Distribution function of fiber length in thermoplastic composites

Masubuchi, Yuichi; Terada, Mariko; Yamanaka, Akihiro; Yamamoto, Tetsuya; Ishikawa, Takashi

doi:10.1016/j.compscitech.2016.08.007

Cited by 24 publications

(10 citation statements)

References 26 publications

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“…The weight‐average (or length‐average) fiber length

L_{W}

is the second moment of the fiber length distribution and emphasizes the proportion of long fibers in the distribution. This is of particular interest for molded LFT samples since they typically show a length distribution with a distinct peak followed by a long tail decay . It is calculated using

L_{W} = \frac{\sum_{i = 1}^{n} (|, N_{i} l_{i}^{2})}{\sum_{i = 1}^{n} (|, N_{i} l_{i})}

…”

Section: State‐of‐the‐artmentioning

confidence: 99%

A novel fiber length measurement technique for discontinuous fiber‐reinforced composites: A comparative study with existing methods

et al. 2017

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The residual fiber length in a molded part is one of the most important microstructural properties of discontinuous fiber‐reinforced composites. While there have been several research studies characterizing the process‐induced fiber length reduction, the measurement procedures vary substantially, calling into question the comparability of reported results. This article introduces a newly developed measurement procedure that aims to provide accurate, repeatable, robust, and time efficient fiber length analyses. A comprehensive study of measurement techniques was performed comparing commercially available systems and the conventional approach of measuring the fiber length manually. The results emphasize the need for a standardized procedure to characterize the fiber length distribution and the risk of generating inadequate results through improper sample preparation. The developed measurement technique was tested and compared for an experimental study of fiber breakage in injection molding. For a simple plaque geometry, the residual fiber length along the flow path was obtained for a long glass fiber‐reinforced polypropylene at 30 and 40%wt for varying process conditions. The new measurement technique showed accurate and repeatable results. The results of the injection molding study showed that screw speed and back pressure are important factors that drive fiber breakage. An increase in back pressure from 13 to 50 bar and screw speed from 27 to 35 rpm reduces the weight‐average fiber length by 37.5%. POLYM. COMPOS., 39:4058–4070, 2018. © 2017 Society of Plastics Engineers

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“…The weight‐average (or length‐average) fiber length

L_{W}

L_{W} = \frac{\sum_{i = 1}^{n} (|, N_{i} l_{i}^{2})}{\sum_{i = 1}^{n} (|, N_{i} l_{i})}

…”

Section: State‐of‐the‐artmentioning

confidence: 99%

A novel fiber length measurement technique for discontinuous fiber‐reinforced composites: A comparative study with existing methods

et al. 2017

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“…These intersecting fibers cannot be counted as the parts of the fibers outside the image, which cannot be seen. 40

Figure 1.Optical microscopy image of short glass fibers in ×40 magnification.…”

Section: Methodsmentioning

confidence: 99%

“…These intersecting fibers cannot be counted as the parts of the fibers outside the image, which cannot be seen. 40 Fiber length distribution factor was measured from optical microscopy images using MATLAB software in which the whole fiber length should be located inside the image. The length of the fiber in MATLAB is expressed in terms of the number of pixels.…”

Section: Measurement Of Fiber Lengthmentioning

confidence: 99%

The Effect of Fibers’ Length Distribution and Concentration on Rheological and Mechanical Properties of Glass Fiber–Reinforced Polypropylene Composite

Asoodeh

Aghvami‐Panah

Salimian

et al. 2021

Journal of Industrial Textiles

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This article aims to investigate the effect of dispersion and uniformity of fiber length distribution on the rheological and mechanical behavior of polypropylene reinforced with short glass fiber. The composites were prepared through melt compounding with three various glass fiber concentrations using a twin-screw extruder. Multiple extrusion processing was used to alter and manipulate the fibers’ length inside the composites. The fiber length distribution was analyzed via the photomicrograph technique. Rheological measurements indicated that the molten samples were visco-plastic fluids and the Herschel–Bulkley model is the best model for fitting on the rheological behavior diagram. Variables of the fitted model are noticeably altered by the fiber length distribution. Moreover, rheological assessments revealed that the non-Newtonian behavior of the molten composites significantly diminished after the second extrusion processing, while it did not have much effect on the fiber length reduction. In the second phase, tensile and flexural properties were determined to detect the mechanical properties. The results indicated that the tensile strength of the composite has a direct relation with the fiber length distribution factor while the flexural strength is independent of fiber length. Furthermore, the highest tensile and flexural strength attained from the composite containing the highest fiber volume fraction.

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“…This apparent correlation will be discussed in further paragraphs. These distributions were found not to fit with regular probability density functions that might characterise FLDs, such as log-normal [17] or Weibull [36,37]. This is mostly due to the characteristic long tail and high peak of the presented FLDs.…”

Section: Measured-orientation Methodsmentioning

confidence: 99%

“…Secondly, the shredding parameters of four-shaft shredders were varied while processing the same type of offcuts. The following combination of blade width [mm] and screen size [mm] were used: , , (29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40) and (29-no screen). The bottom four rows in Fig.…”

Section: The Influence Of Shredding Settings and Sievingmentioning

confidence: 99%

Shredding and sieving thermoplastic composite scrap: Method development and analyses of the fibre length distributions

Vincent

Bruijn

Wijskamp³

et al. 2019

Composites Part B: Engineering

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A B S T R A C TRecycling of thermoplastic composites has attracted considerable attention in the recent years. Several recycling solutions include shredding scrap to centimetre-sized flakes to retain long fibres, followed by a remanufacturing step that prevents fibre breakage. Determining the exact fibre length distribution (FLD) for these routes is crucial, as it is of importance for the processibility of the material as well as the mechanical performance of the recycled parts. In this paper, novel analysis methods are introduced to calculate FLDs based on photographs of flakes. The reliability of the method and of the sampling was found to be high. The relation between flake size and FLD was studied, showing that offcut layup barely influences the FLD in comparison to flake size. The effects of shredding settings and sieving were studied, showing a strong correlation between machine parameters and FLD, whereas the offcut size was found to have no effect on FLD.

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Distribution function of fiber length in thermoplastic composites

Cited by 24 publications

References 26 publications

A novel fiber length measurement technique for discontinuous fiber‐reinforced composites: A comparative study with existing methods

A novel fiber length measurement technique for discontinuous fiber‐reinforced composites: A comparative study with existing methods

The Effect of Fibers’ Length Distribution and Concentration on Rheological and Mechanical Properties of Glass Fiber–Reinforced Polypropylene Composite

Shredding and sieving thermoplastic composite scrap: Method development and analyses of the fibre length distributions

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