Progress 09/15/03 to 09/15/07
Outputs
This project was submitted together with another sister project titled "Production and Characterization of Low-Cost Biodegradable Polylactic Acid Using Cheese Whey" (Dr. Shahbazi PI, J. Lou Co-PI) in 2003 but the latter was rejected in 2003 and later funded in 2004. These two proposals were designed to compliment each other by having distinctive focuses, one on (1) production of and the other on (2) characterization of agriculturally-derived biodegradable polymer. This project focuses on the characterization of the biodegradable polymer. The activities began with the synthesis of biodegradable polymer polylactic acid. The lactic acid was polymerized by direct catalyst polycondensation in a Parr Instrument laboratory-scale stainless-steel vacuum reactor equipped with solvent reflux and temperature control. The polymer was isolated and purified. A series of characterization procedures were followed. Gel-permeation chromatography (GPC), Fourier transfer infrared
spectroscopy (FT-IR), differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA), X-ray Defractioniometer (XRD), capillary rheometer (CR) were used to determine the molecular weight distribution, the chemical structure, the glass transition, the thermooxidative stability, the crystalline morphology, and the polymer processing viscosity, respectively. An ASTM D638 mold was built in this project to make polymer dog-bones by injection molding machine. The mechanical properties of the polymer were determined using an Instron universal testing frame. Two biodegradable polymers, polyvinyl alcohol (PVOH) and polylactic acid (PLA) were studied for biodegradability. Biodegradation experiments were performed in two environments - slurry and compost. In the slurry experiment, a 16-cell respirometer system (AER-200 aerobic/anaerobic respirometer) was used to determine the oxygen consumption of the biodegrading reaction. This system provided a slurry environment in which the
samples could be quickly degraded and monitored in terms of the gas-phase oxygen concentration in each reaction cell. Temperatures studied ranged from 20 C to 45 C. Biodegradation was measured from the oxygen consumption. PLA tests were performed at room temperature using a compost system modeled after those used at Kingsport Plant of Eastman Chemical. This system provides an environment closer to that experienced by a polymer in a landfill. Degradation was determined by the sieve-shaker test which measures the particle size distribution before and after degradation. The slurry experiment with PVOH was found much fast for a duration of four weeks and was most suited for being incorporated into an undergraduate lab class. The biodegradation experiment showed that increasing the concentration of polymer in the slurry provided more carbon source for microbial growth therefore increased the rate of biodegradation reaction. In addition, the biodegradation of PVOH was found to reach its
optimum at 25 C.
PRODUCTS: Biodegradation Experiment as one of the CHEN 310 and CHEN410 experiments for A&T students; Publications as listed above.
OUTCOMES: The experiment was offered as an experiment module for Chemical Engineering Laboratory II (CHEN 410) for students to gain hands-on experience about the polymer and its environmental impact. A student survey was conducted after the experiment to gauge the learning objectives and outcomes of the experiment. The responses from the participants were very positive. This grant supported two Master of Science students, both U.S. citizen or permanent resident and African American. Mr. Dana Warren now works for General Mills and Mr. Pfumai Kuzviwanza now works for Du Pont. Both students have been educated through this project, and they are doing well in Fortune 500 companies. A highlight of the biodegradable polymer experiment was presented at the local Oak Ridge Elementary School by A&T students Vyas Harinath and Ramya Vedaiyan during the annual Science Day Fair. Our work was presented to the American Society for Engineering Education (ASEE) Annual Conference in Salt Lake City in
2004, in Portland in 2005, and in the Global Colloquium on Engineering Education (GCEE) in Sydney, Australia in 2005. Our presentation of the project resulted in broad interest from the attendees, and has prompted many follow-up inquiries.
DISSEMINATION ACTIVITIES:
FUTURE INITIATIVES: Continue to develop new proposals to help improve students learning and training in exciting ares of sustainable technologies.
