ENERGY, ENVIRONMENT, ECOSYSTEMS, DEVELOPMENT and LANDSCAPE ARCHITECTURE

Engineering Sustainable : a Comparison MARILYN WAITE AND JIM PLATTS Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ UNITED KINGDOM [email protected], [email protected], http://www.ifm.eng.cam.ac.uk/people/mjp/

Abstract: This paper delves into a subset of engineering for sustainable development—the engineering of sustainable textiles using bamboo. The experiments performed attempt to answer two main questions: (1) what are the differences in textile properties between chemicallymanufactured and mechanicallymanufactured bamboo textiles? and (2) what are the differences in textile properties between two different species of bamboo? The textile properties examined relate to sustainability: wear and tear (and therefore durability) and moisture wicking (and therefore the need for machine washing and drying). The following are measured for fibre, yarn, and fabric: tear force, breaking force, breaking tenacity, moisture absorption and speed of drying, and surface morphology.

Key-Words: textiles, bamboo, fibre, yarn, fabric, sustainability, renewable, manufacturing, SEM

1 Introduction There are two main manufacturing methods currently One of the earliest engineering practices involved the being employed in the creation of bamboo textiles— use of scientific principles to extract and manufacture chemicallybased (hydroalkalization and multiphase textiles for practical applications. At present, the bleaching) and mechanicallybased (stripping, boiling, industry has a poor track record for social and and enzymeuse) processes. In this paper, bamboo environmental concerns. Textiles made from bamboo textiles made from the chemical process are referred to address the aim of sustainable development by as chemical bamboo and textiles made from the utilizing a renewable resource to make clothes and mechanical process are said to be mechanical bamboo. other textile applications. The earliest record of US Both methods engender negative impacts on the Patents concerning bamboo textiles was made by environment and human health, though there is much Philipp Lichtenstadt in 1864 [9]. The advantages of debate as to which is more sustainable. bamboo textiles can be divided into two main categories: (1) those derived from the use of the plant There are also over 1500 species of bamboo globally, itself and (2) those derived from fabric properties of which only a few are being employed to create given by the plant. The advantages of using bamboo as textiles. Some companies use only one species of a raw material for textiles include its renewability, its bamboo for bamboo , while other biodegradability, its efficient space consumption, its companies use many (such as 13 species) without low water use, its organic status, and its carbon distinguishing between species and textile properties. sequestering abilities given a sustainably managed The experiments performed attempt to answer two bamboo forest. Bamboo is the fastest growing plant in questions: (1) what are the differences in textile the world—it can grow a meter or more per day [5]. properties between chemical bamboo and mechanical Bamboo yields 50 times as much fibre per acre as bamboo textiles (species held constant), and (2) what [3]. Bamboo textiles provide quicker harvest are the differences in textile properties between two readiness compared with 15year old trees that are different species of bamboo used to produce chemical used to make , , and other regenerated bamboo (Phyllostachys edulis and Bambusa fibre [7]. The main constraints of bamboo textiles are emeiensis) (manufacturing method held constant)? those inherent in the textile industry: various energy, water, and chemical requirements that can be involved The textile properties measured here are as follows: in its manufacturing. tear force, breaking force, breaking tenacity, moisture absorption and speed of drying, and surface morphology. Tests are performed at various stages of the bamboo textile manufacturing process: fibre, yarn, 2 Problem and fabric. The properties analysed have special Bamboo textiles present a noteworthy opportunity for relevance to sustainable development. The ability to providing sustainable textiles. Nevertheless, the withstand forces is a key indicator of durability. The renewable properties of bamboo itself do not add longer a textile lasts, the more one can prolong its much to sustainable development if the textiles cannot eventual deposit in landfill, and perhaps the more one serve a practical purpose. Bamboo textiles must can refrain from replacing and wasting further exhibit properties appropriate for its applications, resources. If a textile can absorb moisture quickly and thereby providing the enduser with a useful item. dry moisture quickly, then the need for mechanical

