Biodegradable Polyester Processability via Unsaturated Chain Terminator
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Solution Overview
Problem
Current biodegradable polyesters face limitations due to poor rheological and mechanical properties, environmental impact from chain extenders, and compatibility issues with starch, which restrict their use in various applications and transformation technologies.
Innovation Solution
A substantially gel-free and substantially linear biodegradable thermoplastic polyester is developed using a precursor polyester with an unsaturated chain terminator, allowing for improved processability, compatibility with natural polymers, and reduced use of radical initiators, resulting in enhanced mechanical properties and compatibility with starch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If chain extenders such as isocyanates or epoxy acrylates are used to improve rheological properties, then processability is improved, but environmental impact increases and mechanical properties deteriorate due to chemical residues and smell
Solution Approach 1:
The patent changes the chemical parameters of the polyester by controlling the molar ratio of diacid to diol within 1.5:8.5 to 4:6 and maintaining hydroxy acid content below 3%, thereby improving rheological properties and processability without requiring harmful chain extenders
Solution Approach 2:
The patent replaces persistent harmful chain extenders (isocyanates, epoxy acrylates) with a biodegradable polyester composition that naturally degrades, eliminating long-term environmental impact and chemical residue issues
2Strength
If chain extenders are used to improve mechanical properties, then strength is improved, but smell and chemical residues increase which is critical for food packaging
Solution Approach 1:
The patent optimizes the compositional parameters by controlling diacid-diol ratio and limiting hydroxy acid content to below 3%, achieving satisfactory mechanical properties through composition control rather than additive use, thereby eliminating smell and chemical residues
Solution Approach 2:
The patent converts the typically harmful effect of hydroxy acids (which cause branching and gel formation) into a benefit by carefully controlling their content below 3%, thereby improving mechanical properties while maintaining linearity and avoiding harmful residues
3Strength
If high amounts of radical initiator are used to achieve appropriate rheological and mechanical properties, then molecular weight increases, but gel fraction increases and applicability in transformation technologies is limited
Solution Approach 1:
The patent changes the compositional parameters by controlling diacid-diol ratio and hydroxy acid content, which regulates the polymerization process to achieve high molecular weight with minimal gel formation, maintaining gel fraction below 5%
Solution Approach 2:
The patent uses the hydroxy acid content as a feedback parameter, maintaining it below 3% to control the polymerization process and prevent excessive branching and gel formation, thereby achieving desired mechanical properties without compromising composition stability
4Object-affected harmful factors
If biodegradable polyesters are used for packaging applications, then environmental compatibility is improved, but compatibility with starch and other natural polymers is poor
Solution Approach 1:
The patent changes the surface and compositional parameters of the polyester by controlling hydroxy acid content and diacid-diol ratio, thereby improving interfacial compatibility with starch and other natural polymers while maintaining biodegradability
Solution Approach 2:
The patent creates a composite system where the controlled polyester composition (with hydroxy acid content below 3%) is compatible with starch and other natural polymers, enabling the production of blended biodegradable materials with enhanced versatility and maintained environmental compatibility
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 biodegradable polyester exhibits improved processability, stability, and mechanical properties, particularly with starch, enabling the production of high-quality starch-based compositions with superior tear strength and reduced environmental impact.
Implementation Method 1
reaction with radical initiators starting from a precursor polyester
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
The present invention relates to a substantially gel-free and substantially linear biodegradable polyester obtainable by means of reaction with radical initiators starting from a precursor polyester provided with an unsaturated chain terminator, said terminator having the formula: T-(CH2)n-CH=CH2, wherein "T" is selected from hydroxylic, carboxylic, amine, amide or ester group, and "n" is an integer comprised between 0 and 13.