[ACS Symposium Series] Polymers from Agricultural Coproducts Volume 575 || Polymeric Materials from Agricultural Feedstocks

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<ul><li><p>Chapter 1 </p><p>Polymeric Materials from Agricultural Feedstocks </p><p>Ramani Narayan </p><p>Michigan Biotechnology Institute, 3900 Collins Road, Lansing, MI 48910 </p><p>Agricultural feedstocks should be used for the production of materials, especially plastics, and chemicals because of the abundant availability of agricultural feedstocks, the value it would add to the U.S. economy, and the reduction in U.S. trade deficit that could be achieved. However, the use of agricultural feedstocks for producing plastics, coatings and composites is negligible. New environmental regulations, societal concerns, and a growing environmental awareness throughout the world are triggering a paradigm shift towards producing plastics and other materials from inherently biodegradable, and annually renewable agricultural feedstocks. Potential plastic markets for polymeric materials based on agricultural feedstocks and the rationale for developing such materials are discussed. Technologies for using starches, cellulosics, other polysaccharides, seed oils, proteins and natural fibers in plastics related applications are reviewed. </p><p>There is an abundance of natural, renewable biomass resources as illustrated by the fact that the primary production of biomass estimated in energy equivalents is 6.9 1017 kcal/year (1 ). Mankind utilizes only 7% of this amount, i.e. 4.7 1016 kcal/year. In terms of mass units the net photosynthetic productivity of the biosphere is estimated to be 155 billion tons/year (2 ) or over 30 tons per capita and this is the case under the current conditions of non-intensive cultivation of biomass. Forests and crop lands contribute 42 and 6%, respectively, of that 155 billion tons/year. The world's plant biomass is about 2 1012 tons and the renewable resources amount to about 1011 tons/year of carbon of which starch provided by grains exceeds 109 tons (half which comes from wheat and rice) and sucrose accounts for about 108 tons. Another estimate of the net productivity of the dry biomass gives 172 billion tons/year of which 117.5 and 55 billion tons/year are obtained from terrestrial and aquatic sources, respectively (3 ). </p><p>0097-6156/94/0575-0002$09.26/0 1994 American Chemical Society </p><p>Dow</p><p>nloa</p><p>ded </p><p>by 5</p><p>0.20</p><p>5.51</p><p>.100</p><p> on </p><p>May</p><p> 22,</p><p> 201</p><p>4 | h</p><p>ttp://</p><p>pubs</p><p>.acs</p><p>.org</p><p> P</p><p>ublic</p><p>atio</p><p>n D</p><p>ate:</p><p> May</p><p> 5, 1</p><p>994 </p><p>| doi</p><p>: 10.</p><p>1021</p><p>/bk-</p><p>1994</p><p>-057</p><p>5.ch</p><p>001</p><p>In Polymers from Agricultural Coproducts; Fishman, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994. </p></li><li><p>1. NARAYAN Polymeric Materials from Agricultural Feedstock 3 </p><p>Forests cover one third of the land in the 48 contiguous states (759 M M acres) and commercial forests make up about 500 MM acres. Fortunately, we are growing trees faster than they are being consumed, although sometimes the quality of the harvested trees is superior to those being planted. Agriculture uses about 360 M M acres of the 48 contiguous states, and this acreage does not include idle crop lands and pastures. Again, these figures clearly illustrate the potential for biomass utilization in the U.S. (3). </p><p>However, Federal farm programs idle 15 to 20% of U.S. cropland. Today, much of this land is tied up in the Conservation Reserve Program (CRP) and to build back our supplies from the effects of the year's poor harvest. But as supplies are restored and CRP ends, the long-term capacity dilemma will be with us again. </p><p>It is estimated that U.S. agriculture accounts directly and indirectly for about 20% of the GNP by contributing $ 750 billion to the economy through the production of foods and fiber, the manufacture of farm equipment, the transportation of agricultural products, etc. It is also interesting that while agricultural products contribute to our economy with $ 40 billion of exports, and each billion of export dollars creates 31,600 jobs (1982 