Particle matrix adhesion

The nature of the functional groups of the HBP is a significant factor for the control of viscosity, miscibility with the thermoset precursors, phase separation during cure, and particle-matrix adhesion. 

Decohesion and void growth are controlled by the debonding stress at the particle/matrix interface it only occurs when the local debonding stress is lower than the fracture stress (crazing stress) of the matrix itself G is correlated with the local toughness at the interface it is dependent on the particle/matrix adhesion energy. 

Kaw Kawaguchi, T., Pearson, R. A. The effect of particle-matrix adhesion on the mechanical behavior of glass filled epoxies. Part 2 A study on fracture toughness. Polymer 44 (2003) 4239 247. 

Woo Wooster, T. J., Abrol, S., Hey, J. M., MacFarlane, D. R. The effect of particle matrix adhesion on the mechanical properties of silica filled cyanate ester composites. Macromol. Mater. Eng. 289 (2004) 872-879. 

Fillers, especially high surface area silicas, are commercially available with such hydrophobic surface coatings. They are expensive and seem to be mainly used in sealant and adhesive applications rather than in polymer composites, where they produce low particle matrix adhesion similar to fatty acid and other cheaper additives. 

Extensions to the Crack Pinning Model and the Effect of Particle Matrix Adhesion... 

There are stiU many unanswered questions as to why one LR additive more effectively toughens a particular resin than another LR additive. Microstructural features that may affect fracture behavior such as volume fraction, particle size and size distribution, particle-matrix adhesion, and the structure of dispersed phase are difficult to control independently. As a result, the importance of each has not been quantified. Nevertheless, significant improvements in the fracture toughness of rubber-modified UP and VE resins have been realized. 

From this point, it can be seen that yielding or tensile strength is dependent on particle-matrix adhesion, specific surface area of the particles and thus the volume fraction. The dewetting process also causes the effective load bearing area to be reduced. Based on these factors, Pukanszky et al proposed an expression to describe the tensile yield stress and traisile strength [75]. 

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