Polyolefin Polylactic Acid Blend Compatibilization
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Solution Overview
Problem
Existing polyolefin polylactic acid blends often have limited impact resistance and mechanical properties, especially when using higher molecular weight polylactic acid, and require complex processing, limiting their widespread application and handling.
Innovation Solution
A process involving polyolefin, polylactic acid, and their respective grafts with epoxide-functional and carboxylic acid/anhydride-functional monomers, mixed at elevated temperatures to create blends with improved mechanical properties, independent of polylactic acid type, using a pre-compounded masterbatch as a compatibilizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If higher molecular weight grades of polylactic acid are employed, then mechanical properties should improve, but blend properties deteriorate and processing becomes difficult
Solution Approach 1:
A compatibilizer comprising polyolefin grafted with epoxide-functional monomer and polylactic acid grafted with carboxylic acid or carboxylic anhydride functional monomer is introduced as an intermediary substance. This compatibilizer mediates the interface between polyolefin and polylactic acid phases, enabling effective blending even with higher molecular weight polylactic acid grades, thus resolving the contradiction between improved mechanical properties and processing difficulty
Solution Approach 2:
The invention changes the chemical parameters of the polymer components by introducing grafted functional groups (epoxide on polyolefin, carboxylic acid/anhydride on polylactic acid). These parameter changes enable chemical interaction between the incompatible phases, allowing processing of higher molecular weight polylactic acid while maintaining good blend properties
2Strength
If polypropylene forms the continuous phase with maleic anhydride grafted polypropylene, then impact resistance increases, but miscibility and mechanical properties are limited
Solution Approach 1:
The invention creates a composite compatibilizer system combining two grafted polymers: polyolefin grafted with epoxide-functional monomer and polylactic acid grafted with carboxylic acid or carboxylic anhydride functional monomer. This composite approach provides both interfacial adhesion and phase compatibility, achieving improved impact resistance while ensuring good miscibility between phases
Solution Approach 2:
The dual-grafted compatibilizer acts as an intermediary that simultaneously interacts with both polyolefin and polylactic acid phases through different functional groups, creating a stable interfacial layer that improves both impact resistance and miscibility
3Strength
If reactive compatibilizer is used to improve mechanical properties, then blend strength increases, but processing complexity increases
Solution Approach 1:
The reactive compatibilizer components are prepared in advance with pre-installed functional groups (epoxide on polyolefin, carboxylic acid/anhydride on polylactic acid). This preliminary preparation of functional groups eliminates the need for complex in-situ reaction control during blending, simplifying the processing while maintaining improved mechanical properties
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 process results in polyolefin polylactic acid blends with enhanced mechanical properties and ease of preparation, suitable for broader application of renewable resource-based polylactic acid, regardless of its type, and reduces processing issues like shrinkage and post-crystallization.
Implementation Method 1
providing a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof grafted with at least one epoxide-functional monomer, providing a polylactic acid grafted with at least one carboxylic acid or carboxylic anhydride functional monomer, mixing the components i) to iv) at elevated temperature in a range from 150° C. to 260° C.
Data Source
AI summary
The invention relates to a process of preparing a polyolefin polylactic acid polymer blend comprising the steps of i) providing a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof, ii) providing polylactic acid, iii) providing a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof grafted with at least one epoxide-functional monomer, iv) providing a polylactic acid grafted with at least one carboxylic acid or carboxylic anhydride functional monomer, v) mixing the components i) to iv) at elevated temperature in a range from 150° C. to 260° C., and wherein component i) is provided in an amount of 5.0 to 50.0% by weight, component ii) is provided in an amount of 40.0 to 90.0% by weight, component iii) is provided in an amount of 1.0 to 20.0% by weight, and component iv) is provided in an amount of 1.0 to 15.0% by weight, calculated on the sum of components i) to iv).