Performance from Plants
The overwhelming majority of polymers used in defense equipment are derived from petroleum. Nylons, polyesters, polycarbonates, and polyurethanes all begin as crude oil derivatives. But Arkema's Rilsan PA11, a polyamide derived entirely from castor oil, demonstrates that bio-based polymers can match and in some cases exceed the performance of their petroleum-based counterparts in demanding defense applications.
Rilsan PA11 has been in commercial production since the 1950s, making it one of the oldest bio-based engineering polymers in continuous use. The castor beans from which it is derived are grown primarily in India and East Africa, on land that is generally unsuitable for food crop production. The manufacturing process converts ricinoleic acid, the primary fatty acid in castor oil, into 11-aminoundecanoic acid, which is then polymerized to produce PA11.
Material Properties
PA11 occupies a unique position in the polyamide family. Compared to petroleum-derived PA6 and PA66, which are the most common engineering nylons, PA11 offers several distinct advantages. Its longer carbon chain between amide groups results in lower moisture absorption, approximately 1.9% at equilibrium versus 8.5% for PA66. This low moisture sensitivity means more consistent mechanical properties in wet conditions, a critical consideration for equipment used in maritime, tropical, and high-humidity environments.
PA11 also exhibits superior impact resistance, particularly at low temperatures. Its glass transition temperature of approximately 46 degrees Celsius and excellent notched Izod impact strength make it the material of choice for components that must resist impact at temperatures down to minus 40 degrees Celsius. Petroleum-derived nylons become brittle and crack-prone at these temperatures.
Defense Applications
In defense equipment, PA11 is used for injection-molded components that require a combination of impact resistance, chemical resistance, and dimensional stability. Buckle hardware, connector housings, cable management clips, and structural mounting brackets are all candidates for PA11. The material's resistance to fuels, oils, hydraulic fluids, and common military chemicals, including decontamination agents, makes it particularly suitable for components that may be exposed to these substances during use or maintenance.
PA11 is also used in protective coating applications. Rilsan powder coatings provide abrasion-resistant, chemically resistant surfaces on metal components. Helmet hardware, weapon accessories, and load-bearing frame elements can be coated with PA11 to provide long-lasting surface protection without the environmental concerns associated with chromium or cadmium plating.
Environmental Credentials
The environmental case for PA11 is compelling. Lifecycle analysis conducted by Arkema and verified by independent third parties shows that PA11 production generates approximately 40% less CO2 equivalent emissions than PA66 production. The castor plant used as the feedstock is a net carbon absorber during its growth cycle, partially offsetting the emissions from the manufacturing process.
Castor agriculture does not compete with food production. The plant thrives in semi-arid conditions on marginal land, and its cultivation provides economic benefits to smallholder farmers in developing regions. The entire castor plant is utilized: oil for polymer production, husks for fertilizer, and residual biomass for energy generation.
GoatArma™ Integration
GoatArma™ uses Rilsan PA11 for over 80% of the injection-molded components in both the CAPRASKIN™ and the CapraHelm™. The mounting brackets that secure sensor modules to the helmet shell are molded from glass-fiber-reinforced PA11, providing the impact resistance needed to protect sensitive electronics during rough handling while maintaining dimensional precision for sensor alignment.
The quick-release buckles and adjustment hardware on the CAPRASKIN™ carrier are also PA11, chosen for their reliable performance across the full military temperature range from minus 40 to plus 70 degrees Celsius. Unlike PA66 buckles, which can become brittle and snap in extreme cold, PA11 components maintain their ductility and energy absorption capacity even in Arctic conditions.
Our adoption of PA11 reflects GoatArma™'s position that sustainability and performance are not competing objectives. When a bio-based material outperforms the petroleum alternative on the metrics that matter, in this case moisture resistance, impact toughness, and temperature range, the environmental benefits become a bonus rather than a compromise.