Epoxy Prepreg Composition for Hot-Wet Compressive Strength Retention
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Solution Overview
Problem
Existing prepregs struggle to maintain high compressive strength under both room temperature/dry and hot/wet conditions while also ensuring high damage tolerance and interlaminar fracture toughness.
Innovation Solution
A pre-impregnated composite material using a resin matrix comprising a mixture of non-crosslinked polyamide 11 particles and crosslinked polyamide 12 particles, combined with polyether sulfone as a thermoplastic toughening agent and epoxy resins, to form composite parts with high compressive strength and interlaminar fracture toughness, which retains strength under hot and wet conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If higher modulus resins are selected to increase compression strength, then compressive strength is improved, but damage tolerance is reduced
Solution Approach 1:
The patent uses a composite resin system combining thermoset epoxy matrix with thermoplastic polyamide particles and polyether sulfone toughening agents. This hybrid composite approach allows the thermoset provides high compressive strength while the thermoplastic particles provide damage tolerance and toughness, resolving the contradiction between strength and damage tolerance
Solution Approach 2:
The patent modifies the resin parameters by incorporating specific ratios of crosslinked and non-crosslinked polyamide particles (1:4 weight ratio), along with polyether sulfone content (1-10 parts by weight per 100 parts epoxy resin). These parameter changes enable simultaneous achievement of high compressive strength and damage tolerance
2Reliability
If thermoplastic particles are added to increase interlaminar fracture toughness, then damage tolerance is improved, but compressive strength under hot and wet conditions deteriorates
Solution Approach 1:
The patent carefully controls the particle size distribution (5-50 microns), the weight ratio of crosslinked to non-crosslinked polyamide particles (1:4), and the overall thermoplastic content to optimize both toughness and compressive strength retention under hot and wet conditions
Solution Approach 2:
The patent creates a composite system where crosslinked polyamide particles provide interlaminar fracture toughness while non-crosslinked polyamide particles and polyether sulfone maintain compressive strength under hot and wet conditions by providing flexibility and resistance to moisture-induced degradation
3Strength
If crosslinked polyamide particles are used to improve compressive strength retention under hot and wet conditions, then compressive strength is improved, but interlaminar fracture toughness is reduced
Solution Approach 1:
The patent segments the polyamide particles into two distinct functional groups: crosslinked particles (providing compressive strength retention) and non-crosslinked particles (providing interlaminar fracture toughness). This segmentation allows each particle type to specialize in one function, resolving the contradiction
Solution Approach 2:
The patent optimizes the weight ratio of crosslinked to non-crosslinked polyamide particles at 1:4, ensuring sufficient non-crosslinked particles are present to maintain interlaminar fracture toughness while crosslinked particles provide compressive strength retention under hot and wet conditions
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
The composite parts exhibit compressive strength retention of at least 75% under hot and wet conditions, maintaining high damage tolerance and interlaminar fracture toughness.
Implementation Method 1
a thermoplastic particle component that includes a first group of polyamide particles that do not include crosslinked polyamide and a second group of polyamide particles that include crosslinked polyamide
Implementation Method 2
an uncured resin matrix that includes: a resin component that includes at least one epoxy resin; a curing agent
Data Source
AI summary
Pre-impregnated composite material (prepreg) is provided that can be cured/molded to form composite parts having high, levels of compressive strength under dry conditions at room temperature and which retain their compressive strength when subjected to hot and wet conditions. The pre-impregnated composite materials are composed of reinforcing fibers and an uncured resin matrix. The uncured resin matrix includes a resin component made up of one or more difunctional epoxy resins and multifunctional epoxy resins. The uncured resin matrix further includes a thermoplastic particle component, a thermoplastic toughening agent and a curing agent. The thermoplastic particle component is composed of a mixture of a first group of polyamide particles that do not contain crosslinked polyamide and a second group of polyamide particles that contain crosslinked polyamide.