Sustainable Care of Textile Products and Its Environmental Impact: Tumble-drying and Ironing Processes

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1 Fibers and Polymers 2017, Vol.18, No.3, DOI /s ISSN (print version) ISSN (electronic version) Sustainable Care of Textile Products and Its Environmental Impact: Tumble-drying and Ironing Processes Changsang Yun, Sarif Patwary, Melody L. A. LeHew, and Jooyoun Kim* Department of Apparel, Textiles, and Interior Design, Kansas State University, Manhattan KS 66506, USA (Received September 28, 2016; Revised December 28, 2016; Accepted January 6, 2017) Abstract: Despite the growing attention on sustainable consumption of textile and apparel products, little information is available for consumers guiding their decisions for sustainable consumption and product care. The objective of this study is to develop the logical processes to assess the environmental and economic impacts made by the textile product care and to measure the CO 2 eq. and utility cost during drying and ironing procedures. Particularly, the influence of quick-drying property and durable-press finish on product care and their impacts on CO 2 eq. and utility cost were evaluated. Results indicated quick-drying and hydrophobic fibers consumed less electricity during tumble-drying as it contained less amount of water after spinning for dehydration. A higher spin speed was favorable for saving energy during tumble-drying, as less water remained in wet laundry after spinning. While cotton fabrics were obviously wrinkled after laundering, a polyester/cotton blend in 65/35 with durable-press finish maintained smoothness grade 4 or 5 during ten times laundering period. With a conservative criterion where a grade lower than 5 needs ironing, a polyester/cotton 65/35 with durable-press finish was judged to need ironing once in two cycles of laundering. This can save about 64 % of utility and CO 2 eq. that the cotton fabric would produce in the ironing process. It is anticipated that this study provides information that is useful to consumers in their decision making for sustainable consumption. Keywords: Quick-drying, Durable-press, Drying, Ironing, Monetary cost, CO 2 equivalents (CO 2 eq.) Introduction The textile and apparel industry is one of the largest greenhouse gas-producers, accounting for approximately 10 % of global greenhouse gas emissions [1-4]. Considering the whole lifecycle of textile products from production to disposal, the largest amount of energy is consumed during product care by consumers (i.e., laundering, drying, ironing, and other maintenance processes), accounting for nearly 39 % of these greenhouse gas emissions [5-8]. Thus, sustainable care of textile products is critical to reduce the environmental and economic impacts made by textile products [9-12]. Cotton fiber takes energy-intensive care; for example, a cotton t-shirt consumes 60 % of the total lifecycle energy use during consumer care [5]. The high energy consumption of product care for cotton fabrics results mainly from the drying and ironing processes. Due to the hydrophilic property of cotton fibers, cotton products spend more time and energy in drying process. Also, ironing, one of the most disliked procedures by consumers, is a routine procedure for cotton fabrics [13-16]. To prevent the wrinkle formation, durable-press finish is commonly added to cotton fabrics [17,18]. As a result, consumers can save the ironing efforts and electric consumption. Polyester, on the other hand, is a hydrophobic material with limited moisture absorption [19-21]. Due to its hydrophobic property, it allows faster drying than hydrophilic fibers, and this quick-drying (QD) property is desirable for *Corresponding author: jkim256@ksu.edu sportswear, as sweat evaporates more quickly. Most of the commercial quick-dry (QD) products are made of hydrophobic fibers with multi-channels, through which the wicking of moisture is facilitated [22-24]. From the previous studies that investigated the environmental impacts during the use phase of textiles [3,25], different maintenance scenarios and laundering conditions- including wash temperature, number of rinsing, loading capacity, drying condition- can have a significant influence on water and energy consumption. Recently, Yun et al. [26] developed testing procedures to measure the influence of textile repellent functionality on laundering needs and its environmental impact. In this study, the reduced usage of water and electricity resulting from the reduced laundering was quantified in terms of CO 2 equivalents (CO 2 eq.) and utility cost. Though