Progress 10/01/02 to 09/30/07
Outputs
OUTPUTS: Objective 1: To improve protection and human factor performance of PPE through product development. Influence of fabric characteristics on UV transmission: A study investigating the influence of fabric characteristics on UV transmission was conducted. The study explored the effect of specific fabric parameters such as fiber composition, fabric weight, fabric thickness, cloth cover, chemical pre-treatments and chemical finishes on the Ultraviolet Protection Factor (UPF). Influence of dyeing and chemical finishing on UV transmission: A study examining the Ultraviolet Protection Factor of cotton fabrics dyed with colorants of plant and insect origins was conducted. Three cotton fabrics were dyed with three natural colorants. Fabrics were characterized with respect to fabric construction, weight, thickness and thread count. Influence of fabric characteristics on UPF was studied. Role of colorant concentration on the ultraviolet protection factor was examined via color strength
analysis. In a second study, the UV protective ability of a knit bamboo fabric was studied. Raw bamboo fabric was found to afford poor protection against UV radiation. To enhance UV protection characteristics fabrics were subjected to three different treatments viz., dyeing; finishing with a UV absorber; and one-bath simultaneous dyeing and finishing with UV absorber. Influence of enzymatic treatment on ultraviolet properties: Enzymatic treatment has gained considerable attention in recent years as a useful wet-processing tool to impart value-added properties to fabrics. Of the many enzymes that are used, cellulase is one of the most important because of its wide use in treatments such as bio-polishing to improve fabric smoothness and in bio-finishing to produce the "worn" look. The enzymatic action of cellulase on cellulose is a surface phenomenon that results in significant morphological changes in the treated fabrics. In this study, cotton knit fabric was treated with cellulase and
the effect of structural changes on Percent Cover and Ultraviolet Protection Factor was examined. The fabric used was a bleached cotton T-shirt fabric. The enzyme used was cellulase. Enzymatic treatment was carried out under conditions recommended by the manufacturer. Percent Cover was determined by image analysis using a stereo zoom microscope attached to a Windows XP-based PC and equipped with a CCD camera and below stage illumination. UV properties of nonwovens: Factors affecting UVR transmission of woven and knit textiles include the chemical nature of the fiber, porosity or cover factor, thickness, weight, and wet processing treatments such as dyes and finishes applied to the textile. However, the review of literature reveals no report on the UV properties of nonwovens. The objective of this study was to determine the Ultraviolet Protective Factor of six selected nonwovens. The UPF values obtained were analyzed in relation to the fiber content, thickness and weight of the
nonwovens.
PARTICIPANTS: Individuals: Sarkar, A.K. : Project Director Training or professional development: DiVerdi, J.: Graduate student Dhandapani, R: Graduate student Appidi, A: Graduate student
TARGET AUDIENCES: Target audiences: Textile, apparel and clothing professionals; healthcare professionals; agricultural professionals and other professionals working in outdoor environments.
