Composite materials that are subject to vibration and stress form small fractures and eventually fail irreversibly at the interface of the polymer matrix and the reinforcing fiber. The US Army and Drexel University have developed a solution to this problem by incorporating reversible bonds into polymer networks. The technology combines a furan-functionalized thermoset matrix and a maleimide-functionalized glass fiber. When broken, the thermoreversible bonds between these materials can be healed on site at temperatures above 90oC. Healing efficiencies of 100% have been recorded in single fiber pull-out testing. The technology has demonstrated the ability to heal damage through at least 5 damage/repair cycles. In applications tested to-date, the healing feature has minimal negative impact on other desirable material properties.
The technology represents a simple and effective method for creating a fiber-reinforced composite system with remendable interfaces. Fibers are sized using a simple two-step process to provide maleimide-functionality and the polymer network is functionalized by simply adding a furan group. The Diels-Alder reaction maintains product stability under 60oC.
- On-Site Repair: Potential for on-site healing of composites with a local heat source
- Effective: Laboratory testing of single fibers has realized healing capabilities up to 100%
- Repeated Healing: Demonstrated healing capabilities for at least 5 cycles
- Broadly Applicable: Tested in epoxy-amine systems but the chemistry should be applicable to any composite system with a hydroxyl or vinyl group
- Cost-Effective: Furan chemistry is based on inexpensive, renewable natural products
- Simple: Basic tank mixing and uncomplicated chemistry
- One US patent application available for license
- Method reduced and tested in laboratory samples
- Peer-reviewed journal articles available with additional information under non-disclosure agreement
- Potential for R&D collaboration with inventors