bon monoxide, and carbon dioxide with the nitrite ion peak at 355 µ is completely negligible. Similarly, chloride, bromide, hydroxide, nitrate, sulfate, and carbonate anions do not absorb above 300 µ.

No abstract

On the basis of previous work, a model for the structure of cellulose fibers is proposed. The effect of degree of polymerization (DP), lateral order, and orientation on tensile properties is discussed in the light of this model. A program was set up to determine separately the effects of the different factors on the tensile properties of various fibers. From this work parameters were derived to express these effects quantitatively in a manner that would be applicable to various types of cellulose fibers. This program consisted of three major lines of investigation: (a) the effect of varying stretch in viscose spinning on the tensile properties of rayon fibers, (b) the effect of hydrolytic degradation of various cellulose fibers on their tensile properties, (c) an investigation of the effect of DP, lateral order, and orientation on the tensile properties of a wide variety of commercial rayons. The first study was undertaken to obtain quantitative information about the effect of orientation on tensile properties. The second investigation was attempted to determine the effect of the degree of polymerization. In the third study the findings obtained in the course of the first two ipvestigations were applied to commercial rayon samples for the purpose of demonstrating their applicability in explaining the tensile properties of these fibers. The discussion of the results of these investigations is preceded by a description of the experimental methods applied in spinning or degrading the samples. The analytical methods used in characterizing the samples for DP, perfection of order, and degree of orientation are also discussed. In a study of the effect of molecular orientation on tensile properties, several series of tire rayons were spun under identical conditions except for variations in stretch ratio. Thus, rayon samples were obtained having the same degree of polymerization and, as proven by x‐ray investigations, having the same perfection of order but varying orientation. The results of the x‐ray orientation measurements were evaluated in different ways according to several suggestions found in the literature. It was found that the square of the orientation parameter fr = 1 − 3/2 sin2 β is linearly related to the tensile strength of the conditioned yarns. The tensile strength of the wet yarn and the elongation in the dry and wet states were also found to be related to expressions derived from this parameter. In the second study, the effect of acid hydrolysis on the tensile properties of cotton, textile rayon, high wet modulus rayons, tire yarn, Meryl, and Fortisan was investigated. Since it, was considered a neressary condition that the effect of DP on tensile strength could only be clearly separated when the degradation could be achieved under conditions which did not alter the perfection of order and the degree of orientation of the cellulose molrcules in the fibers, most of the samples were subjected t o x‐ray analysis. The results obtained clearly indicated that in all cases the hydrolysis caused the fo...

No abstract

SynopsisPure regenerated cellulose fibers and those containing various amounts of phosphorus nitride were pyrolyzed under different conditions in the temperature range of 150-440OC. Easily volatile liquid pyrolysis products, the tar fraction of limited volatility, and the charred residue were determined gravimetrically. The liquid volatiles were analyzed by combined gas chromatography/mass spectrometry for their water content. The tar fraction and the charred residue were inspected by infrared (IR) spectroscopy. The studies revealed that the phosphorus nitride flame retardant enhances the onset of the pyrolytic decompcsition and the release of water at substantially lower temperatures as observed for pure cellulose. The water release favors the carbonization and its extent reduces the formation of levoglucosan as a precursor of easily flammable pyrolysis products. Thus phosphorous nitride must be classified into the water release favoring flame retardants.