Impacts
The experiment was offered as an experiment module for Chemical Engineering Laboratory II (CHEN 410) for students to gain hands-on experience about the polymer and its environmental impact. A student survey was conducted after the experiment to gauge the learning objectives and outcomes of the experiment. The responses from the participants were very positive. This grant supported two Master of Science students, both U.S. citizen or permanent resident and African American. Mr. Dana Warren now works for General Mills and Mr. Pfumai Kuzviwanza now works for Du Pont. Both students have been educated through this project, and they are doing well in Fortune 500 companies. A highlight of the biodegradable polymer experiment was presented at the local Oak Ridge Elementary School by A&T students Vyas Harinath and Ramya Vedaiyan during the annual Science Day Fair. Our work was presented to the American Society for Engineering Education (ASEE) Annual Conference in Salt Lake City
in 2004, in Portland in 2005, and in the Global Colloquium on Engineering Education (GCEE) in Sydney, Australia in 2005. Our presentation of the project resulted in broad interest from the attendees, and has prompted many follow-up inquiries.
Publications
- Lou, J., Schimmel, K., Kuzviwanza, P., Warren, D.M., Yan, J., 2007, "Chapter 9. Characterization of Biodegradable Polymers: Biodegradation of Poly(vinyl alcohol) under Aerobic and Aqueous Conditions", in Polymer Durability and Radiation Effects, M. Celina, Ed., American Chemical Society, Washington, D.C., accepted and in press.
- Kuzviwanza, P., Schimmel, K., Harinath, V., Lou, J., 2004, "Characterization of biodegradable polymer materials", Proceedings of 11th Annual International Conference on Composites/Nano Engineering, Hilton-Head Island, South Carolina, August 8-14, Paper No. 405.
- Lou, J., Schimmel, K., Kuzviwanza, P., Harinath, V., 2004, "Biodegradation of polyvinyl alcohol in aqueous environment". Abstracts of Papers, 228th ACS National Meeting, Philadelphia, PA, United States, August 22-26, Paper No. 448.
- Schimmel, K., Lou, J., Kuzviwanza, P., Harinath, V., 2004, "Biodegradable polymer characterization laboratory unit", Chemical Engineering Division, Proceedings of the 2004 ASEE Annual conference, Salt Lake City, June 20-23, Paper No. 3613.
- Lou, J., Schimmel, K., Kuzviwanza, P., Harinath, V., 2004, "Biodegradation of polyvinyl alcohol in aqueous environment", Polymeric Materials Science and Engineering, 91:827-831.
- Schimmel, K., Shahbazi, G., Warren, D.M., Lou, J., 2005, "Using Biodegradable Polymer Experiments to Examine Structure-Function Relationships," Proceedings of the 4th Global Colloquium on Engineering Education, Sydney, Australia, September 26.
- Schimmel, K., Lou, J., Warren, D., 2005, "Using Biodegradable Polymer Experiments to Examine Structure-Function Relationships," Materials Engineering Division, Proceedings of the 2005 ASEE Annual Conference, Portland, OR, June 12-15.
- Lou, J., Harinath, V., Schimmel, K., Sankar, J., 2005, "Effect of fillers on the rheology and biodegradation of polylactic acid", Annual Technical Conference - Society of Plastics Engineers Paper No. 100812.
- Zhang, J., Krishnamachari, P., Yan, J., Uitenham, L.C., Shahbazi, G., Lou, J., 2007, "Biodegradable polymer nanocomposite: I. Synthesis of poly(l-(+)-lactic acid)", Proceedings of 15th Annual International Conference on Composites/Nano Engineering, Hanan Island, July 15-21.
- Krishnamachari, P., Zhang, J., Yan, J., Uitenham, L.C., Shahbazi, G., Lou, J., 2007, "Biodegradable polymer nanocomposite: II. Polylactide-clay nanocomposite", Proceedings of 15th Annual International Conference on Composites/Nano Engineering, Hanan Island, July 15-21.
- Zhang, J., Liang, Y., Yan, J., Lou, J., 2007, "Study of molecular weight dependence of glass transition temperature for amorphous poly(l-lactide) by molecular dynamics simulation", Polymer. 48:4900-4905.
