy from dipolar forces between molecules, and ıH is the energy from hydrogen bonds between molecules.

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Fig. 1. WRA and filling direction TSR results of fabrics treated by BTCA or BPTCA without any catalyst. Note: The WRA of control fabric is 205.1◦ . Before and after separately means treated fabrics were washed without or with NaOH solution as described in Section 2.3. * The pH 2.10 of BPTCA solution was adjusted by 10 M NaOH solution.

Fig. 2. FTIR spectra of fabrics treated by BTCA and BPTCA without any catalyst: (a) BTCA (pH 2.10); (b) BPTCA (pH 1.35); (c) BPTCA (pH 2.10).

3. Results and discussion 3.1. Properties of treated fabrics Both 1,2,3,4-butanetetracarboxylic acid (BTCA) and benzophenone-3,3 ,4,4 ,- tetracarboxylic acid (BPTCA) could crosslink cotton cellulose and simultaneously cause damages to the treated fabrics. But the damage levels caused by both acids are significantly different. The reaction mechanisms of BTCA and BPTCA with cellulose are different. BPTCA crosslinks cellulose by a direct esterification mechanism without formation of anhydride due to its nature of aromatic acid, while acid anhydride is a necessary intermediate in the reaction between aliphatic acid (BTCA) with cellulose (Hou and Sun, 2013; Ji, Tang et al., 2015). Both reactions are catalyzed by the same catalyst under similar conditions (Zhao and Sun, 2015). So, the difference in tensile strength loss may be introduced by the two different kinds of acids. To investigate the causes of the disparity in tensile strength losses resulted by aliphatic and aromatic polycarboxylic acids, BTCA and BPTCA were both employed to treat fabrics under controlled conditions. Firstly, fabrics were treated without catalysts, and the carboxyl concentration in the finishing bath was 0.62 mol/L. Interestingly, at the same pH (pH 2.10) and without any catalyst, filling direction tensile strength retention (TSR) of the fabrics treated by BPTCA was equal to that of BTCA without alkaline washing, though the sample treated by BPTCA showed higher WRA value (Fig. 1). After alkaline washing, both treated fabrics exhibited changes in TSR due to the fact that the ester cross-linking could be destroyed and the tensile strength loss caused by the cross-linking effect could be released (Yang et al., 2000). The existing strength loss of the alkaline washed fabrics should be only caused by the acid damages, since acidic degradation could not recover after the cross-linking were removed (Kang et al., 1998; Yang et al., 2000). The results reveal that the strength losses as a result of the acidic degradation were 8.22% and 26.70% for the fabrics treated by BPTCA and BTCA without use of any catalyst, respectively, confirming that BTCA caused more damages to cellulose even under the same pH condition. However, at lower pH 1.35, BPTCA treated fabrics show much lower TSR due to severe acidic degradation. In order to explain the relationship between WRA and crosslinking (or ester bond), the treated fabrics were measured by FTIR as presented in Fig. 2. The absorbance peaks at 3346 cm−1 and 2900 cm−1 are separately attributed to the O H stretching vibration and the C H stretching vibration in the cellulose (Sayın, Can,

Fig. 3. WRA and filling direction TSR of treated fabrics by BTCA or BPTCA with SHP catalyst.

I˙ mamo˘glu, & Arslan, 2015; Yang, Yan, Chen, Lee, & Zheng, 2007). It indicates that the fabrics treated by BPTCA at pH = 2.10 (Fig. 2c) shows the strongest ester bond absorbance at 1724 cm−1 (Can, Bulut, Örnek, & Özacar, 2013; Yang et al., 2007), matching with the highest WRA in Fig. 1. And the increasing trend of ester bond absorbance (Fig. 2a–c) is in consistence with that of WRA of treated fabrics (Fig. 1). This confirms that higher WRA means more crosslinking between acid and cellulose, resulting in more strength loss of the fabrics. The small peak at 1609 cm−1 due to the plane deformation vibrations of the C H bond in benzene rings (Can et al., 2013) only appears in the spectra of BPTCA treated fabrics. The absorbance at 1583 cm−1 is correlated to the carboxylate ( COO ) absorbance converted from the carboxyl after alkaline washing (Yang, 1993a). The absorbance bands at 1162 and 900 cm−1 are due to the saccharine structure (Cheng et al., 2003). The WRA and TSR results of fabrics treated by these two acids also indicated that BTCA is more dependent on the catalyst in crosslinking cellulose than BPTCA does. The same fabrics were treated by both acids (same carboxyl concentration at 0.62 mol/L) in the presence of SHP catalyst (0.5 mole ratio to acid), respectively. Results of WRA and TSR of the fabrics are presented in Fig. 3. Compared with the finishing conditions without catalyst (Fig. 1), pH of finishing bath increases in the presence of SHP due to the weak alkalinity of the catalyst (Fig. 3). However, under the same pH (pH 2.25) condition, the filling direction TSR of the BTCA treated

