Polyaxial Polymer Composition for Stronger FFF Interlayer Bonding
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Solution Overview
Problem
Additive manufacturing processes, particularly in fused filament fabrication (FFF), often result in asymmetrical strength between the x-y and z-directions of printed articles, leading to undesirable structural weaknesses.
Innovation Solution
The use of polyaxial polymers with specific compositions, such as M(B)2 or M(B)3, where M and B have distinct properties, including a majority of TMC and CAP residues in M and a minority of LAC and GLY residues, and vice versa, to enhance the structural integrity across multiple layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If single-phase thermoplastic polymeric monofilament is used in fused filament fabrication, then the additive manufacturing process is simple and widely applicable, but the printed articles exhibit asymmetrical strength with greater strength in x-y direction than in z-direction
Solution Approach 1:
The patent employs composite polymer compositions consisting of multiple polymer phases with different properties. Specifically, it uses a blend of amorphous polymer (providing adhesion and flexibility) and semi-crystalline polymer (providing structural strength), along with process aids and nucleating agents. This composite approach allows the material to exhibit improved layer adhesion and more uniform mechanical properties in both x-y and z-directions, reducing the asymmetrical strength issue inherent in single-phase materials.
Solution Approach 2:
The patent modifies material parameters by controlling the glass transition temperature (Tg) and melting temperature (Tm) of the polymer components. The amorphous polymer is selected with Tg below the printing temperature to ensure proper flow and adhesion, while the semi-crystalline polymer has Tm above the printing temperature to maintain structural integrity. This parameter optimization enables better interlayer bonding and reduced anisotropy in the printed articles.
2Shape
If multiple x-y planes are printed on top of one another to create 3-dimensional articles, then the article height and complexity are increased, but the connections between planes become weaker than the planes themselves
Solution Approach 1:
The patent optimizes the thermal parameters of the polymer composition, specifically selecting polymers where the glass transition temperature (Tg) is below the printing temperature. This ensures that the material remains sufficiently soft and adhesive during the printing process, allowing strong bonding between layers. The semi-crystalline polymer's melting temperature (Tm) is maintained above the printing temperature to provide structural strength after cooling, creating a balance between adhesion and strength that reinforces interlayer connections.
Solution Approach 2:
The composite formulation combines amorphous polymer (enhancing adhesion between layers) with semi-crystalline polymer (providing structural strength). Additional components including process aids and nucleating agents further improve layer bonding and crystallization behavior. This multi-component composite system addresses the interlayer weakness by providing both adhesive properties for bonding and structural properties for strength, enabling robust 3-dimensional articles with balanced mechanical properties in all directions.
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 polyaxial polymers improve the structural symmetry and strength in 3-dimensional articles, reducing the asymmetry between x-y and z-directional strengths, resulting in more robust printed structures.
Implementation Method 1
The majority of additive manufacturing through FFF utilizes a single-phase thermoplastic polymeric monofilament to generate a print line through melt extrusion
Implementation Method 2
The print line is in a horizontal plane, which may be referred to as a plane in the x-y direction
Data Source
AI summary
Polymers and formulated compositions are designed to have properties that allow their effective use in additive manufacturing processes, particularly for preparing articles wherein molten monofilament polymer is laid down on top of a previously deposited line of molten monofilament polymer.