Adhesion Assessment
Micro-mechanical characterization of the shear strength of the fiber-matrix interface utilizes a single droplet of resin cured on a filament. Using a micro-bond pull-out test allows researchers to measure the force needed to slide the fiber out of the cured resin droplet. In Chinese research centers and composite testing laboratories, the resulting force-displacement curves are recorded to evaluate the quality of chemical treatments on flax fibers.
Experimental Execution
Preparation of the specimens requires deposition of a micro-droplet of polymer onto a single flax fiber under a microscope. After the resin is cured, the fiber is mounted in a tensile testing machine, and the droplet is held by two knife-edges that apply a shear force at the interface. This setup forces the droplet to detach when the applied tensile load exceeds the shear strength of the bond.
Calibration of the knife-edge gap and the droplet diameter is critical to prevent fiber breakage and ensure valid test results.
Data Interpretation
Calculation of the interfacial shear strength is based on the maximum debonding force and the embedded area of the fiber. These results are compiled in the material’s characterization datasheet to compare different surface treatments. A high success rate in droplet detachment without fiber failure verifies the accuracy of the test run.