some efforts have been made to quantify the sustainability aspects of textile products, more research is needed to determine how different maintenance options influence environmental factors. With such information, consumers would be better guided in their choice of textiles and care methods for sustainable consumption. This study aims to measure the electricity consumption of textiles during drying and ironing processes and the resulting environmental and economic impacts. To examine the electricity consumption in drying process, cotton/polyester blend fabrics in different ratios and quick-drying fabrics were used. The ironing need and the associated electricity consumption were investigated for the durable-press fabric in comparison with the unfinished one. Finally, the electricity consumption by drying and ironing processes was converted to the CO 2 eq. and monetary utility cost. The ultimate goal of 590

2 Sustainable Care of Textile Products Fibers and Polymers 2017, Vol.18, No this study is to develop an objective method to assess the environmental and economic impacts of the textile products during product maintenance/care processes, and to analyze the impact of functional textiles. Experimental Materials Cotton (CTTN) 100, polyester/cotton (TC) 50/50, TC 65/ 35, polyester (PET) 100, and TC 65/35 durable-press finished (DP) fabric were purchased from Testfabrics Inc. CTTN 100, TC 50/50, TC 65/35, PET 100, and commercial quick-drying shirts (OMNI-WICK TM, Columbia Sportswear Company, USA) were used for the drying test. CTTN 100, TC 65/35 and TC 65/35 DP were used for the ironing test. The characteristics of test samples are shown in Table 1. Samples were pre-conditioned in a washing machine and dryer with five cycles of wash-rinse-spin-dry [27]. The first two cycles were done with detergent and the last three cycles were done without detergent. The specimen was cut in 40 cm 60 cm for all experiments. The laundering experiment was conducted with 3 kg of laundry including three pieces of each sample and cotton towel dummies. The wash-rinsespin procedure is denoted as laundering process in this paper. In order to measure the accurate weight of samples for drying test, samples were conditioned at 20.0±2.0 o C, 65.0±4.0 % RH in the chamber (BTL-433, ESPEC) [28]. Laundering Procedure To duplicate the most common laundering conditions, the manufacturer s default cycle was chosen for laundering process. The washing machine (FFFW5000QW0, Frigidaire; front-loading type, 0.11 m 3 capacity) was operated with normal cycle at warm wash temperature, high/max spin speed, and normal soil level. Two levels of spin speed were compared to examine the effect of spin speed on the energy usage during the drying process. The amount of liquid detergent (Tide free & gentle, Procter & Gamble) was determined according to the manufacturer s recommendation. The dryer (WED72HEDW0, Whirlpool; 0.21 m 3 capacity) was run with normal cycle at medium temperature and normal drying level. The iron (GI468NN 10, Shark) was operated with linen/cotton or polyester cycles according to fabrics. Calculation of Electricity Consumption to Dry Fabrics Clothes are usually dried excessively by a dryer to avoid uneven drying. Owing to this excessive drying, a gap could occur between the actual energy used by the dryer and the exact energy required to remove all the moisture from the clothes. To minimize this error, the energy usage for drying clothes was calculated using the nominal energy factor for clothes dryer (DEF), issued by the U.S. Department of Energy [27]. DEF assumes that 1.1 kwh of energy is needed for a dryer to remove 1 kg of the moisture in clothes after laundering. The energy to dry fabrics was calculated by multiplying 1.1 kwh by the weight of moisture held in fabrics. To calculate the energy usage till complete dry, the moisture content of the fabrics after laundering was measured, by subtracting the weight of the bone-dried samples from the weight of the wet fabrics after laundering [27,29]. Measurement of Electricity Consumption for Ironing The smoothness appearance of fabrics after the repeated laundering was evaluated by the visual assessment using the AATCC 3-D smoothness appearance replicas [30]. The visual assessment was conducted by a panel of five independent evaluators, under the light source of CIE standard illuminant D65. Five independent evaluators assigned the numerical grade of the replica in a wholenumber or in the midway between the whole-numbers, from the highest grade 5 (very smooth) to the lowest grade 1 (crumpled and severely wrinkled) [30]. The electricity consumption for ironing was measured using a powermeter (WT1600, Yokogawa, Japan) connected Table 1. Test samples Description Thickness (mm) Fabric count (warp weft/in 2 ) (wale course/in 2 ) Weight (g/m 2 ) CTTN 100 Bleached and desized cotton; plain weave Drying Ironing TC 50/50 Polyester/cotton, 50/50; plain weave Drying TC 65/35 Polyester/cotton, 65/35; plain weave Test Drying Ironing TC 65/35 DP Polyester/cotton, 65/35; plain weave with durablepress finish Ironing PET 100 Texturized polyester; interlock knit Drying QD shirt Quick-dry claimed, polyester/spandex, 92/8; men s half zip shirt, interlock knit Drying

