Shrinkproofing Of Wool With Polyglycine From The Polymerization Of Anhydrocarboxyglycine
Shrinkproofing of wool with anhydrocarboxyglycine is not possible from aqueous solution but can be achieved using 2% anhydrocarboxyglycine on the weight of the wool at 50° for 1 hr. in water-washed white spirit or trichloroethylene. Treatments at room temperature require a minimum time of 7 hr. The polymerization, initiated by water present in the wool, produces polyglycine with a degree of polymerization (DPn) about 30. Descaling of treated fibers shows that all the polyglycine is located in the outside 10% by weight of the fiber; a surface layer can be seen by Sellotape microscopy and electron microscopy. It is this surface layer which is responsible for the large increase in the frictional coefficients μ1 and μ2 and decrease in ( μ1- μ2) which in turn effects shrinkproofing. At levels of treatment ⋞ 0.39% polyglycine, partial shrink proofing is produced by small spots of polyglycine distributed at random over the fiber with no appreciable amount of masking of the scale edges.