Biodegradable Polyester Humidity Resistance via Aliphatic Acid
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Solution Overview
Problem
Biodegradable poly(terephthalate-co-sebacate) materials with low terephthalic acid unit content exhibit rapid degradation of mechanical properties in humid environments, necessitating an improvement in mechanical property retention.
Innovation Solution
Incorporating an aliphatic dibasic acid unit with a carbon chain length of 6 or less into the biodegradable polyester, specifically within the composition range of 40-48.5 mol% terephthalic acid, 38.5-50 mol% sebacic acid, and 2-20 mol% aliphatic dibasic acid, enhances mechanical properties and retention, particularly in humid conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of terephthalic acid unit is reduced to less than 49 mol% to achieve rapid biodegradation, then biodegradability is improved, but mechanical properties decrease rapidly in humid environment
Solution Approach 1:
The patent changes the chemical composition parameters by introducing aliphatic dibasic acid units with 6 or less carbon atoms (adipic acid, glutaric acid, or succinic acid) into the polyester structure. This compositional parameter change allows the material to maintain mechanical strength while achieving biodegradability, resolving the contradiction between strength and biodegradability in humid environments
Solution Approach 2:
The patent creates a composite polyester structure containing three types of acid units (terephthalic acid, sebacic acid, and aliphatic dibasic acid) with specific molar ratios. This composite approach combines the biodegradability from aliphatic chains with the mechanical strength from aromatic chains, while the specific dibasic acid units provide humidity resistance, simultaneously achieving both improved biodegradability and maintained mechanical properties
2Productivity
If the content of terephthalic acid unit is kept low to promote biodegradability, then biodegradation speed is improved, but mechanical property retention in humid environment deteriorates
Solution Approach 1:
The patent modifies the compositional parameters by incorporating specific amounts of aliphatic dibasic acid units (2-20 mol%, preferably 2-12 mol%, more preferably 2.5-7 mol%) into the polyester structure. This parameter optimization enables the material to maintain mechanical property retention of 65% or above after one month in humid conditions while preserving rapid biodegradation capability
Solution Approach 2:
The aliphatic dibasic acid units act as intermediary components in the polyester structure, bridging the gap between the need for rapid biodegradation (provided by aliphatic chains) and mechanical property retention (provided by aromatic chains). These intermediary units provide structural stability and humidity resistance while maintaining the overall biodegradable nature of the material
Data Source
AI summary
A biodegradable polyester and use thereof includes components: A) acid components containing following repeating units: 40 to 48 mol % of terephthalic acid A1; 38.5 to 50 mol % of sebacic acid A2; and 2 to 20 mol % of an aliphatic dibasic acid A3 with a carbon chain length of 6 or less; B) butanediol. In the case of low content of the terephthalic acid unit, by introducing the aliphatic dibasic acid unit with the carbon chain length of 6 or less, mechanical properties of the material can be significantly improved, and the mechanical property retention is better especially when stored in a humid environment.