Mesogenic Epoxy Resin Composition for Stable Shear Viscosity
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Solution Overview
Problem
Epoxy resins with mesogenic structures exhibit high viscosity and crystallinity, leading to processing difficulties due to insufficient fluidity and compatibility, especially under shear stress, which affects their use in applications requiring high fracture toughness and heat resistance.
Innovation Solution
The development of an epoxy resin composition comprising specific combinations of epoxy compounds with mesogenic structures, such as those with phenylene and divalent biphenyl groups, to achieve a dynamic shear viscosity ratio of 3 or less, ensuring stable viscosity under shear stress and improved processing compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mesogenic structure is introduced into the epoxy resin molecule to improve fracture toughness, then fracture toughness is improved, but viscosity increases and fluidity becomes insufficient during processing
Solution Approach 1:
The invention changes the molecular weight parameter of the epoxy resin by controlling the reaction between the epoxy monomer and divalent phenol compound to achieve a specific molecular weight range (10,000-50,000), thereby reducing viscosity while maintaining the mesogenic structure for fracture toughness improvement
Solution Approach 2:
The invention creates a composite molecular structure combining mesogenic groups (for toughness) with specific phenolic structures (for fluidity control), achieving a balanced epoxy resin composition that satisfies both mechanical property and processing requirements
2Ease of manufacture
If the molecular weight of the epoxy compound is reduced to improve fluidity, then viscosity is lowered, but fracture toughness may be compromised
Solution Approach 1:
The invention optimizes the molecular weight parameter to a specific range (10,000-50,000) that balances fluidity and mechanical properties, avoiding both high molecular weight (poor fluidity) and low molecular weight (poor toughness) extremes
Solution Approach 2:
The invention introduces mesogenic structures at specific locations within the molecular chain (through controlled reaction with divalent phenol compounds) to provide localized toughness enhancement without requiring high overall molecular weight, thus maintaining good fluidity
3Temperature
If a mesogen-containing epoxy resin is used to achieve higher crystallinity, then heat resistance is improved, but processing compatibility deteriorates due to high viscosity under processing temperature conditions
Solution Approach 1:
The invention changes the molecular weight parameter to a specific range that allows the resin to maintain low viscosity at processing temperatures while still achieving high crystallinity and heat resistance in the cured state
Solution Approach 2:
The invention creates a dynamic viscosity characteristic where the resin exhibits low viscosity at processing temperatures (improving flow and infiltration) but transforms to a high crystallinity structure upon curing (providing heat resistance)
Data Source
AI summary
An epoxy resin, comprising an epoxy compound having a mesogenic structure, and having a value of η'2/η'1 equal to 3 or less, wherein η'1 is an initial dynamic shear viscosity (Pa·s) and η'2 is a maximum value of dynamic shear viscosity (Pa s), in a measurement of dynamic shear viscosity.