Parameters Influencing Morphology

HgureZ.IS Influence of increasing branching degree V in CHj/ 100C  

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Figure 1 Molecular and morphological parameters influencing technological properties of multiphasic polymer blends.

As can be seen from all of these works, sequential IPNs have been extensively used with silicone with various crosslinking reactions and polymers. As a result, attention must be paid to the influence of processing conditions, of the chemical nature of components (silicone and the other polymer), of the evolution of the material at each step of the IPN synthesis etc. Depending on the mastering of these parameters, reactivity, morphology and entanglement can be controlled and consequently targeted properties can be reached. 

Azathioprine As early as 1967, immunosuppression was attempted in PBC by means of azathioprine, but no positive influence on clinical course, laboratory parameters or morphological findings could be achieved. (Ill) Subsequent studies have sometimes yielded encouragingly good results. Side effects are rare despite occasional leucopenia, the risk of infection is not increased. (92)... 

The theoretical predictions of drop deformation and breakup are limited to infinitely diluted, monodispersed Newtonian systems. However, it is possible to obtain valid relationships between processing parameters and morphology. Thus it was found that in the system PS/HDPE the viscosity ratio, blend composition, screw configuration, temperature, and screw speed significantly influence the blend morphology [Bordereau et al., 1992]. For more detail on the topic see Chapter 9, Compounding Polymer Blends, in this Handbook. 

It is possible that equilibrium morphology is not obtained because the movement of the polymer chains is not fast enough to reach that equilibrium within the time-frame of the reaction this is kinetic control of morphology. The kinetic parameters influence the rate of formation of a certain morphology [27, 28], which is basically determined by the interfacial tensions [29]. The parameters of importance are the rate of formation of the polymer (parameters are propagation rate coefficient, and the local monomer and radical concentrations) and the rate of diffusion of the polymer chains (parameters are viscosity in the locus of polymerization, molar mass and topology of the polymer chain). Both the rate of formation and the rate of diffusion of a polymer chain are, for example, affected by the mode of addition of the monomer and initiator. An increased rate of addition of the monomer will lead to a lower instantaneous conversion and thus a lower viscosity in the particle, which in turn increases the rates of diffusion and leads to different morphologies. 

The principal operating parameters influencing the transfer in a membrane separation processes are the hydrodynamic [9], pressure [10,11], solutes nature [12], pH [12], and of course, the nature, morphology, and thickness of the membrane. Usually, during the concentration increase of the compound interacting most strongly with polymer the membrane swells, thus the diffusion coefficient increases [13]. Therefore the compounds flow increases while the selectivity decreases [12]. 

The dominant mechanism of deformation depends mainly on the type and properties of the matrix polymer, but can vary also with the test temperature, the strain rate, and the morphology, shape, and size of the modifier particles (Bucknall 1977, 1997, 2000 Michler 2005 Michler and Balta-Calleja 2012 Michler and Starke 1996). Properties of the matrix determine not only the type of the local yield zones but also the critical parameters for toughening. In amorphous polymers with the dominant formation of crazes, the particle diameter, D, is of primary importance, while in some other amorphous and in semicrystalline polymers with the dominant formation of dilatational shear bands or intense shear yielding, the interparticle distance ID, i.e., the thickness of the matrix ligaments between particles, seems to be also an important parameter influencing the efficiency of toughening. This parameter can be adjusted by various combinations of modifier particle volume fraction and particle size. 

SF Xavier, D Tyagi, A Misra. Influence of injection-molding parameters on morphology and mechanical properties of glass fiber-reinforced polypropylene composites. Polymer Composites 3 88-96, 1982. 

The kinetics of this nucleation and polymer growth, as well as the first step of charge transfer, can be influenced by varying the electrochemical parameters such as current density and potential or solution parameters such as solvent and supporting electrolyte and thus influencing morphology. 

Examination of the composite microstructures by scanning electron microscopy (SEM) reveals the extent to which manufacturing parameters influence the morphology of the film samples. The final structure of the PET in each of the MFC films is presented in Figure 17.5(a) (f). It highlights the wide range of shapes and sizes that the dispersed phase evolves into and clearly signals that dispersed phase development is inextricably linked... 

Parameters influencing the spinning process and fiber morphology examined. The influence of cationic and anionic surfactants on enzymatic degradation rates investigated. 

The most important parameter influencing the final morphology appears to be the maleic anhydride content in the PP-g-MA (Fig. 6.10(b)). Inspection of experimental runs E, B and F indicates that increasing the MA content in PP-g-MA decreases the PP domain size. 

In addition to the study of the structure of materials, the influence of several parameters on morphology can be studied, in particular the influence of mechanical loading. There are several methods to investigate deformation and fracture processes, which are discussed in detail in [1,2,5]. The direct imaging techniques of microscopy allow very direct determination of the morphology and... 

Not only the particle size reduction and the morphology improved but also the SAS parameter influence on PS and PSD were explored. Hence, the operating condition levels... 

The parameters influence the nature and diameter of the final fiber to obtain the ability to control them. It is a major challenge. For selected applications, it is desirable to control not only the fiber diameter, but also the internal morphology [39]. An ideal operation would be the nanofibers diameter to be controllable, the surface of the fibers to be intact and a single fiber would be collectable. The control of the fiber diameter can be affected by the solution concentration, the electric field strength, the feeding rate at the needle tip and the gap between the needle and the collecting screen (Fig. 2.) [1, 12,40]. 

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