ISSN: 1790-5095 362 ISBN: 978-960-474-125-0 ENERGY, ENVIRONMENT, ECOSYSTEMS, DEVELOPMENT and LANDSCAPE ARCHITECTURE

drying and perhaps washing (which can be energy and 1. A rectangular paper frame was constructed water intensive) can be lessened. with a rectangular cut out according to the dimensions in Fig. 1. 2. Doublesided tape was then used to apply an 3 Materials adhesive surface to one side of the paper Bamboo fibre, yarn, and fabric samples were collected frame. The rectangular cut out was preserved using two different species of bamboo—Phyllostachys by cutting through the doublesided tape. edulis and Bambusa emeiensis (formerly known as 3. Five individual fibres were carefully picked Neosinocalamus affinis). To perform the scanning using fine tweezers and placed along the electron microscope (SEM) observations, the rectangular cut as seen in Fig. 1. CamScan MX2600 was used. The mechanical tests 4. Masking tape was cut and placed along both were performed with a Hounsfield Low Load Electric ends of the fibres to hold them in place. Screw Machine. In order to conduct the moisture 5. The paper frame and the attached fibres were absorption and drying experiments, the following then clamped using the Hounsfield tensile materials were used in addition to fabric: 17cm testing machine. diameter embroidery hoop, deionised water, balance, 6. Slits were cut through two ends of the paper pipettes and pipette tips, and a beaker. frame so that the only materials pulled during

the test were the fibres. 7. A standard breaking force program was used 4 Methods with a load range of 5N, a speed of 100 mm/min, and an extension range of 10 mm. 4.1 SEM Images Standard test procedures for live specimens were used Fig. 1: Sample Preparation for Bamboo Fibre to observe the differences in surface morphology among various bamboo fibres. The fibres were cut and goldplated as preparation.

4.2 Moisture Wicking Tests AATCC Test Method 792007 was employed to measure textile absorbency [1]. To measure the speed of drying of the different fabrics, 50 L of deionised water was placed on a piece of fabric cut 4 cm wide and 5 cm long. The weight of the fabric was taken before and after the 50 L of water was introduced, as well as at set time intervals until the weight of the fabric reached its initial recording. 4.3.2 Yarns To measure the tensile properties of yarns, ASTM 4.3 Mechanical Tests standard D 225602, Standard Test Method for Tensile Mechanical tests were completed according to various Properties of Yarns by the SingleStrand Method, was internationallyrecognised standards, including those employed [2]. A total of ten trials were performed for from the American Society for Testing and Materials each yarn type. (ASTM), the International Organization for

Standardization (ISO), the British Standards Institution 4.3.3 Fabric (BSI), and the American Association of Textile To measure the tear properties of fabric, EN ISO Chemists and Colorists (AATCC). 139372:2000, Tear properties of fabrics Part 2:

Determination of tear force of trousershaped test 4.3.1 Fibres specimens (Single tear method), was employed [6]. A To measure the breaking force of the bamboo fibres, total of six trials were performed for each fabric type, standard test methods had to be modified to conduct a three to calculate the tear force across warp and three comparison adequate for the short and fine chemical to calculate the tear force across weft. bamboo fibres. Bamboo fibres were measured at the following stages: thick pulp (earliest stage) chemical bamboo fibre, fine pulp chemical bamboo fibre, and mechanical bamboo fibre. Ten trials were completed 5 Results for each sample type. The following method was employed: 5.1 SEM Analysis - Fibres

ISSN: 1790-5095 363 ISBN: 978-960-474-125-0 ENERGY, ENVIRONMENT, ECOSYSTEMS, DEVELOPMENT and LANDSCAPE ARCHITECTURE

The SEM images show various similarities and Fig. 4: B. emeiensis Chemical Bamboo Fibre (Thick differences among the four bamboo fibre types Pulp) analysed. Both species of chemical bamboo fibre Left: crosssectional direction (SEM Mag1406X) displayed a tubular and ribbed (celerylike) Right: longitudinal direction (SEM Mag3152X), longitudinal surface; the cross sections of both species Diameter is ≈ 31.5 m were filled with voids (Fig. 2 and Fig. 3). The thick pulp of chemical bamboo fibre has a rough and very porous surface (Fig. 4); this is to be expected as it is the closest to the actual bamboo plant among all of the fibre types. Mechanical bamboo fibre displayed a bamboolike longitudinal section, tubular with nodes

(Fig. 5); the cross section displayed some voids, though much fewer than the chemical bamboo fibres. Fig. 5: P. edulis Mechanical Bamboo Fibre The mechanical bamboo fibre also has a higher linear Left: crosssectional direction (SEM Mag4476X) density (5.88 dtex) than the chemical bamboo fibres Right: longitudinal direction (SEM Mag1708X), (1.56 dtex). Diameter is ≈ 16 m

Fig. 2: P. edulis Chemical Bamboo Fibre Left: crosssectional direction (SEM Mag7900X) Right: longitudinal direction, Diameter is 13.4 m 15.6 m (SEM Mag3346X)