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fabrics still exhibited the lower values in comparison to that of the samples treated by BPTCA with or without alkaline washing, though most of the TSR values were higher than those without the SHP catalyst. The WRA values of the treated samples with the catalyst were higher than those without catalyst but the trends were similar, again due to the catalyst effect. The improved TSR and WRA values under the higher pH with the addition of the catalyst indicate the importance of the catalyst in the reaction (Kang et al., 1998; Yang, 1993b). However, the difference in TSR of the treated fabrics by BPTCA and BTCA under the same pH values cannot be explained so far. 3.2. Effects of molecular size on strength loss Based on the above results (Figs. 1 and 3), other than pH solution and cross-linking effect between polycarboxylic acids and cellulose, there must be other factors that affect the tensile strength of the treated fabrics. From the point of view of acid chemical structures, their molecular sizes are very different, which could have an influence on their diffusion into the inner part of the cellulose fiber. Therefore, molecular volumes of the selected acids were calculated according to the method described in Section 2.5, and molecular radii of the acids were calculated based on Eq. (1). Diffusion coefficient, D, of a compound can be calculated (Fernandez, Ying, Albanesi, & Anderson, 2002; Li, Kagan, Hopson, & Williard, 2009) according to D=

1 f

kT

(3)

where f is frictional coefficient, k is Boltzmann’s constant, and T is absolute temperature. f can be calculated by using the Stokes equation: f = 6r

(4)

where  is viscosity of cellulose, and r is radius of sphere of a compound. The value of f calculated for a sphere is a minimal value, and asymmetric shape of molecule or non-elastic interaction with solvent (e.g., hydration) will increase f. Based on Eqs. (3) and (4), the diffusion coefficient ratio (R) of diffusion coefficients D1 (BTCA) and D2 (BPTCA) can be expressed as following R=

r2 D1 = D2 r1

(5)

where r1 and r2 are separately the molecular radius of BTCA and BPTCA in Table 1. Thus, the calculated R value is about 1.1. The molecular volume of BPTCA is much larger than that of BTCA (Table 1) and the radius of the molecule is larger too. So according to Eqs. (3) and (4), the diffusion coefficient (D) of BPTCA will be smaller than that of BTCA. In order to estimate the diffusion depths of the acids into the cellulose fiber, cross sections of the treated fibers were observed by using an optical microscope. Bromophenol blue was used as an indicator, since blue color can be observed where the acid diffuses to. For each fiber, three positions in the cross section were measured and averaged as the diffusion depth of the acid as shown in Fig. 4. And the average value of diffusion depths of three fibers in different view fields was measured as the final diffusion depth of the acid in the fiber. The observed diffusion average depths are 5.4 ␮m for BTCA and 4.9 ␮m for BPTCA, respectively. The testing results and the calculated R value based on Eq. (5) can confirm that BTCA diffused deeper into cellulose fibers and consequently could crosslink and interact with more cellulose inside the fibers than BPTCA did. Thus, the potential acid damages to the cellulose caused by BTCA could be more significant, resulting in lower TSR of the BTCA treated fabrics. Yang also reported the similar results that the total strength

Fig. 4. Optical microscope images of cross sections of dyed fibers: (a) control; (b) BTCA treated fabrics; (c) BPTCA treated fabrics.

loss of the fabrics treated by BTCA was more under the similar WRA than that by all-cis-1,2,3,4-petanetetracarboxylic acid without analyzing their differences in diffusibilities (Yang et al., 2000). More interestingly, it was noticed that the diffusion depth ratio of BTCA and BPTCA into the cellulose fiber is also about 1.1, which equals to the diffusion coefficient ratio R or the reciprocal of molecular radius ratio. Thus, it is proposed that the diffusion depth of polycarboxylic acid into the cellulose fiber may be an inverse linear relationship with the acid radius, i.e., the smaller the acid radius is, the deeper level the acid will diffuse into the cellulose fiber.

