Multilayer Thermoplastic Recycling via Hydrolytically Unstable Polymers
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Solution Overview
Problem
Existing plastic recycling processes are complicated and costly due to the difficulty in separating additives like oxygen scavengers and colorants from the base thermoplastic material, leading to contamination of the recycle stream.
Innovation Solution
Incorporating hydrolytically unstable polymers, such as Polyglycolic Acid (PGA), into multilayer thermoplastic articles to facilitate the separation of additives during the recycling process by hydrolyzing in alkaline wash conditions, allowing for easy removal and separation from PET.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additives like oxygen scavengers and colorants are incorporated into thermoplastic material during manufacturing, then consumer and product considerations are improved, but separation during recycling becomes difficult and costly
Solution Approach 1:
The patent divides the thermoplastic article into functional components by incorporating additives into specific polymer phases. The additives are segregated into the hydrolytically unstable polymer phase rather than being uniformly distributed, which enables selective removal of the additive-containing phase during recycling while retaining the base polymer for reuse.
Solution Approach 2:
The patent enables extraction of additives from the thermoplastic material by utilizing the hydrolytic instability of specific polymer phases. The hydrolytically unstable polymer containing additives is selectively degraded and removed during the recycling process, separating the additives from the base thermoplastic material that can then be recycled.
2Productivity
If conventional recycling processes are used with additives present, then base polymer can be recycled, but additives contaminate the recycle stream and complicate the process
Solution Approach 1:
The patent converts the harmful effect of additives (which cause contamination) into a beneficial feature by utilizing the hydrolytic instability of the polymer phase containing the additives. This instability, which would normally be a disadvantage, is exploited to enable selective degradation and removal of the additive-containing phase during recycling, thereby eliminating contamination while improving recycling efficiency.
3Ease of manufacture
If hydrolytically unstable polymers are used to facilitate additive separation, then recycling is simplified, but the polymer structure becomes more vulnerable to hydrolysis
Solution Approach 1:
The patent applies local quality by confining the hydrolytically unstable polymer phase to specific regions or layers within the multilayer structure, specifically where additives are located. The base polymer phases maintain their full stability, while only the localized additive-containing phases exhibit hydrolytic instability, enabling selective removal without compromising the overall structural integrity and reliability of the material system.
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
Enables efficient and cost-effective recycling by ensuring additives are removed during the recycling process, reducing contamination and simplifying the recycling procedure.
Implementation Method 1
Incorporating hydrolytically unstable polymers, such as Polyglycolic Acid (PGA), into multilayer thermoplastic articles to facilitate the separation of additives during the recycling process by hydrolyzing in alkaline wash conditions
Data Source
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AI summary
A multilayer thermoplastic article blended with hydrolytically unstable polymers and an additive for improved recyclability. The multilayer thermoplastic article having an inner layer being made of a thermoplastic material, an outer layer being made of a thermoplastic material, and an intermediate layer disposed between the inner layer and the outer layer. The intermediate layer is made of a blended material comprising 50 to 99 wt. % of a hydrolytically unstable polymer and 1 to 50 wt. % of an additive.