Bio-based Solvent Treatment for Epoxy Composite Recycling
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Solution Overview
Problem
Current methods for recycling fiber-reinforced epoxy composites are inefficient due to the high cross-linking of epoxy resins, which limits diffusion and degradation rates. Existing solvent pretreatments, such as those using benzyl alcohol, rely on industrially produced solvents from oil feedstocks, raising sustainability concerns and not adequately addressing the need for increased swelling and exfoliation.
Innovation Solution
A method involving the use of levoglucosenone and its derivatives as bio-based solvents, which are applied to fiber-reinforced epoxy composites at a temperature exceeding the composite's glass transition temperature by at least 10°C. This solvent system facilitates the swelling and exfoliation of the composite, enhancing the diffusion rate and subsequent chemical degradation of the epoxy resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional solvents like benzyl alcohol are used for pretreatment, then the diffusion rate increases and degradation is accelerated, but the sustainability is compromised due to reliance on oil-based feedstocks
Solution Approach 1:
The patent changes the chemical composition parameter of the solvent from oil-based (benzyl alcohol) to bio-based (levoglucosenone and derivatives), while maintaining the functional parameters of swelling capability and diffusion enhancement. This substitution resolves the sustainability issue without sacrificing degradation efficiency.
Solution Approach 2:
The patent employs bio-based solvents that can be derived from renewable resources, effectively replacing expensive and unsustainable oil-based feedstocks. The bio-based solvents serve as a sustainable, replenishable alternative that maintains process effectiveness while improving environmental credentials.
2Strength
If the epoxy resin is highly cross-linked, then the structural integrity is maintained, but the diffusion rate and degradation become extremely slow
Solution Approach 1:
The patent applies a preliminary swelling action using levoglucosenone solvent before the main degradation process. This preliminary action creates channels and increases free volume within the cross-linked epoxy matrix, enabling subsequent chemicals or enzymes to diffuse more effectively without compromising the structural integrity during the pretreatment phase.
Solution Approach 2:
The levoglucosenone solvent acts as an intermediary substance that temporarily interacts with the cross-linked epoxy matrix to increase its permeability. This intermediary action facilitates the passage of degradation agents through the otherwise impermeable cross-linked structure, enabling efficient fiber recovery without direct attack on the intact composite.
3Productivity
If the treatment temperature is increased above the glass transition temperature, then the swelling ratio and diffusion rate improve, but the energy consumption increases
Solution Approach 1:
The patent optimizes the treatment temperature parameter to exceed the glass transition temperature by at least 10°C, which is the minimum threshold required to achieve effective swelling and diffusion. This precise parameter control ensures adequate productivity while minimizing unnecessary energy consumption that would result from higher temperature excursions.
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 proposed method effectively increases the swelling ratio of fiber-reinforced epoxy composites, enhances the diffusion rate of enzymes or chemicals, and facilitates the recovery of reinforcing fibers, thereby improving the recycling efficiency of these composites while using sustainable, bio-based solvents.
Implementation Method 1
the solvent penetrates the cross-linked network, enabling reactant molecules to reach cleavable bonds more easily, thus reducing eliminating the rate-limiting effect of diffusion
Implementation Method 2
a particular organic solvent which can swell and exfoliate the fiber-reinforced epoxy composite
Implementation Method 3
the treatment temperature Ttr exceeds by at least 10°C the glass transition temperature Tg of the fiber-reinforced epoxy composite
Implementation Method 4
causing the degradation of the epoxy component without substantially impairing the reinforcing fibers
Data Source
AI summary
The invention relates to a method of treatment of a fiber-reinforced epoxy composite which comprises contacting the fiber-reinforced epoxy composite with a bio-based solvent S chosen from levoglucosenone and/or a levoglucosenone derivative such as cyrene, wherein the treatment temperature generally exceeds by at least 10° C. the glass transition temperature of the fiber-reinforced epoxy composite.