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Table 1 pKa 1 values (Haynes, 2013) and molecular sizes of acids. Acid

pKa 1

Carboxyl concentration (mol/L)

Molecular volume (Å3 )

Molecular radius (Å)

BTCA BPTCA SUA 3,4-DHBA DCAA 2,4,6-THBA

3.43 2.39 4.21 4.48 1.35 1.68

0.62 0.62 0.13 0.13 0.11 0.11

175.7 233.7 69.0 104.5 75.9 111.8

3.5 3.8 2.5 2.9 2.6 3.0

Table 2 HSP of different acids and Hansen distances to water (Ra1) and cellubiose (Ra2) (25 ◦ C). Acid

BTCA BPTCA DCAA 2,4,6-THBA SUA 3,4-DHBA H2 O Cellubiose

Fig. 5. Filling direction TSR of fabrics treated by different acids.

To support the above analysis, several monocarboxylic acids (about 0.1 mol/L) were selected to treat the cotton fabrics with intention to further demonstrate the impacts of molecular sizes on the tensile strengths of the treated fabrics. Their property parameters are presented in Table 1. All these acids, due to the nature that monocarboxylic acids are unable to crosslink celluloses, the strength loss of the treated fabrics should be purely due to the acid degradation of cellulose. Fig. 5 indicates that at very similar pH condition for different acid solutions, TSR value of the fabric treated by 2,4,6-THBA is about two times higher than that by DCAA, and TSR value of the fabric treated by 3,4-DHBA is also much higher than that by SUA. Here, the tensile strength losses of the treated fabrics are purely caused by acid damage to cellulose. These results are consistent with the assumption that large size molecules would cause lower damages to cellulose (Yang et al., 2000) due to the difference in diffusion distances in the fibers. 3.3. HSP effects of acids on strength loss More interestingly, the strength loss of BPTCA treated fabrics at much lower pH (1.69) were close to that of BTCA treated ones at higher pH value (pH 2.25) (Fig. 3). Similarly, although pH of 2,4,6THBA solution is much lower, TSR of its treated fabric is a little higher than that of the SUA treated one (Fig. 5). Here, such a disparity in TSR cannot be explained by using the diffusion difference of the chemicals in the fibers. However, when acids interact with cellulose, their affinity to cellulose may determine their reactivity as well, such a case may also occur in the anti-wrinkle finishing process. If an acid has high affinity to cellulose chains, it will be more attractive to cellulose and possibly more reactive with it, causing more damages to the chains as well. Now we would like to use Hansen solubility parameter as a tool to illustrate the interaction levels of acids and cellulose. HSP distances (Ra values) were used to characterize the affinity of an acid to cellulose and to water. Since the HSP of cellulose is difficult to get and the degradation of

HSP (MPa1/2 )

Ra1 (MPa1/2 )

ıD

ıP

ıH

18.1 22.5 17.7 20.2 17.4 20.3 15.5 15.6

12.2 12.3 8.8 10.7 10.3 8.9 16.0 17.2

26.8 9.3 14.5 26.0 22.1 18.7 42.3 20.4

16.8 36.0 29.1 19.6 21.3 26.5 0 21.9

Ra2 (MPa1/2 )

9.5 18.4 11.1 12.6 8.0 12.7 21.9 0

cellulose is mainly the breakage of glycoside bond, cellubiose was selected as the model of cellulose to calculate the HSP distance. Table 2 shows that Ra1 values of both BPTCA and BTCA are higher than their Ra2 values, indicating that both are more interactive with cellubiose than with water. Ra2 of BTCA (9.54) is much smaller than that of BPTCA (18.38), meaning that BTCA is structurally closer to or more interactive with cellubiose. The larger Ra2 of BPTCA reflects its weaker affinity to cellubiose and furthermore weaker ability to interact or degrade cellulose. Similarly, the Ra2 of 2,4,6-THBA is larger than that of SUA, well explaining the lower TSR of the SUA treated fabric (Fig. 5). The Ra2 differences between DCAA and 2,4,6THBA or between SUA and 3,4-DHBA are also in consistence with the TSR results in Fig. 5. Thus, we believe that both the difference of diffusion coefficients of the large polycarboxylic acid and its affinity to cellulose contribute to the disparity in tensile strength losses of the polycarboxylic acid treated fabrics. Another possible reason is that the acid with a lower pKa 1 value (Table 1) is easier to ionize more protons to depolymerize the cellulose and cause more strength loss to the treated fabrics (Kang et al., 1998). Temperature has a significant impact on diffusion coefficient D (Eq. (3)) and HSP of a compound (Hansen, 2007). Here, Hansen distances of different acids to water and to cellubiose are calculated at different temperatures. Results are presented in Fig. 6. Overall, when temperature increases from 25 ◦ C to 60 ◦ C (Fig. 6a), the Hansen distances of different acids to water (Raw ) all decrease rapidly, meaning increasing affinity of the acids to water. However, further increase in temperature from 60 ◦ C to 180 ◦ C did not cause more reduction in Raw values. Generally speaking, Raw value of an aromatic acid, such as BPTCA, is much higher than that of corresponding aliphatic acid such as BTCA in water. Thus, BPTCA may need an elevated temperature to have an increased solubility in water. The Hansen distances of different acids to cellubiose (Rac ) decrease steadily with temperature increasing from 25 ◦ C to 180 ◦ C (Fig. 6b), which is a little different from Raw . Rac values of the aromatic acids are higher, indicating their lower affinity to cellubiose than those of the aliphatic acids. As a result, the strength loss, due to acid degradation, of the fabrics treated by the aromatic acids could be much less than that treated by the aliphatic ones. Such a speculation based on the affinity of acids to cellulose is consistent with the results in Figs. 1, 2 and 5. In addition, to further investigate the effects of affinity of acids to cellulose estimated by using HSP distances of acids to cellubiose on

