Environmentally Benign Manufacturing in Massachusetts: Green Chemistry and Biotech Solutions

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

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.

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.

1.723% expanded state(0.08088mg)

3.565% normal state as of June(0.3808mg)

EPS in regular and expanded states

96

97

98

99

100

101

Wei

ght (

%)

80 100 120 140 160 180 200 220 240 260

Temperature (°C)

TGC-I-2-b.002––––––– TGC-I-1-b.001– – – –

Universal V4.1D TA Instruments

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.

Some Possible SolventsBlowing Agent MSDS Chart

Solvent Health Flammability Reactivity Contact bp (C)2-ethylhexanol 2 2 0 183butane 1 4 0ethanol 0 3 0 79ethyl acetate 2 3 0 1 77ethyl lactate 1 2 1 154hexanes 1 3 0 2 68hexanol 1 2 0 2 157methanol 1 3 0 65pentane 2 4 0 2 36pentanes 1 4 0 28t-butanol 1 3 0 82

current useSummer 2005: TGC possible future use

solubilizes EPSexperimental control

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.

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

Steaming Setup

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.

Expanded Normal vs. Expanded Hexanes

6.855% pentanes(0.2658mg) 7.723% pentanes and hexanes

(0.1881mg)

3.565% pentanes(0.3808mg)

EPS when received, EPS as of June, hexanes EPS

90

92

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96

98

100

102

Wei

ght (

%)

0 50 100 150 200 250 300 350 400

Temperature (°C)

EPS(3-4-05).001––––––– TGC-I-3-hgood.001– – – – TGC-I-1-b.001––––– ·

Universal V4.1D TA Instruments

TGATGA

0.8477% expanded hexanes(0.03443mg)

EPS after expansion

1.723% expanded normal EPS(0.08088mg)

98.0

98.5

99.0

99.5

100.0

100.5

Wei

ght (

%)

60 80 100 120 140 160 180 200 220 240

Temperature (°C)

TGC-I-3-a.001––––––– TGC-I-2-b.002– – – –

Universal V4.1D TA Instruments

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.

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.

0.5021% pentanes and EtOH(0.03621mg)

99.4

99.6

99.8

100.0

100.2

Wei

ght (

%)

50 100 150 200 250 300 350

Temperature (°C)

Sample: TGC-I-3-fSize: 7.2130 mgMethod: RampComment: EtOH EPS microwave vacuum dry overnight after fixed tga

TGAFile: C:...\TGA Data\TGC-I-3-f.001Operator: tim new guyRun Date: 2005-06-10 09:15Instrument: TGA Q50 V6.3 Build 189

Universal V4.1D TA Instruments

0.4184% pentanes and methanol(0.01743mg)

98.8

99.0

99.2

99.4

99.6

99.8

100

100.2

Wei

ght (

%)

0 50 100 150 200 250 300 350 400

Temperature (°C)

Sample: TGC-I-3-gSize: 4.1650 mgMethod: RampComment: methanol EPS microwave vacuum dry overnight after fixed tga

TGAFile: A:\TGC-I-3-g.001Operator: tim new guyRun Date: 2005-06-10 11:40Instrument: TGA Q50 V6.3 Build 189

Universal V4.1D TA Instruments

7.723% pentanes and hexanes(0.1881mg)

90

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94

96

98

100

102

Wei

ght (

%)

50 100 150 200 250 300 350 400

Temperature (°C)

Sample: TGC-I-3-hgoodSize: 2.4360 mgMethod: RampComment: hexanes EPS microwave vacuum dry overnight after fixed tga

TGAFile: A:\TGC-I-3-hgood.001Operator: tim new guyRun Date: 2005-06-10 14:00Instrument: TGA Q50 V6.3 Build 189

Universal V4.1D TA Instruments

0.9812% left over pentanes and hexanes(0.01420mg)

98.5

99.0

99.5

100.0

100.5

Wei

ght (

%)

0 100 200 300 400 500 600

Temperature (°C)

Sample: TGC-I-3-h1Size: 1.4470 mgMethod: RampComment: hexanes expanded PS microwave vacuum dry

TGAFile: C:...\TGA Data\TGC-I-3-h1.001Operator: tim new guyRun Date: 2005-06-10 16:00Instrument: TGA Q50 V6.3 Build 189

Universal V4.1D TA Instruments

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

DSC Analysis

We used the DSC to compare the Glass Transition Temperatures (Tg) of:

EPS

Expanded EPS

Hexanes EPS

Expanded hexanes EPS

74.04°C(I)

72.80°C

81.93°C

74.88°C(I)

72.40°C

77.02°C

-0.4

-0.3

-0.2

-0.1

0.0

0.1

Hea

t Flo

w (

W/g

)

40 60 80 100 120 140 160

Temperature (°C)

TGC-I-7-A.001––––––– TGC-I-7-C.001– – – –

Exo Up Universal V4.1D TA Instruments

Normal EPS and Hexanes EPS (Tg) Compared

98.98°C(I)

93.65°C

103.91°C

95.09°C(I)

92.86°C

97.34°C

-0.4

-0.3

-0.2

-0.1

0.0

Hea

t Flo

w (

W/g

)

60 80 100 120 140 160 180

Temperature (°C)

TGC-I-7-D.001––––––– TGC-I-7-B.001– – – –

expanded EPS and expanded hexanes EPS: comparing glass transition states

Exo Up Universal V4.1D TA Instruments

Expanded EPS and Exp. Hexanes EPS (Tg) Compared

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.

Future Work

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

6.715%

3.240%

2.659%

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We

igh

t (%

)

60 80 100 120 140 160

Temperature (°C)

March 4, 2005––––––– May 24, 2005– – – – July 25, 2005––––– ·

EPS Pentanes % Loss by Date

Universal V4.1D TA Instruments

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.

List of References• Schwoegler, Edward J. Impregnating polystyrene beads with a blowing agent. U.S.

(1972), 3 pp. CODEN: USXXAM US 3650992 19720321 CAN 77:6540 AN 1972:406540 CAPLUS

• Corrons Mas, Juan. Expanded polystyrene. Span. (1983), 8 pp. CODEN: SPXXAD ES 515886 A1 19830601 CAN 99:123745 AN 1983523745 CAPLUS

• Schleith, Oskar. Effect of physical blowing agents on foam formation of polystyrene. Schaeume Thermoplast Schmelze (1981), 17-38. CODEN: 46VQAB CAN 96:36173 AN 1982:36173 CAPLUS

• Shekhtmeister, I.E.; Ivanov, V.M.; Deiline, V.I.; Kusheverskaya, S.V. Effect of storage time of expandable polystyrene properties. Plasticheskie Massy (1983), (6), 24-5. CODEN: PLMSAI ISSN: 0554-2901. CAN 99:71563 AN 1983:471563 CAPLUS

• Rode, Daniel J.; Greenawald, Glenn. Expandable polystyrene impregnated with a hydrocarbon blowing agent. U.S. (1967), 4 pp. CODEN: USXXAM US 3342760 19670919 CAN 67:100717 AN 1967: 500717 CAPLUS

• Kawaguchi, Yasuhiro; Oishi, Tsutomu. Journal of Applied Polymer Science. Vol. 93, 505-512 (2004)

• Daigneault, Louis; Gendron, Richard. Journal of Cellular Plastics. Vol. 37, (May 2001).

• Crevecoeur, J.J.; Coolegem, J.F.; Nelissen, L.; Lemstra, P.J. Polymer 40. 3697-3702 (1999).