Modified PAEK Polymer for Additive Manufacturing
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Solution Overview
Problem
Additive manufacturing processes using polyaryletherketone (PAEK) polymers face challenges due to rapid crystallization, leading to brittle and weak parts, especially in the 'z' direction, where adhesion between layers is poor.
Innovation Solution
A PAEK polymeric material with specific shear viscosity and isothermal crystallinity half-life properties is used, which modifies the crystallization kinetics to improve interlayer adhesion and mechanical properties. This is achieved by adjusting the polymer backbone through variations in repeat unit ratios and incorporating bulky side-groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional PAEK polymers are used in additive manufacturing, then the material provides good mechanical strength and thermal resistance, but the rapid crystallization causes poor interlayer adhesion and weak components in the z-direction
Solution Approach 1:
The patent modifies the crystallization kinetics of PAEK polymers by changing material parameters - specifically by incorporating bulky side-groups and adjusting repeat unit ratios to achieve a crystallization half-life greater than 12 minutes at 280°C. This parameter change allows the material to maintain strength while preventing rapid crystallization that causes layer delamination.
Solution Approach 2:
The invention creates a modified PAEK polymer system that combines the base polymer with specific molecular structures (bulky side-groups and controlled repeat units) to achieve desired crystallization behavior. This composite approach at the molecular level resolves the contradiction between maintaining mechanical strength and preventing rapid crystallization.
2Strength
If the extrusion process is slowed to improve layer fusion, then interlayer adhesion improves, but manufacturing time increases significantly
Solution Approach 1:
By changing the crystallization kinetics parameter (achieving T1/2 > 12 min at 280°C), the material remains in a fusible state longer during extrusion, allowing adequate bonding time at normal extrusion speeds without requiring process slowing.
3Ease of manufacture
If standard PAEK materials are used, then the process is simple and economical, but the rapid crystallization locks in shape too quickly preventing adequate fusion between layers
Solution Approach 1:
The patent modifies the material parameter (crystallization half-life) rather than the process parameters, maintaining process simplicity while achieving the desired fusion quality through material design with controlled repeat units and bulky side-groups.
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 modified PAEK polymeric material results in components with improved mechanical properties, particularly in the z-direction, by controlling the crystallization rate to enhance layer adhesion in additive manufacturing processes.
Implementation Method 1
PAEKs typically crystallise rapidly as they cool... the rate of solidification is far quicker than with amorphous polymers because PAEKs can crystallise rapidly... modifying the crystallisation kinetics
Data Source
AI summary
A polyaryletherketone PAEK polymeric material and use thereof is disclosed, the polymeric material comprising a homopolymer and/or a copolymer, suitable for use in an additive manufacturing process to make an object. The PAEK polymeric material has a shear viscosity, SV, of at least 145 Pa·s and less than 350 Pa·s, measured using capillary rheometry operating at 400° C. at a shear rate of 1000 s−1 using a circular cross-section tungsten carbide die, 0.5 mm (capillary diameter)×8 mm (capillary length). The PAEK polymeric material has an isothermal crystallinity half life, T1/2, of greater than 12 minutes at a temperature of 280° C., measured by Differential Scanning Calorimetry, DSC.