Lactide Stereocomplex Polymer Melt Processing
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Solution Overview
Problem
There is a need for an environmentally friendly and sustainable method to prepare a highly-elastic, lactide-based polymer system that can be processed efficiently without requiring solvent-based methods or thermal post-treatment.
Innovation Solution
A method involving the preparation of a melt of a copolymer based on L-lactide and D-lactide with a lactide-containing stereocomplex forming agent, where the stereocomplexes are formed spontaneously during thermoplastic processing, eliminating the need for thermal post-treatment and allowing for solvent-free processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-based processes are used to prepare PLLA/PDLA blends, then the stereocomplex formation is facilitated, but the environmental friendliness and sustainability are reduced
Solution Approach 1:
The patent changes the fundamental parameter of the processing medium from solvent-based to solvent-free melt processing. This parameter change enables stereocomplex formation without using harmful solvents, thus resolving the contradiction between ease of manufacture and environmental friendliness. The melt processing at elevated temperatures allows direct contact and interaction between PLLA and PDLA chains, facilitating stereocomplex formation in an environmentally benign manner.
Solution Approach 2:
The patent replaces the chemical mechanism of solvent-mediated mixing with a physical/thermal mechanism of melt processing. By heating the polymer blend to temperatures above the glass transition temperature, the polymers become mobile and can form stereocomplexes through thermal energy-driven chain mobility, eliminating the need for solvent-based chemical processing and thereby improving environmental sustainability.
2Stability of the object's composition
If thermal post-treatment (tempering) is applied to obtain sufficient crystallites, then the shape stability is improved, but the energy consumption and processing time increase
Solution Approach 1:
The patent performs preliminary action by forming stereocomplexes during the main processing step itself rather than requiring a separate subsequent tempering step. The stereocomplex formation occurs in-situ during melt processing, which preliminarily establishes the crystalline structure needed for shape stability, thereby eliminating or reducing the need for additional thermal post-treatment and associated energy consumption.
Solution Approach 2:
The patent merges the stereocomplex formation step with the main processing step into a single integrated operation. Instead of separating crystallization from processing, the method combines them so that stereocomplexes form during the extrusion or molding process itself, reducing the number of discrete steps and eliminating the need for separate thermal post-treatment, thus lowering energy consumption and processing time.
3Reliability
If multiple separate steps (blend preparation, extrusion, drying, tempering) are used, then the processing completeness is ensured, but the productivity and simplicity are reduced
Solution Approach 1:
The patent merges multiple separate processing steps into a single integrated extrusion or molding operation. The blend preparation, extrusion, and stereocomplex formation are combined into one continuous process step, eliminating intermediate drying and tempering operations. This merging maintains processing completeness while significantly improving productivity by reducing the number of steps and associated handling time.
Solution Approach 2:
The patent makes the main processing step multi-functional by having it simultaneously perform blend mixing, extrusion, and stereocomplex formation. The extrusion process serves multiple purposes: it mixes the polymers, forms the desired product shape, and induces stereocomplex formation through controlled cooling, thereby eliminating the need for separate dedicated steps for each function and improving overall production efficiency.
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
This method results in a biodegradable and biocompatible polymer system with high shape stability and elasticity, enabling cost-effective and energy-efficient production of lactide-based polymers suitable for various thermoplastic processes.
Implementation Method 1
adding a lactide-containing stereocomplex forming agent to the melt, wherein the stereocomplex forming agent is selected such that the resulting polymer system comprises a combination of constitution units derived from L-lactide and constitution units derived from D-lactide forming stereocomplexes
Implementation Method 2
preparing a melt of a copolymer based on a first comonomer and at least one second comonomer
Data Source
Figure 1a~2b
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Figure 5~6
AI summary
The invention provides a method of preparing a lactide-based, biodegradable (biocompatible), physically cross-linked and highly elastic polymer system. The method comprises the steps of: preparing a melt of a copolymer based on a first comonomer and at least one second comonomer, the first comonomer being selected from L-lactide and D-lactide; and adding a lactide-containing stereocomplex forming agent to the melt, wherein the stereocomplex forming agent is selected such that the resulting polymer system comprises a combination of constitution units derived from L-lactide and constitution units derived from D-lactide forming stereocomplexes.