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is close to the value of 85.18% treated by SUA at 160 ◦ C. This may be due to the higher Rac of 3,4-DHBA at 180 ◦ C than that at 160 ◦ C or its lower affinity to cellulose, which also supports the speculation that the affinity of the acid to cellulose has an impact on the strength loss of the treated fabrics. 4. Conclusion Tensile strength loss of anti-wrinkle fabrics treated by polycarboxylic acids is a result of cross-linking and acidic degradation of cellulose chains. More cross-linking of cellulose is beneficial to increase wrinkle recovery angle, but can cause more strength loss to the treated fabrics. Among these acids, aromatic and large acids cause less strength loss to the treated fabrics at the same or even lower pH. The study revealed that aliphatic acids could diffuse into the deeper section of the fibers due to smaller molecular sizes, form more cross-linking, and consequently damage cellulose in deeper level. Besides, selected acids with different molecular sizes also proved this phenomenon. Moreover, the affinity of the acid to cellubiose also has an effect on the strength loss, which could be reflected by calculating the Hansen solubility parameters of the acids. Acids with smaller Hansen distances to cellulose have better affinity to and would cause more damage to the polymer, resulting in lower TSR of the treated fabrics. Temperature could affect the diffusion coefficient of an acid into the cellulose fiber, and affect the Hansen solubility parameters of an acid or its affinity to cellulose. Acknowledgement This research was supported by the Chinese National Science and Technology Support Program (No. 2012BAE11G00) and the Graduate Student Degree Thesis Innovation Foundation Projects of Donghua University (CUSF-DH-D-2015092). Besides, Bolin Ji is grateful for the Outstanding Graduate Student Scholarship Fund of Donghua University and for the financial support from Cotton Incorporated, USA. We also appreciate the assistance of Peixin Tang in collecting the data of experiments. References

Fig. 6. Hansen distances of different acids to water (a) and to cellubiose (b), and the TSR results of fabrics cured for 3 min under different temperatures (c).

the strength loss of the treated fabrics, SUA and 3,4-DHBA were selected to treat fabrics under 180 ◦ C curing temperature. Compared with that cured at 160 ◦ C, TSR of the fabrics cured at 180 ◦ C is lower for the same acid. However, the TSR of the fabrics treated by 3,4-DHBA is as high as 83.19% at 180 ◦ C, much higher than 68.32% for the sample treated by SUA at the same temperature (Fig. 6c), and

Álvarez, V. H., & Aznar, M. (2008). Thermodynamic modeling of vapor-liquid equilibrium of binary systems ionic liquid + supercritical {CO2 or CHF3 } and ionic liquid + hydrocarbons using Peng-Robinson equation of state. Journal of the Chinese Institute of Chemical Engineers, 39(4), 353–360. Can, M., Bulut, E., Örnek, A., & Özacar, M. (2013). Synthesis and characterization of valonea tannin resin and its interaction with palladium(II), rhodium(III) chloro complexes. Chemical Engineering Journal, 221, 146–158. Chen, W., Lickfield, G. C., & Yang, C. Q. (2004). Molecular modeling of cellulose in amorphous state part II: effects of rigid and flexible crosslinks on cellulose. Polymer, 45(21), 7357–7365. Cheng, M., Deng, J., Yang, F., Gong, Y., Zhao, N., & Zhang, X. (2003). Study on physical properties and nerve cell affinity of composite films from chitosan and gelatin solutions. Biomaterials, 24(17), 2871–2880. Fernandez, I., Ying, Y., Albanesi, J., & Anderson, R. G. (2002). Mechanism of caveolin filament assembly. Proceedings of the National Academy of Sciences of the United States of America, 99(17), 11193–11198. Hansen, C. M. (2007). Hansen solubility parameters: a user’s handbook (2nd ed.). Boca Raton: CRC Press. Hansen, C. M., & Hansen, K. M. (1988). Solubility parameter prediction of the barrier properties of chemical protective clothing. In S. Z. Mansdorf, R. Sager, & A. P. Nielsen (Eds.), Performance of protective clothing: second symposium, ASTM STP 989 (pp. 197–208). Philadelphia, PA: American Society for Testing and Materials. Haynes, W. M. (2013). CRC handbook of chemistry and physics (94th ed., pp. 5–93). Boca Raton: CRC Press. Hou, A., & Sun, G. (2013). Multifunctional finishing of cotton fabrics with 3,3 ,4,4 benzophenone tetracarboxylic dianhydride: reaction mechanism. Carbohydrate Polymers, 95, 768–772. Ji, B., Qi, H., Yan, K., & Sun, G. (2015). Catalytic actions of alkaline salts in reactions between 1,2,3,4-butanetetracarboxylic acid and cellulose: I. Anhydride formation. Cellulose, http://dx.doi.org/10.1007/s10570-015-0810-0 Ji, B., Tang, P., Yan, K., & Sun, G. (2015). Catalytic actions of alkaline salts in reactions between 1,2,3,4-butanetetracarboxylic acid and cellulose: II Esterification. Carbohydrate Polymers, 132, 228–236.

