Binary Colloidal Alloy Test Low Gravity Phase Kinetics-1-Product Shelf Life (BCAT-KP-1-Shelf Life) - 07.29.14
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Binary Colloidal Alloy Test - Kinetics Platform-Shelf Life (BCAT-KP-1-Shelf Life) enables industrial scientists to investigate the physics of colloid phase changes in microgravity. Colloids are suspensions of small particles evenly distributed throughout a solution, and examples range from detergent to milk and are greatly affected by gravity on Earth. A greater understanding of colloid kinetics could lead to products with longer shelf lives, benefiting consumers and industries on Earth.
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ZIN Technologies Incorporated, Cleveland, OH, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
National Laboratory (NL)
Earth Benefits, Scientific Discovery
ISS Expedition Duration
September 2013 - September 2014
Previous ISS Missions
- This application describes the development and deployment of a colloidal investigation platform, the Binary Colloidal Alloy Test Low Gravity Phase Kinetics Platform (BCAT-KP). The applicants identify characterization of phase kinetics for emulsions in a low gravity environment as a major application area, citing the low gravity environment as an idealized condition in which to examine attractive colloidal systems for optimal product shelf life. The application described a device with 10 sample chambers that allows parametric studies of variations in particle size and functionalization in generating phase maps. Specific solvent mixtures to allow buoyant matrix, similar to those corresponding to ground studies, are utilized along with non-buoyancy-matching solvents to greatly expand the knowledgebase of phase transitions in colloids. Mixtures are photgraphed using fluorescence and a Nikon digital camera currently mounted in WORF. Alternate imaging modalities are not explored.
- The formation of ordered phases in colloidal suspensions is profoundly affected by gravity via sedimentation processes. Chaikin and Russel demonstrated this effect in space experiments; their experiments explored the simplest of all entropic transitions, the hard-sphere liquid-solid phase transition. There are many ways to understand the reasons for the difficulties posed by gravity. Sedimentation causes particles to fall so rapidly that there is insufficient time for particles to explore the full phase space of positions and velocities that are required for thermodynamic assembly processes. In a different vein, a substantial particle concentration gradient arises in the earthbound sample. In the given samples the gravitational height, h = kT/ΔρVg, ranges from a few microns for the case of polystyrene in water to a fraction of a micron for some of the other particles considered. Here k is the Boltzmann constant, T is temperature, Δρ is the density difference between the particles and the background fluid, V is the particle volume, and g is the gravitational acceleration on the Earth’s surface. This height is typically much smaller than the sample size. In addition, the shear forces of fluid flow, due to the sedimentation of particles, are often sufficient to breakup crystals that are forming thermodynamically not allowing the scaling and understanding to a wider variety of compositions.
- One reason Procter and Gamble is involved in this proposal is their interest in understanding phase separation kinetics of colloids, which is masked by gravity on Earth. The small blobs that form and grow in microgravity, instead of the simple top and bottom phase seen on Earth, allow the kinetics of this process to be recorded in microgravity. The scientific findings allow one to believe that additional results from having this data available can, and likely will, lead to more efficient/improved product formulations which are less expensive to produce and/or provide longer shelf life. For a product like Downy, which sells about $4B worth of product a year, even a small 1% savings in production costs or allowing a longer shelf life provides a significant return on the investment. P&G, which is represented by one of the research scientists on this proposal, will spend $10M this year on research to address product shelf life problems. The results of this work can impact far more than fabric softener.
- The other colloidal samples described have similar potential but have a more long-range commercialization potential through development of new suspension materials and their Intellectual Property protection. Their material formulations and suspension intellectual property have resulted in several patents, and could lead to new companies and license revenues for their organizations. The opportunity to establish new models and formulations through low gravity investigations cannot be replicated or achieved on Earth and provide unique commercialization potential to these inventor/investigators and their organizations.
The BCAT-KP investigation and SGM series objectives are to provide a macro colloidal phase kinetic platform allowing fast turnaround for colloidal investigations to examine equilibrium conditions that result in colloidal crystallization, melting and self-organization. This BCAT-KP provides colloidal investigators recurring opportunities for each 3 month ISS Increment giving the U.S. its first fast turnaround physical science platform offered through CASIS. These colloidal systems and the ability to support a series of multiple samples allows for parametric investigation of colloidal suspension structures enabling characterization of phase maps that cannot be produced on Earth at size scales of commercial and scientific interest. The equilibrium state and progression toward that are different for different types of samples. Phase separation samples may ultimately evolve into two distinct phases. While this happens quickly on Earth, the gradual evolution to this state in microgravity is especially important when it comes to understanding and designing new emulsions for longer product shelf life or for new material development, this coarsening behavior and the rate of coarsening of attractive colloid systems is of special interest providing valuable data to design new material emulsions.
