44th International Conference on Environmental Systems Paper Number 13-17 July 2014, Tucson, Arizona

Non-Flammable Containment Bag and Enclosure Development for International Space Station Use

David P. Cadogan 1 and Sunil Inamdar 2 ILC Dover LP, One Moonwalker Rd., Frederica DE, 19946

Erica S. Worthy 3 NASA, 2101 NASA Pkwy, Houston, Texas 77058

I. Abstract

Work conducted on the International Space Station (ISS) requires the use of a significant quantity of containment bags to hold specimens, equipment, waste, and other material. The bags are in many shapes and sizes, and are typically manufactured from polyethylene. The amount of bags being used on ISS has grown to the point where fire safety has become a concern because of the flammability of polyethylene. Recently, a new re-sealable bag design was developed and manufactured from a specialized, non-flammable material called ArmorFlex™ 301 specifically for this application. ArmorFlex™ 301 is also FDA compliant, clear, flexible and damage tolerant. The bags can be made with a closure mechanism similar to that of a ZipLoc ® bag or can be open top. Sample Flex- Loc™ bags were laboratory tested by NASA to verify materials properties and evaluated by astronauts on the ISS in 2012. Flex-Loc™ bag manufacturing will commence in 2014 to support a transition away from polyethylene bags used on ISS. In addition to resealable bags, other larger containment systems such as flexible gloveboxes, deployable clean rooms, and other devices manufactured from ArmorFlex™ 301 are being explored for use on ISS and in similar confined space locations where flammability is a concern. This paper will describe the development of the ArmorFlex™ 301 material, the Flex-Loc™ bag and other containment systems being explored for use in confined areas.

II. Introduction iploc ® bags are one the most common used items on the International Space Station 1 (Figure 1). They are Zprimarily used for stowage, transport, and containment of a number of materials ranging from materials for experiments, to waste products. The benefits of using Ziploc ® bags include availability in many sizes, ease of opening and closing, easy of temporary stowage in ISS, optical clarity for easy recognition of contents, ease of labeling and protection of contents from external harmful agents. Ziploc ® bags also offer containment by providing some level of barrier between contents of the bag and astronauts. However, the versatility and ease of use of commercially available polyethylene Ziploc ® bags is marred by their flammability. Therefore, when used in large quantities on ISS they pose a severe fire safety risk. This risk resulted in the development of a non-flammable alternative to the Ziploc ® bags currently in use.

No non-flammable bag alternative was commercially available. Several material candidates were considered for use in the construction of new resealable, non-flammable bags. The non-flammable alternative bag are needed in multiple sizes, must be easy to seal and able to maintain its seal be transparent so that items within the bag can be easily identified, be visually differentiated from the existing bags, and be compliant with NASA’s materials requirements in NHB 8060 2. Enhanced barrier properties were also desired for the new bag.

1 Director Engineering, ILC Dover LP, [email protected] 2 Lead Materials Development Engineer, ILC Dover LP, [email protected] 3 Assistant, Structural Materials, NASA, erica.s.worthy@nasa.gov

Figure 1. Examples of the use of polyethylene storage bags on ISS. Astronaut Don Pettit’s space Zucchini – Astronaut Sandy Magnus showing citrus fruit storage - Astronauts Michael Fincke, Sandra Magnus and cosmonaut Yury Lonchakov at dinner on ISS. Images courtesy of NASA.

ILC Dover was engaged by NASA to develop a new resealable, non-flammable bag because of previous experience in space suit design & manufacture, and with understanding material interface and acceptance requirements for use inside the ISS. ILC Dover has extensive experience in developing and producing thin-film containment systems and specially tailored materials for the pharmaceutical & biopharmaceutical markets. This experience was leveraged to develop several material candidates and trade them against system requirements. A new barrier film called ArmorFlex™ 301 was developed and converted into roll-goods and resealable closures that could be used in the construction of the new ISS bags. The new Flex-Loc™ bags were constructed, laboratory tested, and then evaluated on ISS.

Feedback from the on orbit evaluation and the Crew Office was used for the development of an improved bag. . The level of containment and protection offered by the Flex-Loc™ bags makes them ideal for confined space use such as on ISS, but also for use in submarines, biomedical research labs, aerospace applications, etc.