5.2. Mechanical Tests

5.2.1 Mechanical Tests - Fibres The results for fibre breaking force and breaking tenacity illustrate that mechanicallymanufactured B. emeiensis Fig. 3: Chemical Bamboo Fibre bamboo fibre is more than two times stronger than Left: crosssectional direction (SEM Mag3346X) chemicallymanufactured bamboo. There are no Right: longitudinal direction (SEM Mag2086X), significant differences between species at the fibre Diameter is 12.3 m 15.2 m level. The breaking tenacity of cotton, , viscose rayon, and are all below that of the bamboo fibres tested; therefore, bamboo fibres may be more resistant to wear and tear than conventional fibres. The raw chemical bamboo fibre was not used for comparative purposes; however, it is clear that the strength of the bamboo fibres are more present before continual processing. Graph 1 shows the mechanical testing results for bamboo fibres.

Graph 1: Fibre Breaking Force and Breaking Tenacity Comparison

ISSN: 1790-5095 364 ISBN: 978-960-474-125-0 ENERGY, ENVIRONMENT, ECOSYSTEMS, DEVELOPMENT and LANDSCAPE ARCHITECTURE

5.2.2 Mechanical Tests - Yarn difference between the mechanical properties of The breaking force and breaking tenacity of bamboo different bamboo species in yarn form. Graph 2 yarn reveal small differences between species and illustrates the mechanical testing results for bamboo manufacturing method. It appears that the processing yarn. of fibre into yarn creates some level of strength degradation for mechanicallymanufactured bamboo. As with bamboo textile fibres, there was no significant

Graph 2: Yarn Breaking Force and Breaking Tenacity Comparison

5.2.3 Mechanical Tests - Fabric bamboo. However, the woven chemical bamboo fabric The fabric tear results show that woven fabrics are sample contained a floral pattern which almost created more resistant to tear forces than knit fabric. Also, a doublelayer; therefore, it is difficult to say with Bambusa emeiensis endured a higher tear force than certainty that there is a difference in manufacturing Phyllostachys edulis. Ironically, mechanically method for these tests. Graph 3 shows the mechanical manufactured bamboo showed a much lower testing results for bamboo fabric. resistance to tear force than chemicallymanufactured

Graph 3: Fabric Tear Force Comparison

ISSN: 1790-5095 365 ISBN: 978-960-474-125-0 ENERGY, ENVIRONMENT, ECOSYSTEMS, DEVELOPMENT and LANDSCAPE ARCHITECTURE

5.3 Moisture Wicking Tests - Fabric chemical bamboo woven made from Phyllostachys Graph 4 shows the moisture wicking results for edulis. It should be noted, however, that the design of bamboo fabric. Phyllostachys edulis has by far the the chemical bamboo woven fabric could have slowed quickest absorption time. The fastest drying fabric was the drying time because of the doublelayer nature of the mechanical bamboo made from Phyllostachys the pattern. edulis, while the slowest drying fabric was the

Graph 4: Moisture Wicking Properties of Bamboo Fabric

6 Discussion however this could be due to the woven design in the There are noticeable differences between textile chemical bamboo fabric. strength in fibre, yarn, and fabric form, with some apparent degradation in processing. At the fibre level, The moisture absorption tests revealed welldefined mechanical bamboo’s breaking tenacity is at least differences between species, manufacturing method, twice as big as chemical bamboo fibre. At the yarn and textile specification. In general, the woven level, there are small differences between species and bamboo fabric absorbed water much quicker than the manufacturing method for breaking tenacity. At the knit bamboo fabric. In knit chemical bamboo textile fabric level, Bambusa emeiensis has a bigger tear force form, Bambusa emeiensis took four times longer than and tearing tenacity than Phyllostachys edulis. Phyllostachys edulis to absorb water. In woven form Nevertheless, specie differences in fabric form are (species kept constant with Phyllostachys edulis) the small. The tearing strength of mechanical bamboo chemical bamboo absorbed water instantaneously, fabric was much smaller than chemical bamboo fabric, while the mechanical bamboo took 163 s on average to absorb. Based on these results, chemical bamboo

