Asymmetric Fibrous Particle Sintering for Ductile Polymer Articles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Selective laser sintering of polymer powders typically produces rigid three-dimensional articles that are prone to cracking and breaking under stress due to the use of spherical or irregular particles with low aspect ratios, limiting the ductility and suitability for biodegradable and bioresorbable medical applications.
Innovation Solution
The use of asymmetric fibrous particles with a high length-to-width ratio, produced through milling or electrospinning, which are preferentially oriented in layers to form a two-dimensional network, enhancing ductility and resistance to cracking by increasing bonding between particles and allowing for elongation without breaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spherical or irregular particles with low aspect ratio are used in selective laser sintering, then the manufacturing process is simple and particles pack efficiently, but the resulting article is rigid and prone to cracking under stress
Solution Approach 1:
The patent applies asymmetry by using fibrous particles with high aspect ratios (length-to-diameter ratio greater than 2:1, preferably greater than 5:1) instead of conventional spherical particles. This asymmetric shape allows the particles to orient preferentially during deposition and sintering, creating a network structure that can flex and distribute stress more effectively, thereby reducing cracking while maintaining manufacturability through standard SLS processes.
2Reliability
If high aspect ratio fibrous particles are used to improve ductility, then the article can flex and resist cracking, but particle orientation control and processing complexity increase
Solution Approach 1:
The patent applies parameter changes by modifying the physical dimensions of the particles (high aspect ratio geometry) and controlling processing parameters such as laser power, scanning speed, and deposition temperature to achieve preferential orientation of fibrous particles. These parameter adjustments enable ductility improvement without requiring fundamentally new processing equipment or methods, thus managing complexity through optimized parameters rather than complex mechanisms.
3Stability of the object's composition
If conventional spherical particles are used, then the article structure is rigid and dimensionally stable, but the article cannot bend or flex under stress
Solution Approach 1:
The patent applies composite materials by creating a composite network structure within each layer where high aspect ratio fibrous particles form an interconnected framework. This composite-like internal structure combines the dimensional stability of a rigid network with the flexibility of elongated fiber elements, allowing the article to maintain shape while accommodating bending and flexing under stress without cracking.
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 resulting polymeric articles exhibit improved ductility, with ultimate strength reached at 10% to 20% strain and breaking stress at >30% to 50% strain, making them suitable for implantable medical devices that can flex and resist breakage.
Implementation Method 1
a laser is used to soften the particles and produce a first layer of an article from bonded particles
Implementation Method 2
the laser is used to soften the particles in the second layer, fusing them both to each other and to the first bonded layer
Implementation Method 3
The asymmetric particles may be characterized by scanning electron microscopy, particle size distribution, and/or a mean length L and a mean width W, wherein L>2 W; L>5 W; or L>10 W
Implementation Method 4
the particles in each layer are fused to each other and to particles in adjacent layers, forming a rigid three-dimensional network
Data Source
AI summary
A polymeric article of high ductility produced by rapid prototyping or selective laser sintering, and a method of making the same. The article comprises a plurality of layers of a fused thermoplastic powder, the thermoplastic powder comprising asymmetric fibrous particles having a mean length L and a mean width W, wherein L>2 W. Within each of the layers, the mean length L of the asymmetric fibrous particles is preferentially oriented in a plane parallel to the layer. The polymeric article has a stress-strain curve such that ultimate strength is reached at a strain of 10% to 20%, and breaking stress is reached at >30% strain.