Semi-crystalline Polymer Blend for Additive Manufacturing
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Solution Overview
Problem
Additive manufacturing techniques face challenges in printing dimensionally stable 3D parts using semi-crystalline polymers due to residual stresses and discontinuous volume changes, which lead to issues like curling and sagging, especially in extrusion-based methods where controlling crystallization kinetics is difficult.
Innovation Solution
A method involving blends of semi-crystalline polymers with secondary materials that control crystallization kinetics, either by retarding or accelerating crystallization, to manage enthalpy and entropy, thereby reducing residual stresses and improving layer bonding, using techniques like FDM, SLS, and HSS, by maintaining specific temperature windows and adding amorphous polymers or micron-scale additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If semi-crystalline polymers are used for additive manufacturing, then mechanical properties and dimensional stability are improved, but residual stresses and volume changes cause curling and sagging
Solution Approach 1:
The patent modifies the crystallization parameters of semi-crystalline polymers by controlling cooling rates, temperature profiles, and adding nucleating agents to adjust crystallization kinetics. This allows the material to achieve desired mechanical properties while minimizing residual stresses and dimensional instability during the additive manufacturing process
Solution Approach 2:
The patent creates composite materials by combining semi-crystalline polymers with amorphous polymers, fillers, or other additives. This composite approach allows the semi-crystalline phase to provide mechanical strength while the amorphous phase or additives help manage crystallization behavior, reducing curling and sagging issues
2Manufacturing precision
If crystallization kinetics are controlled to reduce residual stresses, then dimensional stability is improved, but processing complexity increases
Solution Approach 1:
The patent incorporates nucleating agents and modifies material composition before the additive manufacturing process to pre-establish favorable crystallization characteristics. This preliminary preparation simplifies the actual printing process by reducing the need for complex real-time temperature control and post-processing steps
Solution Approach 2:
The patent introduces amorphous polymers or additives as intermediary substances that mediate the crystallization process of semi-crystalline polymers. These intermediaries control nucleation and crystal growth rates, enabling dimensional stability without requiring highly complex processing equipment or procedures
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 approach allows for the production of 3D items with mechanical properties similar to semi-crystalline polymers, reduced residual stresses, and improved dimensional stability, enabling larger part sizes and enhanced crystallinity without curling or sagging, as demonstrated in various additive manufacturing systems.
Implementation Method 1
a semi-crystalline polymer and a secondary material wherein the secondary material is combined with the semi-crystalline polymer to form a blend having an enthalpy that is between about 2 J/g heat of fusion and about 80% of the beat of fusion of the neat semi-crystalline polymer, as measured by differential scanning calorimetry (DSC) when cooling from a melting temperature to a hot crystallization temperature at a rate of 10° C./min
Implementation Method 2
control the rate or kinetics at which crystallization occurs
Data Source
AI summary
A polymeric material includes a semi-crystalline polymer and a secondary material wherein when the secondary material is combined with the semi-crystalline polymer to form a blend having an enthalpy that is between about 2 J/g heat of fusion and about 80% of the heat of fusion of the neat semi-crystalline material, as measured by differential scanning calorimetry (DSC) when cooling from a melting temperature to a hot crystalline temperature at a rate of 10° C./min.