Dynamic hairspray analysis. III. Theoretical considerations.
Model mechanical calculations were carried out to simulate the properties of hair fiber assemblies operating in the bending mode. It was assumed that the fibers were in omega-loop configuration (as in experimental work), and the theory of deformation of thin rings provided a fundamental relationship between stress and strain. A dependence on the stiffness of multi-fiber assembly was derived and verified empirically. Theoretical bending stiffness for fixative-treated hair was calculated for various model fiber distributions by calculating their area moment of inertia according to the parallel axis theorem. General equations for stiffness of fiber assemblies were derived for cross sections placed on cubic and hexagonal lattices. The results suggest a good agreement between the theoretical and experimental data.
Polyquaternium-69: A New Fixative Polymer with Enhanced Styling Benefits
PVP and PVP/VA have long been the mainstay of traditional styling gels and mousses but the rapid release of new hair care launches and the drive for product differentiation on the shelves has created demand for expanded performance of styling resins. In order to achieve improved performance, a new polymer has been designed by polymerization of vinyl pryrrolidone, vinyl caprolactam, DMAPMA, and the alkylated quaternary DMAPMA + - C12H 25 CL ‐ , INCI designation Polyquaternium-69 (AquaStyle™ 300). Improvements have been achieved in humidity resistance, shine, frizz control and mechanical properties without compromising basic attributes such as gel clarity, stability, mousse foam properties, and low VOC requirements. Polyquaternium-69 is a hydrophobic polymer, yet water soluble and predominately non-ionic with a weakly cationic nature providing a broad range of compatibility with cosmetic ingredients including anionic gellants. Polyquaternium-69 can be easily incorporated into various styling products such as clear and cream gels, aerosol and non-aerosol mousses, styling lotions, and sprays.
Fine details on the surface of human hair
Some previously unreported fine variations in the form of normal hairs are described as they are observed in the scanning electron microscope (SEM). They all arise in the course of surface frictional wear and the chipping away of the hair surface scale edges and include remanent surface impressions of cuticle scale edges, ‘false’ scale edges, granular surface remnants and highly irregular (chevron) scale patterns. Mechanisms are proposed for the way in which each of these different fine features arise.