The Differential Thermal Analysis of Natural and Modified Wool and Mohair

Abstract

JUNE 1963 .oj~l.l I 465 set. Thus, except in the case of the T -set condition, the fibers were exposed to water at 97°C for 4 hr, and therefore the differences in fiber structure of the p-set and P-T-set fibers must be due to the mechanical restraint conditions imposed during the treatments. The fact that the P-T fibers are stronger and less extensible than the corresponding P-set fibers suggests a more perfect network of secondary and primary bonding in the P-T condition. It would also suggest that relaxation at the temperature of boiling water causes some breakdown of network bonding with subsequent deorientation.The differences in behavior among the four keratin fiber types are relatively minor, although in many instances si~ificant and i~triguing.~hese differences in behavior may possibly be associated ith the varied cortical structures, although definite ;:Isignments in regard to the effect of setting on the h anical properties of the ortho-and the paramec h basi f cortex are not possible on t e asis 0 these results. AbstractFour types of wool and three types of mohair were examined by differential thermal analysis (DTA) in the natural and dried states. The DTA curves of wool and mohair were not significantly different. Curves for both in the natural state showed an endotherm at 130-145°, ascribed to the vaporization of bound water, and endotherms at 220-230°and 230-250°accompanied by charring, the release of gaseous decomposition products, and, ultimately, liquefaction. Derivatives of one type of wool and one type of mohair prepared by acetylation or modification of the disulfide cross-linkages were compared with unmodified materials by DTA. Differences in the DTA curves are described, and possible correlations of these with the changes in chemical structure are suggested. Collagen, gelatin, silk, horn keratin, cystine, and cysteine hydrochloride were also characterized. AbstractA. method. for ca~rying out potenttometric~itration of reduced vat dyes in aqueous alkaline solutions usmg a potassium ferricyanide solution as the oxidant is described The standard method is modified on the basis of certain assumptions, and the values of potentials~re~lculated and termed.".01aracteristic redox potentials." An account of the deter':lIn~tlOn of these charac~e\lslc redox potential values for a series of purified vat dyes IS given. The.characteristie redox potential values of vat dyes are compared with the ease of reduction of these dyes and also with their tendering behavior. The effect of substitution on these values is discussed.

Thermoanalytical investigations of extended and annealed keratins

“…In the DSC curves of cr-keratins, one or two endothermic peaks are observed in the temperature range 230 ~ ~ (see Fig. 2) which have been interpreted contradictorily in terms of helix melting points [3][4][5] (i. e. microfibrillar origin) and cystine decomposition points [6][7][8][9] (i. e. matrix origin). DSC investigations of isolated microfibrillar and matrix proteins in the disulphide form have shown that the two endothermic peaks have a different origin: the first peak (lower temperature) is a microfibrillar peak and the second peak, a matrix peak [10].…”

A study of the thermal behavior of graft copolymers of wool and methyl methacrylate

“…6 The elimination of such simple molecules should be diminished by the grafting of MMA on the reactive sites, and this should increase the decomposition temperature of grafted wool compared to the natural sample. Chemical modification of wool which involves tlhe breakage of hydrogen bonding (formic acid treatment), formation of lanthionine, or reduction should also affect the decomposition temperatures.…”

Thermoanalytische Untersuchungen von Wollproteinen in der Disulfidform

“…Die Mikrofibrillen bestehen aus teilhelikalen, schwefelarmen (LS = Low-sulfur) Proteinen und sind in einer nichthelikalen, schwefelreichen (HS = High-sulfur) Matrix eingelagert. In den Thermogrammen von a-Keratinen beobachtet man im Temperaturbereich yon 230 bis 250 ~ einen bis zwei endotherme Peaks, die sowohl ais Helixschmelzpunkte [1][2][3] als auch als Cystinzersetzungspunkte [4][5][6][7] gedeutet worden sind. Deshalb schien es angebracht, die entsprechenden thermoanalytischen Untersuchungen an isolierten Mikrofibrillen-und Matrixproteinen durchzufiihren.…”