Characterization of Fibres and Fibre Collectives with Common Laser Diffractometers

Size and shape characterization of polydisperse short-fiber systems

“…Ref. 11. Above the median size the cumulative laser diffraction PSDs exhibit a "kink" (and the frequency curves a maximum, a so-called "mode"), which could be indicative of the fact that precisely this value (smallest-size mode of the laser diffraction frequency curve) corresponds to the thickness of the fibers.…”

“…Moreover, depending on the hydrodynamical situation, orientation effects of fibers in the flowthrough cells of laser instruments can lead to strongly noncircular diffraction patterns, which can have a strong impact on the result when the photodetector is not equivalent to a full circle. 11 Therefore, in this case microscopic image analysis is an indispensible tool to obtain unbiased information on the size and morphology of fiber systems. Indeed, it seems that, in spite of all disadvantages and difficulties, image analysis is so far the most reliable source of unbiased information on particle size and shape in the case of fibers.…”

Particle shape and suspension rheology of short-fiber systems

“…23 An earlier laser diffraction study with the wollastonite type HSV 45 demonstrated the effect of particle orientation in the flow-through cell of laser instruments on the interference pattern. 41 It has been shown that the interference pattern of this type of wollastonite is highly noncircular when the particles are aligned in the flow direction. 41 According to laser diffraction (Analysette 22, Fritsch GmbH, Idar-Oberstein, Germany), only 77 and 60 vol.% for WM 45 and HSV 45, respectively, are <45 m. Table 4 lists the size characteristics 23 determined by laser diffraction and by microscopic image analysis (Lucia G, Laboratory Imaging s.r.o., Prague, Czech Republic).…”

Graphical comparison of image analysis and laser diffraction particle size analysis data obtained from the measurements of nonspherical particle systems

“…Furthermore, evidence exists to support the conclusion that flow orientation of particles within the measurement cells of LD psa systems is the rule rather than the exception. Berthold et al 19 demonstrated in 2000 that the flow within LD psa systems in general has to be laminar to prevent the formation of bubbles. They also demonstrated that this laminar flow condition has the effect of orienting fiber-like particles in the direction of the flow.…”