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1998 Progress Report: Means for Producing an Entirely New Generation of Lignin-Based Plastics
EPA Grant Number: R825370C032Subproject: this is subproject number 032 , established and managed by the Center Director under grant R825370
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: EERC - National Center for Clean Industrial and Treatment Technologies (CenCITT)
Center Director: Crittenden, John C.
Title: Means for Producing an Entirely New Generation of Lignin-Based Plastics
Investigators: Sarkanen, Simo
Institution: University of Minnesota
EPA Project Officer: Karn, Barbara
Project Period:
Project Period Covered by this Report: January 1, 1997 through January 1, 1998
RFA: Exploratory Environmental Research Centers (1992)
Research Category: Center for Clean Industrial and Treatment Technologies (CenCITT) , Targeted Research
Description:
Objective:This project is dedicated to developing technology to establish a plant where the first biodegradable plastics that are truly lignin-based can be manufactured. The industrial byproduct lignin for producing these plastics has been isolated from kraft black liquor generated by a pulp mill in International Falls, Minnesota.
Progress Summary:The conversion of wood chips to pulp for manufacturing paper generates huge quantities of byproduct lignins annually in the United States. The best estimates indicate that more than 26 million tons of kraft lignins are generated as byproducts of such pulping operations every year. As steps have been taken to maximize production, the recovery furnaces in an ever-increasing number of mills have become overloaded; the result is that all the byproduct lignin can no longer be used in its traditional role as a fuel.
Unfortunately, the necessary capital investment usually precludes construction of a new recovery furnace so there is little prospect of rectifying the situation in the majority of recovery-loaded mills. Even though untreated black liquor cannot be discharged directly into rivers, an exacerbation of pollution originating from pulp mills is likely to occur. A compelling way of responding to the problem may be found in creating biodegradable plastics from the kraft lignin in surplus black liquor.
Intensive efforts have been under way for twenty years to incorporate surplus byproduct lignins from pulp mills into useful plastics. Until 1994 it had been thought that most polymeric materials inevitably become brittle and weak when their lignin contents exceed 25-40%. However, the first 85% industrial kraft lignin-based thermoplastics with promising tensile strengths were reported by the principal investigator in 1995 and a more detailed description of this work appeared two years later.
Now, through CenCITT funded work, alkylated 100% kraft lignin-based plastics with tensile properties very similar to those of polystyrene have been produced. Thus the proposed work seeks to develop feedstocks suitable for injection-molding biodegradable plastic components that are solely composed of simple industrial kraft lignin derivatives in blends with commercially available plasticizers.
Ultrafiltration has been employed to purify and fractionate industrial kraft lignin samples that, after simple derivatization, can be extrusion-molded into strong plastic components. The compositions of the preparations are being evaluated through chromatographic analyses and molecular weight determinations. The plasticizers being sought for use with the new alkylated kraft lignin-based plastics are to be commercially available and inexpensive (not more than about $1.50 per lb.). A low threshold for effectiveness in blends with the alkylated kraft lignin preparations is centrally important. The final step in making these new biodegradable plastics involves spray-drying aqueous suspensions of the kraft lignin derivatives to produce powders that will be pelletized for extrusion-molding purposes.
In the quest to broaden the range of thermoplastic formulations with very high lignin contents, the feasibility of creating polymeric materials composed exclusively of alkylated kraft lignin has been fully established. In the absence of plasticizers, these new materials exhibit tensile behavior very similar to that of polystyrene. From the perspective of all previous accomplishments, such a result is remarkable.
In the first instance, kraft lignin preparations had been alkylated with the corresponding dialkyl sulfates in solution at pH 11-12. Solvent-casting from DMSO of the alkylated derivatives thus produced had yielded plastics containing 95-100% alkylated kraft lignin that exhibited very encouraging mechanical properties. In contrast to the earlier results with 85% kraft lignin-based plastics, variations in the degree of association between the individual molecular components before derivatization seemed to have no effect upon the tensile properties of the corresponding alkylated kraft lignin-based polymeric materials. This arose from the casting conditions employed, where heavy association is promoted.
It was then found that removal of the low molecular weight kraft lignin components by ultrafiltration yields improved preparations for successful polymeric material formulations. This first became evident with an ethylated higher molecular weight kraft lignin fraction obtained by ultrafiltration through a 10,000 nominal molecular weight cutoff membrane, which exhibited substantially better tensile behavior than the parent preparation. When compared with common synthetic polymeric materials, alkylated kraft lignin preparations are closest to polystyrene as far as tensile strength (37 MPa), Young's modulus (1.9 GPa) and elongation to failure (2%) are concerned. In regard to the relatively low elongation to failure, alkylated 100% kraft lignin-based polymeric materials are quite brittle and therefore need to be plasticized or toughened if the goal of injection-molding useful components from them is to be realized.
