Effect of Structures and Concentrations of Softeners on the

2502

Ind. Eng. Chem. Res. 2008, 47, 2502-2510

Effect of Structures and Concentrations of Softeners on the Performance Properties and Durability to Laundering of Cotton Fabrics Narendra Reddy,† Abdus Salam,† and Yiqi Yang*,†,‡,§ Department of Textiles, Clothing and Design, Department of Biological Systems Engineering, and Nebraska Center for Materials and Nanoscience, 234 HECO Building, UniVersity of NebraskasLincoln, Lincoln, Nebraska 68583-0802

This paper provides a comparison of the performance of eight industrial softeners using equal amounts of softeners and also at three different manufacturers recommended concentrations before and after five home laundering cycles. Four non-siloxane softeners containing anionic, non-ionic, cationic, and non-ionic polyethylene groups and four siloxanes containing reactive, nonreactive, primary, and tertiary aminofunctional groups were evaluated. The eight softeners were padded on to 100% cotton fabrics and the changes in the tear strength, abrasion resistance, flexibility, whiteness, and hydrophylicity of the fabrics were studied. The performance of the softeners before and after laundering in terms of changes (increase/decrease or no change) in fabric properties has been explained based on the concentrations and structure of the softeners used. This study shows that the extent to which a softener improves or affects fabric properties are influenced by the structure, the add-on, and the ability of the softener to be retained after laundering. Laundering caused a substantial decrease in fabric properties compared to the properties of the softener treated fabrics before laundering. All the softener-treated fabrics had greater loss in tear strength and whiteness index after laundering compared to the loss in abrasion resistance and flexibility. Overall, the aminofunctional softeners have better improvement and retention of properties among the softeners studied. 1. Introduction Softeners are mainly used to improve the hand and strength but could affect the whiteness and hydrophylicity of fabrics.1-13 A number of studies have been conducted to understand the influence of softeners on fabric properties and the mechanism of softening textile fabrics.1-10,14 Most of these studies have analyzed the influence, advantages, and disadvantages of a particular class of softener, especially the siloxanes, on fabric properties. Studies have also been conducted on the durability and influence of home laundering softeners on fabric properties.11-13 Previous studies on softeners provide information on the durability and efficiency of a particular type of softener on a particular type of substrate. These studies have shown that softeners have positive attributes such as increasing strength, abrasion resistance, and softness of fabrics, but softeners may also decrease the whiteness and water absorbency of the treated fabrics. Differences in the chemical composition of softeners, amount of softener, type of substrates, and application and evaluation methods used in previous studies make comparison between studies unreliable. On the basis of our knowledge, there are no studies comparing the performance of softeners before and after laundering using similar % add-on on the fabrics. It is generally accepted that siloxanes provide the best softness among the softeners currently used in the textile industry.6 The better performance of siloxanes is due to their extremely flexible backbone structure, high heat stability, and reduced friction.6,15 Siloxanes are broadly classified as nonreactive, reactive, and organofunctional.4 Of the three classes, organofunctional siloxanes provide better softness than the other two classes of * To whom correspondence should be addressed. Phone: (402) 4725197. Fax: (402) 472-0640. E-mail: [email protected]. † Department of Textiles, Clothing and Design. ‡ Department of Biological Systems Engineering. § Nebraska Center for Materials and Nanoscience.

siloxanes.4,5 Further, increasing the number of amine groups in the organofunctional siloxanes provides better properties such as reduced friction and increased whiteness, water absorbency, and soil release.5,6 Therefore, knowing the chemical composition, structure, and properties will be critical in choosing the best softener for a particular type of fabric intended for a particular end-use. Several methods of classifying softeners are in practice to recognize the differences in the structure and type of interaction of a softener with a substrate. Any softener can be broadly classified as being anionic, non-ionic, or cationic based on the charge the softener carries when in water. Softeners are also differentiated based on the functional groups they contain and on their reactivity or substantivity with a substrate. In one study, softeners are classified based on their substantivity as substantive, nonsubstantive, reactive, amphoteric, and special softeners.1 Classifying softeners based on their substantivity has the limitation that a softener classified as nonsubstantive could become substantive under certain conditions. Softeners have also been classified based on their amphotericity.8 However, the classification of softeners based on amphotericity is not strict since the pH used determines the amphotericity of a softener. For example, a non-ionic softener could become cationic under strong acidic conditions. A general classification of softeners is given in Figure 1. On the basis of this classification, any softener can be recognized as either a siloxane or a non-siloxane. The softeners can then be further classified based on their reactivity or based on the charge they carry when in water. Softeners in each class have been further classified based on the type of chemical reaction and the ionic interaction between the softener and substrate. In this study, eight different types of commercial softeners at four different concentrations are studied and the softeners are evaluated for their influence on various fabric properties before and after five laundering cycles. The changes in the