III. New Storage Bag Requirements The operational requirements as supplied by NASA for storage bags used on ISS are listed below:

• Opening and sealing: The storage bags need to be easily opened and sealed without requiring any assisting tools. The integrity of the seal should be comparable to a Ziploc ® bag.

• Multiple use cycles: The bags should be reusable and should remain functional for multiple uses.

• Robustness: The bags must be resistant to damage under the conditions of use on ISS.

• Handling: The astronauts should be able to open and seal the bags while wearing laboratory gloves. The bags shouldn’t be too slippery to make them difficult to operate, or exhibit high levels of tack (or blocking) that would make insertion & removal of material difficult.

• Sizes: 10 sizes ranging from 2 in.x2 in. up to 36 in.x36 in. and have scalable, cost-effective design.

The resealable bag l is used to contain and hold tools, chemical waste, food, medicine and other waste, and must meet many requirements (Table 1). The film needs to be tough with an elongation-to-break of greater than 300% and tensile strength of greater than 3500 psi, similar to polyethylene. The bags will be used to store various chemical containers, various chemical reaction products and cleaning materials. Hence the film material needs to be chemically inert and resistant to degradation from exposure to a wide range of chemicals. To contain food and medicine, the film needs to be clean and FDA approved. To be considered a candidate, the material must meet flammability criteria in NASA-STD- 6001, Test no.1 upward flame propogation 3. Samples were tested in 24.1% oxygen which is the environment on ISS. To see and identify the items in the bag, the film needs to be optically clear or see-through clear with an acceptable level of Haze and Optical transmission. Thousands of bags are used at 2 International Conference on Environmental Systems

any point in time on Space Station, and the bag material must meet an acceptable level of offgassing per NASA- STD-6001, Test no.7, which specifies toxicity limits.

Material Property Requirement Tensile Modulus Equal to Polyethylene or minimum 3500 psi Elongation Equal to PE or minimum to 300% Chemical Resistance Similar to Polyethylene (resistance to physical or chemical attack of same chemical list) Food Contact Approved Yes - 21 CFR 174 - 21 CFR 190 Flammability NASA-STD-6001B, Test no.1 upward flame propagation Optical Similar to Polyethylene in transmittance and haze ASTM-D1003 Toxicity NASA-STD-6001B, Test no. 7

Table 1: Material Requirements for non-flammable bags

IV. Flex-Loc™ Development The development team approached the challenge by identifying several conceptual configurations for resealable bags, and identifying or creating materials options. The concepts were then evaluated in a trade study and the leading candidates were identified. The requirements were used as the evaluation attributes in the trade studies, and each was assigned a weighting factor to emphasize the most critical needs. Once the leading candidate materials and bag configurations were identified, samples were made and testing conducted to select the final design.

A. Bag Configuration Concepts

The first decision point in the configuration discussion was whether to consider three-dimensional configurations (as with a paper grocery bag or a cylindrical bag with a round base. In some cases, these bag configurations can offer advantages in support during filling or handling operations. However, these characteristics are not as valuable in the microgravity environment, so only flat bags were considered. The use of tube stock was considered for the manufacture of the bags to reduce seaming (cost & risk), but since numerous sizes are required this was not economically viable. The configuration selected was two flat sheets sealed around three edges, with a closure mechanism on the opening end.

Several options for closure mechanisms were considered: • Ziploc ® or similar (interfacing plastic male/female extrusions) type • Stiffener plate(s) at opening, fold and fasten with hook & loop • Stiffener plate(s) at opening, fold and fasten with resealable pressure sensitive adhesive • Stiffener plate or rod at opening, fold and fasten with a clip • Bunch, fold and lock-down with an elastic band

All of the options considered could be engineered to meet most or all of the requirements. However, the zippered seal type closure was selected because of its familiarity in operation and cost advantages in production. A dual interlocking extrusion system was selected over a single interlocking extrusion for purposes of redundancy in the sealing feature.

B. Material Concepts

Development of a material that would meet and exceed all of the performance requirements for the nonflammable bags was challenging. Not only did a film have to be developed for the bag material, but the same basic material needed to be able to be extruded into complex shapes to form the closure mechanism.