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Progress 01/01/06 to 12/31/06
Outputs
In 2006, we have worked on refining the biodegradation experiments performed with a 16-cell respirometer system (AER-200 aerobic/anaerobic respirometer). This system provided a slurry environment in which the samples could be quickly degraded and monitored in terms of the gas-phase oxygen concentration in each reaction cell. Temperatures studied ranged from 20 C to 45 C. We spent most of 2006 working on the repair and reconditioning of the used Waters GPC system donated by Tradegar Corp. This important piece of characterization instrumentation was finally repaired with a number of replacement components, and it was recently used to determine the molecular weight distribution of the biodegradable polymer, made by our graduate student James Zhang by the polycondensation chemical reaction in our lab, using the lactic acid from the fermentation of an agricultural source. We started with L(+) lactic acid, Tin catalyst and xylene in a 600 mL Parr 4590 series stirred
reactor, and the reaction mixture was heated. The water was azeotropically distilled off for 24 hours under vacuum. The resulting polymer was dissolved in chloroform, and then washed by methanol. The product was dried in a vacuum oven at 60 C until constant weight was attained. We used the Waters Styragel column (7.8 x 300 mm) with broad molecular weight range of 5000 to 10,000,000 daltons to aid the characterization of the extent of biodegradation of polylactic acid derived from agricultural raw materials. We separated the polymer sample at flow rate of mobile phase at 1mL/min. The sensitivity of the Waters 410 detector was set to 128, and a scale factor of 100 was adopted. The universal calibration was conducted for the system using polystyrene standards. The obtained weigh-average molecular weight of our PLA was 30,000 daltons. This allows us to characterize the biodegradable polymer much more accurately than the respirometer, since the molecular weight distribution of the
biodegradable polymer changes drastically after biodegradation. Secondly, we installed the state-of-the-art Instron model 5566 Universal Testing Frame to characterize the biodegradable polymer under ASTM D638 standards. Additionally, nanofillers were compounded into the polymer at a melt temperature of 190 C using 15/8 inches of counter-rotating intermeshing twin-screws. This allows us to gain understanding of the mechanical properties and biodegradation of polymers. In addition, thermal analysis of the resulting PLA was carried out under a nitrogen atmosphere with samples sealed into the standard aluminum sample kits using DSC Q100 (TA instruments). The polymer was preannealed at 110 C for 30 minutes. The glass transition temperature of our PLA was 46.25 C.
PRODUCTS: na
OUTCOMES: We offered the new hands-on experiment to our class CHEN410 Lab and received positive feedback from the students. We supported U.S. citizen Mr. Warren for his M.S. degree and his work was published in both ASEE Conference in Portland and in Global Colloquium on Engineering Education in Sydney, Australia in 2005.
DISSEMINATION ACTIVITIES: na
FUTURE INITIATIVES: We will test the new experiment in several more classes in the future. We will finish the testing of the chromatography to provide further characterization for the biodegradable polymer to validate the degradation results from respirometer. We will develop new proposals to be submitted to USDA and NSF for furthering this area of research and educational enhancement.
Impacts
Our approach to characterizing biodegradable polymers is novel and has improved understanding and techniques for characterizing and controlling the properties of biodegradable polymers. The characterizing techniques can be applied to further research and/or manufacture of biodegradable polymers.
Publications
- Jianzhong Lou, Keith Schimmel, Pfumai Kuzviwanza, Dana Warren, and Jizhong Yan. Characterization of Biodegradable Polymers. Book Chapter, Biodegradable Polymers, American Chemical Society Symposium Series, accepted, 2006.
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Progress 01/01/05 to 12/31/05
Outputs
After we had successfully developed biodegradation experiments in two environments - slurry and compost - we spent most of 2005 fine-tuning the experimental set-up and conditions. We refined the respirometry used for the degradation experiments. We also initiated the gel permeation chromatography to characterize the polyvinyl alcohol before and after the biodegradation reaction. Data strongly support that the polymer molecules were broken down into smaller chains during the biodegradation reaction. In the latter part of 2005, we also initiated mechanical characterizations of polymers in order to demonstrate to students that after the polymer is degraded, its mechanical properties will also reduce. This part of the work required additional time and capital since we did not have a tensile frame that was suitable for the polymer specimens. We conducted numerous tests of injection molding for the standard ASTM D-638 tensile test. A mold was designed and created for this
project.
