profile reached 700 u00b0 c the fibers were tested for burst pressure the results of this are shown in table ii table ii______________________________________t u00b0 c of hcl p burst introduction bar ______________________________________tr 20 25120 40160 120______________________________________ a study was conducted of the factors affecting carbonization of cuprammonium regenerated cellulose hollow fiber of wall thickness 16 u03bcm and outer diameter of 175 200 u03bcm the three factors were humidity density and ageing a factorial design was used in which levels were assigned a value of 1 is applied intentionally or 0 if reasonably prevented this created 2 3 combinations table iii______________________________________ treat fract no of fractures in of dense ment cell each membrane cell cells wetted aged pack no ______________________________________ 8 4 8 0 3 0 1 0 25 5 6 0 0 0 09 2 14 3 8 12 4 0 0 1 11 7 4 1 0 3 0 1 0 27 gt gt 100 6 7 3 0 1 1 3 gt gt 100 1 1 0 0 4 gt gt 20 100 100 18 4 1 0 1 5 gt gt gt 100 1 1 1 0 6 gt gt gt 100 1 1 1 1 7______________________________________ gt gt no of fractures too large to count gt gt gt crushed bundle hundreds of fractures the carbonization apparatus used was as in fig1 and the temperature profile as in fig2 unless specified in the table footnotes the experimental conditions and definitions of criteria are as follows 2 dense packing into a 7 5 mm id tube 300 320 fibers loose packing 200 250 fibers bundle length 85 100 cm 3 ageing time 5 10 days for dry bundles overnight for a wet bundle fresh bundle dry position 10.