Bleaching of hydroentangled greige cotton nonwoven fabrics without scouring

Abstract

Previous research had shown that processing greige cotton on a commercial-grade hydroentanglement (HE) system at a water pressure greater than 120 bar resulted in a low-weight hydrophilic nonwoven fabric. With that ability to make hydrophobic greige cotton easily wettable and hence absorbent without the conventional scouring phase, an investigation was conducted to determine whether a fabric made by hydroentangling greige cotton fibers at a high water pressure could be successfully bleached without the traditional scouring. The investigation involved production of greige cotton nonwoven fabrics at a low hydroentangling water pressure of 60 bar and at a high hydroentangling water pressure of 135 bar and their subsequent evaluations before and after scour only, one-stage bleach only, and two-stage scour and bleach. In the results, both the 60 bar and 135 bar fabrics bleached successfully in the two-stage bleaching process and yielded acceptable absorbency and whiteness values. However, when bleached in the single-stage bleaching process with no separate scour, the 135 bar fabric still produced the whiteness index almost equal to that obtained in the two-stage bleaching process and even equal to that of a fabric made with commercially scoured and bleached cotton fibers, but the 60 bar fabric yielded about 15% lower whiteness index value while its wettability-induced improved water absorbency still was comparable to that obtained via the two-stage bleaching. This shows that a hydroentangled greige cotton fabric produced at a high enough water pressure (hydro energy) could be bleached satisfactorily without the traditional scouring chemicals and that a fabric produced even at a lower water pressure and bleached without scouring could still be satisfactory for subsequent aqueous treatments for certain end-use applications where the whiteness may not be as critical as the absorbency.

Keywords

hydroentanglement of greige cotton fibers nonwoven fabrics scour-less bleaching whiteness absorbency wax content fabric properties

Classical greige (raw) cotton lint, as it is generally supplied in standard compressed bales of 480 lbs net each to user mills, invariably carries varying amounts of foreign matter such as the plant debris, dirt, trash, and seed-coat fragments generated in the ginning of harvested seed cotton.¹ In addition, the cotton lint inherently contains native waxes of high molecular weight, pectin, and coloring matter that are naturally formed partly for the fibers’ protection against the environmental hazards during the fiber growth and partly due to the cultivar environment and the fiber aging.^2–5

A cotton user-facility generally must remove, to the extent possible, the extraneous foreign matter at the first opportunity before the fiber, at least mechanically, can be efficiently processed into various textile products such as yarns in traditional textile manufacturing and certain premium-quality nonwoven textiles. However, the greige cotton’s natural wax content renders the fibers and, consequently, their resulting fabric hydrophobic, not easily and efficiently wettable and absorbent in the down-stream aqueous chemical treatments, including bleaching, dyeing, printing, or other special-purpose wet finishing. Perhaps the most important attribute of a cotton fabric from the consumer’s perspective is the fabric’s comfort factor, which also is induced by the fiber absorbency. So, the scouring of greige cotton fibers or fabrics is a common chemical process that removes the fiber’s natural waxes and thus improves its absorbency and facilitates its efficient chemical finishing, including bleaching. Almost all greige cotton fabrics are scoured or scoured and bleached (generally, in one combined process step) before they are further chemically processed (bleached, dyed, and/or functionally specific finished) and then converted into final products for consumer use. Greige cotton, in fiber form, is also commonly scoured and bleached white, generally for blending with the manufactured fibers that mostly are white.

Since the commonly used alkaline scouring of greige cotton fabric is considered by some to be somewhat tedious and time consuming, any reduction or, preferably, elimination of the scouring phase in the cotton textile manufacturing can be expected to benefit the industry and the environment. This study was performed to determine whether a hydroentangled greige cotton fabric made at a high water pressure could be directly bleached without scouring to attain the whiteness and absorbency comparable to those of a scoured-and-bleached fabric and to those of a fabric made with commercially scoured and bleached cotton fibers. The report presented here describes the various operations involved in the productions, treatments, and evaluations of the hydroentangled nonwoven fabrics made with a pre-cleaned greige cotton and a commercially bleached cotton (which almost always is scoured and bleached). The hydroentanglement system (HE) is a commercial process to fabricate a nonwoven (roll goods) fabric by directly converting a fibrous web into a woven-like fabric, using the hydro pressure or energy for the conversion. The abbreviation “HE” is also used to express “hydroentangled” throughout the manuscript.