For the proposed phase separation samples, the objective is to measure phase separation rates in microgravity (u-g) to develop an underlying theory for predicting product shelf life (P & G) and for colloidal material engineering having scientific and commercial interest. The first set of samples investigate colloidal collapse [irreversible separation] which occurs on Earth and must be mitigated with expensive particle additives. The solution to this problem is a series of non-optimal trades between more particles to jam system (expensive) versus greater attraction properties to gel system having undesired rheological properties. Researchers intend to photograph initially randomized colloid samples to determine their resulting structure over time. Theory tells that one can adjust the rate of phase separation by changing the amount of polymer in the solution of polymethyl methacrylate (PMMA) spheres. Doing this adjusts the depletion attraction force between particles. This gives a window into the underlying physics that is not open on Earth where only a top and bottom phase is visible. The results are of particular relevance to product manufacture and production designs for the pharmaceutical, food and cleaning industries (in terms of shelf life and mechanical and thermodynamic properties).
Binary Colloid Alloy Test (BCAT) investigation helps scientists characterize the underlying physics of colloidal materials, including how particles clump and sink inside a liquid. Colloidal mixtures form small blobs in microgravity, rather than the clear distinction between top and bottom that occurs in the presence of gravity on Earth. Examining how these clumps form and grow can provide unique insight into the physics of this process. The BCAT hardware has potential for commercial use in space, and the investigation also lays a foundation for research in nanotechnology and nano-mechanical systems in microgravity.
Understanding the physics of colloidal materials, including how they separate into distinct layers, can help scientists develop more stable colloidal mixtures that have longer shelf lives. But the kinetics of this process are masked by gravity on Earth, making it difficult to study even with powerful computer simulations. The BCAT investigations allow scientists to monitor colloidal materials’ behavior over time, which will shed light on the physics involved as well as provide data to improve computer models. Ultimately, improved colloidal materials may last longer and cost less to produce, which will benefit a wide range of consumers and industries.
BCAT consists of a set of ten small samples of colloidal particles. The BCAT samples are each contained within a small case the size of a school textbook. The experiment requires a crew member to set up the experiment using a handrail/seat track configuration, ISS Laptop and the Kodak 760 or Nikon D2Sx camera to take digital photographs of the samples at close range. The pictures are down-linked to investigators on the ground for analysis.
The current plan for this experiment is to conduct it over a 7 or 14-day session, each of which can be run incrementally and require a minimum amount of crew time due to powering the digital camera with the new AC power available through the inverter to be available in 2012; a third session to mix and photograph all 10 samples and then a fourth session, prior to the increment completion and bringing the samples down for the next increment set of hardware, to photograph all ten samples which is slotted to take a minimal amount of crew time. As such, new information will undoubtedly be learned, and the nature of the experiments conducted will evolve to take advantage of this new information.
Session 1: Set up hardware, take baseline photos of all ten samples; homogenize samples 6-10 then samples 9 and 10, then automatically photograph sample 1 (using EarthKAM software on laptop) every hour for 7 days. Perform sample 1 daily status check each day. After seven-day run, perform crystal search/photography on 6-10. Homogenize sample 2, automatically photograph sample 2 (using EarthKAM software on laptop) every hour for 7 days. Perform sample 1 daily status check each day. After seven-day run, perform crystal search/photography on 6-10. If necessary, tear down after operations are complete but keeping setup intact is preferred to save crew time.
Session 2: Set up hardware, homogenize samples 3, 4 and 5 one at a time then automatically photograph each sample (using EarthKAM software on laptop) every hour for 14 days each. Perform Crystal Check and Photography procedures on 6-10 if crystals not found/photographed in Session 1. If necessary, tear down after operations are complete but keeping setup intact is preferred to save crew time.
Session 3: Homogenize and photograph samples 1-10 (using EarthKAM software on laptop) and stow sample module for six months. The experiment is torn down after operations are complete.
Session 4: At the end of increment after homogenization, manually photograph samples 1 through 10. Re-stow sample module and tear down after operations are complete