10.1021/ie071564f CCC: $40.75 © 2008 American Chemical Society Published on Web 03/15/2008

Ind. Eng. Chem. Res., Vol. 47, No. 8, 2008 2503

Figure 1. General classification of softeners. Table 1. Type of Softener and Concentrations Used and Symbol Used to Represent the Softenera softener type

general structure

symbol

anionic non-ionic cationic non-ionic (PE)

Non-Siloxanes ROSO3Na -(CH2CH2O)nHOC2H4(R)N+(C2H4OOCR)2X-(CH2-CH2)n-

AI NI CI NI-PE

reactive nonreactive tertiary aminofunctional primary aminofunctional

Siloxanes -[Si(Me)2-O]m-[Si(Me)(H)O]n[Si(Me)2O]n [Si(Me)2O]m[Si(Me)YO]n [Si(Me)2O]m[Si(Me)ZO]n

SR SNR SN3 SN1

a Where X- ) a negatively charged ion, Y ) (CH ) N(Me) , Z ) 2 n 2 (CH2)nNH2, R ) alkyl group, Me ) CH3, and PE is polyethylene. m and n are whole numbers.

Table 2. Amount of Softeners Used According to Manufacturer’s Recommendation and to Obtain Similar % Add-on on the Fabrics for All the Softeners amount of softener used (g/L)

softener anionic non-ionic cationic non-ionic (PE) reactive nonreactive tertiary aminofunctional primary aminofunctional

manufacturers recommended solid similar % content (%) low medium high add-ona Non-Siloxanes 93.5 1 10.6 5 97.6 3 39.9 10

3 10 5 30

5 15 7 50

5 40 5 10

Siloxanes 38.8 3 39.8 10 39.2 10 43.9 10

5 15 15 15

7 20 20 20

10.5 10 10 10

a Amount of softener required to obtain about 4% of softener on the fabric (add-on) based on weight of the fabric used.

properties of the fabrics before and after laundering are studied in comparison to the control fabric. 2. Materials and Methods 2.1. Materials. Bleached plain weave 100% cotton fabric was obtained from Test Fabrics (style no. 400). The type of softeners used in this study, their general structure, and the concentrations used are given in Tables 1 and 2. Three concentrations were selected based on the manufacturer’s recommended concentration for a particular softener, and the fourth concentration used was to achieve a common add-on for all the softeners based on the dry weight of each softener. For example, softener concentrations of 1, 3, and 5 g/L were chosen if the recommended range was 1-5 g/L. The % add-on of softeners on the fabrics was calculated based on the solid content of the softeners. The

solid content in each softener was determined by heating the softeners at 105 °C for 8 h and then at 165 °C for 5 min. Softeners were cured at 165 °C for 5 min to emulate the same conditions of treatment to which the softener-treated fabrics were exposed. The solid contents and the amount of softener used to obtain the same % add-on have been included in Table 2. Each softener has been identified by letters to indicate the class and type of softener as given in Table 1. 2.2. Methods. 2.2.1. Softener Application. Softeners with the required concentration were padded onto the Test Fabrics style no. 400 cotton fabric using a laboratory padding machine (EVAC padding machine, L&W machine works, McConnells highway, SC) with a wet pickup of 100 ( 2%. The fabrics were then dried under an infrared dryer and cured at 165 °C for 5 min. The dried and cured samples were conditioned for 24 h under standard testing conditions before testing. 2.2.2. Laundering. The softener-treated fabrics were subjected to five continuous washing and drying cycles using AATCC standard detergent without optical brighteners. The control and fabrics treated with softeners were washed using home washing and drying machines according to AATCC Test Method 135. A water temperature of 41 ( 3 °C under normal machine cycle with a fabric load of 1.8 kg and 66 g of detergent was used for each laundering. After each laundering, fabrics were dried in a home drying machine using a permanent press cycle. 2.2.3. Tear Strength. The control and softener-treated fabrics were tested for tear strength in the warp direction using an MTS tensile tester (model Q Test/10) according to ASTM D 2261. A gauge length of 3 in. and a crosshead speed of 2 in./min were used for testing. Five samples were tested for each condition, and the average of the readings was calculated. To exclude the effect of laundering on fabric properties, the % change in the property of the fabric instead of the absolute value was used to compare the performance among the softeners. The % change for a particular evaluated property was calculated according to eq 1.

