Oriented Polymeric Tubes via Planar Stretching and Multi-Layer Expansion
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Solution Overview
Problem
Existing methods for producing polymeric tubes, such as extrusion and annular expansion, are limited in achieving uniform molecular orientation throughout the wall thickness, leading to gradients in molecular orientation and suboptimal mechanical and thermodynamic properties.
Innovation Solution
The use of planar stretching and multi-layer annular expansion processes to produce polymeric tubes with controlled molecular orientation, involving the combination of crystallizable biodegradable polymers and adhesive materials to create oriented polymeric tubes with enhanced strength and heat shrinkable properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If extrusion and annular expansion processes are used to produce polymeric tubes, then molecular orientation is increased leading to improved strength, but uniform molecular orientation throughout the wall thickness cannot be achieved resulting in orientation gradients
Solution Approach 1:
The tube wall is divided into multiple discrete layers, each independently formed with controlled molecular orientation. This segmentation allows each layer to be optimized for uniform orientation without the gradient effects that occur in conventional single-layer extrusion processes.
Solution Approach 2:
The invention transitions from conventional radial expansion in one dimension to a multi-dimensional approach where multiple layers are formed and assembled. This dimensional change enables control of molecular orientation throughout the entire wall thickness by independently controlling each layer's orientation during the forming process.
2Ease of manufacture
If conventional extrusion and annular expansion methods are used, then production is simplified, but the degree of molecular orientation achievable throughout the wall thickness is limited
Solution Approach 1:
Molecular orientation is established during the layer formation process itself, before the layers are assembled into the final tube structure. This preliminary action of orienting molecules during extrusion or forming of each layer allows for greater overall orientation achievement without complicating the subsequent assembly process.
Solution Approach 2:
The tube is constructed as a composite of multiple layers, each potentially with different polymer compositions and molecular orientations. This composite structure enables the combination of materials with different properties to achieve both ease of manufacture and high degree of molecular orientation throughout the wall.
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 method achieves more uniform molecular orientation and improved mechanical and thermodynamic properties, including increased strength and controlled heat shrinkable properties, compared to traditional methods.
Implementation Method 1
the at least one polymeric material being stretched in a manner that increases the first dimension; and forming the oriented polymeric tube using the at least one stretched polymeric material
Data Source
AI summary
Methods for preparing oriented polymer tubes, such as biodegradable polymer tubes suitable for in vivo use, are provided herein. The disclosed methods provide alternatives to the typical extrusion/expansion methods by which oriented polymeric tubes for such uses are commonly produced. Advantageously, the disclosed methods can provide more homogeneous molecular orientation of crystallizable polymers within the tube walls, which can endow such polymeric tubes with enhanced strength (e.g., resistance to compression) and toughness.