Progress 12/01/02 to 11/30/06
Outputs
The guiding premise of this work has been that 100% biobased thermosets are both feasible as well as necessary in view of reports raising serious toxicological and environmental impact questions surrounding current practice and use of styrene, divinylbenzene, VOCs, and other petroleum-derived components in current resin manufacture, formulations, and compounding. Our initial investigations revealed that triglyceride-based materials as additives would not alone afford sufficient property enhancements, invariably owing to phase separation as was confirmed by SEM examination of copolymerized fatty acid esters of saccharidic materials with commercial resins. In the 100% biobased aspect of the work, systems containing comonomers from commercially available, bioderived triglyceride and saccharidic materials were designed with principal consideration given to the development of multiply-crosslinked, rigid systems having the requisite crosslink densities necessary for
substantial mechanical and thermal properties. Extensive investigations included screening of over 50 formulation systems, Soxhlet extractions to ascertain amounts of polymerized material, mechanical property and chemical structure comparisons, cure and post-cure regimes of 2, 4, 6, 8, 12, 14, and 29.3 hrs, dynamic mechanical analyses with cycling between -125 C to +125 C for storage and loss moduli and glass transition temperature determination, and crosslink density calculations and comparisons. Investigations also relied on infrared spectral analysis and dynamic mechanical testing to extract information on functional group changes, extent of cure, and maximum obtainable cure. Calculations of average molecular crosslink densities and segmental molecular weights between crosslinks, and the consequences of these parameters on thermomechanical properties were performed. Examination was made of the effect of formulation variation in terms of chemical modification and sequential cure
protocols including photochemical and thermal cures for development of comparative property data among the obtained resins. Resin properties were able to be modulated by proportional variation of individual components and composition stoichiometries. The outcomes of these investigations include 100% biobased materials which are rigid, crosslinked hybrid polyesters from triglycerides formulated with select saccharidic-derived materials, some of the latter indicated by a US DOE 2004 government report to be among the top value added, biobased chemicals for future US production. Obtained materials were homogeneous with no phase separation. The resins set as pale, straw-colored, translucent, stiff solids which represent a class of crosslinked materials previously unknown which have moduli and stiffness comparable to partially biobased formulations in the prior literature. In related work, hybrid resin materials were prepared using bisphenolics co-formulated with biobased starting
materials. Although these latter were not 100% biobased, the materials displayed the advantage of decreased brittleness compared with the corresponding resins prepared from usual bisphenolic materials alone.
Impacts
Prior to this investigation, few biobased materials from either saccharidic materials or triglycerides were thought to possess the required conformational stiffness long-regarded as necessary to impart sufficient thermomechanical properties to triglyceride-based resins; petrochemically-produced aryl ring monomeric materials are without exception used for resin formulations in order to impart requisite stiffness to resin materials. Our investigations have dislodged some of these assumptions and commercial resin markets may anticipate impact by the investigations performed though this project. Impacts include: (1) The technology developed is a unique chemistry for resin manufacture, strongly suggesting further research and development along similar lines is warranted; (2) The starting materials consist solely of 100% biomolecular entities from commercial agricultural sources, potentially arguing for more aggressive agricultural production of triglyceride and saccharidic
materials for resin markets; (3) Unlike virtually all commercialized bioresins to date, the formulations contain no styrene, divinylbenzene, VOCs, or other petroleum-derived components, nor are heavy metal catalysts used in the curing process; they thus have potential to favorably alleviate negative environmental and toxicological impacts of current technologies and materials; (4) The material is curable by a variety of methods, may be staged to partial cure using thermal, photochemical, or a combination of both methods, imparting property and processing advantages.
Publications
- Boyles, David A., Completely Biobased Plastic Formulations for Structural Applications, South Dakota School of Mines and Technology, August 23, 2005. SDSM&T patent disclosure; Patent disclosure has hindered publication.
- While, Michelle R.; Thompson, Annie; Boyles, David A.; Kellar, Jon J.; Cross, William M. Nano-Bio-Plastics and Composites from Linseed Oil and Saccaridic Source Materials, 89th Annual South Dakota Academy of Sciences, Chamberlain, SD, April 2-3, 2004.
- While, Michelle R.; Thompson, Annie; Boyles, David A.; Cross, William M.; Kellar, Jon J. Sucrose and Beta-Cyclodextrin Linolenate Ester Modifiers-Synthesis and Mechanical System Characterization, Annual South Dakota NSF EPSCoR Conference, Ramkota Hotel and Conference Center, Rapid City, SD, September 17, 2004.
- Laurenz, Bobbie; Al-Omar, Mohammad; Earnest, Tyler; Boyles, David A. Characterization of Thermal-Cured and Photo-cured Systems for Biobased Resins, South Dakota EPSCoR Conference, Rapid City, SD, September 25-26, 2006.
- Al-Omar, Mohammad. Synthesis and Mechanical Properties of Novel, Doubly-Crosslinked Biobased Resins, MS Thesis, Materials Engineering and Science, South Dakota School of Mines and Technology, 2007.
