Multifunctional benzoxazines and composite materials incorporating the same
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Solution Overview
Problem
The commercial use of pure benzoxazine matrices in high-performance composites is limited due to their low flexural and tensile modulus, which is mitigated by hybridizing with epoxy, but this compromises their beneficial properties, and there is a need to reduce solvent uptake without increasing water absorption.
Innovation Solution
Blending difunctional benzoxazines with multifunctional benzoxazines having an average functionality of 2.1 to 3, which retards organic solvent uptake without significantly affecting mechanical properties or water absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If pure benzoxazine matrices are used in high-performance composites, then beneficial properties such as high glass transition temperature, high modulus, good flame retardant properties, low moisture absorption, and low shrinkage are achieved, but the flexural and tensile modulus are insufficient
Solution Approach 1:
The patent applies composite materials by blending difunctional benzoxazine with multifunctional benzoxazine (functionality >2) to create a hybrid resin system. This composite approach combines the high Tg and low shrinkage of pure benzoxazine with enhanced mechanical properties from the multifunctional component, achieving both high temperature resistance and improved flexural/tensile modulus without using epoxy or rubber modifiers
2Strength
If benzoxazine is hybridized with epoxy to improve flexural and tensile modulus, then mechanical strength is enhanced, but beneficial properties such as flame retardancy, low moisture absorption, and low shrinkage are compromised
Solution Approach 1:
The patent changes the chemical parameters of the resin system by using multifunctional benzoxazine with functionality greater than 2 (particularly 2.1 to 3) instead of epoxy. This parameter change allows achieving improved mechanical properties while maintaining the inherent fire resistance and low moisture absorption characteristics of the benzoxazine chemistry
Solution Approach 2:
The patent applies local quality by selectively introducing multifunctional groups into specific regions of the molecular structure. The multifunctional benzoxazine component provides localized crosslinking density enhancement to improve modulus, while the overall benzoxazine matrix structure maintains its flame retardant and low moisture absorption properties
3Object-affected harmful factors
If conventional benzoxazine systems are used, then good solvent resistance is achieved, but the rate of organic solvent uptake is relatively high
Solution Approach 1:
The patent changes the network density parameter by incorporating multifunctional benzoxazine with functionality >2, which increases crosslinking density. This parameter change reduces the rate of organic solvent uptake while maintaining good overall solvent resistance, as the tighter network structure slows down solvent penetration kinetics
Data Source
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AI summary
A curable resin composition containing a blend of multifunctional benzoxazines, and composite materials derived therefrom. The benzoxazine blend contains the combination of (A) a difunctional benzoxazine component and (B) a multifunctional benzoxazine component with functionality of greater than 2. Cured matrix resins and cured composite materials containing such benzoxazine blend exhibit a significant retardation in the rate of organic solvent uptake as compared to the same cured matrix resins and composite materials without component (B).