Polymeric specimens

Signer, et have studied the viscosity and double refraction of flow of one of the more highly polymerized specimens of desoxyribosenucleic acid, and conclude that the molecular weight lies between 5 times... 

Important parameters are the concentration and concentration ratios of the components, the way the components are added to the final mixture, the temperature and ageing processes. Hydrolysis under strongly acidic conditions is necessary to obtain polymeric specimen. Characterisation is usually done by SAXS measurements. 

For load values from Pmin up to Pmax with stepwise velocity increase, a limiting value for sliding velocity (Vmeix) is found at which the material suffers frictional failure. In the course of testing the coefficient of friction (curve l) and temperature in the subsurface layer of the polymeric specimen (curve 2) are recorded. 

Kalthoff J.F. (1993) On the validity of impact energies measured with polymeric specimens in instrumented impact tests. Impact Dynamic Tract Polym Compos ESIS, Vol. 19. 

Two-Photon Confocal Microscopy. Confocal microscopy provides the possibilities of optical sectioning of a sample by the use of a spatial filter to improve axial resolution of the optical microscope (20). These optical sections can be used to reconstruct the 3D structure of a polymeric specimen. Confocal microscopy using fluorescence is usually performed by a single-photon excitation (linear absorption) of a fluorophore which may be chemically an integral part of the system (polymer) being investigated or just... 

A.A. Tager [110] determined the change of AG k by producing thermodynamic cycles using static sorption of solvent vapors on the polymeric specimens. However, in solution the polymer compatibihty is influenced by the difference of the thermodynamic interaction parameters of the common solvent with each indvidual polymer. Additionally, compatibility in solution does not always correspond to that in the solid state (without a solvent). These shortcomings limit the applicability of the AG ix estimation method that Tager developed. 

Indeed, an especially low power x 1 objective lens may be more value in the objective set than a x 100 lens. If the use of higher magnification is necessary it is particularly important with polymeric specimens that the user commences the observation at low power and work up. The interrelationship between micro-structural features in polymers can be complex and isolated observations at high magnification can be misleading. 

The surface of a polymeric specimen may behave differently fi-om the bulk in its glass transition behavior. For example (82), the surface Tg of a monodis-perse polystyrene film was observed to be lower than the bulk Tg. This result was interpreted in terms of an increase in the free volume near the surface region, being induced by the preferential surface localization of chain end groups. 

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