- Laurenz, Bobbie; Al-Omar, Mohammad; Earnest, Tyler; Boyles, David A. Novel Biobased Resins From Agriculturally Renewable Linseed Oil: Characterization of Photo-Cured and Thermally Cured Systems, South Dakota Legislative Student Research Day, Pierre, SD, February 10, 2007.
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Progress 10/01/03 to 09/30/04
Outputs
Two full-time graduate students have worked on this project the past project period: Ms. Michelle While, PhD student in Materials Science and Engineering, and Ms. Annie Thompson, MS student in Materials Science and Engineering. Ms. While works under the direction of Dr. Boyles in the Department of Chemistry and Chemical Engineering and carries out the organic synthesis for the project, and Ms. Thompson works under the direction of Drs. Jon Kellar and William Cross in the Department of Materials and Metallurgical Engineering, working on the mechanical testing of the materials. Annie now has experience in the formulation, casting, and mechanical testing and evaluation of resin materials, including fracture and scanning electron microscopy (SEM) of testing specimens. Michelle has continued to perform numerous syntheses and developed expertise in synthetic methods and spectral characterization, including infrared spectroscopy (IR) and nuclear magnetic resonance
spectroscopy (NMR). Both individuals have jointly presented their work.
Impacts
The success of this project will provide proof-of-principle for a new commercial niche for oilseed and saccharidic materials as alternatives to current inorganic fiber reinforcements, and as useful plastic materials.
Publications
- Michelle R. While, Annie Thompson, David A. Boyles, William M. Cross, Jon J. Kellar. "Sucrose and b-Cyclodextrin Linolenate Ester Modifiers--Synthesis and Mechanical System Characterization," Annual South Dakota NSF EPSCoR Conference, Ramkota Hotel and Conference Center, Rapid City, SD, September 17, 2004.
- While, Michelle R.; Thompson, Annie; Boyles, David A.; Kellar, Jon J.; Cross, William M. "Nano-Bio-Plastics and Composites from Linseed Oil and Saccaridic Source Materials," 89th Annual South Dakota Academy of Sciences, Chamberlain, SD, April 2-3, 2004.
DT While, Michelle R.; Thompson, Annie; Boyles, David A.; Kellar, Jon J.; Cross, William M. "Nano-Bio-Plastics and Composites from Linseed Oil and Saccaridic Source Materials," 89th Annual South Dakota Academy of Sciences, Chamberlain, SD, April 2-3, 2004.
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Progress 10/01/02 to 09/30/03
Outputs
(1) Synthesis of New Biobased Materials. Synthetic routes have been designed for the synthesis of fatty acid esters of cellulose, sucrose, and b-cyclodextrin. Archer Daniels Midland (ADM) has graciously provided us with two gallons of Emery 644 Linseed Fatty Acids isolated from flaxseed. We have converted this by sequential bromination, zinc dehydrobromination to the pure linolenic acid in accordance with the standard McCutcheon procedure in Organic Syntheses, CV 3, 531. To date, seven batches of material have been processed in this manner. The product has been converted to the corresponding linolenoyl chloride and also to the methyl linolenate ester for subsequent reaction with saccharidic substrate materials. Specifically, methyl linolenate has been reacted via a solution process unique to our laboratory with cellulosic material to obtain linolenates of cellulose. This procedure continues to be optimized and affords the desired target material in a single step.
Linolenoyl chloride obtained as described above has been reacted with heptakis-(6-O-tert-butyldimethylsilyl)-B-cyclodextrin to afford the desired heptakis-(2,3-O-linolenyl-6-O-methyl)-B-cyclodextrin. The later is currently being characterized by nuclear magnetic resonance. Ms. While is the synthetic chemist performing all the above work. Also, she has prepared the unsaturated sucrose polystearates which will be used as a standard comparison against the desired sucrose linolenate, the latter of which is in the process of synthesis. A purification procedure is being attempted which would afford pure sucrose octastearate, the procedure for which will then be applied to the sucrose polylinolenates to isolate the sucrose octalinolenate. Pure compounds of known structure rather than mixtures are desired to afford the best structure-property relationships of the composite materials, although mixtures are desirable from an economic point of view and we are pursuing these in parallel. (2)
Composite Formulation and Testing. Ms. Annie Thompson has been hired as graduate research assistant on the project and has been working parallel with Ms. While, but in the polymer composites laboratory. Annie has cast tensile test specimens from Derekane resin, and compared the tensile test results from the MiniMaterials testor with those of materials cast from Derekane with the incorporation of 5 wt % methyl linolenate. We have seen enhanced elongation and decrease in Youngs modulus in all cases from coupons made with the methyl linolenate incorporation compared to those without. This preliminary work has afforded her practical training which will be applied as Ms. Whiles target compounds above continue to come online for testing.
Impacts
This research has an anticipated impact on the utilization of saccharidic materials and agriculturally-derived fatty acids on composite materials, and thus on US agriculture. In particular, it seeks to find new uses for linseed oil in the biocomposites market sector by developing new materials for composites as well as bio-based additives to current composite resins. If successful the results of this research could argue strongly for increased flax production.
Publications
- No publications reported this period
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