Page 149 - Handbook of Properties of Textile and Technical Fibres

Physical, chemical, and tensile properties of cashmere, mohair, alpaca 127

dromedary camel (Msahli et al., 2008). With commercial dehairing equipment, where
carding actions should be optimized to reduce breakage, the mean length of dehaired
cashmere was substantially less than the staple length of raw cashmere (McGregor and
Butler, 2008). Dehaired length was positively linearly related to staple length and
quadratically related to fiber diameter. There were different relationships for white
and colored cashmere in the response to fiber diameter. A consequence of fiber
breakage is that most dehaired cashmere is only of sufficient length to be spun on
the woollen system. Physical properties of the cashmere that affected the proportion
of cashmere recovered were MFD, staple length, fiber curvature, vegetable matter con-
tent, proportion of cashmere in the raw fiber, color of cashmere, cotting (felting) of fi-
ber, and the length of the guard hair (McGregor and Butler, 2008).
No research has been located on quantifying the effect of cashmere fiber tenacity on
fiber breakage during processing. Cashmere, like wool, requires combing before use
on the worsted spinning system. There is little published information on topmaking
performance of cashmere. Given the short length of dehaired cashmere, adjusting
the comb setting to achieve longer Hauteur significantly increases noil. Using dehaired
cashmere with length after carding of 28.8 mm to obtain Hauteur of 41 mm gave noil
of 16%, changing comb settings to produce Hauteur of 50 mm increased noil to 50%
(McGregor and Postle, 2004a).

4.4.2 Yarns and fabrics

Because of the smooth fiber, slippage tends to make mohair knitting yarns weaker than
wool, but the data of Onions (1962) show mohair yarns with the same twist to be stron-
ger than wool yarns. Bursting strength, mass loss to abrasion, and fabric extension are
available for mohair woven fabrics (Table 4.5).

Table 4.5 Some properties of mohair and mohair/wool blend woven
fabrics

Fabric property Warp Weft Mean Warp Weft Mean
Sett (threads/cm) 21.1 20.1 20.9 19.7
2
Mass after relaxation (g/m ) 195 197
Thickness after relaxation (mm) 0.489 0.492
Martindale abrasion 4.99 4.53
(% mass loss, 10,000 cycles)
2
Bursting strength (kN/m ) 869 874
Breaking strength (N) 300 329 315 295 342 319
Extension (%) 35.5 21.8 28.7 35.3 22.4 28.9

Adapted from Hunter L, Smuts S, Kelly IW: The effect of fibre diameter on the wrinkling and other physical properties of
mohair and mohair/wool woven fabrics, Tech. Rep. 446, Port Elizabeth, 1979, South African Wool and Textile Research
Institute.