Interphase layer

The fraction of polymer confined in the interphase layers was estimated using the empirical formula [60, 61] ... 

The exponentials Ki and K2 in the model account for the degree of heterogeneity of the interphase layer. The ratio of these exponentials is representative, as suggested in [121], of the load transmission between the fiber and the matrix (the adhesion factor a). 

When a - 1 ( perfect adhesion) the elasticity modulus of the interphase decreases continuously from the fiber value to the matrix value, the interphase layer modulus being higher than that of the matrix. When a < 1, the interphase layer modulus assumes, some distance off the fiber surface, a minimum value smaller than the matrix value, and then increases tending asymptotically to the matrix modulus. 

Lhotellier, F.C. and Brinson, H.F. (1988). Matrix fiber stress transfer in composite materials Elasto-plastic model with an interphase layer. Composite Structures 10, 281-301. 

Morel, M., Saravanos, A. and Chamis, C.C. (1991). Interphase layer optimization for metal matrix composites with fabrication consideration. NASA TM-105166. 

Because of the chemical and structural differences of this coupling agent interphase layer, the mechanical properties of this region would be expected to be quite different from the bulk epoxy. Indeed, Lipatov 62) has shown that the addition of silanes changes the mechanical strength and chemical resistance of interphase regions. 

Exposure at 125 °C is very severe for this epoxy matrix (Fig. 25). Permanent changes in the matrix are noted. The interphase layer, however, acts to mitigate some of the deleterious interfacial effects and allows that system to regain a larger portion of its interfacial shear strength after moisture exposure and dehydration. The fiber without the finish layer has lost almost all of its interfacial shear strength and recovers very little after dehydration. 

Interphase inhibition [52] occurs where the inhibitive layer has a three-dimensional structure situated between the corroding metal and the electrolyte. The interphase layers generally consist of weakly soluble compounds such as oxides, hydroxides, carbonates, inhibitors, etc. and are considered to be porous. Non-porous three-dimensional layers are characteristic of passivated metals. The inhibitive efficiency depends on the properties of the three-dimensional layer, especially on porosity and stability. Interphase inhibition is generally encountered in neutral media, either in the presence or absence of oxygen. In aerated solutions, the inhibitor efficiency may be correlated with the reduction in the oxygen transport limited current at the metal surface. 

The above CVD techniques have been widely applied and used to fabricate superconductor wires and interphase layers for fibre-reinforced metal- and ceramic- matrix composite materials. 

Below the critical concentration of filler some polymer is converted to the interphase layer where the polymer has a higher density because of closer packing,... 

Krotov, V. V., Rheological analysis of the Marangoni effect for an ideal interphase layer, Colloid Journal, Vol. 48, No. 1, 1986. 

It is also noted, that relative elongation at a break and a limit of fluidity better characterize the nature of a continuous phase, than relative strength at the stretching. At the same time, the deviation of the curve break stress - composition from additivity (nonmonotonic dependence) - relative strength under the stretching - can be considered as a proof of strengthening of interaction in an interphase layer in mixtures of polymers under the influence of nonlinear vibrations. 

Considering an increase of shift deformations under the influence of vibrations, it is possible to believe that vibrating influence in this case leads to the effect similar to that under plastification on rollers, where there are conditions for orientation of structural formations of a filler and polymer and strengthening of their interaction in an interphase layer. Similar effects have been noted earlier in solid mixturing of hard-chain crystallizing flourine-containing copolymers with flourine rubber [13]. 

The role of the POE phase is more complex. As many elastomers, it undergoes extensive cavitation when it is hydrostatically loaded within the interphase layers and the isolated nodules. However, it is often seen in the micrograph (especially after stress triaxiality has been released by void nucleation) that POE is capable to undergo considerable stretching without further damage. The net effect could thus be to reduce volume strain. 

The electrical conductivity for SiC/SiC is strongly affected by the matrix conductivity and in the fiber direction, it is usually dominated by conduction through the PyC (Pyrolitic Carbon) interphase By 2-probe DC (direct current) and AC (alternating current) and 4-probe DC methods, Youngblood et al measured the EC-values of 2D Hi-Nicalon S/PyC interphase/ICVI SiC matrix composites, and composites with the PyC interphase layer removed by oxidation (in plane) at temperatures up to 500 "C. It was found that by removing the PyC interphase, in plane EC of the composites decreased 30%. 

The charge density accumulation cannot be neglected for interphase layers such as the electrical double layer. Using a nondimensionalized form of Equation 2.2, it was shown that the electroneutrality condition is a direct result of the Debye screening length, where the ratio of the Debye length Xx, to the field length L is described as follows (Eq. 2.3) (Chu, 2005) ... 

SiC matrix, and the number of He bubbles and cracks strongly depended on the fabrication process of SiC/SiC composites. The size of the bubbles also depended on the fabrication process of SiC/SiC composites. The turbostratic carbon structure was formed in the carbon interphase layer due to irradiation, although the interphase layer was the nongraphitic carbon structure before irradiation. Furthermore, a new crystalline SiC phase was observed in the carbon interphase irradiated with Si ions. Details of irradiation effects on SiC/SiC composites are described in Refs. [67-69]. 

In a case of a microheterogeneous system, polymerisation proceeds in the three reaction zones in saturated monomer-polymeric solution, at the interphase layer of the boundary of MPPh and micrograins of PMPh, and in the solid polymermonomeric solution. 

Polymerisation of the interphase layer of the boundary of MPPh and PMPh, proceeds accordingly to Scheme (4.1), but the constant rate of linear chain termination is different. This is because the solid PMPh creates an ordered structure of the nearest reaction space, in which the translational movement and segmental mobility of macroradicals are significantly reduced. Let us assume that the concentration of monomer and photoinitiator in the interphase layer are equal or proportional to their concentration in MPPh. 

Specific rate of polymerisation in the interphase layer is described by the classic Equation (4.6), but with the constant rate of termination in which the contribution of diffusion... 

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