ISSN: 1790-5095 366 ISBN: 978-960-474-125-0 ENERGY, ENVIRONMENT, ECOSYSTEMS, DEVELOPMENT and LANDSCAPE ARCHITECTURE

woven fabric is better at water absorption than mechanical bamboo exhibits better moisture wicking mechanical bamboo woven fabric, but chemical properties than chemical bamboo. bamboo knit fabric takes a very long time to absorb. There also is a difference in absorption properties between bamboo species in textile form, and perhaps 8 Limitations the same differences can be found in raw bamboo in This paper shows how the properties of bamboo can be nature. useful for textile applications in the realm of sustainable development. It is important to emphasize The moisture drying tests revealed that some fabrics that bamboo, or any single textile source, will not were better at absorbing than drying. Phyllostachys serve as a panacea to the sustainability issues of the edulis chemical bamboo woven fabric was the quickest textile sector. Overreliance on one source, whether it to absorb, but the longest to dry. This may have been is for energy or for textiles, is contrary to the due to the double layer of woven material to create the underlying principles of sustainable development. In floral pattern. When manufacturing method and addition, different materials have different mechanical, specification was held constant, Phyllostachys edulis physical, chemical, and technical properties that will absorbed and dried faster than Bambusa emeiensis; serve for a diverse range of applications. The current this supports the SEM images since there are more textile mix, with a clear majority belonging to visible voids in the chemical bamboo Phyllostachys petroleumbased synthetics and cotton fibres, is edulis species. However, the fabric that has the best presented in Fig. 6. A future range of textile mix moisture wicking property is the mechanical bamboo possibilities, randomly chosen, is shown in Fig. 7 and made of Phyllostachys edulis. This sample absorbed Fig. 8. water in a short time (163 s) and dried water in a short Fig. 6: World Textile Mix time (452 s); though it did not show many voids in the (2006) SEM crosssectional image, the longitudinal section resembled a bamboo as a tubular shape with nodes. Perhaps there is some level of biomimicry in the fibres of bamboo that can be further explored.

7 Conclusion There are two main conclusions that are drawn from the results: the species of bamboo is not trivial for bamboo textile applications and there are fundamental differences between the type and function of bamboo textiles that are manufactured chemically versus those Note: Chart generated using data provided by Textile that are manufactured mechanically with the aid of Outlook International [8]. data taken enzymes. Currently, many manufacturers who make from the Organic Cotton Report [4]. NB: man- chemical bamboo fabric add various species of made fibre demand figures are based on production bamboo into the mixture, without consideration of the data; natural fibre demand figures are based on differences. Although the research did not indicate a consumption data to avoid inaccuracies arising from significant difference in mechanical properties such as wide stock variations from year to year; numbers may breaking tenacity between species, moisture wicking not sum precisely due to rounding properties varied significantly. There are blogs that state that mechanicallymanufactured bamboo is better Fig.7 and Fig.8: Textile Mix Possibilities than chemicallymanufactured bamboo; this study shows that the two textiles are not interchangeable, and that their appropriateness will depend on the goals of the application.

Three specific conclusions can be made from the experimental tests: (1) mechanical bamboo fibres are much stronger than those chemically manufactured, but this strength at the fibre level does not remain consistent with further processing in yarn and fabric form, (2) Phyllostachys edulis exhibits better moisture wicking properties than Bambusa emeiensis, (3)

ISSN: 1790-5095 367 ISBN: 978-960-474-125-0 ENERGY, ENVIRONMENT, ECOSYSTEMS, DEVELOPMENT and LANDSCAPE ARCHITECTURE

Bamboo textiles present many solutions to the present unsustainable nature of textile engineering; however, energy, water, and chemical concerns in manufacturing still must be addressed. Further work could explore more species of bamboo, as well as how small changes in the manufacturing process may change the quality of the textile at the fibre, yarn, and fabric levels. In summary, there is room for many different types of species and manufacturing methods for bamboo in the textile industry.

References: [1] AATCC, A Glossary of AATCC Standard Terminology, Research Triangle Park, American Association of Textile Chemists and Colorists, 2008. [2]ASTM, Annual Book of ASTM Standards Section 7: Textiles, West Conshohocken, American Society for Testing and Materials, 2003. [3] Durst, S., The Panda Food in Your Pants, Business 2.0, Vol. 7, No. 9, 2006. [4] Ferrigno, S., Organic Cotton Fiber Report, www.organicexchange.org/Documents/fiber_2006.pdf 2006. [5] Fu, J., Chinese Moso Bamboo: Its Importance, ABS Magazine, Vol.22, No.5, 2001. [6] ISO, Textiles—Tear properties of fabrics Part 2: Determination of tear force of trouser-shaped test specimens, International Organization for Standardization, 2000. [7] Rodie, J.B., Quality Fabric of the Month: Spotlight on Bamboo, Textile World, March/April, 2007. [8] Simpson, P., Global Trends in Fibre Prices, Production and Consumption, Textile Outlook International, SeptemberOctober, No.31, 2007. [9] Lichtenstadt, P., Verification of Bamboo Fibre, US Patent & Trademark Office, 1864.

ISSN: 1790-5095 368 ISBN: 978-960-474-125-0