3 592 Fibers and Polymers 2017, Vol.18, No.3 Changsang Yun et al. Table 2. Conversion factor for electricity consumption (U.S. National) [31] Tariff CO 2 equivalent Conversion factor $ /kWh kg CO 2 eq./kwh to an iron when a fabric specimen was ironed for 3-5 minutes until the smoothness appearance reaches to about grade 5 from AATCC 124. The energy usage was converted into monetary cost and CO 2 eq. by the conversion factors offered by United States Environmental Protection Agency (Table 2). Results and Discussion Drying Properties of Quick-drying Fabric To calculate the energy usage for complete dry, the water content remaining after laundering with two different spin speed levels were examined (Figure 1). In general, the remaining water content was higher as the content of cotton fiber increased; 3 kg of CTTN 100 retained 2.01 kg of water while 3 kg of QD shirts held only 0.54 kg of water after spinning for dehydration at the high spin speed. Therefore, as the content of cotton fiber increases, more energy will be consumed in the drying process. The remaining water content by high spin speed and maximum spin speed are also compared in Figure 1. High spin speed is usually selected by consumers, because it is the default option for the spin speed. As expected, the maximum spin speed left the fabrics with lower amount of remaining water, at the cost of 2 Wh additional energy consumption than the high spin speed. From our earlier study [26], the laundering process (washrinse-spin) consumed approximately 140 Wh energy, while the tumble-dry process consumed approximately 230 Wh to 2200 Wh depending on fiber types. As tumble-dry process consumes significantly more energy than the laundering process, laundering at the maximum speed spin, by leaving less remaining water, may eventually save more energy during the drying process. However, the maximum spin speed may cause more fabric damage during laundering procedure, and this needs to be taken into consideration. The energy consumption for different fibers at two different spin speeds is also presented in Figure 1. When selecting the maximum spin speed, 173 Wh of energy for CTTN 100 could be saved because of less remaining water. The reduced energy consumption of 173 Wh at the maximum spin speed is comparable to the energy (140 Wh) that is required for one complete laundering cycle (washrinse-spin) examined from the prior work [26]. The results demonstrate that the significant energy is consumed during the tumble-drying process compared to the laundering process itself, and significant portion of energy from the drying process can be saved if the maximum spin speed is used. For hydrophobic fibers including PET and QD shirt, less amount of energy is used to dry the fabrics. Also, the saved amount of energy in drying by choosing the maximum spin speed becomes lower; therefore, consumers may opt for high spin speed for these fabrics if they are concerned more about the fabric damage that may be caused by the maximum spin speed. When energy usage for drying was calculated by DEF, bone-drying 3 kg of cotton fabrics consumed 2208 Wh energy (at high spin speed); when the actual energy usage was measured by the powermeter at the same condition (load size; 3 kg, cycle; normal, drying temperature; medium, drying level; normal), 2649 Wh was consumed by the dryer from our previous study [26]. Likewise, in common consumer practice, clothes can be excessively dried by tumble-drying to avoid uneven drying. Fibers have their own moisture regain and they differ depending on fiber types and humidity of environment. The moisture content of fabrics at the standard condition (20.0±2.0 o C and 65.0±4.0 % RH) was examined for 3 kg of laundry, and the electric energy required to remove the moisture completely from the standard condition to the bone-dry condition was calculated by DEF (Table 3). When Figure 1. Remaining water content after spinning and energy consumption calculated by DEF to bone-dry fabrics.

