Debonding mechanisms

Kalanta, J. and Drzal, L.T. (1990). The debonding mechanism of aramid fibers to epoxy matrices, part II. An experimental investigation. J. Mater. Sci. 25, 4194-4202. 

The development of a criterion for debonding mechanism, which assumes that the debonding stress is proportional to the strength of adhesion and depends on the particle size of the filler, might explain the experimental observations on toughness. 

This brings us back to more interfacial properties. It is interesting to investigate what becomes of the effect of adding diblock in the adhesive when the PSA is detached not from steel but from a low-adhesion surface such as a polyolefin, a silicone layer, or any other release surface. We have carried out a comprehensive investigation of the debonding mechanisms of the adhesives of Table 22.1 from a surface of ethylene-propylene (EP) copolymer [45]. The copolymer layer was spin-coated from a xylene solution onto the flat end of the steel probe. 

Most of the previous works used a static debonding mechanism. Thus it is mostly based on linear elastic analysis. The importance and usefulness of linear elastic fracture mechanics is well recognized, especially for the case of interfacial fracture. However, the analysis requires serious theoretical approximations (I) It... 

Poly(butylene adipate-co-terephthalate) (PBAT), poly(butylene succinate) (PBS) or poly(ethylene succinate) (PES) are flexible biodegradable polyesters that have also been considered for blending with PLA. PBAT and PLA are immiscible polymers where PBAT phase formed small droplets in the PLA matrix. Drastic increase of elongation at break was observed (200% with only 5 wt% of PBAT) due to interfacial debonding mechanisms as the interfacial adhesion between the two polymers was low. The impact... 

Fibre Pullout. The debonding mechanism in fibre-reinforced... 

The propagation of fatigue cracks is controlled by fiber distribution and the toughness of the matrix materials. Fatigue damage initiates in all materials by debonding mechanisms . 

The peak at small distances in the force versus distance curve is related to the onset of cavitation, or the formation of small air pockets between the polymer gel and the probe (c.f. Figure 11b). Once cavitation occurs, the measured force decreases significantly. The air pockets then grow as the polymer gel is stretched further and fibrils are formed. The force increases as the fibrils are stretched and strain harden. Finally, the fibrils detach cleanly from the probe and the measured force returns to a value of zero. The debonding mechanisms are discussed further in Section 4. 

FIGURE 2.6 Schematic of proposed fracture mechanism of a composite system (a) crackbowing mechanism (b) crack deflection mechanism (c) step structure mechanism, and (d) debonding mechanism. 

The debonding mechanism is affected by many factors, such as the size of the particle and the interfacial adhesion. A simple equation was proposed to predict the relationship between the critical stress (a) and the radius of the particles (Pukanszky et al., 1994) ... 

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