For the first time ever, extensive plasticization of alkylated 100% kraft lignin-based polymeric materials was achieved in 1998 with single commercially available blend components. By blending with such components at levels ranging to 30%, alkylated kraft lignin-based polymeric materials were progressively plasticized and exhibited extensive plastic deformation before fracture. The ultimate strains extended comfortably beyond 60%. The blend components themselves do not have any measurable tensile strengths and therefore they act as true plasticizers, presumably separating the macromolecular lignin chains so as to facilitate chain segmental mobility. A 30% plasticizer content may be too high for industrial applications (although such levels have been studied with PVC), and so the major focus of the project became the attainment of comparable degrees of plasticization using only 10-15% blend component levels.
The final phase of the project involves injection-molding studies with the plasticized alkylated 100% kraft lignin-based polymeric materials. This work is dedicated to making tensile test pieces with a Randcastle RC-0250 single screw extrusion molding unit, and constitutes a vital step toward the industrial production of these novel biodegradable plastics.
In August 1998, graduate student Y. Li was conferred the 1998 Bio/Environmentally Degradable Polymer Society Student Award at their 7th Annual Meeting held in Cambridge, MA. The objectives of the Society are to promote basic research, education, and training in the design, synthesis, characterization, testing, and processing of biodegradable and other environmentally degradable polymers; as well as, to facilitate information exchange among researchers in the areas of agriculture, biomedical applications, environmental and wildlife protection, forestry, and waste management.
Journal Articles:No journal articles submitted with this report: View all 10 publications for this subproject
Supplemental Keywords:Geographic Area, Sustainable Industry/Business, Scientific Discipline, RFA, Midwest, Technology for Sustainable Environment, Sustainable Environment, Chemical Engineering, Civil/Environmental Engineering, Chemistry, Environmental Engineering, cleaner production/pollution prevention, New/Innovative technologies, Civil Engineering, Engineering, State, lignin, polymer formulations, environmentally conscious manufacturing, plastics, biodegradable, polbiny acetate, polymer design, pulp, biodegradable materials, polymers, innovative technology, innovative technologies, pollution prevention, Minnesota, International Falls
Progress and Final Reports:
1996 Progress Report
1997 Progress Report
Original Abstract
1999 Progress Report
Main Center Abstract and Reports:
R825370 EERC - National Center for Clean Industrial and Treatment Technologies (CenCITT)
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825370C032 Means for Producing an Entirely New Generation of Lignin-Based Plastics
R825370C042 Environmentally Conscious Design for Construction
R825370C046 Clean Process Advisory System (CPAS) Core Activities
R825370C048 Investigation of the Partial Oxidation of Methane to Methanol in a Simulated Countercurrent Moving Bed Reactor
R825370C054 Predictive Tool for Ultrafiltration Performance
R825370C055 Heuristic Reactor Design for Clean Synthesis and Processing - Separative Reactors
R825370C056 Characterization of Selective Solid Acid Catalysts Towards the Rational Design of Catalytic Reactions
R825370C057 Environmentally Conscious Manufacturing: Prediction of Processing Waste Streams for Discrete Products
R825370C064 The Physical Properties Management System (PPMS™): A P2 Engineering Aid to Support Process Design and Analysis
R825370C065 Development and Testing of Pollution Prevention Design Aids for Process Analysis and Decision Making
R825370C066 Design Tools for Chemical Process Safety: Accident Probability
R825370C067 Environmentally Conscious Manufacturing: Design for Disassembly (DFD) in De-Manufacturing of Products
R825370C068 An Economic Comparison of Wet and Dry Machining
R825370C069 In-Line Copper Recovery Technology
R825370C070 Selective Catalytic Hydrogenation of Lactic Acid
R825370C071 Biosynthesis of Polyhydroxyalkanoate Polymers from Industrial Wastewater
R825370C072 Tin Zeolites for Partial Oxidation Catalysis
R825370C073 Development of a High Performance Photocatalytic Reactor System for the Production of Methanol from Methane in the Gas Phase
R825370C074 Recovery of Waste Polymer Generated by Lost Foam Technology in the Metal Casting Industry
R825370C075 Industrial Implementation of the P2 Framework
R825370C076 Establishing Automated Linkages Between Existing P2-Related Software Design Tools
R825370C077 Integrated Applications of the Clean Process Advisory System to P2-Conscious Process Analysis and Improvement
R825370C078 Development of Environmental Indices for Green Chemical Production and Use