Composites interphase

Lipatov YuS, Babich FV, Korzhuk NJ (1985) In Molecular characterization of composite interphases, Plenum Press New York, p 237... 

Thomason, J.L. (1990). Investigation of composite interphase using dynamic mechanical analysis artifacts and reality. Polym. Composites 11. 105-113. 

Al-Moussawi, H., Drown, E.K., and Drzal, L.T. (1993), The silane/sizing composite interphase. Polvm. Composites 14, 195-200. 

Fig. 22 a and b. Schematic diagram of the effect of THF washing on the final composite interphase, a As treated b THF washed... 

Blends of PVDE with PMMA have been studied by several authors. All three types of segregation were detected, which was attributed to variation of the crystallization temperature by Stein et al. [1981] and Morra et al. [1982]. Hahn [1987] reported the existence of a compositional interphase (a region of varying polymer composition) between the lamellae and the amorphous interlayer. The order-disorder interphase seemed to contain pure PMMA, while in the remaining interlamellar region a homogeneous mixture of PMMA and amorphous PVDE was located. 

The order-disorder interphase was defined as the region of loss of crystalline order. Kumar and Yoon (1991) examined this interface and found that in blends the thickness of this transition zone was essentially independent of the interaction parameter between the two polymers (when Xi2 varied from —1 to —0.005). Following the theoretical predictions, the thickness of this region increases only slightly when stiffer chains are considered. Due to the higher degree of order of segments of the crystallizable component in this zone, the penetration of the amorphous component is limited. The compositional interphase, however, is influenced by the stiffness of both chains and by the interaction parameter (the interfacial thickness varies with the reciprocal of This prediction seems to... 

Performance of immiscible blends depends on the composition, interphase and morphology. At equilibrium, for < ) < < > s 0.16 droplets are expected, while at higher concentrations fibers and lamellae are found [4]. Further increase of concentration leads to phase inversion at = 4>ii ... 

In composites, interphase hydrolysis can occnr, e.g. in the case of silane... 

Drzal, L.T., Composite interphase characterization. SAM PE J., 19, 7-13 (1983). Broutman, L.J., Measurement of the fiber-polymer matrix interfacial strength. In Interfaces in Composites, American Society for Testing and Materials, Philadelphia, PA, 1969, STP 452, pp. 27-41. 

Figure 7 Shear-stress distribution in the epoxy/CNT interphase of DWCNT/epoxy composites interphase combination BB stages of strain (see legend) represented by the different graphs.

According to data /3/, the AE sources in the fibrous composites are plastic deformation and cracking of the die material, shift stratification on the fibre-die interphase border, fibre destmction and stretching fibres out of the die. 

Surfaces are formed in the transition from one state of matter to another, whether the two phases are chemically distinct or not. Thus, surfaces exist at interphases or interfaces between two phases of either the same or different materials. For example, the surface of an ice cube in a glass of water represents an interface between two phases that are identical in chemical composition. The surface of a straw in the same glass of water represents an example of an interface between chemically distinct materials. 

As we have already seen, when an alloy contains more of the alloying element than the host metal can dissolve, it will split up into two phases. The two phases are "stuck" together by interphase boundaries which, again, have special properties of their own. We look first at two phases which have different chemical compositions but the same crystal structure (Fig. 2.5a). Provided they are oriented in the right way, the crystals can be made to match up at the boundary. Then, although there is a sharp change in... 

Assuming the work of adhesion to be measurable, one must next ask if it can be related to practical adhesion. If so, it may be a useful predictor of adhesion. The prospect at first looks bleak. The perfect disjoining of phases contemplated by Eq. 1 almost never occurs, and it takes no account of the existence of an interphase , as discussed earlier. Nonetheless, modeling the complex real interphase as a true mathematical interface has led to quantitative relationships between mechanical quantities and the work of adhesion. For example, Cox [22] suggested a linear relationship between Wa and the interfacial shear strength, r, in a fiber-matrix composite as follows ... 

Once it is recognized that particles adhere to a substrate so strongly that cohesive fracture often results upon application of a detachment force and that the contact region is better describable as an interphase [ 18J rather than a sharp demarcation or interface, the concept of treating a particle as an entity that is totally distinct from the substrate vanishes. Rather, one begins to see the substrate-particle structure somewhat as a composite material. To paraphrase this concept, one could, in many instances, treat surface roughness (a.k.a. asperities) as particles appended to the surface of a substrate. These asperities control the adhesion between two macroscopic bodies. 

Changes observed in the composition of the rubber/brass interphase correlated well with results of adhesion tests carried out on brass-plated steel wires embedded in blocks of rubber [46]. The force required to pull the wires out of the blocks decreased steadily as vulcanization temperature increased. This effect was especially pronounced when the specimens were aged at elevated temperature and humidity for several days before the wires were pulled out of the rubber blocks. 

The volume of substance in a composite material that exists in a nonequilibrium state due to its proximity to an interface has been termed an interphase [1]. The interphase is a zone of distinct composition and properties formed by chemical or physical processes such as interdiffusion of mutually soluble components or chemical interaction between reactive species. 

Diffusion theory involves the interdiffusion of macromolecules between the adhesive and the substrate across the interface. The original interface becomes an interphase composed of mixtures of the two polymer materials. The chemical composition of the interphase becomes complex due to the development of concentration gradients. Such a macromolecular interdiffusion process is only... 

Jones, F.R., Interfacial aspects of glass fibre reinforced plastics. In Jones, F.R. (Ed.), Interfacial Phenomena in Composite Materials. Butterworths, London, 1989, pp. 25-32. Chaudhury, M.K., Gentle, T.M. and Plueddemann, E., Adhesion mechanism of poly(vinyl chloride) to silane primed metal surfaces. J. Adhes. Sci. Technol, 1(1), 29-38 (1987). Gellman, A.J., Naasz, B.M., Schmidt, R.G., Chaudhury, M.K, and Gentle, T.M., Secondary neutral mass spectrometry studies of germanium-silane coupling agent-polymer interphases. J. Adhes. Sci. Technol., 4(7), 597-601 (1990). 

A unique but not yet widespread technique that may influence the interfacial bond quality relies on the localized variation in the polymer modulus normal to the polymer-substrate junction in the composite assembly, as illustrated schematically in Fig. 15 [41,52]. The transversal modulus variation may be accomplished by interposing a tertiary interphase between the substrate and... 

The fiber-reinforced composite materials include three phases surface of fiber side, the interface between fiber and matrix, and the interphase. These phases are collectively referred to as the interface [12]. The characteris-... 

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