Viscoelastic properties INDEX

Ninomiya,K., Ferry,J.D. Phenomenological relation for viscoelastic properties of polymer diluent systems the relative dissipation index N21. J. Macromol. ScL-Phys. B 3.237-258 (1969). 

In order to supply consistent gaskets with appropriate tolerances the viscoelastic properties of the gasket prepolymers are an important parameter. A low viscosity is beneficial for processing. Eor plastic materials usually the mold flow rate (MER) or mold flow index (MFI) are specified by the supplier, supporting the manufacturer for plastic parts with information relevant for processing properties. However, these data are standard data and not always compatible with the molding conditions or equipment... 

FIG. 77 Relationship between relative haze Hz) and processing index (PI) of LDPE. PI = B /B (where B < B ) where B is the equilibrium die swell of the extrudate after the shearing and B is the swell ratio of the material in the stable state after solvent or heat treatment. When the PI is unity, the viscoelastic properties of the materials are independent of the shear processing but as the PI becomes smaller than unity, the materials become sensitive to the shearing. (From Ref. 136.)... 

The mixture of long and short chains also has striking effects on the viscoelastic properties. Thorough experimental studies of polymer melts with sharplv peaked bimodal distribution of polymerization indexes, have shown qualitative discrepancies with the blending law... 

An overview of the physics of glassy polymers and the relationships between molecular mechanisms and macroscopic physical, mechanical and transport properties of polymer glasses is presented. The importance of local translational and/or rotational motions of molecular segments in the glass is discussed in terms of the implications for thermodynamic descriptions of the glass (configurational states and energy surfaces) as well as history dependent properties such as expansivity, refractive index, gas permeability, and viscoelastic mechanical behaviour. 

The nematic liquid crystal is orientationally soft, since restoring forces associated with deformation in the director field are very weak. This softness makes alignment of n in bulk samples occur even in very weak external magnetic or electric fields, F s H or E, or by interaction with boundary surfaces and flows in the liquid. This softness also allows for long wavelength thermal fluctuations in the director field. The Leslie viscosity parameters rather than the viscosity coefficients are the more natural quantities of interest for those methods that monitor the viscoelastic response of the nematic to director field modulations. Modulation of n in space and time manifests itself in variations of many bulk properties, e.g. the refractive index [27-37,41-44,48,51,94-106], electric susceptibility [38,39,107-110], or magnetic resonance spectra [40,45-47,111-113]. However, only a limited number of the viscosity parameters/coefficients can be precisely determined by these methods. 

Uses Detergent slurry emulsifier, thickener suspending agent in aq. and org./aq. suspensions emulsifier for silicone fluids and org. soivs. viscoelastic index improver used in detergents, toiletries, polishes, paints, textile industry Properties Sol. in water and org. soivs, dens. 0.45 g/cc pH 6.5-7.0 (0.5% aq. disp.)... 

Uses Thickener, suspending agent In detergents, toiletries, polishes and paints, textile industry resin and rubber modifier viscoelastic Index improver Properties Sol. in water, org. soivs. sp.gr 0.45 pH 6-7.5 (0.5% aq. disp.) Toxicoiogy Not known to be dangerous hamrful If swallowed Nevex i100 [Neville]... 

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