Materials and methods

Production of hydroentangled greige cotton fabrics made with a low 60 bar hydroentangling water pressure and a high 135 bar water pressure

A commercially available pre-cleaned Upland greige cotton (now commercially available⁶), along with a sample of its raw version, and a comparable commercially scoured and bleached cotton that is commonly used in cotton-based nonwoven fabrics were selected for the study. Advanced Fiber Information System (AFIS) properties of the two cottons are given in Table 1. AFIS⁷ is a standard system for measuring properties of generally in-process cotton fibers. Both the (pre-cleaned) greige cotton and the commercially scoured-and-bleached cotton were uniformly processed on commercial-grade fiber preparatory equipment in the Center’s textile pilot plant to produce their respective substrates for hydroentanglements. Although both the cottons were very clean and really did not require the conventional cotton cleaning processes, each, however, still was subjected to the conventional opening and cleaning line in the textile pilot plant, since the supplied cotton bales still required a thorough opening of their densely compressed fibers. The fiber preparatory equipment was comprised of a Whitin feed hopper, a Hollingsworth step cleaner, a Saco Lowell fine opener/cleaner, and a Crosrol automatic chute feed system to feed the opened fibers to a 40 inch wide, Crosrol, Mark IV cotton card with revolving flats. The carded web of nominal 11 g/m² was lapped (20 layers) on a Technoplants Liliput,⁸ commercial-grade crosslapper to produce a lapped material (batt). The batt was continuously fed to a Technoplants Liliput needlepunch system that was operated with only one of its two installed needle boards to produce a lightly needled substrate of 70 g/m² nominal weight. The Foster⁹ needling metrics were 110 punches/cm²; penetration depth of 12 mm; material entry speed 1.19 m/min; and the exit speed was 3.4 m/min. The needlepunched substrates of the greige and bleached cottons were separately wound onto cardboard tubes and taken to a Fleissner¹⁰ commercial-grade, LeanJet (MiniJet) 2-1000-3 hydroentanglement system for converting the substrates into hydroentangled nonwoven fabrics of nominal 70 g/m² basis weight. Figure 1 shows a block diagram of the flow of material through the hydroentanglement system.

Figure 1.

Flow of the material through the hydroentanglement process.

Table 1.

Advanced Fiber Information System (AFIS) fiber properties of the greige and scoured-and-bleached cotton lint fibers

Fiber	Upper quartile length – cm (by wt.)	Mean length – cm (by wt.)	Short-fiber content (%)	Neps (#/g)	Visible foreign matter (%)	Trash content (count/g)
Greige	2.71	2.05	10.4	556	0.08 (After proprietary cleaning)	9 (Before proprietary cleaning)
Scoured and bleached	2.67	1.95	15.4	943	0.11	6

The hydroentangling process conditions were as follows: the pre-wet water pressure of 50 bar for both the greige and bleached cotton fibers; the fiber-bonding water pressure of 135 bar, at each of the system’s two hydroentangling heads (jet-strips) for both the greige and bleached cottons; the fiber-bonding water pressure of 60 bar, at each of the system’s two hydroentangling heads, for the greige cotton only; and the production speed of 5 m/min for all the fabrics. The pre-wetting and the fiber-bonding strips both had 40, 0.12 mm-diameter orifices per inch (2.54 cm). The resulting fabric was dried online at 180℃ in a gas-fired, hot-air chamber of a large perforated drum. An optional mobile water extractor (padder), installed in-between the fiber hydroentangling zone and the fabric drying zone, was not activated in this study. Since the bleached cotton was known to have been fully scoured and hence absorbent, its fabric production at 60 bar water pressure obviously was not considered necessary in this investigation.

Scouring and scouring and/or bleaching of the greige cotton fabrics

The scouring-only and the scouring and/or bleaching of the 60 bar and 130 bar greige cotton fabrics were conducted on a Mathis padder/steamer,¹¹ using the commonly implemented commercial chemical formulations shown in Tables 2 –4. The bleaching was done in one bath without a separate scouring process and also in two baths including a separate alkaline scouring process. The bleach formulae used for the bleached-only and the scoured-and-bleached fabrics were appropriately normalized to allow for the difference in their wet pickup values, thus assuring that equal amounts of bleach chemicals were applied to the fabrics in both the scenarios of the one-stage and the two-stage bleaching(s). The fabric made with the commercially scoured and bleached cotton fiber obviously did not require any scouring or bleaching.

Table 2.