Impacts
Outcomes: Influence of fabric characteristics on UV transmission: Cotton/polyester blend fabrics offered superior protection than 100% cotton fabrics. For 100% cotton fabrics a greater thickness afforded better protection whereas for blends thickness was not a significant factor influencing UPF. Similarly, a higher fabric weight imparted good protective properties whereas for blends fabric weight was immaterial. Preparatory treatments such as desizing and bleaching reduced the UPF. Influence of dyeing and chemical finishing on UV transmission: Dyeing with natural colorants dramatically increased the protective abilities of all three fabric constructions. Additionally, as the colorant concentration in the fabric increased the UPF values also improved. For the bamboo fabric study, results obtained showed that the UPF values increase with increase in UV absorber and dye concentration. Influence of enzymatic treatment on ultraviolet properties: Rate of agitation and
duration of treatment were important parameters influencing the UPF value of enzymatically treated fabrics. For example, increasing the rate of agitation during enzymatic treatment resulted in higher increase in UPF values with correspondingly higher percent cover. Similarly, longer the enzymatic reaction, higher was the UPF value and percent cover. The increase in UPF after enzymatic treatment is due to a decrease in porosity. It may also be that enzymatic treatment by degrading and removing the protruding microfibrils leads to a more compact knit structure thereby making the fabric more opaque to UV radiation. UV properties of nonwovens: Nonwoven substrates with bleached cotton fibers afford very little UVR protection. Likewise, nonwovens with white undyed rayon fibers offer poor protection. However, bleached cotton fibers blended with combernoil waste increases the category of protection to "Good". Nonwoven from wool fiber was found to have a high UPF value and can be classified in
the "Excellent UV Protection" category. Polyester nonwovens fell in the "Good UV Protection" category. Heavier and thicker nonwovens permit less UVR to be transmitted presumably because smaller spaces are available for the radiation to pass through. Impacts: - Studies delineated the most important fabric characteristics with regard to protection from UV radiation. The results will help in developing fabrics with the required characteristics as well as determining suitable finishing treatments to overcome deficiencies in fabrics and enhance protective performance. - Dyeing cotton fabrics with natural colorants increases the ultraviolet protective abilities of the fabrics and can be considered as an effective protection against UVR. - Enzymatic treatment was shown to increase the ultraviolet protective abilities of a knit fabric. This is a hitherto unknown and unintended but welcome benefit of bio-finishing cotton fabrics. - Nonwoven substrates were not previously studied for their
protective abilities against ultraviolet radiation. The results of this study showed that fiber composition, thickness and weight are important parameters determining the UPF values of uncolored nonwoven substrates.
Publications
- Sarkar, A.K. 2002. Influence of fabric characteristics on UV transmission [Abstract]. In: American Association of Textile Chemists and Colorists International Conference and Exhibition, American Association of Textile Chemists and Colorists Review, 2(8), 42.
- Sarkar, A.K. 2007. On the relationship between fabric processing and ultraviolet radiation transmission. Photodermatology, Photoimmunology & Photomedicine, 23, 191-196.
- Sarkar, A.K. 2004. Influence of enzymatic treatment on ultraviolet properties of cotton fabrics [Abstract]. In: Conference Proceedings, 4th International Conference on Safety & Protective Fabrics, Industrial Fabrics Association International, 283.
- Sarkar, A.K., & DiVerdi, J.A. 2004. A method for predicting the ultraviolet protection factor of fabrics by calculating percent cover using a digital stereo microscope [Abstract]. Proceedings from the Sixty-first Annual Conference of the International Textile and Apparel Association, International Textile and Apparel Association.
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Progress 01/01/06 to 12/31/06
Outputs
Objective 1: To improve protection and human factor performance of PPE through product development. The beneficial effect of textiles as a barrier to UV radiation has been well documented in literature. Factors affecting UVR transmission of textiles include the chemical nature of the fiber, porosity or cover factor, thickness, weight, and wet processing treatments such as dyes and finishes applied to the textile. However, the review of literature reveals no report on the UV properties of nonwovens. The objective of this study was to determine the Ultraviolet Protective Factor (UPF) of six selected nonwovens. The UPF values obtained were analyzed vis-a-vis the fiber content, thickness and weight of the nonwovens. Data obtained show that fiber content has a significant influence on the UPF value and hence the protective ability of a nonwoven substrate. Nonwoven substrates with bleached cotton fibers afford very little UVR protection. Likewise, nonwovens with white
undyed rayon fibers offer poor protection. However, bleached cotton fibers blended with combernoil waste increases the category of protection to "Good". Nonwoven from wool fiber was found to have a high UPF value and can be classified in the "Excellent UV Protection" category. Polyester nonwovens fell in the "Good UV Protection" category. The best UV protection ability was exhibited by a composite of polyester, rayon and activated carbon suggesting that activated carbon is a very potent absorber of UV radiation. Substrate weight and thickness have an influence on UVR transmission. A positive correlation was observed between the weight and thickness of the nonwovens and UPF values. Heavier and thicker nonwovens permit less UVR to be transmitted presumably because smaller spaces are available for the radiation to pass through.