figures), foreign oil imports drain our economy and make up 23% of the U.S. trade deficit (U.S. Department of Commerce 1987 estimate) </p><p>Given these scenarios of abundance of biomass feedstocks, the value added to the U.S. economy, and reduction in U.S. trade deficit, it seems logical to pursue the use of agricultural feedstocks for production of materials, chemicals and fuels (4 ). </p><p>Biomass derived materials are being produced at substantial levels. For example, paper and paperboard production from forest products was around 139 billion lb. in 1988 (5 ), and biomass derived textiles production around 2.4 billion lb. (6 ). About 3.5 billion pounds of starch from corn is used in paper and paperboard applications, primarily as adhesives (7 ). However, biomass use in production of plastics, coatings, resins and composites is negligible. These areas are dominated by synthetics derived from oil and represent the industrial materials of today. </p><p>This chapter reviews the production of polymeric materials from agricultural feedstocks for applications in plastics, coatings, and composites. Subsequent chapters in the book showcase emerging polymeric materials technologies based on agricultural feedstocks. Figure 1 shows the various agricultural feedstocks available for production of polymeric materials. </p><p>Drivers for Production of Polymeric Materials Based on Agricultural Feedstocks </p><p>New environmental regulations, societal concerns, and a growing environmental awareness throughout the world have triggered a paradigm shift in industry to develop products and processes compatible with the environment. This paradigm shift has two basic drivers: </p><p> Resource conservation/depletion - utilization of annually renewable resources as opposed to petroleum feedstocks and the potential environmental and economic benefits that go with it </p><p> Environmental Concerns. products and processes that are compatible with the environment Compatibility with the environment ties into the issue of waste management, that is, disposing our waste in an environmentally and ecologically sound manner. This brings up questions of recyclability and biodegradability of materials and products. </p><p>Dow</p><p>nloa</p><p>ded </p><p>by 5</p><p>0.20</p><p>5.51</p><p>.100</p><p> on </p><p>May</p><p> 22,</p><p> 201</p><p>4 | h</p><p>ttp://</p><p>pubs</p><p>.acs</p><p>.org</p><p> P</p><p>ublic</p><p>atio</p><p>n D</p><p>ate:</p><p> May</p><p> 5, 1</p><p>994 </p><p>| doi</p><p>: 10.</p><p>1021</p><p>/bk-</p><p>1994</p><p>-057</p><p>5.ch</p><p>001</p><p>In Polymers from Agricultural Coproducts; Fishman, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994. </p></li><li><p>4t </p><p>Ag</p><p>ricu</p><p>ltura</p><p>l Fee</p><p>dst</p><p>ock</p><p>s </p><p>Cel</p><p>lulo</p><p>sics</p><p> &amp; </p><p>ligno</p><p>cellu</p><p>losi</p><p>cs </p><p>Exam</p><p>ple:</p><p>woo</p><p>d Ex</p><p>ampl</p><p>es: </p><p> ke</p><p>naf </p><p> si</p><p>sal </p><p>Exam</p><p>ples</p><p>: </p><p>corn</p><p>pota</p><p>to </p><p>Exam</p><p>ples</p><p>: </p><p>pect</p><p>in </p><p> ch</p><p>itin </p><p> le</p><p>van </p><p> pu</p><p>llula</p><p>n </p><p>Exam</p><p>ples</p><p>: Ex</p><p>ampl</p><p>es: </p><p> so</p><p>ybea</p><p>n </p><p>zein</p><p>lesq</p><p>uere</p><p>lla </p><p> so</p><p>y </p><p>rape</p><p>seed</p><p> pr</p><p>otei</p><p>n </p><p>Figu</p><p>re </p><p>1. A</p><p>gric</p><p>ultu</p><p>ral </p><p>feed</p><p>stoc</p><p>ks </p><p>avai</p><p>labl</p><p>e fo</p><p>r th</p><p>e pr</p><p>oduc</p><p>tion </p><p>of p</p><p>olym</p><p>eric</p><p> m</p><p>ater</p><p>ials</p><p>. </p><p> &gt; cl cl </p><p>Dow</p><p>nloa</p><p>ded </p><p>by 5</p><p>0.20</p><p>5.51</p><p>.100</p><p> on </p><p>May</p><p> 22,</p><p> 201</p><p>4 | h</p><p>ttp://</p><p>pubs</p><p>.acs</p><p>.org</p><p> P</p><p>ublic</p><p>atio</p><p>n D</p><p>ate:</p><p> May</p><p> 5, 1</p><p>994 </p><p>| doi</p><p>: 10.