The scour formulation for the scour-only and the scour-and-bleach treatments for both 60 bar and 135 bar base fabrics

Chemical	g/L	% on weight of liquor	% Wet pick-up	% on weight of fabric
Triton X-100	2	0.2	145	0.29
Triton C Liquid	5	0.5	145	0.73
NaOH (50%)	40	4.0	145	5.8

Process conditions of the scouring treatment: pH = 12.94; steamer dwell time = 25 minutes; pressure = 1 bar; speed = 0.3 m/min; time in steamer = 25 min; steam temp = 100℃.

Table 3.

The bleach formulation for the 60 bar and 135 bar scoured fabrics

Chemical	g/L	% on weight of liquor	% Wet pick-up	% on weight of fabric
NaOH 50%	10	1.0	173	1.7
Tanachem T CB 01	6.3	0.63	173	1.1
Triton C liquid	1.2	0.12	173	0.27
H₂O ₂ (50%)	19	1.9	173	3.3

Process conditions of the bleaching treatment: bath solution brought to pH of 11.52; steamer time = 16 minutes; residual peroxide content after steamer = 0.17% OWF (on weight of fabric) or 10.3% of the total applied. Note: as mentioned in the text, the chemical concentrations of the ‘bleach baths’ were appropriately adjusted, in order to keep equal amounts of the chemicals applied to the non-scoured fabric as well as to the scoured fabric.

Table 4.

The bleach formulation for the 60 bar and 135 bar HE (non-scoured) fabrics

Chemical	g/L	% on weight of liquor	% Wet Pick-up	% on weight of fabric
NaOH 50%	13	1.3	137	1.8
Tanachem T CB 01	8	0.8	137	1.1
Triton C liquid	2	0.2	137	0.27
H₂O₂ (50%)	24	2.4	137	3.3

Process conditions for the bleaching treatment: pressure: 1 bar; speed: 0.5 m/min.; time in steamer: 16 min; steam temp. = 100℃; brought pH to 11.52; residual hydrogen peroxide content after the steamer = 0.17% OWF or 10.3 % of the total applied.

The suppliers of the various chemicals used were as follows:

Tanatex Chemicals B.V., Ede, Nederland: for Tanachem T-CB 01;

BASF, Florham Park, NJ 07932, USA: for Trilon C Liquid 50%;

Sciencelab. Com, Inc., Houston, TX 77396: for sodium carbonate and hydrogen peroxide 30%;

EMD Chemicals Inc., Gibbstown, NJ 08027: for sodium silicate solution, 40-42 Degrees; Baume, Titristar;

Industrial Chemicals, Inc., Birmingham, Alabama: for sodium hydroxide (caustic soda) 50%.

Comparative evaluations of the fabrics for their physical and mechanical properties, absorbency, whiteness, and hexane extractables (wax content) before and after the various treatments

All the hydroentangled fabrics were tested for weight, thickness, air permeability, tensile breaking strength and elongation, absorbency characteristics, whiteness, and hexane extractables, using standard equipment, methods and procedures.^12–17 To determine the amount of hexane extractable (which primarily consists of cotton’s natural waxes) from the fabrics before and after their various chemical treatments, the AATCC Method 97-2009 was used, using the Dionex Accelerated Solvent Extraction system. The fabric whiteness was determined using the Hunter Lab MiniScan XE Plus colorimeter. The illument was D₆₅ and the Observer Angle was 10° (AATCC Method 110). The Sink Time and Absorbency Capacity of the various fabrics were determined using ASTM D 1117. All the objective quality tests were repeated at least three (3) times and the resulting data of statistically validated standard deviations have been reported. The fabric made with the bleached cotton fiber obviously did not require any scouring and/or bleaching and, hence, it was tested as such after the hydroentanglement only.

Results and discussion

Measured properties of the greige and bleached cotton fibers

Table 1 shows the measured properties of the greige and bleached cotton fibers used in this study. As seen, both the cottons generally are comparable, except that the nep count of bleached cotton, as expected, is almost double that of the greige cotton. Although the bleached cotton’s own inherent nep count might have been high to start with, a greige cotton when scoured and bleached in fiber form (using the traditional batch-kier process) generally results in a higher nep count compared to its original nep count.¹⁸ This increase in nep count primarily is due to the fiber entanglements caused by the mechanical forces occurring during the wet processing of loose fibers. Table 1 further shows the bleached cotton approximately has about 50% more short fibers than the pre-cleaned greige cotton. This, to an extent, could have affected tensile properties of the resulting fabrics.