% change ) average value of softener-treated fabric average value of control × 100 (1) average value of control 2.2.4. Abrasion Resistance. Abrasion resistance was measured in terms of the number of abrasion cycles required for failure with a 1 lb load on a Universal Tester according to ASTM D 3886. Five specimens were tested for each condition, and the average abrasion resistance of the softener is reported. The % change in abrasion resistance calculated according to eq 1 has been used for comparison among the softeners. 2.2.5. Flexibility. Fabric flexibility was measured in terms of flexural rigidity according to ASTM D 1388 using eq 2. The higher the flexural rigidity of a fabric, the lower is the flexibility, and vice versa. Therefore, the inverse of flexural rigidity gives an indication of fabric flexibility.

G ) WC3

(2)

where G ) flexural rigidity, mg‚cm; W ) fabric mass per unit area, mg/cm2; and C ) bending length, cm. The % change in flexibility was calculated using eq 1 and has been considered for comparison of flexibility among the softeners. 2.2.6. Whiteness Index. A Hunterlab Ultrascan XE spectrophotometer with a viewing area of 1 in. and D65/10° illuminator was used to measure the fabric whiteness in terms of CIE

2504

Ind. Eng. Chem. Res., Vol. 47, No. 8, 2008

Figure 2. (a) Changes in the tear strength of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations before laundering. (b) Changes in the tear strength of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations compared to the control fabric after five laundering cycles.

whiteness index. Three samples were tested for each condition, and the average was calculated. The ratio of the average whiteness index of the softener-treated fabric to that of the control was taken to calculate the whiteness index ratio (WI) according to eq 1. The % change in whiteness index calculated using eq 1 has been used for comparison of whiteness index of the softener-treated fabrics. 2.2.7. Water Repellency. Fabrics were tested for water repellency according to AATCC Test Method 22. The % change in hydrophylicity was calculated using eq 1. 3. Results and Discussion 3.1. Influence of Softeners on Fabric Properties. 3.1.1. Effect of Softener Concentrations on Tear Strength before Laundering. The effect of concentrations on the tear strength of the fabrics before and after five launderings is shown in parts a and b of Figure 2, respectively. All the softeners provide higher strength to the fabrics before laundering compared to the control fabric, and the extent of the increase in tear strength varies from 19 to 139% depending on the structure and concentration of

the softeners used. At low concentrations, the tertiary aminofunctional softener provides the highest increase in strength (105%) followed by the primary aminofunctional (SN1) and reactive softener (SR) treated fabrics. Increasing the concentration of the softener from low to medium further increases the tear strength, except for in the case of the non-ionic softenertreated fabrics. The two aminofunctional softeners have similar tear strengths, with that for the reactive softener being the highest and those for the non-ionic non-siloxane and nonreactive siloxane softener being the lowest at medium concentrations. At similar concentrations, the reactive siloxane softener SR provides the highest increase in tear strength and softener SNR provides the lowest. Softeners NI-PE, SNR, and SN1 have relatively low strengths when similar concentrations are used compared to their respective strength retentions at medium and high concentrations, most likely due to the relatively low amounts of softener used. Contrarily, softeners AI and NI have better strength retentions when similar concentrations are used compared to their strengths at low and medium concentrations.


