A method for estimating the fibre length in fibre‐PLA composites

Abstract

SummaryWood pulp fibres are an important component of environmentally sound and renewable fibre-reinforced composite materials. The high aspect ratio of pulp fibres is an essential property with respect to the mechanical properties a given composite material can achieve. The length of pulp fibres is affected by composite processing operations. This thus emphasizes the importance of assessing the pulp fibre length and how this may be affected by a given process for manufacturing composites. In this work a new method for measuring the length distribution of fibres and fibre fragments has been developed. The method is based on; (i) dissolving the composites, (ii) preparing the fibres for image acquisition and (iii) image analysis of the resulting fibre structures. The image analysis part is relatively simple to implement and is based on images acquired with a desktop scanner and a new ImageJ plugin. The quantification of fibre length has demonstrated the fibre shortening effect because of an extrusion process and subsequent injection moulding. Fibres with original lengths of >1 mm where shortened to fibre fragments with length of <200 µm. The shortening seems to be affected by the number of times the fibres have passed through the extruder, the amount of chain extender and the fraction of fibres in the polymer matrix.

Industrial Hemp Fibers: An Overview

“…Fiber dispersion, length, orientation, and volume fraction in the matrix have a significant effect on the mechanical properties of the composites [2,77]. Increasing the hemp fiber length and/or decreasing its diameter increase the fiber aspect ratio (length/diameter), which induces a positive effect on the mechanical properties of polymer composites [85]. Decreasing the fiber length more than the critical length over which the fiber stress is decreased from the maximum value reduces the stress transfer between matrix and fiber [2].…”

Transverse permeability of dry fiber preforms manufactured by automated fiber placement

“…A bimodal threshold was applied to the voxel intensity histogram to segment the pores and the preform [24,25].…”

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

“…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.…”