Esterified Starch Linear Polyester Blends Humidity Stability
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Solution Overview
Problem
Starch-based materials exhibit poor physical properties at high relative humidity and a tendency to embrittle at low relative humidity, limiting their dimensional stability and mechanical performance.
Innovation Solution
A composition comprising esterified starch with an amylose content of at least 50% combined with a linear polyester, which can be formed into articles through heat and pressure, eliminating the need for low molecular weight plasticizers and enhancing biodegradability and processing behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If starch-based materials are used, then biodegradability is improved, but dimensional stability and mechanical properties deteriorate at high relative humidity
Solution Approach 1:
The patent combines esterified starch with linear polyester to create a composite material that maintains biodegradability while improving dimensional stability. The polyester component provides structural integrity that prevents the material from becoming too soft at high humidity, while the starch component ensures biodegradability.
Solution Approach 2:
The patent modifies the starch through esterification to change its physical and chemical parameters. By introducing ester groups onto the starch backbone, the material's resistance to water absorption and swelling is improved, thereby enhancing dimensional stability while retaining biodegradability.
2Reliability
If starch-based materials are used, then biodegradability is improved, but mechanical strength deteriorates at low relative humidity
Solution Approach 1:
The linear polyester component acts as a reinforcing phase in the starch matrix, providing mechanical strength particularly under low humidity conditions where the starch would otherwise become brittle. This composite structure allows the material to maintain both biodegradability and adequate mechanical strength.
Solution Approach 2:
Esterification of starch modifies its molecular structure and intermolecular forces, improving mechanical properties while maintaining processability. The degree of substitution and type of ester groups are controlled to optimize the balance between strength and biodegradability.
3Ease of manufacture
If low molecular weight plasticizers are added, then processing behavior is improved, but biodegradability deteriorates
Solution Approach 1:
The patent eliminates low molecular weight plasticizers from the formulation, removing the harmful component that compromises biodegradability. Instead, the processing behavior is improved through the inherent properties of the esterified starch-polyester blend, which provides adequate melt flow and成型ability without requiring external plasticizing agents.
Solution Approach 2:
The esterified starch-polyester blend serves its own plasticizing needs through the molecular structure and intermolecular interactions of the components themselves. The linear polyester provides flexibility and processability without requiring external low molecular weight additives, thus maintaining biodegradability.
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 composition achieves good dimensional stability and mechanical properties across varying humidity levels without embrittlement, retaining excellent biodegradability and processing characteristics.
Implementation Method 1
heating an esterified starch, preferably having a degree of substitution of at least about 1.5 and preferably an amylose content of at least about 50% in the presence of a linear polyester as described herein to an elevated temperature and plastifying the thus heated composition until a uniform melt is obtained
Implementation Method 2
plastifying the thus heated composition until a uniform melt is obtained
Data Source
AI summary
According to the present invention there is provided a composition as obtained from a melt comprising esterified starch, preferably having a degree of substitution of at least about 1.5, and preferably an amylose content of at least about 50% by weight with respect to that of the starch, and a linear polyester. The invention further provides the composition in the form of a melt or when shaped into articles.