Environmentally Benign Manufacturing in Massachusetts: Green Chemistry and Biotech Solutions

1. Environmentally Benign Manufacturing in Massachusetts: Green Chemistry and Biotech Solutions “Alternative EPS Blowing Agents” Justin Whitfield and Timothy Connelly Center for Green Chemistry University of Massachusetts Lowell Summer 2005

2. Background Information • The Massachusetts OTA has identified pentanes emissions from EPS plants to be potentially hazardous and, as a result, may possibly be restricting manufacturing in the near future. The particular company involved in this case study is CBIS-Korfill of Brookfield, MA. According to the company, they are currently at the halfway point for allowable pentanes emissions. In this endeavor, projected cost and “green-ness” are two design priorities.

3. Expandable Polystyrene (EPS) • The EPS that this company uses contains an average of 6% pentanes by weight. • Merely lowering the petanes % does not yield desirable material properties. • The price of EPS has increased over the past year from $0.57/lb up to $0.97/lb • TGA (thermogravimetric analysis) and DSC (differential scanning calorimetry) are our main analysis tools.

5. Our Approach • In order to replace pentanes in EPS, a solvent with similar chemical properties must be found. • By heating EPS in the hot vapor of a solvent similar to pentanes, which is already present in EPS up to 6%, we could possibly infuse EPS with that solvent, test its properties in the regular and expanded states, and then compare those properties with the properties of the original EPS in both its regular and expanded states. • Later on, we hope to perhaps reengineer the synthesis of the EPS beads to avoid pentanes infused material all together. • First, keeping the principles of green chemistry in mind, we gathered data on potential solvent candidates.

6. Some Possible Solvents

7. Another Option… Super Critical CO2 SC CO2 is carbon dioxide that is heated above its boiling point using very high pressures. In this super critical state, CO2 takes on very interesting properties. SC CO2 may also be used as an alternative blowing agent. However this requires a complete revamping of the manufacturing process which is not within the scope of what we are pursuing in our design. This may be a worthy pursuit in the near future.

8. Steaming • Initial testing involved containing sample material over a beaker of boiling solvent. Expansion was also achieved using a handheld steamer (Scϋnci 900). • TGA’s were taken after this process, then again after expansion with steam. • Tested Solvents: • EtOH • MeOH • Ethyl Acetate • Ethyl Lactate • Hexanes

9. Steaming Setup

10. RotoVap • Sustained high temperature solvent vapor infusion was accomplished by using a rotary evaporator. • This testing was applied to EtOH, MeOH, Ethyl Lactate, and Hexanes. • Hexanes once again gave us positive analytical results. • The physical appearance of expanded PS and hexanes-expanded PS are quite different, the following TGA’s are examples of some of the positive results from using hexanes.

11. Expanded Normal vs. Expanded Hexanes

12. TGA TGA

14. Microwave • Using the sealed reaction vessels of our microwave reactor, we were able to achieve solvent temperatures previously unattainable. • EtOH, MeOH, Ethyl Lactate, and Hexanes were heated at 100oC for up to five minutes.

15. Microwave Results • After microwaving, the EtOH and MeOH infused EPS did not expand with our traditional water steam method, but the hexanes EPS did. Ethyl lactate dissolved EPS and therefore no analysis was pursued. The following TGAs represent our data for unexpanded EtOH, MeOH, and hexanes EPS and expanded hexanes EPS.

20. More Information… • After expanding hexanes EPS, density was calculated to be: 3.12 lb./cu.ft. • Desired density according to CBIS: 1.00 lb./cu.ft. • 1 L of hexanes costs about $21.00 • 1 L of n-pentanes (98%) costs about $20.00

21. DSC Analysis We used the DSC to compare the Glass Transition Temperatures (Tg) of: EPS Expanded EPS Hexanes EPS Expanded hexanes EPS

22. Normal EPS and Hexanes EPS (Tg) Compared

23. Expanded EPS and Exp. Hexanes EPS (Tg) Compared

24. Conclusion(s) • Through extensive thermal testing, hexanes appears to be the only solvent to yield positive results. • Though the environmental benefits of hexanes over pentanes is debatable at best, the cost is quite similar. • Hexanes is not a viable alternative for pentanes. Therefore further research on other viable solvents must be conducted. • This testing has proved as a model for our research methodology.

25. Future Work • Exploration of the loss of pentanes from EPS over time during storage.

27. Future Work • Exploration of the loss of pentanes from EPS over time during storage. • Exploration of relationships between EPS bead size, pentanes % and final product density. • Green Chemisty and Biotech? • EPS is not a sustainable material. • EPS is not a biodegradable material. • CGC is working on biodegradable and enzymatically degradable polymers that hopefully one day could ultimately replace such materials as EPS.

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