Overall, softeners AI and SNR have relatively less change in strength with the change in concentration compared to the other six softeners. 3.1.2. Effect of Softener Concentrations on Tear Strength after Laundering. Three (AI, CI, and SR) of the eight softeners studied have lower strengths after five launderings compared to the strength of the untreated fabric when low concentrations of softeners are used, as seen from Figure 2b. The tertiary aminofunctional softener (SN3) has the highest retention in tear strength after laundering at a low concentration of softeners. Except for the anionic and SNR-treated fabrics, all the other fabrics show higher strength retentions when medium concentrations of softeners are used compared to their respective strength retentions after laundering when low concentrations of softeners are used. At high concentrations of softeners, all the fabrics show higher strength retention than the control; the tertiary aminofunctional softeners have the highest retention, and the non-ionic and cationic softener-treated fabrics have the lowest retention. The non-ionic polyethylene and tertiary aminofunctional softeners have the highest strength retentions after five launderings among the siloxane and non-siloxane softeners, respectively. Softeners improve the tear strength of fabrics by lubricating the yarns and fibers and making them more flexible. The extent of increase in tear strength depends on the type of chemical and physical interactions between the softener and the substrate, the amount of softeners used, and the extent of lubrication provided by the softener. The reactive softener can covalently bond to the hydroxyl groups in cellulose and, therefore, can provide better strength improvement before laundering.3 However, the reactive softener is not durable to laundering, and the reactive softener-treated fabrics have the lowest strengths among all the softeners after laundering. Aminofunctional siloxanes provide better lubrication, form a film on the fiber surface, and also have strong interaction with the negatively charged hydroxyl groups of cellulose.6 Therefore, both the primary (SN1) and tertiary aminofunctional (SN3) softeners have relatively better improvement in strength before laundering, as seen from Figure 2a. Similarly, the non-ionic polyethylene softeners can also form films and provide lubricating action to the yarns and, therefore, provide better strength retention compared to the other non-siloxane softeners at all concentrations. 3.1.3. Effect of Softener Concentrations on Abrasion Resistance before Laundering. Six of the eight softeners studied provide similar improvement in abrasion resistance when low concentrations of softeners are used, as shown in Figure 3a. All the siloxane softeners improve the abrasion resistance to a similar extent at low concentrations. When the concentration is increased from low to medium, the anionic softener (AI) provides the highest abrasion resistance and the non-ionic, cationic, and reactive siloxane softeners show the lowest improvement. At high concentrations, the reactive and nonreactive softeners provide the highest improvement and the nonionic polyethylene provides the lowest. Unlike the other softeners, the anionic and non-ionic polyethylene softener-treated fabrics show a decrease in abrasion resistance with the increase in concentration, probably due to excess lubrication leading to easy movement of yarns and, therefore, lower abrasion resistance. At similar concentrations, the reactive softener provides the highest abrasion resistance and the primary aminofunctional softener provides the lowest. Overall, the reactive and nonreactive siloxane softeners provide better abrasion resistance to the fabrics when the manufacturers recommended range of concentrations are used.

3.1.4. Effect of Softener Concentrations on Abrasion Resistance after Laundering. Except for the tertiary aminofunctional softener, all the other softeners have higher or at least the same abrasion resistance as the control fabric after five launderings, as seen from Figure 3b. The non-ionic polyethylene softener-treated fabrics lose only ∼50% of the resistance to abrasion compared to its resistance before laundering, whereas the non-ionic softener-treated fabrics lose all of their abrasion resistance after five laundering cycles when low concentrations of softeners are used. At medium concentrations, all the softeners except for the tertiary aminofunctional softener have higher abrasion resistance than the control after five launderings. At high concentrations, the anionic and tertiary aminofunctional softeners do not show any improved abrasion resistance compared to the control, whereas the nonreactive, reactive, and primary aminofunctional softeners show relatively better retention of abrasion resistance. At similar concentrations, only the tertiary aminofunctional softener has ∼12% lower abrasion resistance, the anionic softener-treated fabrics show no improvement, and the non-ionic softener shows the highest improvement of ∼34%. Overall, the non-siloxane softeners show better retention of abrasion resistance after laundering compared to the siloxane softeners. Softeners improve the abrasion resistance of fabrics because of two major factors. First, softeners form a film on the surface of the fibers and yarns that would act as a protective layer and, therefore, provide better resistance to abrasion. Second, the lubricating action of the softener on the fabric will reduce the friction between the fabric and the abradant and also improve the flexibility of the fibers and yarns. Lower friction and better flexibility will provide higher resistance to abrasion compared to the untreated fabric. The non-ionic polyethylene (NI-PE) softener has relatively poor affinity to water but can interact with the polymers in the fibers. Therefore, NI-PE has relatively good abrasion resistance at all four concentrations studied and has good durability to laundering. Similarly, the reactive softener can form covalent bonds with the hydroxyl groups and can provide relatively better durability in terms of improving and retaining the abrasion resistance. 3.1.5. Effect of Softener Concentrations on Flexibility of the Fabrics before Laundering. Softener-treated fabrics have better flexibilities ranging from 23 to 153% compared to the untreated control even at low concentrations, as seen from Figure 4a. Among the non-siloxane softeners, the non-ionic polyethylene softener provides the highest flexibility among the four non-siloxanes studied, and the nonreactive siloxane provides the highest flexibility among the four siloxanes. The anionic, cationic, reactive, and primary aminofunctional softeners provide similar flexibilities, whereas the tertiary aminofunctional softener provides the lowest flexibility among the eight softeners. Increasing concentration from low to medium further increases the flexibility of all the softener-treated fabrics except for the non-ionic softener, which remains the same. The non-ionic polyethylene softener-treated fabrics still have the highest flexibility and the tertiary aminofunctional softeners have the lowest when medium concentrations of softeners are used. However, the tertiary aminofunctional softener shows the highest improvement in flexibility when the concentration is changed from low to medium compared to the other softeners. At high concentrations, the anionic and cationic softener-treated fabrics do not show any further increase in flexibility compared to the flexibility of the respective fabrics at medium concentrations, whereas the flexibility of the tertiary aminofunctional (SN3) treated fabrics increases by >100% when the concentration is

