Miscanthus Fiber Separation for Bio-Composite Quality

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Solution Overview

Problem

The quality and properties of miscanthus fiber mixes used in bio-based composites are unpredictable, leading to inconsistent performance and lower-than-expected environmental friendliness due to suboptimal fiber utilization, with fibers sometimes being detrimental to the final product.

Innovation Solution

Separating miscanthus fibers by size through sieving and grinding to create distinct fractions with specific physical and chemical properties, allowing for optimal selection and mixing based on desired product characteristics, such as moisture absorption and bulk density, and using these fractions with a binding agent to produce bio-based composites like bio-concrete.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If miscanthus fibers are used directly in bio-based composites without separation, then the production process is simple, but the quality and properties of the fiber mix are unpredictable leading to inconsistent product performance

Engineering Contradiction:
Improvesimplicity of production processVSAvoidpredictability of fiber quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies segmentation by separating the raw miscanthus fiber mix into distinct size fractions (e.g., fine fibers <2mm, medium fibers 2-6mm, coarse fibers >6mm) through sieving and grinding processes. This segmentation allows each fraction to be independently characterized and selected based on specific application requirements, thereby achieving predictable fiber quality while maintaining a relatively simple production process.

Inventive Principle:
Principle #1Segmentation

2Productivity

If all fiber sizes are used in the composite mix, then fiber utilization is maximized, but fibers with detrimental properties (high moisture absorption) degrade the final product quality

Engineering Contradiction:
Improvefiber utilization efficiencyVSAvoidproduct quality consistency
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by assigning different fiber size fractions to different functional roles within the composite. Fine fibers (<2mm) with high surface area are used when high binding or surface properties are needed, while coarse fibers (>6mm) are used when structural reinforcement is required. This allows each fiber fraction to contribute its optimal properties to the final product, maximizing overall fiber utilization while ensuring consistent quality by selecting appropriate fractions for specific applications.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If fiber separation into multiple fractions is implemented, then fiber properties can be optimized for specific applications, but the production process becomes more complex

Engineering Contradiction:
Improveoptimization of fiber propertiesVSAvoidcomplexity of separation process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing fiber size separation and characterization before composite manufacturing. The miscanthus fibers are pre-separated into standardized size fractions and their properties are predetermined, allowing for easy selection and combination of appropriate fractions during composite production. This preliminary classification simplifies the overall process by eliminating the need for complex real-time fiber property adjustment during manufacturing.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3601415B1Method for processing a mix of miscanthus fibers for the production of a bio-based composite
Publication Date: 2022.08.31 NNRGY BV
  • EP3601415B1 patent drawingFigure 1
  • EP3601415B1 patent drawingFigure 2
  • EP3601415B1 patent drawingFigure 3

AI summary

The invention relates to a method for processing a mix of lignocellulose fibers, such as miscanthus or sorghum fibers, for the production of a bio-based composite, comprising the steps of: harvesting lignocellulosic crops and processing the harvested lignocellulosic crops to obtain a raw mix of lignocellulose fibers, separating the raw mix of lignocellulose fibers, such as by sieving or grinding, into a first fraction (f1) comprising a mix of fibers having a fiber size of approximately &lt; s1 and having first physical/chemical properties and a second fraction (f2) comprising a mix of fibers having a fiber size of approximately &gt; s1 and having second physical/chemical properties being different from the first physical/chemical properties, mixing the fibers of the first fraction (f1) or the fibers of the second fraction (f2) with a binding agent (3), letting the binding agent harden, to obtain the bio-based composite.