Crosslinked Lignin Thermoplastic Copolymers Melt-Processibility
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Solution Overview
Problem
Lignin, a valuable by-product from the pulp and paper industry, is difficult to convert into high-value products due to its rigid and brittle nature, limiting its applications as it is primarily processed into non-melt-processible thermosets, lacking the necessary strength, toughness, and recyclability.
Innovation Solution
Development of high-performance lignin-based thermoplastics through crosslinking lignin with non-lignin thermoplastic polymer segments, allowing for a range of mechanical property adjustments and achieving melt-processibility, solubility, and a combination of strength and elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If lignin is converted into thermoset plastics, then strength and durability are improved, but melt-processibility and recyclability are lost
Solution Approach 1:
The patent applies parameter changes by controlling the degree of crosslinking in lignin to create a thermoplastic material. By adjusting crosslinking parameters (using mild conditions with formaldehyde or glyoxal at controlled concentrations), the lignin achieves optimal balance between strength (through crosslinking) and melt-processibility (by avoiding excessive crosslinking that would create thermoset behavior). This enables the lignin to be processed like conventional thermoplastics while maintaining enhanced mechanical properties.
2Strength
If lignin is crosslinked to improve strength, then mechanical strength is improved, but brittleness increases and elasticity is reduced
Solution Approach 1:
The patent controls the crosslinking parameters to achieve optimal strength without excessive brittleness. By using mild crosslinking conditions with specific aldehydes at controlled concentrations and ratios, the lignin develops sufficient crosslinking for strength while maintaining adequate chain mobility for flexibility and elasticity.
Solution Approach 2:
The patent creates composite materials by combining crosslinked lignin with other polymers or additives. This composite approach allows the lignin component to provide strength through crosslinking while the other components contribute flexibility and processability, reducing overall brittleness while maintaining mechanical strength.
3Quantity of substance
If lignin is used as a by-product from pulp and paper industry, then availability is improved, but conversion to high-value products remains difficult
Solution Approach 1:
The patent simplifies the conversion process by optimizing chemical parameters for lignin modification. By controlling crosslinking conditions (aldehyde type, concentration, temperature, time) and using readily available lignin from pulp and paper industry, the process becomes economically viable and technically straightforward, transforming abundant low-value by-product into high-value thermoplastic materials.
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 resulting thermoplastics exhibit significant strength, durability, and moldability, enabling a wide range of applications while being recyclable and tunable in properties, overcoming the limitations of existing lignin-containing plastics.
Implementation Method 1
crosslinked lignin units are covalently linked with non-lignin thermoplastic polymer segments
Implementation Method 2
The resulting thermoplastic material generally exhibits a multi-phase (e.g., two-phase or three-phase) morphology
Data Source
AI summary
The present invention relates to a crosslinked lignin comprising a lignin structure having methylene or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, wherein said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least 10,000 g/mol, is melt-processible, and has either a glass transition temperature of at least 100° C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. Thermoplastic copolymers containing the crosslinked lignin are also described. Methods for producing the crosslinked lignin and thermoplastic copolymers are also described.