</p><p>1021</p><p>/bk-</p><p>1994</p><p>-057</p><p>5.ch</p><p>001</p><p>In Polymers from Agricultural Coproducts; Fishman, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994. </p></li><li><p>1. NARAYAN Polymeric Materials from Agricultural Feedstocks 5 </p><p>Key international companies and industrial organizations meeting in Rotterdam recently endorsed a set of principles and a charter that will commit them to environmental protection into the 21st century (8 ). Some of the key principles of the charter are: </p><p> Develop and operate facilities and undertake activities with energy efficiency, sustainable use of renewable resources and waste generation in mind. </p><p> Conduct or support research on the impact and ways to minimize the impacts of raw materials, products or processes, emissions and wastes. </p><p> Modify the manufacture, marketing, or use of products and services so as to prevent serious or irreversible environmental damage. Develop and provide products and services that do not harm the environment. </p><p> Contribute to the transfer of environmentally sound technology and management methods. The International Standards Organization (ISO) has formed a technical </p><p>committee (ISO/TC 207) to address standardization in the field of environmental management and brings to the forefront the need for industry to address issues relating to how their products and processes impact the environment It is anticipated that these standards will impact the industry similar to the impact of the ISO 9000 quality assurance standards. </p><p>Polymer materials derived from agricultural feedstocks can play a major role under this heightened environmental climate. Clearly, the processes, products and technologies adopted and developed utilizing renewable resources will have to be compatible with the environment Furthermore, the wastes generated should be recycled or transformed into environmentally benign products. </p><p>The timing is right for polymer materials (plastics) and products designed and engineered from agricultural feedstocks to enter into specific markets currently occupied by petroleum based feedstocks. However, displacing a high-sales, low-cost material like plastics, that are produced by a process that operates profitably in an vertically integrated industry, is difficult The problem is compounded by the fact that the capital for these plants has been depreciated already and they continue to operate profitably. </p><p>"Cradle to Grave" Design of Plastics </p><p>Today's plastics are designed with little consideration for their ultimate disposability or the impact of the resources (feedstocks) used in making them. This has resulted in mounting worldwide concerns over the environmental consequences of such materials when they enter the waste stream after their intended uses. Of particular concern are polymers used in single use, disposable plastic applications. Plastics are strong, light-weight, inexpensive, easily processable and energy efficient They have excellent barrier properties, are disposable and very durable. However, it is these very attributes of strength and indestructibility that cause problems when these materials enter the waste stream. In the oceans, these light-weight and indestructible materials pose a hazard to marine life. This resulted in the Marine Plastic Pollution Research and Control Act of 1987 (Public Law 100-230) and the MARPOL Treaty. Annex V of the MARPOL Treaty prohibits "the disposal of all plastics including but not limited to synthetic ropes, synthetic fishing nets, and garbage bags". U.S. Environmental </p><p>Dow</p><p>nloa</p><p>ded </p><p>by 5</p><p>0.20</p><p>5.51</p><p>.100</p><p> on </p><p>May</p><p> 22,</p><p> 201</p><p>4 | h</p><p>ttp://</p><p>pubs</p><p>.acs</p><p>.org</p><p> P</p><p>ublic</p><p>atio</p><p>n D</p><p>ate:</p><p> May</p><p> 5, 1</p><p>994 </p><p>| doi</p><p>: 10.</p><p>1021</p><p>/bk-</p><p>1994</p><p>-057</p><p>5.ch</p><p>001</p><p>In Polymers from Agricultural Coproducts; Fishman, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994. </p></li><li><p>6 POLYMERS FROM AGRICULTURAL COPRODUCTS </p><p>Protection Agency (US EPA) estimates that 4,205 metric tons of plastic wastes are produced each year aboard government ships </p><p>Therefore, there is an urgent need to redesign and engineer new plastic materials that have the needed performance characteristics of plastics but, after use, can be disposed in a manner that is compatible with the environment Thus, the twin issues of recyclability and biodegradability of polymeric materials are becoming very