Physical and mechanical properties of the various fabrics

Table 5 shows properties of the variously treated fabrics. The various aqueous chemical treatments of the fabrics hydroentangled at both water pressures caused slight decrease in the fabric weight and air permeability, as expected. However, they caused a rather considerable decrease in the fabric thickness: about 25% in the 135 bar fabric compared to about 18% in the 60 bar fabric. This partly could also be attributed to compression from the padder involved in the chemical treatments.¹⁹ Other notable observations were significant declines in the MD (machine direction) breaking elongations of both the 135 bar and 60 bar fabrics after the scour-only, the two-stage scour-and-bleach, and the bleach-only treatments, even though the fabrics’ MD tensile breaking strengths and the CD (cross-direction) breaking elongations seemed to be unaffected. The only exception, however, was that the CD strength of the 135 bar fabric, especially after the two-stage scour-and-bleach treatment, also declined considerably, while the CD strength of the 60 bar fabric, on the other hand, actually increased substantially after the scour-only treatment and remained almost unaffected after the bleaching(s). Although it is difficult to precisely explain the above phenomenal changes particularly in reference to the differently treated hydroentangled greige cotton nonwoven fabrics, the wettability and the water retention of traditional cotton woven fabrics, as affected by alkaline and bleaching treatments,²⁰ could possibly be applied to the cotton-based nonwoven fabrics investigated in this study, as well. According to Hsieh et al.,²⁰ the water retention properties of scoured and bleached cotton fabrics are directly related to their wetting properties in water, or inversely related to their water wetting contact angles. However, they also concluded that the effects and effectiveness of scouring and bleaching of cotton assemblies are ‘highly sensitive’ to properties of the treated fabrics. Similar to the observations of Hsieh et al., it seems likely that the mechanical conditions involved in the fiber preparatory and hydroentangling processes, by way of imposing considerably more stress on the fibers in the MD compared to the CD, probably could also have contributed to the resulting fabric properties. The fibers in the fabric’s MD are held in higher tension compared to the fibers in the fabric’s CD, and the subsequent aqueous processes possibly could cause the tense fibers in the MD to relax and somewhat un- or de- entangle to yield lower elongation values, especially in the case of the scour-and-bleach scenario that may have had a compounding effect. As seen from Table 5, the two-stage, ‘scour-and-bleach’ treatment caused a considerable decline in the CD tensile strength, 88 N/5 cm, of the 135 bar fabric. On the other hand, the bleaching component in the bleached-only scenario did not cause as much loss in the fabric’s CD strength, 100 N/5 cm, which is even slightly greater than the strength, 97 N/5 cm, of the fabric made with commercially bleached cotton fiber. Further, as seen from the table, the 60 bar HE fabric, compared to the 135 bar HE fabric, has a very low tensile strength. This obviously is mostly due to its comparatively much less effective hydroentanglements due to the low hydroentangling water pressure (hydro energy) applied to fabricate the fabric. Furthermore, as seen from Table 6, the 60 bar HE fabric, compared to the 135 bar HE fabric, also has a slightly elevated level (0.14%) of its constituent fiber’s natural wax content.²¹ The wax, being a lubricant, reduces the inter-fiber-to-fiber cohesion or coherence and thus may also have partly contributed to an extent to the overall lower strengths of MD 51.0 N/5 cm and CD 51.5 N/5 cm of the 60 bar HE-only fabric. However, after scouring the fabric and removing most of its wax content, the fabric strength in both the directions increased, likely due to increased inter-fiber-cohesion and, consequently, less fiber slippage during stress loading of the fabric.

Table 5.