Impacts
The results of this study show that fiber composition, thickness and weight are important parameters determining the UPF values of uncolored nonwoven substrates. Nonwoven substrates have previously not been studied for their protective abilities against ultraviolet radiation.
Publications
- Sarkar, A.K., Ramkumar, S.S., Kanukuntla, S., and Dhandapani, R. 2006. UV characteristics of cotton and blended nonwovens [Abstract]. In: Proceedings of the Beltwide Cotton Conferences, National Cotton Council of America.
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Progress 01/01/05 to 12/31/05
Outputs
Objective 1: To improve protection and human factor performance of PPE through product development. Enzymatic treatment has gained considerable attention in recent years as a useful wet-processing tool to impart value-added properties to fabrics. Of the many enzymes that are used, cellulase is one of the most important because of its wide use in treatments such as bio-polishing to improve fabric smoothness and in bio-finishing to produce the worn look. The enzymatic action of cellulase on cellulose is a surface phenomenon that results in significant morphological changes in the treated fabrics. In the current study, cotton knit fabric was treated with cellulase and the effect of structural changes on Percent Cover and Ultraviolet Protection Factor (UPF) was examined. The fabric used was a bleached cotton T-shirt fabric (Weight 124 g/m2; Testfabrics, Inc.). The enzyme used was Cellulase (Cellusoft L; Novozymes NA, Inc.). Prior to enzymatic treatment fabric samples were
subjected to boiling water treatment for 10 minutes. Enzymatic treatment was carried out under the following conditions: pH 4.8 (acetate buffer); liquor ratio 40:1; temperature 50C; enzyme concentration: 2 g/L; Agitation: 50 rpm and 80 rpm (VWR Scientific reciprocating water bath model # 1217); treatment time: 1h and 4h. Enzyme activity was terminated by boiling in distilled water for 10 minutes. Percent Cover was determined by image analysis using a stereo zoom microscope attached to a Windows XP-based PC and equipped with a CCD camera and below stage illumination (Model DM 143 Motic Instruments, Inc., Vancouver, BC). Software applications used for analysis included Photoshop (v7.0, Adobe Systems, Inc. San Jose, CA), ImageJ (v1.3, National Institutes of Health, Bethesda, MD) and a Photoshop plug-in to control the camera supplied by Motics standard software. UPF was measured using a labsphere UV Transmittance Analyzer. Results showed that enzymatic treatment increased the ultraviolet
protective ability of the cotton knit fabric. Rate of agitation and duration of treatment were important parameters influencing the UPF values. Increasing the rate of agitation during enzymatic treatment results in higher increase in UPF values with correspondingly higher percent cover. After a 1h treatment, the UPF increased by 70% at 80 rpm compared to an increase of 54% at 50 rpm. Also, longer the enzymatic reaction, higher is the UPF value and percent cover. At 50 rpm, the UPF increased by 65% after a 4h treatment compared to an increase of 54% after an hour of treatment. The increase in UPF after enzymatic treatment is probably due to a decrease in porosity. Porosity is a measure of the degree of closed versus open space in a fabric and reflected in the values of percent cover. It may also be that enzymatic treatment by degrading and removing the protruding microfibrils leads to a more compact knit structure thereby making the fabric more opaque to UV radiation.
Impacts
Enzymatic treatment has been shown to increase the ultraviolet protective abilities of a knit fabric. This is a hitherto unknown and unintended but welcome benefit of bio-finishing cotton fabrics. On-going studies are directed towards investigating the effect of post-enzymatic dyeing on UPF and percent cover. Other fabric constructions are also being studied to verify whether the results obtained for the knit fabric holds for other fabrics as well.
Publications
- Sarkar, A.K. 2005. Textiles for UV protection. In: Scott, R.A. (Ed.), Textiles for protection. Cambridge, UK: Woodhead Publishing Limited.