important. It is also important to have appropriate waste management infrastructures that utilize the biodegradability or recyclability attributes of the materials, and that these materials end up in the appropriate infrastructure. This leads us to the concept of designing and engineering new biodegradable materials materials that have the performance characteristics of today's materials, but undergo biodgradation along with other organic waste to soil humic materials (compost). Plowing the resultant compost into agricultural land enhances the productivity of the soil and helps sustain the viability of micro and macro flora and fauna (biological recycling of carbon). </p><p>This "cradle to grave" concept of material design, role of biodegradable polymers in waste management, and the relationship to the carbon cycle of the ecosystem have been discussed in detail by Narayan (9-11 ). The production of biodegradable materials from annually renewable agricultural feedstocks for single-use disposable plastics in conjunction with composting waste management infrastructure offers an ecologically sound approach to resource conservation and material design, use, and disposal. Figure 2 shows the "cradle to grave concept" for material design from agricultural feedstocks. The concept involves integration of material redesign with appropriate waste disposal infrastructure. </p><p>Polymeric Materials (Plastics) Markets For Agricultural Polymers </p><p>The paradigm shift in material design discussed above offers new market opportunities for agricultural polymer materials. As discussed earlier, the environmental attributes of being annually renewable and biodegradable, in contrast to the current petroleum based plastics will be a major driver for entry of biodegradable plastics and other biodegradable materials based on agricultural feedstocks into the market place. However, cost and performance requirements will dictate whether or to what extent these new materials will displace current products. </p><p>Figure 3 shows the amount of thermoplastic resin sales and use by major market. As can be seen from this figure, packaging has the largest market share with 18.2 billion pounds, consumer and institutional products and adhesives/ink/coatings represent an additional 7.1 billion pounds use. Overall this represents 44.1 % of the entire plastics market. These single-use disposable plastics are not degradable and pose problems when they enter the waste stream after use. It is these plastics that have been singled out by consumers, environmentalists, legislators and regulatory agencies for attention. Thus, there is a need today to engineer single-use plastic products that have the appropriate performance properties but when disposed of in appropriate disposal infrastructures, such as composting, can biodegrade to environmentally benign products (CO2, water, and quality compost). </p><p>Dow</p><p>nloa</p><p>ded </p><p>by 5</p><p>0.20</p><p>5.51</p><p>.100</p><p> on </p><p>May</p><p> 22,</p><p> 201</p><p>4 | h</p><p>ttp://</p><p>pubs</p><p>.acs</p><p>.org</p><p> P</p><p>ublic</p><p>atio</p><p>n D</p><p>ate:</p><p> May</p><p> 5, 1</p><p>994 </p><p>| doi</p><p>: 10.</p><p>1021</p><p>/bk-</p><p>1994</p><p>-057</p><p>5.ch</p><p>001</p><p>In Polymers from Agricultural Coproducts; Fishman, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994. </p></li><li><p>a. </p><p>ri Sa I </p><p>Figu</p><p>re 2</p><p>. C</p><p>radl</p><p>e-to</p><p>-gra</p><p>ve </p><p>conc</p><p>ept </p><p>for </p><p>biod</p><p>egra</p><p>dabl</p><p>e m</p><p>ateria</p><p>ls in</p><p> fa</p><p>st-fo</p><p>od </p><p>resta</p><p>uran</p><p>t pac</p><p>kagi</p><p>ng ap</p><p>plic</p><p>atio</p><p>ns. </p><p>Dow</p><p>nloa</p><p>ded </p><p>by 5</p><p>0.20</p><p>5.51</p><p>.100</p><p> on </p><p>May</p><p> 22,</p><p> 201</p><p>4 | h</p><p>ttp://</p><p>pubs</p><p>.acs</p><p>.org</p><p> P</p><p>ublic</p><p>atio</p><p>n D</p><p>ate:</p><p> May</p><p> 5, 1</p><p>994 </p><p>| doi</p><p>: 10.</p><p>1021</p><p>/bk-</p><p>1994</p><p>-057</p><p>5.ch</p><p>001</p><p>In Polymers from Agricultural Coproducts; Fishman, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994. </p></li><li><p>Figu</p><p>re 3</p><p>. 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