ABA Polyester Polyol Toughness via Lactide Chain Optimization
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Solution Overview
Problem
Known polyurethanes with ABA-structured polyester polyols exhibit low toughness, which is insufficient for various applications, and the toughness is not stable over time.
Innovation Solution
A polyester polyol with an ABA structure, where the initiator comprises long chain dicarboxylic acid components and the lactide oligomer part has a specific weight percentage, combined with a method that involves controlled reaction conditions to form a hydrophobic and hydrophilic blend, enhancing the toughness of the resulting polyurethane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyester polyol with ABA-structure and long lactide oligomer chains (20-140 lactate units) is used, then glass temperature and mechanical properties are improved, but toughness remains too low for applications
Solution Approach 1:
The patent changes the parameters of the polyester polyol structure by reducing the lactide oligomer chain length from 20-140 lactate units to 2-10 lactate units per arm, and adjusting the lactide content to 10-70 wt%. This parameter optimization resolves the contradiction by achieving both improved mechanical properties and sufficient toughness (above 50 MPa) in the resulting polyurethane elastomer.
Solution Approach 2:
The patent creates a composite polyol structure combining short lactide oligomer chains with specific initiators (polyester polyols, polycarbonate polyols, or polyether polyols). This composite approach allows the polyurethane to achieve both enhanced mechanical properties from the lactide segments and adequate toughness from the optimized overall structure, with toughness stabilizing over time.
2Reliability
If polyester polyol with high lactide content is used to improve mechanical properties, then toughness increases, but toughness stability over time deteriorates
Solution Approach 1:
The patent optimizes the lactide content parameter to a specific range of 10-70 wt% and controls the oligomer chain length to 2-10 lactate units. This precise parameter control ensures that the polyurethane achieves high toughness (above 50 MPa) while maintaining stable toughness properties over time, preventing degradation that would occur with higher lactide contents.
3Strength
If lactide oligomer chain length is increased to improve mechanical properties, then strength increases, but toughness decreases
Solution Approach 1:
The patent identifies and applies the optimal parameter range for lactide oligomer chain length (2-10 lactate units per arm) and lactide content (10-70 wt%). Within this optimized parameter space, the polyurethane achieves the desired balance between mechanical strength and toughness (above 50 MPa), resolving the contradiction that exists at extreme values.
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 polyurethane composition achieves high toughness values above 50 MPa, with stable elongation-to-break properties over time, and improved mechanical properties, utilizing the hydrophobic and hydrophilic combination in the polyol structure.
Implementation Method 1
the use of lactide-containing polyester polyols having an ABA-structure with initiators B having a hydrophobic character increase the toughness of the polyurethane manufactured on the basis of such polyols. Without being bound by theory, the inventors believe that the combination of hydrophilic (lactide-based) and hydrophobic (initiator based) parts in a polyester polyol with an ABA structure is essential to the improved toughness properties
Data Source
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AI summary
The present invention relates to a polyester polyol, suitable for use in the manufacture of a polyurethane, suitable for use in the manufacture of a polyurethane, the polyester polyol having an ABA-structure, in which A represents a lactide-oligomer and in which B represents an initiator. The initiator includes a reaction product having long chain dicarboxylic acid components having 18 or more carbon atoms. The invention also relates to a method for the manufacture of the polyester polyol. The invention further pertains to polyurethanes including the before-mentioned polyester polyol as well as the use of these polyurethanes as an elastomer having a high toughness. The toughness is believed to originate from the combination of the hydrophobic character of the initiator and the hydrophilic character of the lactide parts in the polyol structure. The strength of the invented polylactide-polyurethane elastomers can be further improved by incorporating a carbodiimide in the elastomer material.