It is very difficult to test the tensile properties of individual fibers thus the test was performed on the fiber tow removed from the fabric tested instead in accordance with the procedure described above. Table 11.6 lists the fiber tows come from dif­ferent treated and untreated fibers that were tested as well as their tensile properties. The tows in the longitudinal direction in the fabric are denoted as parallel, whereas the ones in the orthogonal direction are denoted as perpendicular.

It is evident from Table 11.6 that the tensile properties of the fiber tow did not change much for most of the systems indicating that the treatment did not generally have a detrimental effect on tensile properties except for fibers treated with alkali metal hydroxide alone (e. g., KOH and NaOH). It is clear, therefore, that cellulose materials treated with both alkaline earth metal salt and alkali metal hydroxide are advantageously fire retardant, often self-extinguishing, while retaining good tensile

properties,

in contrast to fibers treated only with alkali metal hydroxide or treated

with another metal salt.

TABLE 11.6

Tensile Force of Tows of Treated C2 Fibers

Max load pounds force (N)

Fiber

Description

Parallel Perpendicular

C2

Untreated C2

4.6 (20.4) 5.4 (23.8)

C2-1/P1

Ba(OH)2

4.9 (21.7) 5.4 (24.1)

C2-2/P1

BaCl2

4.7 (21.1) 5.6 (25.1)

C2-4/P1

Mg(NO3)2

5.4 (23.8) 5.7 (25.5)

C2-7/P1

Mg((OH)2

4.3 (19.2) 5.3 (23.6)

C2-10/P1

KOH

3.6 (15.8) 4.5 (20.2)

TABLE 11.6 (Continued) Max load pounds force (N) Fiber Description Parallel Perpendicular C2-11/P1 NaOH 3.6 (15.8) 4.3 (19.0) C2-13/P1 NaOH then washed 3.0 (13.2) 4.1 (18.4) C2-15/P1 Al(OH)3 5.1 (22.8) 5.3 (23.6) C2-17/P1 MgCl2 + NaOH 4.8 (21.3) 5.3 (23.7) C2-18/P1 MgSO4 + NaOH 5.2 (23.0) 5.8 (25.8) C2-19/P1 CaCl2 + NaOH 4.4 (19.5) 5.6 (24.9) C2-20/P1 Ca(NO3)2 + NaOH 5.5 (24.4) 5.6 (24.8)