Crosslinked PTFE Tubing for Radiation-Resistant Sterilization
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Solution Overview
Problem
Polytetrafluoroethylene (PTFE) polymer chains are highly susceptible to degradation through irradiation, leading to unacceptable loss in physical properties during sterilization processes using gamma or electron beams, which is a challenge in manufacturing radiation-resistant medical devices.
Innovation Solution
A continuous method for crosslinking PTFE by irradiation at high temperatures, optimizing temperature, dosage, and atmosphere to enhance radiation resistance, allowing for efficient production of crosslinked PTFE products suitable for gamma and electron-beam sterilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTFE is subjected to gamma or electron beam irradiation for sterilization, then sterilization is achieved, but the polymer chains undergo scission leading to loss of physical properties
Solution Approach 1:
The patent applies preliminary crosslinking action to PTFE before sterilization irradiation. By pre-crosslinking the polymer chains through controlled irradiation at elevated temperatures (200-400°C) in an inert atmosphere, the PTFE develops a crosslinked network structure that resists subsequent chain scission during sterilization, thereby preserving physical properties while maintaining sterilization effectiveness
Solution Approach 2:
The patent changes the temperature parameter during irradiation from ambient to elevated temperatures (200-400°C). This parameter change enables crosslinking reactions to occur during the irradiation process, transforming the PTFE structure to be more resistant to degradation. The elevated temperature facilitates bond formation between polymer chains, creating a crosslinked network that maintains mechanical integrity
2Reliability
If batch process is used to crosslink PTFE sheets at high temperatures, then radiation resistance is improved, but the process becomes cumbersome and expensive
Solution Approach 1:
The patent transforms the batch crosslinking process into a continuous process suitable for extrusion operations. The PTFE extrusion line is integrated with a crosslinking chamber that continuously exposes the extruded material to irradiation at elevated temperatures. This continuous action eliminates the need for separate batch processing steps, reducing complexity and cost while maintaining radiation resistance
Solution Approach 2:
The patent merges the extrusion process with the crosslinking process into a single integrated operation. The extrusion line and crosslinking chamber are combined such that PTFE is extruded and crosslinked in sequence without interruption. This merging of processes eliminates intermediate handling steps and reduces overall process complexity while achieving the desired radiation resistance
3Manufacturing precision
If PTFE is extruded and sintered, then the polymer chains become oriented and dense, but this impedes crosslinking ability under irradiation
Solution Approach 1:
The patent changes the temperature parameter to elevated levels (200-400°C) during irradiation, which increases polymer chain mobility and facilitates crosslinking reactions despite the oriented and dense structure from extrusion and sintering. The elevated temperature provides sufficient thermal energy to overcome the reduced mobility caused by molecular orientation, enabling effective crosslinking
Solution Approach 2:
The patent employs periodic heating during the crosslinking process to enhance crosslinking efficiency. By applying cyclic thermal energy, the polymer chains periodically gain mobility to facilitate crosslinking reactions, then cool to maintain the crosslinked structure. This periodic action overcomes the impediment caused by the dense, oriented structure from extrusion
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 produces crosslinked PTFE products with improved radiation resistance, enabling efficient industrial-scale manufacturing of medical devices that maintain physical properties during sterilization without the need for additional etching steps.
Implementation Method 1
subjecting them to radiation at high temperatures in an inert atmosphere. Such treatment was noted to crosslink the polymer chains
Implementation Method 2
irradiation at high temperatures as well as tubes and profiles made from such a method. Crosslinked PTFE is more resistant to gamma and electron-beam irradiation
Implementation Method 3
PTFE polymer chains are highly susceptible to chain scission when irradiated, thereby leading to an unacceptable loss in physical properties
Implementation Method 4
sterilized through irradiation by gamma sources or electron beams
Implementation Method 5
sterilized through irradiation by gamma sources or electron beams
Data Source
AI summary
The present application relates generally to tubes, such as thin walled catheter liners with small wall thicknesses (e.g., less than 1 mm), including crosslinked fluoropolymers, e.g., crosslinked poly(tetrafluoroethylene). The disclosure further provides methods of manufacturing such tubes and systems for manufacturing such tubes.