4 Sustainable Care of Textile Products Fibers and Polymers 2017, Vol.18, No Table 3. Moisture regain, moisture content, and energy to remove moisture from fabrics Moisture regain (%) Moisture content in 3 kg of laundry (g) Energy required to remove moisture (Wh) PET TC 65/ TC 50/ CTTN QD shirt bone-dried fabrics were conditioned at the standard condition, CTTN 100 regained 7.4 % moisture and quick-drying (QD) shirt regained 0.4 % moisture compared to their own weight. This means that 3 kg of bone-dried cotton would reabsorb 222 g of moisture at the standard condition, and 244 Wh of electric energy to dry up 222 g moisture was an unnecessary loss of energy from the excessive drying. It would be desirable to avoid this excessive drying and energy loss, leaving the fabrics to hold some moisture up to about their standard moisture regains by selecting a lower drying temperature and a shorter time than required for a complete dry. Influence of Durable-press Finish on Energy Consumption During Care The appearance of fabric wrinkles for different fibers were evaluated after the repeated laundering (Table 4). The smoothness grade of CTTN 100 was in between 1.6 and 2.1, which is an obviously wrinkled appearance according AATCC evaluation method. TC 65/35 was graded from 3.7 to 4.5 grade, for fairly smooth appearance. TC 65/35 DP maintained very smooth appearance corresponding from 4.4 to 5.0 grade throughout ten times of laundering. While TC 65/35 showed lower grades than TC 65/35 DP, TC 65/35, without DP finishing, considerably improved smoothness grades compared to CTTN 100. The lowest grades for TC 65/35 during ten laundering was 3; consumers with tolerant with wrinkles may save ironing efforts at this level of Figure 2. Electricity consumption by ironing: for a fabric 40 cm 60 cm, during two launderings. wrinkles. Both fiber content and DP finishing affected wrinkle formation. Though fabric construction such as fabric count, weave pattern and thickness generally affects wrinkle formation, the influence of fabric construction (for CTTN 100, TC 65/35, and TC 65/35 DP) on results of ironing study will be limited as the fabrics had similar constructions. If the necessity of ironing is judged by the most conservative criteria, any fabrics with lower than 5 grade can be judged for ironing. With such a scenario, TC 65/35 DP would need ironing at every second laundering; that is, fabrics would need ironing after 2nd, 4th, 6th, 8th, and 10th laundering during ten times laundering period. CTTN 100 and TC 65/35 would need ironing at every laundering in that scenario. Electricity consumption by the ironing process was measured for a fabric in 40 cm 60 cm (Figure 2). CTTN 100 and TC 65/35 were ironed every time after laundering until the surface appearance reaches closest to grade 5 of AATCC standard reference, while TC 65/35 DP fabrics were ironed once in two launderings. CTTN 100 consumed the largest amount of electric energy, due to the higher ironing temperature and the frequency of ironing. Table 4. Wrinkle evaluation after repeated laundering by the AATCC assessment

5 594 Fibers and Polymers 2017, Vol.18, No.3 Changsang Yun et al. Table 5. Monetary cost and CO 2 eq. of 3 kg of laundry for 50 cycles of drying process Remaining water content after spinning (%) Monetary utility cost ($/3 kg of laundry) CO 2 eq. (kg/3 kg of laundry) High spin speed Max spin speed High spin speed Max spin speed High spin speed Max spin speed PET TC 65/ TC 50/ CTTN QD Shirt Conversion of Energy Consumption to CO 2 eq. and Utility Cost To calculate the energy consumption, it was assumed that normal clothing experiences 50 times of laundering until it is disposed [3,25,26]. The electricity consumption by the drying process was determined with 3 kg of laundry in order to duplicate the use conditions in daily life. Electricity consumption was converted into the monetary utility cost and CO 2 equivalent using the conversion factors shown in Table 2, and the results are shown in Table 5. When choosing the high spin speed, the QD shirts