an
information obtained from the XRD data, suggests that the im- posed treatments have resulted in the splitting of larger semi-crys- talline domains into smaller ones having more closely packed polymer chains. Quantitative assessment of hair photodamage with and without application of sunscreen products is an important input to cos- metic chemist for product development and evaluation. However, the task has not been easy due to the complexity of the situation. Hence, often a combination of analytical methods each giving spe- cific information is needed for a comprehensive evaluation. How- ever, most of the available analytical methods index the damage to the cuticle, while the damage to the inner mass (cortex), partic- ularly at the molecular level, remains largely not investigated. From this angle, the positron method utilizes positronium as its de- fect probe, which due to its small size (2 Å) and penetrability can directly characterize the microstructural damage to the cortex re- gion. This special feature of PALS technique, exploited in this study, could be the basis for an important and unique method of product testing and evaluation in the cosmetic industry.
Acknowledgements
The authors thank Dr. R. Somashekar, Professor, DOS in Physics, University of Mysore, Mysore, for his guidance in interpreting the XRD data. One of the authors (MNC) thanks University Grants Commission (UGC), New Delhi, for awarding the FDP teacher fel- lowship, and University of Mysore, Mysore, for providing the labo- ratory facilities.
References
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M.N. Cha