Fibers from Switchgrass

image16Natural Cellulose Fibers from Renewable Resources

Keywords

Switchgrass • High-yield • Cellulosic ethanol • Stem fiber • Leaf fiber

Switchgrass is a high-yielding, low-input biomass crop that is considered to be the most suitable crop for cellulosic ethanol production. Although not a by-product, switchgrass can be a source for fibers requiring fewer inputs to grow and could be economically more viable than traditional fiber crops such as jute and flax. In addition, about 25-30 % of switchgrass can be obtained as long fibers for high — value applications, and the remaining 20-25 % of short fibers and hemicellulose could still be used for ethanol production. Switchgrass consists of outer leaves (45 % of total plant weight) and inner sheath (stem) (55 % of total plant weight). Both the leaves and stems were used for fiber production [07Red]. As seen in Table 11.1, fibers obtained from switchgrass have very unique and distinct properties not seen in any other fiber obtained from lignocellulosic by-products. Fibers obtained from the leaves had high strength but low elongation similar to that of linen, whereas fibers from the stems of switchgrass had lower strength but high elongation, similar to that of cotton. A single plant producing two types of fibers with such distinct characteristics is unique. The relatively low fineness of fibers obtained from switchgrass leaves implies that the fibers could be processed on textile machinery. Low costs to grow, high fiber yield (20-25 %), and distinct fiber properties make switchgrass a crop with high potential for fiber production.

Table 11.1 Properties of fibers obtained from the leaf and stems of the renewable switchgrass

Switchgrass

Leaf

Stem

Linen

Cotton

Fineness [denier]

30 ± 12

60 ± 20

1.7-17.8

1-3.3

Length [cm]

6.5 ± 4.3

5.8 ± 3.3

20-140

1.5-5.6

Strength [g/den]

5.5 ± 1.2

2.7 ± 0.8

4.6-6.1

2.7-3.5

Elongation [%]

2.2 ± 0.7

6.8 ± 2.1

1.6-3.3

6.0-9.0

Modulus [g/den]

240 ± 74

70 ± 23

203

55

From [07Red]

Reference

[07Red] Reddy, N., Yang, Y.: Biotechnol. Bioeng. 97(5), 1021 (2007)