A High-Performance/High-Temperature 

Resin for Implantable Devices 

Robert G. Bryant, PhD 

Branch Head, Advanced Materials & Processing Branch 

NASA Langley Research Center 
A Brief History : NASA HSR Program: 

• Develop a matrix resin and high performance adhesive that provides 

continuous service for 10,000 hrs at 177°C – properties defined by 

Boeing. 

• Maximum processing conditions are 350°C, 100 psi. 

• Use as many COTS monomers as possible. 
NASA’s LaRCTM-SI : Chemistry: 

LaRCTM-SI - synthesized from the following commercially available monomers: 

O O 

O 

O 

O 

O O 

O 

O O 

O O 

O 

O NH 

H N 2 

2 

ODPA BPDA 3,4’-ODA 

Dianhydrides Diamine 

Molar ratio of ODPA to BPDA is typically 1:1, but can be adjusted up to 1:3 favoring either 

dianhydride. Glass transition temperatures range from 230°C to 265°C depending on the 

offset and chemistry used. 

LaRCTM-SI Performance - excellent processability and mechanical properties. 

LaRCTM-SI is solution processable as the polyamic acid and as the final polyimide. 

The polyimide also lends itself readily to melt processing. Thus, a wide range of 

processing options are available. Neat resin, adhesive and composite properties 

are excellent. 

LaRCTM-SI Cost - the cost when compared to conventional high performance 

polymers (e.g. polyimides) is relatively high. Cost is based on economics of scale. 
NASA’s LaRCTM-SI : Room Temp. Properties: 

Neat Resin IM7 Composite* 

Tg (°C) 248 - 251 SBS Str. (MPa) 95 

Density (g/mL) 1.376 0° Flex Str. (MPa) 1600 

Hardness (HK50) 23-27 Modulus (GPa) 134 

Thermal Cond. (W/m-K) 0.244 DCB Fract. Tough. (kJ m-2) 1.72 

CTE (ppm °C) 48 - 60 90° Flex Str. (MPa) 144 

Tensile Str. (MPa) 141 0° Tensile Str. (GPa) 2.71 

Tensile Mod (GPa) 4.05 IITRI Comp. Str. (MPa) 1.03 

K1c (MN/m-3/2) 4.4 OHC Str. (MPa) 296 

G1c (MN/m-2) 4.6 CAI str. (MPa) 348 

Ti/Ti Lap Shear (MPa) 39 

Al/Al Cleave Str. (MPa) 17 

*60/40 (v/v/) Fiber/ Resin 
LaRCTM-SI Thermoplastic / Thermoset Roadmap: 

PI 

Solution 

PI 

Powder 

PAA 

Solution 

Film 

Reactor Base Products 

Extruded 

Stock 

Molded 

Stock 

Powder 

Coating 

Varnish 

Prepreg 

Demonstrated Products 

Adhesives: supported and 

unsupported 

Composites: structural foam, 

FR-dielectric 

Thin Dielectric / Protective: 

Wire, Fiber optic, Spray coat 

Mechanical Parts: filled & 

Unfilled 

Melt Production: Fiber, 

Film, Tubes, Parts 

Thick coating:: Parts, pipes, 

structure, porous & solid 

Applications 

•Thin Films for Flexible Circuitry & Cables 

•Coated Wire 

•Optical Fiber Cladding 

•Carbon Fiber and E/S-glass Prepreg

•Rigid and Flexible Foam 

•Extruded Rods, Fibers, Film, Wire 

Insulation and Hollow Tubing 

•Compression Molded Articles (Gears, 

Rings, etc) 

•Advanced Composites 

•Hot Melt Adhesive film 

•Flame Sprayed Protective Coatings 

•Multilayer flexible and Semi-rigid circuits 

THUNDER Actuator E/M 

Apps 

TRL 1-4 Lab to Vender TRL 4-7 Vender to OEM TRL 7-9 OEM to Customer 

Repeatability & Supply Reliability & Verification Testing & Economics 
NASA’s LaRCTM-SI : (Products): 

LaRCTM-SI has been solution processed to produce the following: 

• Thin Films for Flexible Circuitry and Cables 

• Wire Coating 

• Optical Fiber Cladding 

• Supported and Unsupported Adhesive Films 

• Carbon Fiber and E-glass Prepreg 

• Sprayable Ultrathin Coatings 

• Rigid and Flexible Foam 

3-Layer SI high speed 

A/D flex circuit board 

LaRCTM-SI has been melt processed to produce the following: 

• Extruded Rods, Fibers, Film, Wire Insulation and Hollow Tubing 

• Compression Molded Articles (Gears, Rings, etc) 

• Advanced Composites 

• Hot Melt Joining of Various Metals 

• Flame Sprayed Protective Coatings 

• Multilayer flexible and Semi-rigid Circuits 

LaRCTM-SI coated 

pacemaker lead wires 

LaRCTM-SI mechanical parts 
NASA’s LaRCTM-SI: Medtronic Pacemaker Lead 

SI Polyimide (SI-PI) is a 

unique polyimide developed 

by the NASA Langley 

Research Center. The 

material was specifically 

created by NASA to withstand 

harsh environments and 

extreme temperatures. SI 

Polyimide has all the features 

of conventional polyimide, 

plus the added benefits of 

hydrolytic stability and selfadhesiveness. Medtronic 

optimized the wire coating 

process, enabling SI 

Polyimide to be applied for 

the first time to an 

implantable medical device.” 

- Medtronic 

“Surgeons wanted us to develop small diameter leads that could 

navigate the intricate curves of the heart’s left side. The common 

wisdom in the industry was that silicones and polyurethanes were the 

only available materials with properties acceptable for insulating leads. 

But, with those materials, it was extremely difficult to design a truly 

small lead. It seemed that this new polyimide might open the way to 

smaller leads and provide better therapy for heart failure patients.” 

 - Ken Brennen, Medtronic 
NASA’s LaRCTM-SI: Medtronic Pacemaker Lead 

http://www.youtube.com/user/TechnologyGateway#p/u/7/uCw26BFRYVw 
Collaboration Opportunities 

Seeking potential licensees to serve as commercial partners 

Material Characteristics: 

Biologically inert 

FDA-approved 

Moisture resistant 

Radiation resistant 

Resistant to oxidation 
Contact Information 

Rheal P. Turcotte

Partnership Development Manager 

757-864-8881 

rheal.p.turcotte@nasa.gov 

Moline K. Prak

Technology Manager 

757-864-7579 

moline.k.prak@nasa.gov 

For further information, please contact: