Interfacial bond strength

B. Degradation of the fiber-matrix interface resulting in loss of adhesion and interfacial bond strength. 

Ultrasonic vulcanisation also tends to change the interfacial property of the rubber and the reinforcing materials to improve bonding. Improved wetting and flow characteristics produced by ultrasonic vulcanisation have the potential to increase the interfacial bond strength between the rubber and the reinforcing materials currently used. 

Fig. 5.7. Effect of immersion in hot water on interfacial bond strength of silane treated glass fiber-epoxy matrix composite. After Koenig and Emadipotir (1985).

Fig. 5.8, Effect of diamino-silane solution concentration and modification on interfacial bond strength rh of GFRP (O) silane treated ( ) silane treated and partially removed. After Koenig and Emadipoiir...

In the equation, Db, is the interfacial bond strength normalized with respect to the maximum bond strength in the composite and the integration variable, t, represents the time an incremental area came into intimate contact. 

The following advantages come to mind. The increased interfacial bond strength often observed when an aminosilane coupling agent is used may be explained by the in situ formation of an interpenetrating network. This would... 

Crucially, structure of CNTs and polymers plays a key role on mechanical properties and load-transfer of nanocomposites. Efficient load-transfer is only possible when adequate interfacial bonding strength is available. Interfacial failure may compromise the reinforcement effect and then the full potential of CNTs may not be realized (11). Therefore, it is of great importance to understand the effect of molecular structure, interfacial structure and morphology characteristics on the tensile properties of nanocomposite materials. 

Figure 8. Schematic stress-strain relations for a noncross-linked (I), lightly cross-linked (II), and highly cross-linked (III) polymer. The horizontal line denotes a possible level of the interfacial bond strength the dashed lines denote the limiting strain attainable in each case. R represents bond rupture.

The mode of bond failure in the unexposed films was mainly cohesive. However, when a cross-linked polymer matrix was formed with UV exposure, the mode of bond failure was interfacial at all testing temperatures. We believe that by cross-linking the polymer with UV radiation, the modulus of the polyester was increased. This in turn caused the cohesive strength to be much greater than the interfacial bond strength. As a result, the mode of bond failure became interfacial, or adhesive (10) (Figure 8). 

Figure 6.14 shows that a plasma-sprayed hydroxyapatite coating on a porous titanium layer covering the titanium alloy surface (solid bars) will improve the interfacial bond strength compared to uncoated porous titanium (light bars)... 

Figure 6.14 Comparison of early stage interfacial bond strength of porous titanium with (solid bars) and without (light bars) a plasma-sprayed hydroxyapatite coating (Cook, 1991. (Modified after Hench (1991).)...

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