No abstract

No abstract

No abstract

No abstract

No abstract

Table XI. Vegetable Motor Fuel Specifications Chinese Government China Vegetable Oil Specifications Corp. Standards _Vegetable Gasoline Color Light yellow Light yellow Sp. gr. at 15.5°C. 0,800 max. 0.790 max. Acid No. 0.20 max. 0.08 max. Corrosion test Negative Negative Gum content, mg. /100 cc.

Rate Data on Reduced and Nitrided Fischer-Tropsch Catalysts 1039 larger diameter range of 80-200 Á. increases regularly with beating time.Despite the theoretical uncertainties in Kelvin equation applications such as the Pierce calculation, the conclusion is inescapable that the ball-mill beating of wood cellulose creates additional pores or fissures in the amorphous regions of the fiber, "or at least enlarges existing pores, all the way down to 50 A. or so in pore diameter. Relation to Fine Structure of Cellulose.-The break in the descending isotherm between relative pressure 0.50 and 0.45 (Fig. 1) appears consistently in all cellulose samples, beaten and unbeaten, and has been independently observed by four different experimenters in these laboratories, as well as by Hunt, Blaine and Rowan.aa Even though any present method of calculating the absolute value of the pore sizes and pore volumes concerned may be open to some criticism as to accuracy, the generalized conclusion from these facts is inescapable, viz., wood and cotton cellulose in the native, swollen state contain a sizable volume (ca. 0.05 cc./g.) of pores rather narrowly distributed in a range with a median pore diameter of about 40 A. The results of this particular investigation further indicate that the volume of these very small pores does not change appreciably with moderate amounts of wet maceration but does increase somewhat with severe and continued mechanical treatment in the wet state.The inference from these observations and conclusions is that the 40 A. diameter pore size is a characteristic of the fine structure of wood cellulose fibers and may be related to the basic structural unit in wood cellulose. It may be hypothesized, for example, that the elementary building blocks of "solid" cellulose are laid down in some sort of array (e.g., hexagonal) permitting the regular occurrencejof "holes" approximately the size of an elementary polymer unit. It is not difficult to imagine several possible combinations of structural units, consistent with the known Xray identity periods of cellulose, which would permit such regular occurrence of holes. The elucidation of such possibilities should provide a fertile field for further research. ConclusionsThe increase in total (internal and external) surface of wood cellulose fibers upon wet maceration in a ball mill is a linear function of time and is principally accounted for by the increase ip volume of submicroscopic pores in the range of 44-800 A. diameter. The most common pore size of 38 Á.diameter is unaffected by beating and the total volume in the range about that pore size is but slightly affected. It is suggested that this most common pore diameter is a fundamental property of the cellulose and that it is structurally related to the elementary polymer unit of cellulose.

No abstract