Correction of the measurement of fiber length of short fiber reinforced thermoplastics

Short fiber reinforced thermoplastics are often made using extrusion compounding and injection moulding techniques. Fiber breakage takes place during processing. In finished fiber reinforced parts, there often exists a fiber length distribution. Measurement of fiber length is often performed on photographs of short fibers obtained from burning off or dissolving the matrix. However, relatively long fibers crossing the photographs cannot be counted, leading to underestimation of mean fiber length. In this paper, the effect of fibers intersecting the photographs is discussed on the measurement of fiber length. Correction of the measurement of fiber length is carried out and the real value of mean fiber length and the real fiber length distribution can then be obtained. An example is given to illustrate the correction of the measurement of fiber length.