Evolution of lignocellulosic fibre lengths along the screw profile during twin screw compounding with polycaprolactone

Novel automated method for evaluating the morphological changes of cellulose fibres during extrusion-compounding of plastic–matrix composites

“…While in some cases no average fibre length reduction is observed between a sampling point farther from the die plate and another closer to it (see Table 2), the average fibre length show an overall decreasing trend as the material moves forward along the extruder, thus evidencing the increasing fibre damage that takes place as compounding progresses. A similar trend has been also found in a recent work focused on the compounding by extrusion of polycaprolactone/ hemp composites [21]. However, the fibre damage does not result in relevant changes in the distribution of fibre lengths, as revealed in the rather similar polydispersity index (PDI) values obtained.…”

“…Terenzi et al found an aspect ratio distribution similar to fibre length distribution for LINCELL A cellulose fibres/PP composites, but these fibres had a constant diameter [3]. Berzin et al also found that, along the screws of the extruder, aspect ratio follows the same evolution as average length for polycaprolactone/hemp composites [21]. However, in a previous study, a different result was obtained.…”

“…Fibre geometrical parameters determination has been carried out by analysing the images captured with a digital camera or different transmission light optical microscopes and scanners [2,3,[14][15][16][17][18][19][20][21]. Many of the methods used for determining the geometrical parameters of natural fibres are manual to a considerable extent, thus requiring the manual marking (e.g., with a light pen connected to a computer) of both ends of each one of the fibres to obtain the fibre length, as well as the marking of several points along the length of the fibre to estimate the mean fibre diameter.…”

Fibre Length Reduction in Natural Fibre-Reinforced Polymers during Compounding and Injection Moulding—Experiments Versus Numerical Prediction of Fibre Breakage

“…Therefore, compounds with long fibres need to be produced, and different compounding process parameters need to be adapted, because high screw speeds and low feed rates increase the fibre fragmentation [59]. In addition to the breakage behaviour, it is important to analyse the possible fibre-matrix separation with long fibres in complex and thin-walled moulds.…”

X-ray computed microtomography and 2D image analysis for morphological characterization of short lignocellulosic fibers raw materials: A benchmark survey

“…The length and diameter of the fiber element (individual or bundles) provide an interface to transmit stresses from the matrix to the core of the fiber element, which was recently confirmed using synthetic fibers [16]. However, during processing of short fiber composites, the lignocellulosic fibers break, which reduces the fiber length and accordingly, under certain conditions, reduces the reinforcing efficiency of the fibers [17,18]. In previous study [17,19], it was demonstrated that defibrization or 'breakage' affect the fiber morphologies, which impact on the composite's mechanical properties.…”