Cotton tensile strength

Brysson and co-workers (7) conducted a study in St. Louis, Missouri, on the effects of urban air pollution on the tensile strength of cotton duck material. Samples were exposed at seven locations for up to 1 year. Figure 9-3 shows the relationship between tensile strength and pollutant exposure. For two levels of ambient air exposure, the materials exhibited less than one-half their initial tensile strength when exposed to air pollution for 1 year. 

Fig. 9-3. Effects of sulfation and time on tensile strength of cotton duck. Source Brysson, R. Trask, B. ], Upham, J. B., and Booras, S. A. /. Air PoUut. Control Assoc. 17, 294 (1967).

The molecular structure of cellulose, unlike that of starch, allows for strong hydrogen bonding between polymer chains. This results in the formation of strong water-resistant fibers such as those found in cotton, which is 98% cellulose. Cotton actually has a tensile strength greater than that of steel. The major industrial source of cellulose is wood ( 50% cellulose). 

There was no significant difference between treatments in microbial biomass, cotton strip tensile strength, or earthworms. 

Physical Properties. Bast and leaf libers are stronger thicker tensile strength and modulus of elasticity but lower in elongation (extensibility) titan cotton. Vegetable libers arc stiffer bin less tough than synthetic libers. Kapok and coir are relatively low in strength kapok is known Ibr its buoyancy. 

All manifestations of early attack on the cotton fiber are compatible with the interpretation that it is the Cx enzymes that initiate the attack. This is true whether it is fragmentation into short fibers (16,39), increase in the uptake of alkali (S factor) (16,26), or loss in tensile strength (16). It is possible that some of these early changes may reflect action only on a very small portion of the fiber, such as the amorphous or less orderly hydrogen bonded areas, the primary wall (44), or the areas of structural weakness that are reported to traverse the whole cell wall (45). At the same time, there must be some significance in the fact that it is, in the main, only the Cx enzymes that produce changes detectable by these methods. 

Carbon fiber electrode - Edison produced the first carbon fibers by carbonization of cotton threads in 1879. Today polyacrylonitrile (as well as Rayon and various other organic precursors) is the most common precursor for carbon fiber formation [i]. Carbonization of polyacrylonitrile is carried out at 1500 °C to give highly electrically conducting fibers with 5-10 pm diameter. Fibers carbonized at up to 2500 °C are more graphitic with a carbon content of >99%. Carbon fiber-based materials have found many applications due to their exceptionally high tensile strength. In electrochemistry carbon fiber -> micro electrodes are very important in analytical detection [ii] and for in vivo electrochemical studies [iii]. Carbon fiber textiles are employed in - carbon felt electrodes. 

Figure 9. Relationship between relative concentrations of carboxyl groups as measured by Turnbull9s Blue test and the tensile strength of degraded cotton print cloth...

Figure 1. The tensile strength of degraded cotton print cloth (50-Mrad dose) after application of various acrylic resins (A1-A4) and grafted monomers (M1-M4) U = untreated fabric, PE = polyethylene, AD — air dried. See text for identification of resins and monomers.

---