Sizing Compositions for Thermoplastic Composite Fiber Wetting
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Solution Overview
Problem
Current methods for forming thermoplastic fiber reinforced composites face challenges such as significant fiber shortening and high costs due to viscosity issues and branching/cross-linking polymerization during extrusion and injection molding, limiting their use in vehicle parts and other applications.
Innovation Solution
The use of sizing compositions containing non-isocyanate polymerization initiators and catalysts, such as Grignard salts, applied to fibers and flakes to initiate anionic polymerization of caprolactam monomers at elevated temperatures, allowing for in-mold polymerization and reducing branching/cross-linking, thereby enabling the production of lightweight, recyclable thermoplastic composite parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If thermoplastic polymers are extruded at elevated temperature to wet out glass fibers, then fiber wetting is improved, but fiber length is significantly shortened due to maceration
Solution Approach 1:
The invention changes the chemical parameter of the resin by using reactive thermoset resin compositions that can polymerize at lower temperatures or with controlled reactivity, reducing the mechanical shear and thermal degradation that cause fiber maceration while still achieving adequate wetting
2Ease of manufacture
If reactive materials are used in extrusion and injection molding, then in-situ polymerization is achieved, but viscosity and shear resistance increase prohibitively
Solution Approach 1:
The invention applies sizing compositions to fibers before processing that contain polymerization initiators, so that polymerization begins on the fiber surface during mold filling before the resin viscosity becomes prohibitively high, enabling reactive materials to be used without excessive viscosity penalties
Solution Approach 2:
The invention creates local polymerization zones on fiber surfaces through sizing, rather than bulk polymerization of the entire resin, which controls viscosity increases to manageable levels while still achieving the benefits of in-situ polymerization
3Ease of manufacture
If branching and cross-linking polymerization occur during extrusion, then polymerization is achieved, but production cost increases extremely costly or prohibitive
Solution Approach 1:
The invention changes the polymerization mechanism by using anionic polymerization with Grignard salts, which proceeds through a different chemical pathway that avoids the branching and cross-linking reactions that occur with conventional free-radical polymerization, thereby reducing production costs
4Reliability
If conventional sizing compositions are used on fibers, then fiber protection is achieved, but participation in polymerization reactions with resin is prevented
Solution Approach 1:
The invention creates multi-functional sizing compositions that simultaneously provide fiber protection through conventional mechanisms and enable polymerization participation by incorporating initiators that react with the resin, making the sizing serve both protective and reactive functions
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 allows for the production of lightweight, recyclable thermoplastic composite parts with superior mechanical properties, reducing production costs and overcoming viscosity challenges, thus enabling their use in vehicle parts and other applications.
Implementation Method 1
The use of sizing compositions containing non-isocyanate polymerization initiators and catalysts, such as Grignard salts, applied to fibers and flakes to initiate anionic polymerization of caprolactam monomers at elevated temperatures
Implementation Method 2
there is a need for methods of polymerizing and forming thermoplastic polymers, copolymers and homopolymers in situ surrounding the fiber reinforcements in a mold
Data Source
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Figure 2A~2E
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AI summary
Sizing compositions to size fibers or particles used in plastic composites are described. The compositions may include a solution with a polymerization compound selected from: (a) at least one non-isocyanate-containing polymerization initiator (PI) for initiating the polymerization of caprolactam monomers; or (b) at least one precursor for a non-isocyanate-containing PI for initiating the polymerization of caprolactam monomers. Methods of making the sizing the composition, as well as methods of making reinforced thermoplastic composites from sized fibers or particles, are also described.