Microbond tests

In Toughened Composites, ASTM STP 937, (N.J. Johnston ed.) ASTM, Philadelphia, PA, pp. 179-196. Wu, H.F. and Claypool, C.M. (1991). An analytical approach of the microbond test method used in characterizing the fiber-matrix interface. J. Mater. Sci. Lett. 10, 260-262. 

Craven JP, Cripps R, Ciney V (2000) Evaluating the silk/epoxy interface by means of the microbond test. In Composites Part A - Applied Science and Manufacturing 31(7) 653-660... 

Still another micromechanical method for single fiber simulation of a polymer composite interfacial adhesion is the microbond test. This method was developed by Miller et al. [52] and initially applied for S3mthetic fibers. As mentioned by Craven et al. [53], the microbond test is suitable for any fiber that can carry only low loads. This is the particular case of silk, a strong natural fiber but with limited load bearing capacity due to diameters that can be finer than 50 pm. This could be the case of some lignocellulosic fibers such as the ramie with diameters of the order of 10 pm. 

The microbond test is also mentioned as the microdroplet test [39] and believed to possess some of the characteristics of fiber pullout in composites [34]. The test consists of a microdroplet of still fluid polymeric resin deposited onto a fiber, as shown in the schematic diagram of Fig. 9.9 [53]. 

Fig. 9.9 Schematic diagram of the microbond test. Reproduced with the kind permission of the publishers of [53]...

It is recognized that the microbond test has the advantage of permitting almost any fiber/polymer matrix combination with a pullout force measurement at the moment of debonding. However, Herrera-Franco and Drzal [34] indicate serious inherent limitations ... 

The microbond technique was analyzed by Naim [56] and more recently by Scheer and Naim [57]. In the first paper, a variational mechanics analysis of the stresses in the microbond specimen was completed. In the second paper, a new, more complete shear-lag analysis was presented. The proposed shear-lag result for analyzing the microbond test results is given by the equation in terms of the force of debonding ... 

Scheer, R.J. and Naim, J.A., A comparison of several fracture mechanics methods for measuring the interfacial toughness with microbond tests. J. Adhes., (1994). 

The microbond test measures the force, Fmax, required to pull the fiber out of a small resin droplet restrained by two knife-edges. The interfacial shear strength is determined... 

R.J. Day, Modelling of the Micromechanics of the Microbond Test, 2nd International Conference on Deformation and Fracture of Composites, (1993)... 

---