The Effect of pH and Detergents on the Felting of Shrink-Resistant Wool

Abstract

The rate of felting of an untreated wool fabric increases with decreasing pH of the felting solution over the pH range 2-10. The felting rate is increased at all pH values by the addition of nonionic detergent to the solution.The felting, relative to untreated wool, of wool made shrink-resistant with permanganate/salt, acid chlorine, permonosulfuric acid followed by sulfite, permanganate hypochlorite, peracetic acid/hypochlorite, hypochlorite at pH 8, or gaseous chlorine increases with decreasing pH of the felting solution. The magnitude of this effect can he reduced by treatment with higher concentrations of reagents. After treatment with reagents of the concentrations used industrially, no change in felting rates with pH can be detected at pH values above 5. The actual rate of felting of wool treated with reagents of these concentrations is low and is not significantly affected by the addition of soap or nonionic detergents to the solutions. The felting, relative to untreated wool, of wool treated with ethanolic thioglycolate, aqueous hisulfite (on extracted wool). hydrogen peroxide folluwed hy bisulfite, ethanolic sodium hydroxide, or sodium hydroxide saturated salt does not vary with pH in the absence of detergent. Felting is increased by the addition of detergent to the solutions. In detergent solutions, the relative felting of wool treated with ethanolic thioglycolate, aqueous bisulfite (on extracted wool), or hydrogen peroxide bisulfite does not change with pH. hut the relative felting of wool treated with sodium hydroxide in ethanol or saturated salt solution reaches a maximum at pH 7-9.Frictional properties of fibers treated with some of the reagents have been measured (by the capstan method using a keratin rod at different pH values in the presence and absence of detergent. Felting behavior does not appear to be explained by these frictional properties alone. Some other property, or properties, of treated wool, which vary differently with pH than do similar properties of untreated wool, must play a part in felting.

Chemical Processing of Wool: Sustainability Considerations

“…Chlorination treatment not only removes the covalently bonded fatty acid (18-methyleicosanoic acid) from the epicuticle, but also erodes scale edges to some level and disrupts disulfide bonds [16]. Other than chlorine, some other oxidizing agents such as UV/O 3 , O 3 , peracetic acid in combination with sodium hypochlorite, and persulfuric acid also have been investigated with limited success [17][18][19]. Various plasma treatments including corona discharge and atmospheric glow discharge have been investigated to achieve shrink-resistant wool [20,21].…”

The Effect of Detergents on the Felting of Wool

“…thetic detergents have been reported. [11][12][13][14]18] m ostly concerning the felting of . .untreated woo1.'…”

“…Felting rates in soap solutions are generally lowerthan in solutions of sy nthetic , detergents [12][13][14] ] and, in some cases, less' felting has heen ohsen e<1 in detergent solutions than, in water or huffer solutions alone [12][13][14]. However, other work, has shown ' that detergents are also capable of causing increases in 'felting rates and that the 'actual, rates can vary markedly with the detergent concentration [~; 8, 18).…”

“…The danger of erroneous conclusions being drawn from choice of arbitrary concentrations is great, being illustrated by our previous conclusion tliat felting rates are very close in soap or nonionic detergent solutions [18], As wull be shown here, that conclusion is only valid for one concentration (0,05%) of the particular), nonionic detergent in that type of washing macb}ne, , ' This paper descril>es an investigation of the effects of soap and synthetic&dquo; detergents on the felting of normal, and shrink-resistant wool , in domestic washing machines, One impor'tant feature is that wool has been treated lry different shrink-resist processes to give identical shrinkage-time curves when, washed in water aloe. Otherwise, it the respective treatments arc' used to give various levels of shrinkresistance, conclusions mav be drawn as to differehces in behavior being a function of the processes, -whereas the differences could be due merely to the level of treatment.…”