Giuliana C. Tesoro

Flame-Retardant Properties of Phosphonate Derivatives of Cotton Cellulose

The Arbuzov reaction of cotton fabric containing the haloacetamidomethyl groups Cell-OCH2NHCOCH 2X (X=I, Br, Cl) has been studied systematically to prepare new cellulose phosphonate ester derivatives. Comparison of flame-retardant properties of the phosphonate derivatives with those of fabric containing a deposited polymer of related structure showed that phosphorus is more efficient in the form of a cellulose derivative. Problems generally associated with fabrics containing flame-retardant finishes, notably stiffness, were also minimized in the case of derivative formation. Laundering durability was excellent. Further studies on the synergistic effect of nitrogen on flame retardant properties confirmed earlier results and showed that cotton sheeting fabric containing an N/P ratio of 3 at 2% P, 6 at 1.4% P, and about 12 at 0.9% P passed the vertical flame test.

Effect of Surface-Limited Reactions on the Properties of Kevlar® Fibers

Aromatic diamides have been investigated as models for aramid fibers to select reagents and conditions suitable for surface-controlled heterogeneous reactions on Kevlar filaments. Reactions have been done on Kevlar fibers to introduce functional groups designed to interact with matrix resins and improve adhesion in fiber reinforced composites. The effects of reaction environments and conditions on the mechanical properties and surface topography of modified fibers have been investigated. For Kevlar fibers modified by nitration and subsequent reduction of nitro groups to amino groups, significant concentrations of functional groups have been introduced on the surface with minor strength losses and with improvements in the interfacial shear strength measured with an epoxy resin using the microbond technique. Surface-controlled chlorosulfonation reactions (in solutions of chlorosulfonic acid and by exposure to chlorosulfonic acid vapor) have also been investigated for Kevlar fibers to introduce chlorosulfonyl groups on fiber surfaces and to study conversion of — SO2Cl to sulfonic acid (hydrolysis) and sulfonamide (reaction with amines). For Kevlar modified by chlorosulfonation, followed by reaction of — SO2Cl with some amines [e.g., ethyl enediamine (EDA) and triethylenetetramine (TETA)], the improvement in interfacial shear strength of chlorosulfonated / aminated fiber with epoxy resin ( evaluated by the microbond method) was significant.

Cross-Linking of Cellulose with Polyfunctional Sulfones under Anhydrous Conditions1

1. Baker, W. O., Fuller, C. S., and Pape, N. R., J. Am. Chem. Soc. 64, 776-782 (1942). 2. Buras, E. M., Jr., Hobart, S. R., Hamalainen, C., and Cooper, A. S., Jr., Textile Research J. 27 , 214222 (1957). 3. Conrad, C. M., Stanonis, D. J., Harbrink, P., and Creely, J. J., Textile Research J. 30, 339-348 (1960). 4. Conrad, C. M. and Creely, J. J., to be published. 5. Creely, J. J., Stanonis, D. J., and Klein, E., J. Polymer Sci. 37, 43-49 (1959). 6. Hess, K. and Trogus, C., Z. physik. Chem. 5B, 161176 (1929). 7. Rowland, R. A., Weiss, E. J., and Bradley, W. F., National Academy of Science, National Research Council Publication No. 456, 85-95 (1956). 8. Segal, L. and Conrad, C. M., Am. Dyestuff Reptr. 46, 637-642 (1957). 9. Sprague, B. S., Riley, J. L., and Noether, H. D., Textile Research J. 28, 275-287 (1958). 10. Weiss, E. J. and Rowland. R. A., Am. Mineralogist 41, 117-126 (1956).

The Cross-Linking of Cotton Cellulose with Quaternary Ammonium Derivatives of Bis Chloromethyl Ethers

A theoretical discussion of the mechanism leading to resin deposition inside cotton fibers is given, and the hypothesis presented is substantiated by experimental results. It is demonstrated that expression of excess precondensate from fabrics in the padding process does not play a decisive role. A simple immersion process without squeezing, or spraying with the precondensate, is sufficient to obtain the desired crease resistance and swelling reduction. Roll pressure affects the results of the treatment only insofar as it determines the amount of add-on and the uniformity of the finishing effect. Resin applied by immersion or by spraying is also deposited inside fibers. and therefore the result is nearly the same as that obtained by padding. Resin deposition and location inside cotton fibers, achieved by the various application methods, is demonstrated by means of an especially developed staining test.

Chemical Modification of Cotton with Derivatives of Divinyl Sulfone

An experimental investigation of the reaction of divinyl sulfone with cellulosic fabrics was carried out in our laboratory, using essentially the procedures taught by Schoene. The treated fabrics exhibited excellent wet crease recovery and dimensional stability, with moderate improvements in dry crease recovery. The concomitant losses in tensile and tear strength were in the range observed as a result of other known cross-linking treatments. and the overall fabric performance could he considered excellent. However, the use of divinyl sulfone as a crosslinking agent presented such overwhelming disadvantages that the treated fabrics appeared doomed to remain in the realm of laboratory curiosities. In physiological behavior, divinyl sulfone is similar to mustard gas. It is extremely toxic, both when inhaled and when absorbed through the skin. It is

Effect of Radial Location of Cross Links in Cellulose Fibers on Fabric Properties1

Mercerized cotton fabrics cross-linked preferentially in the core of the individual fibers were prepared by rinsing off part of the DMEU before curing from the peripheral areas with ethanol. Native cotton, due to its pore structure, does not lend itself readily to this technique. This pore structure is also reflected in the dyeability of native cotton from alcoholic dye solution in contrast to the behavior of the mercerized fiber. The core-crosslinked fibers give much higher substitution in carbanilation and benzoylation than uniformly cross-linked fibers of the same content of fixed cross-linking reactant. The fabrics of core-crosslinked cotton exhibit a favorable balance of mechanical properties. Such fabrics were shown, e.g., to possess a dry crease recovery angle of 280° (W + F) and, at the same time, the abrasion resistance equal to that of uncrosslinked fabrics.

Polymethylol Polycarbamates in Durable Press1

The cross-linking effectiveness of polymethylol polycarbamates for cotton fabrics has been studied by various application techniques. Poly(N,N-dimethylol) and poly (N-methyl, N-methylol) polycarbamates were compared under reaction conditions designed to give one-step and two-step cross-linking. The compounds react with cotton in high yields and impart excellent wash-wear properties without discoloration. Cotton samples cross-linked with poly(N,N-dimethylol) polycarbamates exhibit outstanding resistance to hydrolysis under acidic conditions, and their performance properties are compared to those of fabrics treated with N,N-dimethylol monocarbamates.

Minimizing waste polymers in space

Waste polymers, essentially plastic packages, make up a significant fraction of solid wastes in a crewed space habitat. While logistic limitations preclude consideration of recovery/recycling technologies that have proven viable on Earth, the challenge in space is to provide materials and processes that minimize the volume of stored waste plastics and which allow recovery at the completion of a mission.