SBIR-STTR Award

Shipboard structures can benefit from the relatively high performance-to-weight ratio, fatigue life, durability, processability and multi-functionality of polymer composites (versus metals). The fire, smoke and toxicity (FST) performance and the initial economics of composites, however, cannot match those of metals. Efforts to replace metals with composites in shipboard structures have emphasized the use of brominated vinyl esters as fire-retardant polymers in composites. Despite their relatively low cost and ease of fabrication, such halogenated polymers are toxic and potentially carcinogenic, and their compatibility with carbon fiber is less than desirable. There is thus a need for environmentally friendly and affordable polymers which offer desired FST behavior, processability, structural performance and compatibility with carbon fiber. We propose to meet this challenge by developing a tailored polymer chemistry which embodies synergistic and affordable features of organic-inorganic hybrids with nano-scale inorganic constituents and benzoxazines with phosphorus- or silicon-based chemistry. The proposed Phase I project will: (i) synthesize and screen refined epoxy resins incorporating selected elements of the new molecular structure; (ii) thoroughly characterize selected refined epoxies, and identify the system with a preferred balance of performance, cost and sustainability for use in composite topside structures; and (iii) verify the competitive technical, economic and sustainability merits of the refined epoxy system versus brominated vinyl esters and standard phenolic resins. The follow-up Phase I Option will optimize the refined epoxy chemistry embodying organic-inorganic hybrids and phosphorus-/silicon-containing benzoxazines.

Benefit:
The global markets for flame-resistant polymer systems account for $15 billion of annual sales. These markets are projected to grow at an average annual rate of 5.5% over the next decade. Construction, electronic and motor vehicle applications constitute the primary markets for fire-retardant polymers; marine structures also offer the potential to consume large quantities of the next-generation fire-retardant polymers. Brominated flame-retardant polymers dominate these markets, accounting for one-third of total sales; their adverse environmental and health impacts, however, have created an opening for market introduction of alternative (non-halogenated) flame-retardant polymer technologies. The novel and patentable features of our approach promise to yield a new class of polymer chemistry with a distinct balance of fire resistance, cost, sustainability, processabiltiy and mechanical performance. We have reached agreements with major manufacturers of composites and shipboard structures towards cooperative market transition of the technology in the context of license agreements developed around the novel features of our approach. The new fire-resistant polymer would also have applications in infrastructure, electronic and aerospace systems. We have conducted a preliminary financial planning for market transition of the technology, and have identified sources to finance this transition effort.

Keywords:
phosphorus-containing benzoxazines, phosphorus-containing benzoxazines, shipboard structures, cost, polymer chemistry, carbon fiber composites, nano-scale molecular constituents, organic-inorganic hybrids, mechanical properties, Flame resistance, sustainability.

Efforts to replace metals with composites in shipboard applications have emphasized the use of brominated vinyl esters as fire-retardant polymers. Despite their relatively low cost and ease of fabrication, such halogenated polymers produce toxic and potentially carcinogenic gases; their compatibility with carbon fibers is also less than desirable. There is thus a need for environmentally friendly and affordable polymers that offer desired fire resistance, processability, structural performance and compatibility with carbon fibers. This challenge is addressed in the project by developing a modified epoxy chemistry which employs the organic-inorganic hybridization principle. Chemical integration of phosphorus- and silicon-based compounds into selected epoxy systems yielded a single, inherently flame-retardant polymer structure with a desired balance of fire, smoke and toxicity behavior, compatibility with the resin-infusion approach to room-temperature processing of composites, thermo-mechanical performance, bonding characteristics, and economics. The Phase II project will optimize this modified epoxy chemistry, and will undertake laboratory investigations and scale-up efforts towards qualification of the new polymer composite for use in shipboard structures. The proposed project will be implemented in a base (Phase II) and two option steps, and will be guided by the experience gained in successful qualification of composites for use in Naval surface combatants.

Benefit:
Polymer composites offer important advantages in application to the topside structures of ships. When compared with steel and aluminum, composites provide high stiffness-to-weight and strength-to-weight ratios, and improved fatigue life, chemical and weathering/corrosion resistance. Composites can also provide multi-functionality and a high degree of flexibility during manufacturing. The modified epoxy systems which are under development in the project will play enabling roles towards broad transition of polymer composites to shipboard structures by enhancing their fire, smoke and toxicity performance, and also lowering the initial cost of composite structures. Shipboard structures and broader applicaitons of flame-retardant polymers in motor vehicles, infrastructure, electronic and aerospace systems account for $15 billion annual sales with 5.5% rate of growth. Brominated vinylester currently dominates these markets for flame-retardant polymers; its adverse environmental and health impacts, however, have created an opening for market introduction of alternative (non-halogenated) flame-retardant polymer technologies. The novel polymer chemistry developed in the project offers a distinct balance of fire resistance, safety, cost, sustainability, processabilty and mechanical performance to effectively meet the demands in marine and other applications for enhanced flame-retardant polymers. We have reached agreements with major manufacturers of composites and shipboard structures to undertake cooperative efforts towards full development, qualificaiton and market transition of the technology.

Keywords:
fiber reinforced polymer composites, safety and toxicity behavior, shipboard structures, fire, Structural Performance, Vacuum Assisted Resin Transfer Molding, room-temperature resin infusion, Economics, modified epoxy chemistry