Physical and mechanical properties of the various fabrics produced

Sample ID	Weight (std. dev) (g/m²)	Thickness (std. dev) (mm)	Air perm. (std. dev) (cm³/sec/cm²)	MD tensile strength (std dev) (N/5 cm)	MD elongation (std. dev) (%)	CD tensile strength (std. dev) (N/5 cm)	CD elongation (std. dev) (%)
HE only^a	68.7 (0.97)	0.44 (0.0006)	77.7 (1.80)	107.3 (0.85)	47.80 (1.45)	125.8 (1.12)	42.53 (1.27)
Scour only^a	68.8 (1.02)	0.33 (0.010)	75.0 (1.62)	111.5 (1.18)	25.67 (1.64)	121.3 (1.26)	52.33 (1.58)
Two-stage scour and bleach^a	66.5 (1.66)	0.32 (0.006)	72.5 (1.41)	118.1 (0.92)	19.00 (0.84)	88.8 (0.88)	54.33 (0.95)
Bleach only^a	65.6 (1.65)	0.32 (0.005)	73.6 (2.20)	110.4 (1.31)	27.47 (1.02)	100.7 (1.49)	54.73 (1.12)
Fabric produced with commercially scoured and bleached cotton fiber^a	71.3 (0.78)	0.34 (0.007)	75.2 (1.46)	105.9 (0.89)	22.54 (1.19)	97.2 (0.65)	51.81 (1.46)
HE only^b	66.7 (0.84)	0.52 (0.008)	79.2 (1.97)	51.0 (1.10)	60.47 (1.56)	51.5 (0.97)	59.80 (1.59)
Scour only^b	66.0 (1.27)	0.43 (0.011)	78.3 (2.45)	106.9 (1.48)	32.63 (1.05)	111.2 (1.31	63.71 (1.13)
Two-stage scour and bleach^b	64.4 (0.97)	0.42 (0.006)	75.4 (1.19)	108.1 (1.29)	24.32 (1.29)	113.5. (1.16)	62.59 (1.01)
Bleach only^b	65.1 (1.34)	0.43 (0.007)	74.8 (2.03)	107.3 (0.91)	29.20 (0.91)	94.3 (1.27)	60.69 (0.94)

The base fabric produced at 135 bar water pressure.

The base fabric produced at 60 bar water pressure.

MD: machine direction; CD: cross-direction.

Table 6.

Amount of hexane extractables from the various fabrics (pre- and post-chemical treatments)

Sample ID	Hexane extractables (% on the weight of the fabric) 60 bar (std. dev)	Hexane extractables (% on the weight of the fabric) 135 bar (std. dev)
HE only	0.14 (0.02)	0.11 (0.03)
Scour only	<0.01 (0)	<0.01 (0)
Two-stage, scour and bleach	<0.01 (0)	<0.01 (0)
Bleach only	<0.01 (0)	<0.01 (0)

Whiteness and absorbency of the various fabrics

Table 7 shows the whiteness and absorbency – the properties of primary interest in the study – of the various fabrics. As seen, the whiteness and absorbency values of the 135 bar, bleached-only fabric were comparable to those of the scoured-and-bleached fabric and also equal to the fabric made with the commercially scoured-and-bleached cotton fiber. Figure 2 shows a representative digital glimpse of the greige cotton fabrics before and after scouring-only, bleach-only, and scour-and-bleach treatments, compared to that of the fabric made with commercially scoured and bleached cotton. The 60 bar, bleached-only fabric produced a lower whiteness index of 71.7 compared to 83.2 of the 135 bar, bleached-only fabric. However, the 60 bar fabric, when subjected to the two-stage, scour-and-bleach treatment, produced a whiteness index of 83.56, which was comparable to the 135 bar bleached-only fabric as well as to the fabric produced with the commercially scoured and bleached cotton fiber. This may indicate that the single-stage bleach perhaps was insufficient to fully whiten a fabric hydroentangled at 60 bar and at 5 m/min. Apparently, the higher water pressure allowed one-step bleach whereas the lower water pressure needed separate scour and bleach to attain acceptable whiteness. The natural wax content of greige cotton lint, depending on its variety and cultivar, varies considerably from crop to crop and from year to year and ranges between 0.4% and 1.2 % with an average of ∼0.69 % of the fiber weight.^21,22 This study has confirmed that the hydroentanglement of greige cotton typically does not completely remove all of the cotton’s natural waxes and other non-cellulosic components, although the greater hydroentangling water pressure generally removes more of them.²³

Figure 2.

Digital images of the fabrics made at 130 bar water pressure: From right to left: hydroentangled greige cotton (control) fabric; greige cotton scoured-only fabric; greige cotton bleached-only fabric; greige cotton scoured-and-bleached fabric; and the fabric made with commercially scoured-and-bleached cotton fibers.

Table 7.

