The Fiber Length Measurement of Discontinuous Fiber Reinforced Plastics (Part 1) : Investigation on the Measurement Method and the Preparation of the Samples to Improve the Accuracy and Reproducibility

There is demand for higher mechanical properties of glass fiber-reinforced plastics (GFRP) in line with the expansion of applications. However, as the fiber length shortens during processing, the strength of GFRP decreases. Hence, it is necessary to develop an efficient and accurate method for implementing fiber length measurement, which is an important phase in improving the processing. In this study, we examined the fiber length measurement method from three different points of view : the number of fibers to be measured, the appropriate size of the test piece, and the fiber length distribution, which may be biased due to the dilution of dispersing liquid. The number of fibers for accurate measurement depends on the fiber length distribution. In addition, it was found that the size of the test piece was determined by the fiber length. Moreover, the dilution of the fiber dispersing liquid did not affect the distribution of the fiber length to be tested.