Fiber-Reinforced Thermoplastic Composites via Curative Sizing
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Solution Overview
Problem
The high viscosity of melted thermoplastic resin compositions poses challenges in combining them with fibers effectively, as increasing temperature to reduce viscosity risks thermal decomposition, and existing methods fail to maintain a suitable viscosity without compromising polymerization.
Innovation Solution
Using a low viscosity pre-polymerized thermoplastic resin with curatives applied to sized fibers, allowing for partial or complete removal of curatives from the resin composition, which facilitates polymerization and reduces viscosity, thereby extending pot life and processing temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the temperature of melted thermoplastic resin is increased to reduce viscosity, then the viscosity decreases and fibers can be dispersed more easily, but the resin risks thermal decomposition
Solution Approach 1:
The curative is applied to the fibers in advance (sizing process) before the resin is introduced. This preliminary action ensures that the curative is already positioned on the fiber surfaces, allowing the resin to polymerize immediately upon contact with the fibers during molding, eliminating the need for high-temperature prolonged heating that would cause decomposition
Solution Approach 2:
The invention changes the distribution parameter of the curative from being mixed throughout the resin to being applied on the fiber surfaces. This parameter change allows the polymerization reaction to occur at lower temperatures and shorter times, reducing viscosity without causing thermal decomposition
2Reliability
If curatives are kept in the thermoplastic resin composition to facilitate polymerization, then polymerization can proceed, but the resin composition becomes too viscous to mix properly with fibers and pot life is reduced
Solution Approach 1:
The curative is segmented and applied only to the fiber surfaces rather than being distributed throughout the entire resin composition. This segmentation means that the curative remains dormant on the fiber surfaces during storage and mixing, and only activates when the resin contacts the sized fibers during molding, thereby extending pot life while ensuring complete polymerization
Solution Approach 2:
The sized fibers act as an intermediary carrier for the curative. Instead of adding curative directly to the resin, it is first applied to the fibers which then serve as the medium to transfer the curative to the resin during the molding process, controlling the timing and location of polymerization initiation
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 enables the production of fiber-reinforced composites with improved processing conditions, increased pot life, and higher shelf-life of the thermoplastic polyurethane prepolymer composition, while maintaining the mechanical properties of the composite.
Implementation Method 1
The curative on the fibers facilitate the polymerization of a low viscosity pre-polymerized thermoplastic resin that forms the polymer matrix of the composite
Data Source
AI summary
Methods of making a fiber-reinforced thermoplastic polyurethane composite are described. The methods may include applying a sizing composition to a plurality of fibers to make sized fibers, where the sizing composition may include at least one curative for a thermoplastic polyurethane prepolymer. The sized fibers may be contacted with a thermoplastic polyurethane prepolymer composition to form a resin-fiber amalgam, where the thermoplastic polyurethane prepolymer composition includes 50 wt. % or less of a total amount of the curative that is also present on the sized fibers. The resin-fiber amalgam may then be cured to form the fiber-reinforced thermoplastic polyurethane composite.