Brightness retention

Another measure of stability is the relative brightness retention. Variation of brightness was plotted against aging time. The initial slope of this line was computed by a least-squares treatment. The value of the slope for the control divided by the slope for the treated sample is defined as the relative brightness retention. These results are presented in Tables III and IV. 

Table III. Brightness Retention of Foldur Kraft Paper ...

Table IV shows brightness retention of newsprint papers. Borohy-dride treatment increased initial brightness by as much as 10 brightness units. A decrease in brightness is generally observed when newsprint is subjected to a Ca(OH)2 wash. Treatment with either 0.1 or 1.0 NaBH4 followed by 0.002 calcium hydroxide washing also increased the brightness of newsprint. For the newsprint samples, the borohydride treatment did not produce a significantly greater improvement in brightness retention than the calcium hydroxide wash alone.

Treatment Co(OH)2 Cone. (%) Initial Folds Relative Permanence Initial Brightness Relative Brightness Retention ... 

It has also been demonstrated that mesoporous materials are viable candidates for optical devices [90]. Silicon nanoclusters were formed inside optically transparent, free-standing, oriented mesoporous silica film by chemical vapor deposition (CVD) of disilane within the spatial confines of the channels. The resulting silicon-silica nanocomposite displayed bright visible photoluminescence and nanosecond lifetimes (Fig. 2.12). The presence of partially polymerized silica channel walls and the retention of the surfactant template within the channels afforded very mild 100-140°C CVD conditions for the formation of... 

MIT Fold (Vz kg) Tensile Strength (kg) Thickness (mm) Brightness (%) Fold Retention after Aging (%j ... 

Folding endurance under tension (10) is a favorite physical property for research on paper permanence and is the basis for the TAPPI method (16). Application of the mechanism involved in this test procedure, however, is unknown in practical uses for paper. Comparisons among product choices and estimates of their useful life should be based upon tests that assess physical properties of practical interest. Retention of reflective brightness, tear strength, tensile energy absorption, and... 

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