2506


Figure 3. (a) Changes in the abrasion resistance of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations before laundering compared to the control fabric. (b) Changes in the abrasion resistance of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations after laundering compared to the control fabric.

increased from medium to high. At similar concentrations, however, the non-ionic non-siloxane softener provides considerably higher flexibility than the other fabrics, whereas the tertiary aminofunctional softener-treated fabrics have the lowest flexibility. 3.1.6. Effect of Softener Concentrations on Flexibility of the Fabrics after Laundering. All the softener-treated fabrics retain higher flexibility even after 5 launderings compared to the control fabric at all concentrations studied, as seen from Figure 4b. Although the reactive siloxane softener showed relatively high improvement in flexibility at low softener concentrations before laundering, it has relatively poor retention in flexibility after laundering. Both the aminofunctional softeners show good retention in flexibilities after laundering compared to their respective flexibility before laundering at low concentrations. Increasing concentration of the softeners from low to medium decreases the flexibility of the fabrics for softeners CI and SR, whereas the flexibility of the fabrics improves for the other six softeners. The tertiary aminofunctional softeners (SN3) show considerably higher retentions in flexibility after laundering when high concentrations of softeners are used compared

to the retentions in flexibility after laundering at low and medium concentrations. The flexibility of the control fabrics also increased by ∼60% after five launderings compared to its flexibility before laundering. The increase in the flexibility of the control fabric after laundering could be due to the removal of finishes on the surface and also due to the relatively easy movement of yarns and fibers in the fabrics after laundering. Softeners such as the primary and tertiary aminofunctional softeners that tend to form films on the surface of the fabrics will have lower flexibilities.4,16 However, the differences in the flexibilities of the aminofunctional softener-treated fabrics could be due to the difference in structure between the primary aminofunctional softener (SN1) and the tertiary aminofunctional softener (SN3). 3.1.7. Effect of Concentrations on the Whiteness Index of the Fabrics before Laundering. Except for softener SNR, all other softeners decrease the whiteness of the fabrics at low concentrations compared to the whiteness of the control fabric, as seen from Figure 5a. At low concentrations, the aminofunctional softeners (SN1 and SN3) have the highest decrease in whiteness index (12%) and the non-ionic polyethylene softener


Figure 4. (a) Changes in the flexibility of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations before laundering compared to the control fabric. (b) Changes in the flexibility of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations after laundering compared to the control fabric.

