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.
Dynamic hairspray analysis. II. Effect of polymer, hair type, and solvent composition.
A texture analyzer was employed to study the properties of hairspray resins by measuring a number of mechanical parameters of hair modified by them. Hairset stiffness, stiffness retention at high humidity, and duration and magnitude of polymer film tackiness during drying were the properties employed to characterize fixative-treated hair. They were investigated for formulations containing ethyl ester of PVM/MA copolymer, butyl ester of PVM/MA copolymer, vinyl caprolactam/PVP/dimethylaminoethyl methacrylate copolymer, VA/butyl maleate/isobornyl acrylate copolymer, and polymer blends such as poly(methylvinylether) (PMVE) - ethyl ester of PVM/MA copolymer. It was demonstrated that the properties of hair treated with a fixative are affected by the concentration and molecular weight of a polymer, low-molecularweight additives that can modify the mechanical, surface, or interfacial properties of a polymer film, and the presence of water in the formulation. It was also shown, that the type of hair employed, such as virgin, untreated hair or hair damaged by bleaching, can also have an effect on the performance of a given hairspray formulation. For compositions based on blends of PMVE and ethyl ester of PVM/MA copolymer, the employed method demonstrated the sensitivity of the properties of polymer blends to the presence of a hydrophilic component such as PMVE.
Heat Transfer Characteristic for a New Plate Metal Hydride Reactor
The property of major metal hydride reactors in the world was analyzed and a new plate metal hydride reactor was designed.An experimental facility to test the metal hydride reactor was also designed correspondingly.The effective thermal conductivity of the plate metal hydride reactor was measured by varying the initial metal hydride packing fraction,the kind of filled gas and the pressure of the filled gas,cycle numbers.The test results show that the effective thermal conductivity of the reactor,has exceeded(7.5) W/(m·K) before activation,which is increased greatly.After alloy activation,the effective thermal conductivity of the reactor has a linear change trend with the hydrogen pressure during the interval 0.1~3.5 MPa.The effective thermal conductivity of the reactor just only decreases quickly at the beginning,but becomes stable after several cycles.