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To meet this challenge, the team leveraged materials development experience of highly regulated industries including Pharmaceutical and Bio-pharmaceutical manufacturing 4. For example, ILC Dover developed several specially formulated ArmorFlex™ film materials (104, 110 & 114) that meet the stringent US Food & Drug Administration (FDA), European Food and Pharmacopeia USP Class VI requirements for product contact during the manufacturing process 5. These materials also met the stringent safety protocols outlined by the International Electro-technical Commission (IEC) 61340-4-4 specification for static dissipative characteristics. From a usability perspective, these materials aid in ease of handling and use by providing low coefficient of friction, optical clarity and physical toughness. Much of the same development techniques required to realize these complex films used in the pharmaceutical manufacturing industry were used in the development of the ArmorFlex™ 301 film for the Flex- Loc™ bags, including formulation, special processing, and test.

Several other material candidates were considered prior to determining that a special formulation was warranted. These included:

1) Fire Retardant (FR) Polyurethane (PU). The concern with this approach was in meeting the toxicity limits with components that might offgass. A concern was also raised with plasticizer migration that could contaminate the contents of the bags. A Nylon or Saran layer in the laminate was considered to provide barrier properties. A film similar to this (ArmorFlex 101 – PU/Saran/PU) for NASA JSC on the TransHab program.

2) Fluorinated Ethylene Propylene (FEP). This material, more commonly known as Teflon®, is more challenging to weld to itself but will meet all the materials properties. This material is non-flammable, but concerns still exist over offgassing materials and toxicity limits, and is costly to produce.

3) Polyethylene/nylon laminates. This uses Nylon (or some other FR material that can be laminated to Polyethylene) as the exterior of the bag to act as a FR layer. This approach has considerable risk since it does not specifically comply with all the requirements for the new bags.

4) FR Polyethylene with a non-FR Polyethylene window or side of the bag. This was seen as a simple way to reduce the quantity of flammable Polyethylene on ISS. This material was not seen as a completely nonflammable material.

A trade study of the base materials considered was conducted to assist in the identification of an optimal solution (Table 2). The material concepts are traded against the leading requirements. Weighting factors are applied to the requirements to emphasize the most important issues, such as flammability. Each area was scored from one to ten, with ten being the more positive.

Formable into Easily Non- FDA Clear for Cycle-life / Material Ziploc® Thermally Barrier Offgassing TOTAL Flammable Compliant Visibility Robustness Closure Weldable Weighting Factor 1 1 0.6 0.6 0.6 0.4 1 0.7

ArmorFlex ™ 301 10 10 10 10 10 7 9 10 56.8 Halar ® (ECTFE) 10 8 2 10 10 7 9 7 47.9 Polyethylene (Baseline) 0 10 10 10 10 3 9 10 45.2 Silicone 10 8 7 10 10 4 3 6 43 Saranex ® 0 5 10 10 10 9 10 9 42.9 Teflon ® 10 0 4 10 10 4 10 9 42.3 Polyurethane (FR) 10 10 10 0 2 1 0 10 34.6

Table 2: Material Candidates for Nonflammable BagTrade Study

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Several new base polymers were considered and eventually a proprietary formulation was developed for use, and ArmorFlex™ 301 was created specifically for this application (Table 3). Halar® showed promise but was not thermally weldable so low-cost construction was not possible, and it was therefore eliminated. The flammability of polyethylene, the purpose of this development, eliminated it from consideration. Silicones were eliminated due to offgassing considerations. Saranex® was eliminated from consideration because it couldn’t be extruded into a Ziploc®-type closure mechanism and it is flammable. Teflon® was eliminated because it couldn’t be extruded into a Ziploc®-type closure mechanism and it is difficult to thermally weld. ArmorFlex™ 301 was reformulated a few times during development to enhance handling properties and eliminate toxicity concerns. The film was accepted from a handling perspective and was evaluated for offgassing at WSTF.

Physical Properties Test Method ArmorFlex™301 Elongation at Break MD,% ASTM D 412 624 - Pass Ultimate Tensile Strength, MD, psi ASTM D 412 6120 Ultimate Tensile Strength, CD, psi ASTM D 412 6331 2% Secant Modulus, MD, psi ASTM D 412 74945 - Pass 2% Secant Modulus, CD, psi ASTM D 412 80267 - Pass Tear Strength, MD, lbs/in ASTM D624-91,Die C 1026 Tear Strength, CD, lbs/in ASTM D624-91,Die C 1010 Puncture Resistance ( Tip Force ) , lb. FED STD 191-5120 16.2 Puncture Resistance ( Tip Travel ), in FED STD 191-5120 2.2 Flammability NASA 6001, Test no.1 upward flame Pass propagation Optical Similar to Polyethylene in transmittance and Pass haze ASTM-D1003 Toxicity NASA-STD-6001B, Test no. 7 Pass Food Contact Approved 21 CFR 174 - 21 CFR 190 Pass Chemical Resistance Similar to Polyethylene (resistance to physical Pass or chemical attack of same chemical list) Thickness mil 3.06

