Epoxidized Fatty Acid Alkyl Esters Reduce PLA Tensile Modulus
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Solution Overview
Problem
Biodegradable polymers based on poly(lactic acid) (PLA) exhibit high tensile modulus, leading to stiffness and lack of flexibility in applications like food packaging and films, necessitating a reduction in tensile modulus and enhancement of flexibility.
Innovation Solution
Incorporating an epoxidized fatty acid alkyl ester, such as methyl epoxy soyate, as a plasticizer in PLA compositions to significantly reduce the tensile modulus and improve flexibility, with the plasticizer present in amounts greater than 5% by weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If PLA is used as a biodegradable thermoplastic, then environmental sustainability is improved, but tensile modulus is high leading to stiffness and lack of flexibility
Solution Approach 1:
The patent changes the physical-chemical parameters of PLA by incorporating epoxidized fatty acid alkyl esters as plasticizers. This modifies the molecular mobility and free volume within the polymer matrix, thereby reducing the tensile modulus from its inherent high value to a range suitable for flexible applications while preserving the biodegradable nature of PLA.
Solution Approach 2:
The patent creates a composite material system by combining PLA with epoxidized fatty acid alkyl esters. The ester acts as an internal plasticizer that integrates with the PLA matrix, forming a composite structure that maintains the biodegradability of PLA while introducing flexibility through the ester component's molecular characteristics.
2Strength
If conventional plasticizers are used to reduce tensile modulus, then flexibility is improved, but the specific performance and compatibility with biodegradable polymers may be compromised
Solution Approach 1:
The patent selects plasticizers with specific molecular parameters - epoxidized fatty acid alkyl esters - that match the biodegradable character of PLA. The ester group and epoxide rings provide appropriate polarity and molecular size that ensure compatibility and maintained biodegradability while achieving the desired flexibility reduction in tensile modulus.
Data Source
AI summary
A composition containing (a) at least one biodegradable/biorenewable thermoplastic material that includes poly(lactic acid) (PLA); and (b) at least one plasticizer that includes an epoxidized fatty acid alkyl ester is provided. In some embodiments, the epoxidized fatty acid alkyl ester is methyl epoxy soyate. It was found that epoxidized fatty acid alkyl esters impart a reduction in tensile modulus in compositions containing PLA. The compositions may be formed into films, such as those used in food packaging. A method that includes extruding a composition comprising PLA and at least one epoxidized fatty acid alkyl ester is provided.