Fabric-Based Thermoplastic Prepreg Winding for Recyclable Composites
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Solution Overview
Problem
Conventional filament winding processes are limited by the use of thermoset resins, which have drawbacks such as fiber orientation limitations, heat generation issues during curing, and inability to recycle, while thermoplastic resins are not suitable due to high melt viscosities, making it difficult to produce composite parts with desired properties and fiber orientations.
Innovation Solution
The use of fabric-based thermoplastic prepregs that are fully impregnated with thermoplastic materials, allowing for in-situ polymerization or use of reactive thermoplastic resins, and processed through winding or laying methods that involve heating and pressure to weld the layers without curing, enabling complex fiber orientations and improved composite properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermoset resins are used in filament winding, then fiber-reinforced composites can be produced with good mechanical strength, but fiber orientation is limited and heat generation during curing occurs
Solution Approach 1:
The patent changes the material parameter from thermoset to thermoplastic resin, which fundamentally alters the processing behavior and fiber orientation capabilities. Thermoplastic resins allow for better fiber alignment and complex orientations during winding without the cross-linking constraints of thermoset curing, directly resolving the fiber orientation limitation while maintaining mechanical strength through the thermoplastic matrix.
Solution Approach 2:
The patent utilizes the phase transition properties of thermoplastic resins (melting and solidification) instead of thermoset curing. The resin is heated to melt state for impregnation and then cooled to solidify, eliminating the exothermic curing reaction that causes heat generation issues. This phase transition approach enables better fiber orientation control and eliminates harmful heat generation during processing.
2Reliability
If thermoset resins are used, then composites can be cured to achieve desired properties, but the process generates heat and cannot be recycled
Solution Approach 1:
The patent replaces thermoset curing with thermoplastic phase transitions (melting and solidification). The thermoplastic resin is heated above its melting point for impregnation and then cooled to solidify, forming the composite structure without exothermic curing reactions. This eliminates heat generation issues while achieving reliable composite properties through controlled solidification.
Solution Approach 2:
The patent enables recycling of thermoplastic composites by utilizing the reversible nature of thermoplastic materials. The composite can be reheated to melt the thermoplastic matrix, allowing for disassembly, material recovery, and reuse of both the polymer and fiber components, directly addressing the non-recyclability issue of thermoset composites.
3Adaptability or versatility
If thermoplastic resins are used, then recyclability is achieved, but high melt viscosity makes it difficult to impregnate fibers
Solution Approach 1:
The patent applies preliminary action by pre-heating the thermoplastic resin to its melting point or above before fiber impregnation. This preliminary heating reduces the resin's viscosity to an optimal range for impregnation, overcoming the high melt viscosity issue. The resin is maintained at this reduced viscosity state during the winding and impregnation process, ensuring complete fiber saturation while preserving recyclability.
Solution Approach 2:
The patent dynamically changes the temperature parameter during processing. The thermoplastic resin is heated to a specific temperature range where its viscosity becomes suitable for impregnation, then cooled to solidify the composite structure. This parameter control transforms the high-viscosity thermoplastic into a processable state, enabling complete fiber impregnation while maintaining the recyclable thermoplastic nature of the material.
4Productivity
If conventional filament winding with thermoset resin is used, then production is established, but design freedom and isotropic properties are limited
Solution Approach 1:
The patent changes the fundamental material parameter from thermoset to thermoplastic resin, which enables complex fiber orientations and multi-directional reinforcement patterns during winding. The thermoplastic material accommodates various winding angles and layer configurations without cross-linking constraints, achieving superior isotropic properties and design freedom while maintaining manufacturing efficiency through continuous processing.
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
This approach simplifies the manufacturing process, achieves higher design freedom, and produces reinforced thermoplastic composite parts with improved isotropic properties, high fracture toughness, and recyclability, overcoming the limitations of conventional methods.
Implementation Method 1
applying heat to the thermoplastic prepreg as it is wound about the mandrel to at least partially melt or soften the polymerized thermoplastic material along the nip line
Implementation Method 2
applying pressure to the at least partially melted or softened polymerized thermoplastic material of the prepreg sheet, so as to weld an inner surface of an outer layer of the thermoplastic prepreg to an outer surface of an inner layer of the thermoplastic prepreg
Data Source
AI summary
A thermoplastic product includes a fabric-based reinforcing sheet and a polymerized thermoplastic material. The fabric-based reinforcing sheet is wound about a mandrel to form a plurality of layers having a cross-sectional shape that corresponds to the mandrel. The fabric-based reinforcing sheet includes a plurality of fiber bundles, which may have a bidirectional orientation or configuration. A polymerized thermoplastic material is disposed within each layer of the fabric-based reinforcing sheet. The polymerized thermoplastic material bonds each layer of the fabric-based reinforcing sheet to an adjacent layer.