Transparent Wood Composites Using Selective Lignin Removal to Retain Strength
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Solution Overview
Problem
Existing transparent wood composites require substantial lignin removal, which compromises the integrity of the cellulose-based microstructure and mechanical strength, and involve lengthy processing times and chemical use.
Innovation Solution
A contiguous wood block is subjected to selective lignin removal and UV-assisted photocatalytic oxidation, followed by infiltration with an index-matching polymer, to create transparent and opaque sections that retain mechanical strength and reduce processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If substantial lignin removal is performed to achieve transparency, then transparency is improved, but mechanical strength and microstructure integrity deteriorate
Solution Approach 1:
The patent applies differential delignification treatment to different regions of the wood block - earlywood sections are extensively delignified to achieve high transparency, while latewood sections retain substantial lignin to maintain mechanical strength and structural integrity. This spatially selective approach resolves the contradiction between transparency and strength by assigning different lignin removal levels to different functional zones.
Solution Approach 2:
The patent creates a composite structure within the wood block where delignified earlywood sections (transparent) are combined with lignin-retaining latewood sections (opaque/translucent). This internal composite architecture allows the material to simultaneously exhibit both transparent and opaque regions, maintaining mechanical strength through the lignin-containing portions while achieving transparency in the earlywood regions.
2Illumination intensity
If extensive chemical treatment is applied to remove lignin, then transparency is improved, but processing time and chemical consumption increase
Solution Approach 1:
The patent employs differential delignification where earlywood sections undergo extensive chemical treatment for transparency, while latewood sections receive reduced treatment to retain lignin. This localized approach reduces overall processing time and chemical consumption compared to treating the entire wood block uniformly, as only the earlywood regions require intensive delignification.
Solution Approach 2:
The patent applies partial delignification to latewood sections rather than complete removal, using just enough chemical treatment to achieve the desired optical properties in earlywood while preserving lignin in latewood. This partial action strategy reduces total chemical consumption and processing time while maintaining the necessary transparency in critical regions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces transparent wood composites with improved mechanical strength and reduced chemical and energy consumption, enabling rapid and scalable manufacturing of aesthetically patterned materials for energy-efficient applications.
Implementation Method 1
a UV-assisted photocatalytic oxidation treatment to in situ modify lignin therein, thereby converting a color of the wood to white
Implementation Method 2
The section can be chemically modified such that chromophores of lignin within the wood in its natural state are altered or removed
Implementation Method 3
Subsequent infiltration of the chemically-treated wood block with an index-matching polymer converts the delignified sections to be substantially transparent
Data Source
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Figure 1B
Figure 1C
AI summary
In some embodiments, a material comprises a contiguous block of chemically-modified wood infiltrated with an index-matching polymer. The contiguous block has a first section that is substantially transparent to light and a second section that is translucent or opaque. The first section can have a lower lignin content than the second section. Alternatively, the first section can have a chromophore state altered from that of the wood in its natural state, and the lignin in the second section can retain a chromophore state of the wood in its natural state. In some embodiments, a material comprises a section of wood chemically-modified such that chromophores of lignin within the wood in its natural state are altered or removed, and the section retains at least 70% of the lignin of the wood in its natural state. Methods for forming such materials are also disclosed.