Before investigating the effect of additives, it was desirable to determine the 

 effect of the ash or natural inorganics on the pyrolysis of cellulose, Broido (1966) 

 has pointed out that a contamination as little as 0.1 percent can significantly change 

 the TGA of cellulose. Shown in figure 4 is a comparison of: commercially purified 

 cellulose, ash content 0.01 percent; 8 cotton cellulose, ash content 0.08 percent; and 

 cottonwood cellulose, ash content 0.15 percent. This TGA shows Cottonwood cellulose to 

 behave differently than the "ash free" product and to behave similarly to the cotton 

 cellulose with 0.08 percent ash. 



As cellulose is heated from ambient to 500° C, the TGA and DTA curves clearly 

 show the net effects. Cellulose had a maximum pyrolysis rate of 0.25 mg./°C. and a 

 residue of 6 percent at 450° C. shown by TGA (fig. 5). The temperature of the begin- 

 ning of active pyrolysis was 320° C. shown by TGA (fig. 5) . The first endotherm corre- 

 sponds to water loss and the second endotherm corresponds to major weight loss of the 

 sample. A small exotherm is apparent subsequent to the second endotherm; it occurs at 

 the secession of rapid weight loss. 



The effects of ZnCl2 on cellulose shown by TGA and DTA are to reduce the pyrolysis 

 rate, lower the initiation temperature, and increase the residue. On the DTA curve 

 (fig. 5), the major endotherm was somewhat reduced in size and the peak temperature was 

 lowered drastically. 



100 200 300 400 500 



Temperature ( C.) 



Figure 4. — Thermo gravimetric analysis of: cotton cellulose, ash content 0.08 percent 



(I); cottonwood cellulose, ash content 0.15 percent (II): and commercial "ashless" 

 cellulose, ash content 0.01 percent (III). 



'Analytical filter pulp manufactured by Carl Schleicher and Schuell Co. 



9 