has the lowest (1%). Increasing the concentrations of the softeners from low to medium further decreases the WI of the fabrics. At medium concentration, the primary aminofunctional softener-treated fabric has the lowest WI and the nonreactive siloxane softener has the highest WI, higher than that of the control fabrics. At high concentrations, all the softeners including the nonreactive siloxane have lower WI than the control fabrics. The decrease in whiteness ranges from 9 to 33% compared to the WI of the control fabrics. At similar concentrations, the reactive and nonreactive siloxane softeners have higher whiteness and the anionic softeners have the lowest WI compared to the control fabrics. 3.1.8. Effect of Concentrations on the Whiteness Index of the Fabrics after Laundering. The WI of the control fabric increases by ∼30 units after laundering compared to its WI before laundering. After five launderings, all except the nonreactive softener-treated fabrics have lower whiteness than the control at low and medium concentrations, as seen from Figure 5b. At low concentrations, the anionic softener (AI) treated fabrics have the lowest whiteness index and the nonreactive

softeners have the highest. Softener SNR-treated fabrics still retain higher WI than the control after laundering when medium levels of softeners are used. Four softeners (CI, NI-PE, SR, and SN3) have ∼15% lower WI than the control after five launderings when medium concentration is used. When the concentration is increased from medium to high, the WI of the CI, NI-PE, SNR, and SN3 treated fabrics further decreases, whereas that of the non-ionic softener (NI) remains the same compared to their respective WI at medium concentrations. At similar concentrations, two softeners (SR and SNR) have higher WI than the control and the anionic treated fabrics have the lowest. Overall, softener SNR provides better WI to the fabrics compared to the other softeners used in this study. Differences in the amount of softener used, the chemical composition, and the type of interaction between the softener and the substrate could be responsible for the variations in WI between the softener-treated fabrics before and after laundering. In addition to the concentration of the softeners, the inherent whiteness of the softener will also play a major part in determining the magnitude of change in WI. The aminofunc-

2508


Figure 5. (a) Changes in the whiteness index of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations before laundering compared to the control fabric. (b) Changes in the whiteness index of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations after laundering compared to the control fabric.

tional siloxanes decrease whiteness due to the oxidative decomposition of amino groups at curing temperatures, leading to formation of yellow chromophores.2,5 Increasing the degree of substitution of amine groups is said to provide better whiteness, which is observed in this study also. The tertiary aminofunctional softener (SN3) decreases the WI of the fabrics to a lesser extent than the primary aminofunctional softener. 3.1.9. Effect of Concentrations on the Hydrophilicity of the Fabrics before Laundering. Five out of the eight softenertreated fabrics do not show any change in hydrophylicity when low concentrations of the softeners are used, as seen from Figure 6a. Both the SNR and SN1 softeners decrease the hydrophylicity by ∼50%, and the SN3 softener decreases it by ∼70%. Increasing the softener concentration from low to medium imparts lower hydrophilicity to all the fabrics except the reactive siloxane-treated fabrics. Increasing concentration from medium to high further decreases the hydrophylicity of the cationictreated fabric, but all the other softeners do not show any further decrease in hydrophylicity. At similar concentrations, only the non-ionic softener has no decrease in hydrophylicity whereas

the other softeners decrease the hydrophylicity by 50%, while that of the tertiary aminofunctional-treated fabrics decreases by ∼70%. 3.1.10. Effect of Concentrations on the Hydrophilicity of the Fabrics after Laundering. Laundering has considerable influence on the hydrophylicity in the sense that, except for the aminofunctional softeners, all the other softeners have the same hydrophylicity as the control fabric after laundering, as seen from Figure 6b. However, laundering does not show any influence on the hydrophilicity of the control fabrics. The tertiary aminofunctional softeners have 50% lower hydrophylicity after five launderings at all concentrations used. After five launderings, the primary aminofunctional softener-treated fabrics have lower hydrophilicity only when high concentrations of softeners are used. All fabrics, except those treated with SN3, have the same hydrophylicity as the control after five launderings when treated with similar concentrations of softeners. The extent of decrease in the hydrophylicity of the fabrics is mostly determined by the chemical composition of the softener, the type of interaction between the softener and the substrate,


Figure 6. (a) Changes in the hydrophylicity of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations before laundering compared to the control fabric. (b) Changes in the hydrophylicity of fabrics treated with manufacturers recommended concentrations (low, medium, and high) and at similar concentrations after laundering compared to the control fabric.