Table 3: Typical Physical Properties of ArmorFlex™301 Film

Regulatory Information:

• The base resins used in a) the film and b) the closure component, are compliant with the appropriate section (21 CFR 177.2600) of the FDA regulations, as supplied in pellet form. • The base resins used have been tested and pass USP <88> (Class VI testing), as supplied in pellet form. Additional testing has not been performed on the finished film or closure component. Therefore, no test data is currently available.

Chemical Resistance:

• The material is resistant to strong acids, strong bases, salts, halogens, halogenated solvents, alcohols, nuclear and UV Radiation, oxidants. • The film also provides excellent barrier properties to various gases like water vapor, helium, oxygen, carbon dioxide and nitrogen. • The film provides excellent chemical permeation resistance to various acids, bases, alcohols, halogenated solvents and oxidants. • The film also provides excellent antifungal and antimicrobial properties.

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Toxicity:

The ArmorFlex 301 material was tested for outgassing and toxicity at NASA White Sands Test Facility (WSTF). A limited set of ArmorFlex 301 bags were flown on ISS under a Materials Usage Agreement (MUA) for toxic offgassing with NASA in 2012. After extensive testing and analysis on film and bag samples using different resins JSC and WSTF M&P determined that despite a reduction of known toxic offgassing components, the unidentified fluorinated constituents could not be eliminated. Bake out conditions did not reduce or drive off unidentified compounds. Unidentified compounds receive a very conservative default Spacecraft Maximum Allowable Concentration (SMAC) value of 0.1 which impacts the amount of material that can be safely flown on orbit. SMAC values are used to provide guidance on allowable chemical exposures during normal operations and emergency situations. WSTF identified two out of several unidentified fluorinated constituents using a nonstandard gas chromatography method. JSC Toxicology provided updated SMAC values for those two compounds and based on the new data the Project would still require an MUA for offgassing. However, considering the free volume of the US segment of ISS, the JSC Materials and Processes and Toxicology determined that more than enough resealable ArmorFlex 301 bags in any combination of bag sizes can be safely used to replace the polyethylene bags. The results below are representative of the offgassing components.

C. Closure Development

The different design configurations for storage bags were evaluated against the polyethylene sealable bags currently used by the Space station crew. The development of the ArmorFlex™ 301 enabled ILC to use mimic the simple and effective design of the polyethylene bags, and maintain a high-level of crew familiarity with their operational characteristics. Therefore, a unique extruded polymer closure device was developed as depicted in Figure 2. The closure mechanism and material were designed to have the desired physical characteristics as described in Table 4. Based on crew evaluation of the test group ArmorFlex 301 bags flown on ISS in 2012, some improvements to the sealing mechanism needed to be made. The zipper portion of the bags was dyed so that crew could differentiate the nonflammable bag from a polyethylene one. The crew preferred that no dye be used and asked for a better sealing mechanism. During development of the second generation bag, the bag material was reformulated to improve the zipper. Bag prototypes using a polymeric lubricant to aid with sealing were evaluated by the JSC Crew Office. The evaluation of the improved nonflammable bag with was very positive and large scale manufacture will be based on the approved prototype.

Attribute Benefit Extended flanges outside of closure Ease of operation with & without gloves Slip agents in closure formulation Ease of operation & seal integrity Inner hinge on closure mechanism (bag side) Secures the bag from accidental opening by movement of contents inside the bag Coloring of closure mechanism Differentiation with standard Ziploc® bags Dual extrusion of the closure mechanism Redundant seal feature

Table 4: Typical Physical Properties of ArmorFlex™301 Film

V. Flex-Loc™ Bag Manufacture & Test

The ArmorFlex™ 301 material is a thermoplastic where film is extruded from resin pellets using conventional plastic melt processing equipment . Melt extrusion techniques were employed in manufacturing for both the film and the closure mechanism. In film extrusion, a flat die is utilized at the end of an extruder, to create a sheet of film that is then rolled for transport. A profile die is used to provide the necessary shape to the molten plastic at the end of the extruder to manufacture the closure mechanism. The Flex-Loc™ bags were made from sheets of film extruded to 3 mils in thickness, but thicker films are possible for more durable bag assemblies if required.