PRODUCTS:
OUTCOMES:
DISSEMINATION ACTIVITIES: We graduated a new M.S. in Chemical Engineering student, Mr. Dana Warren, an African American student, with a B.S. in Chemistry from N.C. Central University. Mr. Warren is a U.S. citizen and after he finished his graduate degree while working on this USDA project, he accepted a job in General Mills.
FUTURE INITIATIVES:
Impacts
Mr. Warren's work was published in both the ASEE Conference in Portland and in the Global Colloquium on Engineering Education in Sydney, Australia, in 2005. Both conferences were the most well-attended technical conferences in the engineering education research and our presentation of the project results created a very broad and substantial impact on engineering education. More details on the research activities are provided in the project publications that are referenced in this report.
Publications
- K. Schimmel, J. Lou, D. Warren, "Using Biodegradable Polymer Experiments to Examine Structure-Function Relationships," Materials Engineering Division, Proceedings of the 2005 ASEE Annual Conference, Portland, OR, June 12-15, 2005.
- J. Lou, V. Harinath, K. Schimmel, J. Sankar, "Effect of fillers on the rheology and biodegradation of polylactic acid", Annual Technical Conference - Society of Plastics Engineers 2005, Paper #100812.
- Keith Schimmel, Abolghasem Shahbazi, Dana Warren, Jianzhong Lou, "Using Biodegradable Polymer Experiments to Examine Structure-Function Relationships," Proceedings of the 4th Global Colloquium on Engineering Education, Sydney, Australia, September 26, 2005.
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Progress 01/01/04 to 12/30/04
Outputs
Two biodegradable polymers were studied - polyvinyl alcohol (PVOH) and polylactic acid (PLA). PVOH from Aldrich Chemical with an average molecular weight of 9,000-10,000 and a degree of hydrolysis of 80% was used to provide a biodegradable polymer that would be quickly degraded to allow experiments to be performed in as short a timeframe as possible, i.e., ten days. The PVOH was added to slurry reactors at mass loadings of 100mg and 200mg PVOH on a dry weight basis. PLA from Cargill Dow was used to provide a higher molecular weight biodegradable polymer that has recently been successfully commercialized, and is used in a variety of products. Biodegradation experiments were performed in two environments--slurry and compost. All PVOH tests were performed with a 16-cell respirometer system (AER-200 aerobic/anaerobic respirometer). This system provided a slurry environment in which the samples could be quickly degraded and monitored in terms of the gas-phase oxygen
concentration in each reaction cell. Temperatures studied ranged from 20C to 45C. PLA tests were performed at room temperature using a compost system modeled after those used at Kingsport Plant of Eastman Chemical. This system provides an environment closer to that experienced by a polymer in a landfill. Degradation could be followed by changes in the particle size distribution of the polymer. Both physical and chemical analytical methods were employed to develop insights into structure-function changes accompanying polymer degradation. Physical analytical methods that were used to characterize the biodegradable polymers were Instron tensile stress-strain tests, intrinsic viscosity, dry weights, and particle size distribution tests. Chemical analytical methods that were used to characterize the biodegradable polymers were oxygen respirometry and gel permeation chromatography. The result suggests that increasing the concentration of PVOH will provide more carbon for microbial growth,
consequently increasing the rate of reaction and biological activity of the microorganisms. Hence, the total oxygen uptake increases as substrate concentration increases. At 25C, the total oxygen uptake is greatest. This increase in biological activity is mainly attributed to the fact that the microorganisms were better acclimated to the degradation of PVOH. This suggests that the biodegradation of PVOH is optimum at 25C.
