PVDF Composition Fatigue Strength via Copolymer Plasticizer
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Solution Overview
Problem
Current polymeric compositions used in pipes for transporting liquids and gases, particularly synthetic products like hydrogen, exhibit insufficient fatigue strength, limiting their mechanical reliability over time.
Innovation Solution
A composition combining a polyvinylidene fluoride homopolymer with a copolymer of vinylidene fluoride and another fluorinated comonomer, such as hexafluoropropylene, and a plasticizer, where the copolymer is present in a proportion of 10 to 35% by weight, enhancing elastomeric properties and fatigue strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PVDF homopolymer is used to provide high mechanical strength and chemical resistance, then the pipes meet requirements for strength and chemical resistance, but the pipes exhibit excessive stiffness and limited extrudability
Solution Approach 1:
The patent uses a composite material system consisting of PVDF homopolymer combined with VDF-based copolymer and plasticizer. This composite approach allows the mixture to maintain the high strength properties of PVDF while the copolymer and plasticizer components reduce stiffness and improve extrudability, achieving a balance between mechanical performance and manufacturability
Solution Approach 2:
The patent changes the physical and chemical parameters of the PVDF system by adding copolymer (changing composition) and plasticizer (changing rheological properties). This modifies the material parameters to reduce stiffness and improve extrudability while maintaining adequate mechanical strength for pipe applications
2Strength
If fluoroelastomer is added to PVDF to reduce stiffness, then the stiffness is reduced, but the extrudability remains limited and fatigue strength is insufficient
Solution Approach 1:
The patent changes the composition parameters by using VDF-based copolymer with specific comonomer content (5-25%) and optimizing the plasticizer amount (5-20% by weight). These parameter adjustments achieve the right balance between reducing stiffness for flexibility and maintaining adequate fatigue strength for reliable pipe operation
Solution Approach 2:
The patent creates a three-component composite material system (PVDF homopolymer + VDF-based copolymer + plasticizer) where each component contributes specific properties. The copolymer provides flexibility while the plasticizer enhances extrudability and the PVDF matrix maintains structural integrity and fatigue resistance
3Ease of manufacture
If copolymer content is increased to improve extrudability and reduce stiffness, then the extrudability improves, but the fatigue strength decreases
Solution Approach 1:
The patent optimizes the copolymer content parameter within the range of 10-35% by weight and plasticizer content within 5-20% by weight. This parameter optimization achieves sufficient extrudability for pipe manufacturing while maintaining adequate fatigue strength for long-term reliability
Data Source
AI summary
The invention relates to a composition comprising: a homopolymer polyvinylidene fluoride; a copolymer of vinylidene fluoride and of at least one other fluorinated comonomer copolymerizable with vinylidene fluoride (VDF), the weight proportion of the copolymer in the composition being between 10 to 35%; and a plasticizer, the weight proportion of the plasticizer in the composition being between 1 and 5%. The invention also relates to a method for producing the composition and the use thereof for producing various items.