Postcolor number

Filter Paper with Hemicellulosic Fractions Added On. Hemicellu-lose fractions were isolated from unaged and thermally aged papers by extraction with LiOH, following the procedure described by Giertz and McPherson (6). The changes in postcolor number [100(K/S) — (K/S)0] (7) for various test sheets during exposure to visible and UV radiation and to heat are shown in Figures la, lb, and lc for material extracted from... 

Figure 1. Changes in postcolor number of filter-paper sheets with 15% add-on of hemicellulose fractions derived from various pulps. For comparison, the thermal discoloration of a test sheet of groundwood pulp, gp, is shown. The initial postcolor number represents the increase in color over that of the untreated filter paper a, daylight fluorescent lamps b, black-light fluorescent lamps c, heat (90 °C and 50% rh). Key O, blank filter paper , BP A, GP V, UBP 0, chlorited UBP.

Figure 3. Postcolor number of filter papers saturated to a level of 3% add-on with arabinogalactan. Key (thermal discoloration) , 50% rh and 90 °C , 0% rh and 90 °C and (photochemical discoloration) , daylight fluorescent lamps A, BLB fluorescent lamps V, Fade-ometer.

Figure 5. Postcolor number of test sheets of various contents of y-cellulose that were prepared from UBP by extraction with alkali The 10.5% sample is the starting material Key (percent y-cellulose) 0,0,10.5 8.8 A,A,...

Acetylxylan and arabinogalactan added-on test sheets, postcolor number changes, 383-84... 

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