Impacts
Students equipped with the knowledge of biodegradable polymers will bring skills in this area to their future jobs. One graduate student who conducted thesis work on biodegradable polymers received a job offer from DuPont Polymer Division this year. A website is being developed to educate and inform the public of the ecological importance of biodegradable polymers. In addition, a proceedings book on the topic is being published and distributed by students. In other outreach, the biodegradable polymer experiment was conducted in the Oak Ridge Elementary during the annual Science Day Fair. Students at other universities stand to benefit from this new laboratory experiment. Lehigh University plans to adopt this experiment in its engineering programs. The polymer biodegradation experiment was conducted by a graduate student as a demonstration in the Chemical Engineering Lab II class in fall, 2004. One group of students selected this new experiment, out of a menu of four
different experiments. This group of students conducted the experiment and met their course learning objective, while all of the students in CHEN 410 completed a survey based on their observations on the demonstration of the experiment.
Publications
- J. Lou, K. Schimmel, P. Kuzviwanza, V. Harinath, 'Biodegradation of polyvinyl alcohol in aqueous environment', Polymeric Materials: Science and Engineering, 2004 91, 827-831.
- K. Schimmel, J. Lou, D. Warren, 'Using Biodegradable Polymer Experiments to Examine Structure-Function Relationships,' Materials Engineering Division, Proceedings of the 2005 ASEE Annual Conference, Portland, OR, June 12-15, 2005, accepted.
- J. Lou, V. Harinath, K. Schimmel, J. Sankar, 'Effect of fillers on the rheology and biodegradation of polylactic acid', Annual Technical Conference - Society of Plastics Engineers 2005, accepted. #100812.
- P. Kuzviwanza, K. Schimmel, V. Harinath, J. Lou, 'Characterization of biodegradable polymer materials', Proceedings of 11th Annual International Conference on Composites/Nano Engineering, Hilton-Head Island, August 8-14, 2004. Paper #405.
- J. Lou, K. Schimmel, P. Kuzviwanza, V. Harinath, 'Biodegradation of polyvinyl alcohol in aqueous environment'. Abstracts of Papers, 228th ACS National Meeting, Philadelphia, PA, United States, August 22-26, 2004. Paper #448.
- K. Schimmel, J. Lou, P. Kuzviwanza, A. Harinath, 'Biodegradable polymer characterization laboratory unit', Chemical Engineering Division, Proceedings of the 2004 ASEE Annual conference, Salt Lake City, June 20-23, 2004. Paper #3613.
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Progress 01/01/03 to 12/31/03
Outputs
The experiment provides a hands-on educational experience to students by exposing a variety of polymer samples (such as polyvinyl alcohols, polycaprolactones, polylactic acid) to simulated biomass environments and characterizing the samples against the exposure time. Independent variables that students can explore include biodegradation medium (slurry or soil), microorganism species and concentration, moisture content (for soil), temperature, pH, nutrient species and concentrations, polymer surface roughness, and polymer concentration. Analytical methods available include respirometry, melt index, gel-permeation chromatography, tensile strength, and thermogravimetric analysis. Students are able to study the relationship between polymer structure and biodegradation properties. They are challenged to use statistical methods to determine which polymer physical and chemical property measurements best correlate with biodegradability. Through this process, the students
develop a vivid understanding of fundamental principles of polymer science, as well as the importance of societal and environmental issues with polymer materials design, manufacturing, and applications. Polymers derived from agricultural feedstock can be biodegradable and play a role in helping alleviate the environmental concerns. Biodegradable polymers have a wide range of potential applications in markets currently dominated by petroleum-based materials. These markets include drug delivery systems, biomaterials, flushable diapers, biodegradable agricultural films, controlled release systems for agricultural chemicals, disposable nonwovens, horticultural containers, washable paints, and lubricants. So far, we have received the donated experiment apparatus from our industrial collaborator, Eastman Chemical Corporation. We are setting up the experiment and made some progress. One paper has been accepted on this work so far.
Impacts
Several structural parameters influence the biodegradability of a polymer. Most natural polymers, such as starch, cellulose, and proteins are readily biodegradable through hydrolysis followed by oxidation with the aid of enzymes. Synthetic polymers may attain biodegradability by incorporating hydrolyzable linkages in their backbones. Both molecular weight and crystallinity strongly influence biodegradability and kinetics of biodegradation process.
Publications
- No publications reported this period
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