SBIR-STTR Award

The objective of the proposed program is to demonstrate the feasibility of an innovative, cost-effective, rapid-pultrusion composite processing technique and newly formulated resins which substantially reduce the need for expensive tooling, high puller tensions (dies are expected to be an order of magnitude shorter than conventional pultrusion dies) and slow thermal processing and can cure the composite in seconds (compared to minutes for thermal systems for an expected order of magnitude increase in line speed) at ambient or subambient conditions. The matrix polymers that make graphite-composites manufactured using this process possible are based on electron-beam curing of low viscosity Epoxy Functionalized Siloxane (EFS) polymers that have been shown to resist atomic oxygen, while exhibiting excellent mechanical and physical properties. This resin can be specially formulated with other low cost resins, toughener thermoplastic powers, and a proprietary low-dose-to-cure catalyst to lower the resins cost as well as improve on the already tougher-than-epoxy, hydrophobic, high Tg (>250 C) properties of the base resign. These composites are designed to be environmentally and hygienically friendly and outperform composites produced by competing fabrication techniques.

Novel resins suitable for extremely rapid, highly penetrating 10 MeV electron beam curing (a ambeint temperature) have been developed for fabrication of fiber reinforced composites. Until recently a limited range of resins were available that processed easily, have low cure shrinkag and performance properties equal or exceeding state of the art toughened epoxies. To fill this demand two types of E-Beam curable resins were discovered by ACI to fit two different processing scenarios. Both are E-beam cationically polymerized into low cost high performance composites. Both rapid-curing resins were successfully formulated by ACI to be hot meltable to form powder towpregable solid intermediates (before cure) for thermo/pressure forming or alternatively formulated as low viscosity liquids for rapid penetration through reinforcement preforms using the vacuum-assist pressure bag RTM process to form high fiber volume composites. During the Phase I program the feasibility was demonstrated, two major new resins were discovered and all objectives were achieved. The specific objectives of the Phase II program are to; A) Develop/Optimize Resin/catalyst/toughener system for low cost, low void, low shrink, trouble free rapid manufacturing use yet retain excellent composite mechanical and thermal-wet properties B) Optimize the powder towpreg uniweave fabric layup debulk/devoid/preconsolidation process step for minimum time and voids. C) Optimize the reinforcement fiber interface chemistry in a parallel effort with objective A (above) for graphite and fiberglass reinforcements.

Benefits:
Spin-off commercial applications include exterior hulls and interior composite structures and stiffeners for spacecraft and aircraft; sub and ship hulls, radar, sonar and microwave transparent domes; armor and space bumpers; communication antennas; Composite trusses for high voltage power transmission towers, thick composite armor, Automotive and transportation subchassis, body and structural components.

Keywords:
Electron-Beam Curing Cationic Polymerization Compression Forming Structures Polymer Composites Rapid