cost $ 2.93 and emitted kg of CO 2 eq. by the drying process. Compared to CTTN 100, PET 100 and QD shirt produced % and % of monetary cost and CO 2 eq., respectively. When selecting the maximum spin speed, CTTN 100 will reduce 8% of CO 2 equivalent than it was spun at high speed. Energy consumption by ironing process during lifetime laundering of 50 cycles was calculated for monetary cost and CO 2 eq. in Table 6. It was assumed that CTTN 100 and TC 65/35 needed to be ironed at every laundering, and TC 65/35 DP needed to be ironed after every second laundering cycle. TC 65/35 DP needed to be ironed 25 times in their lifetime, although the durability of wrinkle-free effect during their lifetime laundering of 50 cycles was not tested. Three kg of CTTN 100 cost $ and emitted kg of CO 2 eq. during its lifetime, while TC 65/35 DP was 36 % of utility cost and CO 2 eq. of CTTN 100 ($ 8.96 and kg of CO 2 eq.). Reducing the ironing efforts is meaningful because the ironing procedure is regarded as the most annoying maintenance procedure by consumers. Considering the environmental impacts made by product care during the use phase, TC 65/35 clothing can be maintained with less consumption of energy than CTTN 100 clothing, for its drying efficiency and reduced wrinkle Table 6. Monetary cost and CO 2 eq. by the ironing process of 3 kg of laundry Monetary utility cost ($/3 kg of laundry) CO 2 eq. (kg/3 kg of laundry) CTTN TC 65/ TC 65/35 DP Figure 3. Energy consumption of 3 kg of laundry for 50 laundering cycles [25]. formation even without durable-press finishing. In Figure 3, energy used for 50 cycles of laundering-drying-ironing for 3 kg fabric is approximated. The energy for laundering was measured at the recommended washing temperature for CTTN 100 (60 o C) and TC 65/35 (40 o C) in the previous study [25]. Though the direct comparison of energy usage is not possible, TC 65/35 would consume approximately 76 % of electric energy that CTTN 100 would consume during 50 cycles of laundering-drying-ironing procedures. In this study, the logical processes to measure the environmental impacts made by the drying and ironing processes were designed. Using the developed processes, the energy consumption during the lifetime product care was measured for different fiber types. Particularly, the influence of quick-drying property and durable-press finish on product care and their impacts on CO 2 eq. and utility cost were evaluated. Despite the growing attention on sustainable consumption of textile and apparel products, little information is available for consumers as their decision guide for sustainable consumption and product care. The results of this study would provide a piece of information that consumers can utilize in their decision making for sustainable consumption. Further study in the extended scope of lifecycle of textile produces is recommended. Conclusion The objective of this study is to develop the logical

6 Sustainable Care of Textile Products Fibers and Polymers 2017, Vol.18, No processes to assess the environmental and economic impacts made by the textile products care and to measure the CO 2 eq. and utility cost during the maintenance cycle of launderingdrying-ironing. The influence of fiber properties and durablepress finish on environmental impact was also examined. Hydrophilic fiber consumed more electricity during tumbledrying as it had more water content remaining after spinning than hydrophobic fiber; PET 100 used % of electricity that CTTN 100 used. During laundering, the higher spin speed was favorable in terms of saving energy during tumble-drying, as less water remained in wet laundry after spinning. By choosing the maximum spin speed instead of high spin speed, 3 kg of CTTN 100 during 50 cycles of drying reduced $ 0.86 of utility and 6.13 kg of CO 2 eq. Cotton fabrics had obvious wrinkles after laundering according to AATCC 3-D smoothness appearance replica. TC 65/35 DP maintained smoothness grades 4 or 5 during ten times of laundering. With a conservative ironing criteria where a smoothness