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Progress 01/01/04 to 12/31/04
Outputs
Objective 1: To improve protection and human factor performance of PPE through product development. A study examining the Ultraviolet Protection Factor (UPF) of cotton fabrics dyed with colorants of plant and insect origins was conducted. Three cotton fabrics were dyed with three natural colorants. Fabrics were characterized with respect to fabric construction, weight, thickness and thread count. Influence of fabric characteristics on UPF was studied. Role of colorant concentration on the ultraviolet protection factor was examined via color strength analysis. A positive correlation was observed between the weight of the fabric and their UPF values. Similarly, thicker fabrics offered more protection from ultraviolet rays. Thread count appears to negatively correlate with UPF. Dyeing with natural colorants dramatically increased the protective abilities of all three fabric constructions. Additionally, as the colorant concentration in the fabric increased the UPF values
also improved. The objective of a second study was to develop a method for predicting the Ultraviolet Protection Factor (UPF) of fabrics by calculating percent cover using a digital stereo microscope. A digital stereo microscope with an attached computer was customized with a dual bulb fixture and a frosted Plexiglas faceplate to eliminate field variations caused by the microscope's bulb. The linearity of the microscope's measurements was studied by using a stepped grayscale wedge with known transmittances to determine optimum light levels and magnification for the most accurate and reproducible measurements. The fabric sample to be analyzed was placed under a reference slide. The reference slide consisted of a piece of black paper with two squares. One square was to view the fabric sample and the second square was for light to pass through. Hence, when an image was captured it comprised a light value, a black value and the fabric sample. Images were captured at 4x magnification in
Adobe Photoshop. The 1024 x 768 pixel images were then converted to a grayscale image. The levels function of Photoshop was used to adjust the image so that the light value (from the reference slide) was at 255 and the dark value (from the reference slide) at 0. To calculate percent cover, the adjusted image was analyzed in the histogram function of Adobe Photoshop. The histogram program calculated the mean of the selected image: the sum of the index values divided by the total number of pixels. This number was divided by 255 and then multiplied by 100 to yield percent uncover. Percent uncover was subtracted from 100 to obtain percent cover. The process was repeated on three different regions of the same fabric and the mean as well as the standard deviation was calculated. Finally, an equation was developed to predict the Ultraviolet Protection Factor (UPF)of fabrics using the parameters of percent cover, thickness and weight. UPF values obtained by this method correlate well with UPF
values of fabrics measured by a UV transmittance analyzer.
Impacts
Dyeing cotton fabrics with natural colorants increases the ultraviolet protective abilities of the fabrics and can be considered as an effective protection against ultraviolet rays. Predicting UPF via a stereo microscope is a novel and inexpensive method to rate fabrics according to their UVR protective capability.
Publications
- Sarkar, A.K. 2004. An evaluation of UV protection imparted by cotton fabrics dyed with natural colorants. BMC Dermatology.4:15.
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Progress 01/01/03 to 12/31/03
Outputs
Objective 1: To improve protection and human factor performance of PPE through product development. A study investigating the influence of fabric characteristics on UV transmission was conducted. The study explored the effect of specific fabric parameters such as fiber composition, fabric weight, fabric thickness, cloth cover, chemical pre-treatments and chemical finishes on the Ultraviolet Protection Factor (UPF). It was found that cotton/polyester blend fabrics offered superior protection than 100% cotton fabrics. For 100% cotton fabrics a greater thickness afforded better protection whereas for blends thickness was not a significant factor influencing UPF. Influence of fabric weight was identical in that for 100% cotton fabrics a higher fabric weight imparted good protective properties whereas for blends fabric weight was immaterial. Cloth cover as calculated by Booths formula was an unreliable predictor of UPF. Preparatory treatments such as desizing and bleaching
reduced the UPF. However, it was found that the undesirable effects of desizing and bleaching could be compensated by the presence of an optical brightening agent. An optical brightener coupled with a durable press finish provided the highest UPF rating.
Impacts
The study was conducted to delineate the most important fabric characteristics with regard to protection from UV radiation. The results will help in developing fabrics with the required characteristics as well as determining suitable finishing treatments to overcome deficiencies in fabrics and enhance protective performance.
Publications
- No publications reported this period
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