288

B. Ji et al. / Carbohydrate Polymers 144 (2016) 282–288

Kang, I.-S., Yang, C. Q., Wei, W., & Lickfield, G. C. (1998). Mechanical strength of durable press finished cotton fabrics part I: effects of acid degradation and crosslinking of cellulose by polycarboxylic acids. Textile Research Journal, 68(11), 865–870. Lam, Y. L., Kan, C. W., & Yuen, C. W. M. (2011). Physical and chemical analysis of plasma-treated cotton fabric subjected to wrinkle-resistant finishing. Cellulose, 18, 493–503. Li, D., Kagan, G., Hopson, R., & Williard, P. G. (2009). Formula weight prediction by internal reference diffusion-ordered NMR spectroscopy (DOSY). Journal of the American Chemical Society, 131(15), 5627–5634. Peng, H., Yang, C. Q., & Wang, S. (2012). Nonformaldehyde durable press finishing of cotton fabrics using the combination of maleic acid and sodium hypophosphite. Carbohydrate Polymers, 87(1), 491–499. Sayın, M., Can, M., I˙ mamo˘glu, M., & Arslan, M. (2015). 1,3,5-Triazine-pentaethylenehexamine polymer for the adsorption of palladium(II) from chloride-containing solutions. Reactive and Functional Polymers, 88, 31–38. Welch, C. M. (1988). Tetracarboxylic acids as formaldehyde-free durable press finishing agents. Part I: catalyst, additive, and durability studies. Textile Research Journal, 58(8), 480–486. Yang, C. Q. (1991). FT-IR spectroscopy study of the ester crosslinking mechanism of cotton cellulose. Textile Research Journal, 61(8), 433–440.

Yang, C. Q. (1993a). Infrared spectroscopy studies of the effects of the catalyst on the ester cross-linking of cellulose by poly(carboxylic acids). Journal of Applied Polymer Science, 50(12), 2047–2053. Yang, C. Q. (1993b). Effect of pH on nonformaldehyde durable press finishing of cotton fabric: FT-IR spectroscopy study. Part I: ester crosslinking. Textile Research Journal, 63(7), 420–430. Yang, C. Q. (2001). FTIR spectroscopy study of ester crosslinking of cotton cellulose catalyzed by sodium hypophosphite. Textile Research Journal, 71(3), 201–206. Yang, C. Q., & Wang, X. (1996). Infrared spectroscopy studies of the cyclic anhydride as the intermediate for the ester crosslinking of cotton cellulose by polycarboxylic acids. II. Comparison of different polycarboxylic acids. Journal of Polymer Science Part A: Polymer Chemistry, 34(8), 1573–1580. Yang, C. Q., Wei, W., & Lickfield, G. C. (2000). Mechanical strength of durable press finished cotton fabric. Part II: comparison of crosslinking agents with different molecular structures and reactivity. Textile Research Journal, 70(2), 143–147. Yang, H., Yan, R., Chen, H., Lee, D. H., & Zheng, C. (2007). Characteristics of hemicellulose, cellulose and lignin pyrolysis. Fuel, 86(12), 1781–1788. Zhao, C., & Sun, G. (2015). Catalytic actions of sodium salts in direct esterification of 3,3 ,4,4 -benzophenone tetracarboxylic acid with cellulose. Industrial & Engineering Chemistry Research, 54(43), 10553–10559.