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The resulting film and profile are then cut to the necessary dimensions and heat welded to create a bag using thermal impulse sealing. In this technique heat is applied to melt the interfaces to be welded and is held under pressure for a certain time for the materials to fuse and solidify together. The resulting weld is very robust and retains the majority of the original strength of the materials being combined.

Several process parameters including time, temperature and pressure were analyzed for seam consistency and strength. Many seam samples were made at different process settings and tested for physical strength. Based on the data, one set of conditions and ranges was selected and programed into the machine. A larger sample set of the seams was made utilizing the process settings chosen to establish limits and tolerances.

Bag samples were made utilizing established process setting and sent to NASA for comments. The bags were evaluated for Figure 2. Rendering of the Flex-Loc™ ease of use, robustness and optical characteristics in Closure Mechanism Design laboratory testing. They met NASA’s expectations and subsequently were sent to the Crew Office for evaluations at NASA JSC. The crew evaluated the bags for operational characteristics including ease of opening/sealing, stiffness, amount of grip/slip inside and out, etc. Feedback from the crew was positive and samples were prepared to be tested on ISS.

On July 20 th , 2012 Flex-Loc™ samples were launched on Japan’s robotic HTV-3 cargo spaceship from Tanegashima Space Center in southern Japan. The spacecraft carried supplies for the International Space Station, including the new bags for test.

Results of testing on ISS indicated that the closure mechanism was slightly stiffer than desired. The resulting effect was that the bags were operationally different from the standard polyethylene bags and required the crew to use new methods which was not preferable. Therefore, the closure material was reformulated to create identical performance to the existing bags in stiffness and operation, and the test loop was repeated. Subsequent testing for handling the bags was positive and the bags were approved for use. Production of the Flex-Loc™ bags for use on ISS will begin in late 2014.

VI. Summary

Polyethylene bags are one the most common used items on the International Space Station (ISS) for storage of food, waste, supplies and other materials. These bags are an integral part of operations on ISS but pose a hazard because of their flammability. A new non-flammable material known as ArmorFlex 301™ was developed and used in the construction of a resealable storage bag called Flex-Loc™. The new bag has been tested and validated in laboratory testing and tested on the ISS. The materials have also been qualified by physical properties testing and MATCO testing at NASA WSTF. The scalable bag design will start production in 2014 and begin use on ISS in 2015. The non-flammable nature of the Flex-Loc™ bags will improve ISS safety by reducing the quantity of flammable materials onboard. The newly developed ArmorFlex 301 will enable the development of new larger containment systems such as glovebags for use on ISS, or other confined space use applications, where flammability is an issue.

VII. References 1Mann, Hallie, “A Taste of Space”, NASA Johnson Space Center Features article, August 27, 2009. http://www.jsc.nasa.gov/jscfeatures/articles/000000853.html 2Flammability, Odor, And Offgassing Requirements And Test Procedures For Materials In Environments That Support Combustion, National Aeronautics and Space Administration Office of Safety and Mission Quality, NHB 8060.1B, http://www.dtic.mil/dtic/tr/fulltext/u2/a338807.pdf, May, 1988. 7 International Conference on Environmental Systems

3Flammability, Offgassing, and Compatability Requirements and Test Procedures for Materials in Environments that Support Combustion, NASA-STD-6001, http://nepp.nasa.gov/DocUploads/3CCCD952-3372-4220- ADD6185688CCBC3E/NASA-STD-6001.pdf, February 9, 1998. 4George, A., “Flexible Solutions Broaden Containment Options”, Pharmaceutical Online, February 27, 2007. 21 CFR 177.2600. 5George, A., “Key Regulatory Considerations For Flexible Containment Systems”, Life Science Leader, December 2009.

VIII. Acknowledgements

The authors would like to thank NASA for funding this work, NASA White Sands Test Facility for providing high- quality test support, and the astronauts of Expedition 32 for testing the new bag configurations aboard the International Space Station. Also, Project Manager Philip Watters, Lockheed Martin IS&GS, Bioastronautics Contract Flight Hardware Department.

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