grade lower than 5 needs ironing, TC 65/35 DP fabric was judged to need ironing once in two cycles of laundering, and this saved about 64 % of utility cost and CO 2 eq. that CTTN 100 produced. TC 65/35 clothing can be maintained with less consumption of energy than CTTN 100 clothing, for its drying efficiency and reduced wrinkle formation even without durable-press finishing. This study provides a useful information for sustainable consumption of textile and apparel products. Acknowledgment This work was supported by 3M Non-Tenured Faculty Award and the Contribution no J from the Kansas Agricultural Experiment Station. References 1. K. Fletcher, Sustainable Fashion & Textiles : Design Journeys, pp.3-6, Gutenberg Press, Malta, F. Caniato, M. Caridi, L. Crippa, and A. Moretto, Int. J. Prod. Econ., 135, 659 (2012). 3. J. Kim, C. Yun, Y. Park, and C. H. Park, Fiber. Polym., 16, 926 (2015). 4. S. Saxena, A. S. M. Raja, and A. Arputharaj, Challenges in Sustainable Wet Processing of Textiles, Retrieved September 19, 2016, from content/document/cda_downloaddocument/ c2.pdf?sgwid= p J. M. Allwood, S. E. Laursen, C. M. Rodriguez, and N. M. Bocken, Well Dressed? The Present and Future Sustainability of Clothing and Textiles in the United Kingdom, pp.8-14, University of Cambridge Institute for Manufacturing, Cambridge, J. M. Cullen and J. M. Allwood, J. Ind. Ecol., 13, 27 (2009). 7. Y. Yamaguchi, E. Seii, M. Itagaki, and M. Nagayama, Int. J. Consum. Stud., 35, 243 (2011). 8. B. Anderson, M. LeHew, K. Hiller, S. Sutheimer, and G. Hustvedt, Professional Development and Education for Apparel and Textiles Educators, Retrieved September 19, 2016, from 9. A. Gwilt and T. Rissanen, Shaping Sustainable Fashion : Changing the Way We Make and Use Clothes, pp , Earthscan from Routledge, New York, K. K. Moon, C. S. Lai, E. Y. Lam, and J. M. T. Chang, J. Text. Inst., 106, 939 (2015). 11. F. Harris, H. Roby, and S. Dibb, Int. J. Consum. Stud., 40, 309 (2016). 12. C. M. Armstrong, K. Niinimake, S. Kujala, E. Karell, and C. Lang, J. Clean. Prod., 97, 30 (2015). 13. V. A. Dehabadi, H. J. Buschmann, and J. S. Gutmann, Text. Res. J., 83, 1974 (2013). 14. I. Holme, J. Text. Inst., 84, 520 (1993). 15. W. D. Schindler and P. Hauser, Chemical Finishing of Textiles, pp.51-72, Woodhead Publishing, Cambridge, Department for Environment, Food and Rural Affairs, Reducing the Environmental Impact of Clothes Cleaning, from EV0419_8628_FRP.pdf, Retrieved August 26, Y. L. Lam, C. W. Kan, and C. W. M. Yuen, Text. Res. J., 81, 482 (2011). 18. M. Hashem, M. H. Elshakankery, S. M. A. El-Aziz, M. M. G. Fouda, and H. M. Fahmy, Carbohydr. Polym., 86, 1692 (2011). 19. Y. Zhang, H. Wang, C. Zhang, and Y. Chen, J. Mater. Sci., 42, 8035 (2007). 20. K. Kajiwara, R. Nori, and M. Okamoto, J. Text. Inst., 91, 32 (2000). 21. F. Wang, X. Zhou, and S. Wang, Fibres Text. East Eur., 17, 46 (2009). 22. A. Khoddami, M. I. Soleimani, and H. Gong, Text. Res. J., 81, 2006 (2011). 23. J. Dave, R. Kumar, and H. C. Srivastava, J. Appl. Polym. Sci., 33, 455 (1987). 24. B. Becerir, E. Karaca, and S. Omeroglu, Color. Technol., 123, 252 (2007). 25. J. Kim, Y. Park, C. Yun, and C. H. Park, Energ. Effic., 8, 905 (2015). 26. C. Yun, M. I. Islam, M. LeHew, and J. Kim, Fiber. Polym., 17, 1296 (2016). 27. United States Department of Energy, Energy Conservation Program: Test Procedures for Residential Clothes Washers, Retrieved August 26, 2016, from prod/files/ 2014/04/f14/rcw_tp_nopr.pdf 28. International Organization for Standardization, Textiles Standard Atmospheres for Conditioning and Testing, ISO 139:2005(E), International Electrotechnical Commission, Clothes

7 596 Fibers and Polymers 2017, Vol.18, No.3 Changsang Yun et al. Washing Machines for Household Use Methods for Measuring the Performance, IEC Edition 5.0, American Association of Textile Chemists and Colorists, Smoothness Appearance of Fabrics after Repeated Home Laundering, AATCC Test Method , United States Environmental Protection Agency, Pollution Prevention Tools and Calculators, Retrieved August 26, 2016, from #calc