Interphase interaction

Nanocarbon structures such as fullerenes, carbon nanotubes and graphene, are characterized by their weak interphase interaction with host matrices (polymer, ceramic, metals) when fabricating composites [99,100]. In addition to their characteristic high surface area and high chemical inertness, this fact turns these carbon nanostructures into materials that are very difficult to disperse in a given matrix. However, uniform dispersion and improved nanotube/matrix interactions are necessary to increase the mechanical, physical and chemical properties as well as biocompatibility of the composites [101,102]. 

Although particles in two-phase flow are not uniformly distributed, the dense and the dilute phases can be considered, each in its own, as uniform suspensions, and the global system can thus be regarded as consisting of dense clusters dispersed in a broth of separately distributed discrete particles, as shown in Fig. 1. The preceding correlations will therefore be used respectively in the dilute and the dense phases, for calculating micro-scale fluid-particle interaction, and also for evaluating meso-scale interphase interaction between clusters and the broth, as shown in Table I, for CD, CD[ and CD. ... 

This equation implicitly accounts for the interaction between the velocities of two phases and therefore, enhances convergence rate. When the interphase interaction coefficient is zero, the above equation reduces to that for single-phase flows. It is useful to note here that the coefficient of pressure gradient term also becomes modified by the presence of the second phase. These modified coefficients should be used when... 

It must be noted here that even for Eulerian-Lagrangian simulations, although there is no complexity of averaging over trajectories, the accuracy of simulations of individual bubble trajectories depends on lumped interphase interaction parameters such as drag force, virtual mass force and lift force coefficients. All of these interphase interaction parameters will be functions of bubble size and shape, presence of other bubbles or walls, surrounding pressure field and so on. Unfortunately, adequate information is not available on these aspects. To enhance our understanding of basic... 

The Dynamic flow. The flow curves, n vs. u In Fig. 22, were not corrected for the apparent yield stress. For PP and LLDPE-A the curves nearly reached the Newtonian plateau and the Cole-Cole plots were found to be seml-clrcular Indicating that Oy = 0, However, for blends the situation Is less clear. Judging by the flow curves for BL, BL-1 and BL-2 at low deformation rates, the Newtonian plateau seems to be far away. This may Indicate the Incipient yield stress. To clarify this point n" vs. n was plotted In Fig. 23. An onset of the second relaxation mechanism Is visible. The long relaxation times In BL may only originate In the Interphase Interactions. These usually lead to the presence of the apparent yield stress. 

The concentration dependence of rig conqjuted from Equation 20 Is shown In Fig. 30, where the solid points represent the experimental data and the open points their values corrected for the effects of PP degradation. For System-1 there Is strong negative deviation (NDB) from the log additivity rule, viz. Equation 1, but for System-2 NDB Is visible at low PP content, converting to positive deviation (PDB) at high. It Is worth recalling that ng was computed from corrected for the yield stress values of n. The NDB behavior. Indicative of Interlayer slip, reflects poor miscibility In System-1 and that at low concentration of PP In System-2. The emulslon-llke behavior of Syetem-2 at high PP content reflects a better Interphase Interaction. 

Interphase Interaction. Phase separation in this system is fairly complete, as demonstrated by both electron microscopy and the dynamic mechanical spectra. Nonetheless, interaction is consistent with the extent of separation of the tan 5 peaks, taken as a measure of Tg separation. Inspection of the data in the Tables shows that the greatest reduction in Tg separation occurs in the xx series, that there is some reduction in all series at the longest irradiation delay times, and that there is greater reduction with increasing proportions of PBMA in the mixtures. The changes with increasing delay time are fairly smooth. From the electron micrographs, total particle surface area and the proportion of fine particles increases with increased delay time in all series. 

Nigmatulin RI, Lahey RT Jr, Drew DA (1996) On the Different Forms of Momentum Equations and on the Intra- and Interphase Interaction in the Hydromechanics of a Monodispersed Mixture. Chem Eng Comm 141-142 287-302... 

A. 19.3 While the best model depends on the question being investigated, the Stern model would provide a more accurate model of the interphase because it considers molecular size and non-electrostatic molecular absorption, both of which are very important to biological systems. For example, proteins control the flow of ions through membranes based on size, so if size isn t considered, the interactions leading to flow control would be missing an essential component. Hydrophobic and hydrophilic interactions are also an important part of interphase interactions. 

Morphological study, together with DMTA and DSC results, confirms the expectation of miscibility of the diblock copolymer with each component of the blend. This miscibility occurs at the interphases between the components of blends, allowing enhanced interphase interactions and better stress transfer in the blend system. This is probably due to the anchoring of each sequence of the block with its corresponding component of the blend, which is in good... 