Absorbency and whiteness of the various fabrics (pre- and post-chemical treatments)

Sample ID	Drop test (s) (std. dev)	Sink time (s) (std. dev)	Absorbency capacity (g H₂O per g. of fabric) (std. dev)	Whiteness index (std. dev)
HE only^a	16.7 (1.15)	1.3 (0.44)	7.45 (0.56)	30.92 (0.42)
Scour only^a	<1 (0)	2.3 (0.46)	7.01 (0.64)	54.87 (0.05)
Two-stage scour and bleach^a	<1 (0)	2.3 (0.50)	6.84 (0.52)	83.87 (0.19)
Bleach only^a	<1 (0)	2.4 (0.62)	6.94 (0.41)	83.23 (0.06)
Fabric produced with commercially scoured and bleached cotton fiber¹	<1 (0)	2.3 (0)	6.46 (067)	84.49 (0.03)
HE only^b	>60 (0)	>300 (0)	0 (0)	37.3 (0.51)
Scour only^b	<1 (0)	1.5 (0.38)	8.18 (0.45)	64.7 (0.08)
Two-stage scour and bleach^b	<1 (0)	1.4 (0.71)	8.03 (0.62)	83.56 (0.05)
Bleach only^b	<1 (0)	2.3 (0.56)	8.14 (0.54)	71.7 (0.04)

A Drop Test value of 1 or less than 1 second is considered as an indirect indication of efficient absorbency.

The base fabric produced at 135 bar water pressure.

The base fabric produced at 60 bar water pressure.

The absorbency attributes, Table 7, of the various fabrics surprisingly differed greatly. While the 135 bar, hydroentangled-only fabric sank quickly, the 60 bar, hydroentangled-only fabric practically did not sink (>300 s). However, why the sink time attained with the scoured-and-bleached fabrics (with almost totally removed wax content) was more compared to that with the hydroentangled-only fabric (not completely absorbent yet) was not understandable. The only explanation we possibly can offer at this time is that he ‘Drop Test, ‘Sink Time’, and ‘Absorbency Capacity’ are completely different tests and, depending on the many factors involved, seemingly divulge different information about the absorbency attributes. The data in Tables 6 and 7, however, do support the fact that a hydroentangled greige cotton nonwoven fabric produced at 135 bar water pressure did not have to be scoured before being bleached to attain the whiteness and absorbency that are comparable to a fabric made with commercially scoured-and-bleached cotton fibers. This finding alone could lead to significant reduction in the amount of chemicals used to aqueous finish hydroentangled greige cotton nonwoven fabrics for certain end-use products and applications. In summary, the novel features of the ‘scour-less bleaching’ of hydroentangled (pre-cleaned⁶) greige cotton fabric lie in the following: (1) the hydroentangling process, especially at a relatively high water pressure, itself removes the fiber’s wax content, which reduces or even eliminates the need for conventional scouring of the cotton fabric; (2) the bleaching of a hydroentangled greige cotton fabric is less tedious and time-consuming than the conventional scouring and bleaching of greige cotton fibers; and (3) compared to a conventionally processed/cleaned run-of-the-mill greige cotton, the (proprietary) pre-cleaned greige cotton, used in the study, generally has lower visible foreign matter. This, to a small extent, may also reduce the scouring need in bleaching this cotton either in the fiber form or, preferably, in the fabric form. The conventionally processed/cleaned greige cotton fibers, if bleached without scouring, do not bleach as white as when they are scoured and bleached.

Conclusions

The research has shown that a substrate made with commercially available pre-cleaned greige cotton and hydroentangled at a relatively higher water pressure of 135 bar can be bleached to attain satisfactory whiteness and absorbency without the traditional scouring phase. This is mainly attributed to the removal (without scouring) of greige cotton’s native waxes during the hydroentangling process itself, although the superior cleaning of the UltraClean cotton (used in the research) probably also played a part. Furthermore, the research has also shown that even when the greige cotton substrate is hydroentangled at a lower water pressure of, say, 60 bar, the resulting fabric still can be bleached without scouring to attain acceptable absorbency, although the bleached fabric may have a slightly lower whiteness level compared to the fabric made with 135 bar water pressure. Thus, based on the research results, any reduction or possible elimination of the scouring chemicals in the production of greige cotton nonwoven fabrics is expected to yield economic and environmental advantages towards increased utilization of cotton in certain end-use products that require absorbency and whiteness.

Footnotes

Funding

The work was supported by the US Department of Agriculture, Agricultural Research Service in-House Project No. 6435-41000-094-00D.

Acknowledgments

The authors would like to thank their coworkers Pablo Ali Salame, Lucien Duplessis, Farrell Screen, and Adrian Mejia for their significant ‘hands on’ assistance in conducting the tasks involved in the study presented here.

The SRRC is a research facility of the US Department of Agriculture. Names of the companies and/or their products are mentioned solely for the purpose of identification and do not imply endorsement over others by the USDA.

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