A Diester to Protect Hair from Color Fade and ... - Alluredbooks.com

424
Chapter 35 Gao et al.
shampoo showed 91.42% tryptophan protection. The addition of the
diester to the shampoo improved the protection against degradation
of amino acids in the hair fiber. The tryptophan degradation testing
was not performed on the conditioner series; however, researchers
anticipate similar results would be seen.
Figure 35.7. Change in tryptophan intensity after UV exposure and treatment with diester
shampoo
Testing UVB Protection with Tensile Strength
Fibers showing a decrease in stress-to-break forces after UV exposure
have undergone a loss in mechanical strength primarily due to
the breaking of disulfide bonds inside the hair cortex. A comparison
of the tensile strength of virgin brown hair treated with the diester
shampoo was made to hair similarly treated with the control rinseoff
product. Note that disulfide bonds inside the cortex have been
broken in the tresses treated with the control shampoo, while tresses
treated with the diester have no disulfide bond breakage (see Figure
35.8). The diester shampoo protected the hair from UVB damage
and preserved the hair’s natural strength.
Using the same methodology, virgin brown hair tresses were
treated with the control and diester conditioner, respectively, for
tensile strength measurements. The diester conditioner also provided
protection against damage to the fiber (see Figure 35.9).