1992; Saravanan 1996). The mean length of the fibres of C. pangorei is 724.7 μm with an average diameter of 9.6 μm, which is close to the fibres of C. papyrus, whose minimum length is 300 μm, maximum length is 1500 μm and, diameter between 5 and 25 μm (Rowell et al. 2000). The fibres vary in length between the core and rind regions of C. pangorei culms, as also reported by Lwin et al. (2000) in case of bamboo, where there are variations even within the same plant. Fibre dimension as well as length influences the physico-mechanical properties such as toughness, tensile, and static bending strength, which in turn affect the workability (Parameswaran and Leise 1975; Espiloy 1987; Widjaja and Risyad 1987). Thus longer fibres show higher tenacity. These qualities present in long rind fibres of C. pangorei make it suitable for weaving fine and superfine mats. It was further reported that an increase in the lumen width and fibre diameter also influences the strength properties of fibres. Core fibres have greater lumen width as compared to rind fibres. The lesser the lumen width, the stronger will be the fibre. Lumen width of the fibres shows a strong correlation with the mechanical properties. The mat weavers thus remove the pith region containing the core before splitting of the culm strands.
The derived values of fibre dimensions are slenderness ratio (SR), which is indicative of tear resistance that is more in the rind fibre, when compared to the core fibres. The higher the SR, the stronger will be the resistance to tearing. The preferred SR ratio for use in textile industries is between 200 -3000 (Maiti 1980). However, the SR of the rind and core fibres of C. pangorei is lesser than 100 and therefore may not be suitable for textile industries, but adequate for mat industries. However, when compared with Miscanthus and switch grass (used in paper making), the SR of C. pangorei fibres can be considered good, as they will have high tear indices and bursting strength. Flexibility ratio is inversely proportional to tensile strength. Thus the FR of the rind fibres is less, and thereby the tensile strength is more (Kasim and Jalil 1991; Table 2 and 3). However, fibres with high FR are flexible, crumple readily, and produce good surface contact and fibre-to-fibre bonding, yielding low bulk paper that may not be suitable for the mat industries. Thus, the low FR in fibres of C. pangorei can be justified based on their suitability in the mat industries. The Runkel ratio (RR) is related to lumen width and thickness of the fibre, thereby indicating the suppleness of the fibre. The RR of the rind fibres is 5.74 and that of core fibres is 1.59. RR values between 1 and 2 render the fibres suitable for use in textiles, while RR of 1 or less than 1 is considered to be favorable for papermaking (Tamolong et al. 1980).
The physico- mechanical properties such as actual strength, elongation-breaking force, and tenacity of the processed culm strands (50s dyed, 100s dyed, 120s dyed, and 120s undyed) are given in Table 3. The culm strands of different counts had no differences in their physico-mechanical properties. Flexibility of fibres had a direct correlation with elongation. Maximum percent elongation was in 120s undyed strands (7.37%), and the values correspond to that of ramie yarn (Cheng et al. 1992). The tenacity of the fibre is an important factor in selecting a particular fibre for a specific application (Rowell et al. 2000), and the tenacity of C. pangorei culm strands is higher than that of kenaf and pineapple leaf fibres, however lower than that of cotton (Duraiswamy and Chellamani 1993). The tenacity of fibre depends on the breaking load of the fibres and is inversely proportional to the fineness or tex of the fibres, as found in
Benazir et al. (2010). “Sedge fibers and strands,” BioResources 5(2), 951-967.