Enhanced interphase interactions, deduced from thermal and dynamic mechanical properties and morphology observed by SEM, demonstrate the efficient compatibilizing effect of iPS-fo-iPP copolymer on iPS-iPP blends. Each sequence of the iPS-fc-iPP diblock copolymer can probably penetrate or easily anchor its homopolymer phase and provide important entanglements, improving the miscibility and interaction between the iPS and iPP phases. This is in good agreement with what is inferred from the mechanical properties of the iPS-fo-iPP-iPS-iPP polyblends. 

The effect of structural memory in a wave field has been exsemplarily studied by the IR-spectroscopy method on films made from mixtures of butadiene-styrene and acrylic latex as models of polymeric membranes. The strengthening of the interphase interaction in heterophase systems that can cause change of their local and transmitting mobility has been observed. It has been shown, that the response of polymeric dispersed systems and compositions on influence of nonlinear vibrations proves their influence on deformation properties, like orientation phenomena in solid polymers (where Rebinder s effect can take place) that it is possible to consider as a way of polymer modifications, including the obtaining of nanicomposites, polymeric biocarriers, etc. 

Strengthening of interphase interaction under the influence of so-called vibrating force can be explained by the occurrence of additional chemical bonds. In the case of polymers containing nonsaturated bonds, excitation of nonlinear vibrations can lead to the crossinking of polymeric chains with non saturated bonds, that can be confirmed by the data about the decrease of swelling velocity (Figure 5). 

For the 20-MWNT-TiO2 catalyst the absorption spectrum changes dramatically with relation to neat Ti02 and spawns over the whole range of the UV-vis region, suggesting a strong interphase interaction. 

Carbon phases can be used to support Ti02 efficiently for application in heterogeneous photocatalytic processes. Besides facilitating the recovery and reuse of the photocatalysts, there is a significant increase in the photocatalytic activity, which can be measured in terms of a synergy factor. Particularly in the case of CNTs, this effect results from strong interphase interaction and can be rationalized in terms of the support acting as photosensitizer, adsorbent, and to a certain... 

Functionalized Polyolefins and Aliphatic Polyamide Blends Interphase Interactions, Rheology, and High Elastic Properties of Melts... 

The effect of compatibilization of grafted or block copolymers as controllers of interphase interaction has been well known (1,28). Marosi and Bertlan (29), for example, described the compatibUizing effect of polybutylene terephthalate-polytetramethylene oxide block copolymers on PA6/HDPE blends. The addition of a block copolymer prevents separation in the blends during processing and increases the impact strength of the material several times. 

A more advantageous alternative is to prepare compatibUized PA/PO blends, like many other types of blends, by reactive processing that implies creation of composites with a required level of interphase interaction in situ during compounding (18). Grafted polymers, whose macromolecules contain necessary functional groups, are most often used as compatibilizers. 

It is worth mentioning that interphase interactions in blends proceed only within mesophases whose thickness for incompatible polymers is between 2 and 50 nm depending on the thermodynamic interactions of the phases, temperature, regimes of mixing, and some other factors (7,11,29,30). The mesophase thickness depends on the miscibility of the components and in first approximation (7) is where xi2... 

A high rate of formation of adhesional contact between the phases in a PA/PO-g-MAH system is very important from the technological viewpoint, because fast interphase interactions during compounding of materials depend little on subsequent processing of the blends. 

There are four types of the polymer blends (i) Additive blends whose melt viscosity follows Equation 18.3, (ii) Blends with a positive deviation of from Equation 18.3. These include blends with strong interphase interactions, (iii) Blends with a negative deviation from the logarithmic additivity, which is typical of incompatible components with weak interphase interactions, (iv) Blends that show both positive and negative deviations of py from the additive values (such a relationship is typical of materials in which structural changes take place during flowing). 

Blending of PA with grafted PO (g-PO), or compatibilization of PA/PO blends by addition of g-PO, changes the dependence pattern of r, with component ratio and technological factors. As PA/PO compatibilized blends have a finer dispersed phase with a developed interface and show more intense interphase interactions, flowing disturbs a little the phase morphology, and often becomes higher than the additive values and viscosity of any of the blend s components (6,20,66-69). 

For blends containing 30-40 wt% of g-PO, the value of MFI is between 0.2 and 0.8 g/10 min, which is 10-26 times lower than that of pure PA6 the level of values corresponds with the requirements imposed on extrusion-processed materials (74). It is of interest that irrespective of g-PO type, at a concentration of 30-40 wt%, the MFI values of PA blends are quite similar despite a great difference in melt viscosities of g-POs used for blend preparation (Table 18.1). This can probably be explained by the fact that the continuous phase, during melt flowing of a blend, is formed by lesser viscous PA6 (76), which dominates in the blend. The decisive influence on the flow development of such blends comes from interphase interactions that are alike for all... 

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