Crosslinked UHMW PE Sintering Process for Orthopedic Implants
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Solution Overview
Problem
Ultrahigh molecular weight polyethylene (UHMW PE) is difficult to process due to its intractability above its crystalline melting temperature, leading to retained morphology and increased wear and failure in applications like artificial implants, and existing methods are cumbersome, time-consuming, and negatively impact other properties such as crack resistance.
Innovation Solution
A process involving compacting virgin UHMW PE to a compacted composition, followed by sintering and crosslinking, with crosslinking initiated multiple times using gamma radiation or electron beam radiation, to enhance wear resistance and maintain high crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UHMW PE is sintered at high temperatures to improve wear resistance, then wear resistance is improved, but the polymer retains its original shape and morphology which contributes to wear and failure
Solution Approach 1:
The patent applies crosslinking to change the fundamental parameters of UHMW PE, transforming it from a thermally softening polymer to a crosslinked network structure that maintains dimensional stability at high temperatures. This allows the material to be sintered while preventing morphology retention, thereby improving wear resistance without the detrimental shape retention effect
Solution Approach 2:
The patent creates a composite structure by forming crosslinks within the UHMW PE matrix, effectively creating a new material system with combined properties: the inherent wear resistance and toughness of UHMW PE plus the thermal stability and dimensional control of crosslinked networks
2Ease of manufacture
If conventional sintering processes are used to process UHMW PE, then the material can be formed, but the processes are time-consuming and negatively influence crack resistance
Solution Approach 1:
The patent incorporates crosslinking agents during the compaction or sintering process, performing the crosslinking action preliminarily rather than requiring separate post-processing steps. This preliminary crosslinking improves crack resistance while maintaining efficient processing, eliminating the need for time-consuming conventional multi-step processes
3Reliability
If UHMW PE is processed multiple times to reduce wear, then wear resistance may be improved, but the process becomes cumbersome and time-consuming
Solution Approach 1:
The patent merges the compaction, sintering, and crosslinking steps into a single integrated process sequence. By incorporating crosslinking agents and performing crosslinking during or after sintering in one continuous operation, the patent eliminates the need for multiple separate processing cycles, thereby reducing processing time while achieving improved wear resistance
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 process improves wear resistance and impact strength while minimizing the negative effects on crack propagation resistance, resulting in improved performance for applications like orthopedic implants.
Implementation Method 1
crosslinking initiated multiple times using gamma radiation or electron beam radiation
Implementation Method 2
crosslinking initiated multiple times using gamma radiation or electron beam radiation
Implementation Method 3
sintering said compacted composition
Data Source
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AI summary
Provided are processes comprising crosslinking polyethylene or using crosslinked polyethylene. Furthermore, the processes may include compacting and/or sintering the polyethylene.