and the amount of softeners used. The relatively better performance of the reactive softener (SR) in terms of retention of hydrophylicity could be due to the presence of the hydroxyl group in the softener. Some of the free hydroxyl groups left on softener molecules after the cross-linkages and many of the ether linkages from the cross-linking reactions should facilitate hydrophylicity, and therefore, there is no decrease in the hydrophylicity of the fabrics. 4. Conclusions This study shows that the performance of the softeners is influenced by the structure and amounts of softener used. Among the non-siloxane softeners studied, the anionic softener provides better tear strength to the fabrics but lower flexibility and whiteness retention. The reactive siloxane provides the best improvement in strength, abrasion resistance, flexibility, and whiteness retention among the siloxane softeners. Although the aminofunctional siloxane softeners provide good tear strength

and flexibility when high concentrations are used, they cause considerable decrease in the whiteness and hydrophylicity of the fabrics. Overall, the nonreactive siloxane, anionic, non-ionic polyethylene, and tertiary aminofunctional softeners provide poor tear strength, flexibility, and retention in hydrophylicity, respectively, before laundering. The tertiary aminofunctional softeners have better tear strength retention but poor retention in flexibility after laundering. The reactive softeners have better whiteness retention but poor hydrophylicity after laundering. This study also shows that the manufacturers’ recommended concentration may not be the optimum concentration to obtain the desired improvement in the performance of fabrics. On the basis of the performance of the softeners at similar concentrations, the better performance of some of the softeners could mainly be due to the higher amounts of softener used. Nonsiloxane softeners can have similar performance to that of the siloxane softeners when appropriate amounts of the softeners are used.

2510


Acknowledgment The authors are indebted to the University of Nebraskas Lincoln Agricultural Research Division, Hatch Act, and USDA Multistate Research Project S-1026 for the financial support to complete this research. Literature Cited (1) Teli, M. D.; Paul, R.; Pardeshi, P. D. Softeners in textile industry: chemistry, classification and applications. Colourage 2000, 47 (6), 17. (2) Kang, T. J.; Kim, M. S. Effects of silicone treatments on the dimensional properties of wool fabric. Text. Res. J. 2001, 71 (4), 295. (3) Cheng, K. P. S.; Wong, C. M. Silicone-treated cotton fabrics. Text. Asia 1998, 29 (9), 55. (4) Saraf, N. M. Silicones for textiles. Int. Dyer 1998, 183 (4), 39. (5) Lautenschlager, H. J.; Bindl, J.; Huhn, K. G. Structure activity relationships of aminofunctional siloxanes as components in softening finishes. Text. Chem. Color. 1995, 27 (3), 27. (6) Bereck, A.; Riegel, D.; Matzat, A.; Habereder, P.; Lautenschlager, H. Silicones on fibrous substrates: their mode of action. AATCC ReV. 2001, 1 (1), 45. (7) Achwal, W. B. Permanent hydrophilic softeners based on polydimethyl-siloxane. Colourage 2003, 50 (2), 47. (8) Nostadt. K.; Zyschka, R. Softeners in the textile finishing industry. Colourage 1997, 44 (1), 53.

(9) Joyner, M. M. Aminofunctional polysiloxanes: A new class of softeners. Text. Chem. Color. 1986, 18 (3), 34. (10) Tzanov, Tz.; Betcheva, R.; Hardalov, I.; Hes, L. Quality control of silicone softener application. Text. Res. J. 1998, 68 (10), 749. (11) Robinson, K. J.; Gatewood, B. M.; Chambers, E. Influence of domestic fabric softeners on the appearance, soil release, absorbency, and hand of cotton fabrics. In AATCC Book of Papers, International Conference and Exhibition, Charlotte, VA, 1994; p 58. (12) Chiweshe, A.; Crews, P. C. Influence of household fabric softeners and laundry enzymes on pilling and breaking strength. Text. Chem. Color. Am. Dyest. Rep. 2000, 32 (9), 41. (13) Baumert, K. J.; Crews, P. C. Influence of household fabrics softeners on properties of selected woven fabrics. Text. Chem. Color. 1996, 28 (4), 36. (14) Kut, D.; Gunesoglu, C.; Orhan, M. Determining suitable softener type for 100% PET woven fabric. AATCC ReV. 2005, 5 (5), 16. (15) Poppemwimmer, K.; Schmidt, J. It’s all in the chemistry. Int.Dyer 2001, 186 (3), 34. (16) Haberderer, P. Silicone softeners: Structure-effect-relationship. Melliand Int. 2002, 8 (5), 143.

ReceiVed for reView November 17, 2007 ReVised manuscript receiVed January 31, 2008 Accepted February 9, 2008 IE071564F

Effect of Structures and Concentrations of Softeners on the

Recommend Documents