Grantee Research Project Results
1999 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: Center for Air, Climate, and Energy Solutions
Center Director: Robinson, Allen
Title: Means for Producing an Entirely New Generation of Lignin-Based Plastics
Investigators: Sarkanen, Simo
Institution: University of Minnesota
EPA Project Officer: Aja, Hayley
Project Period:
Project Period Covered by this Report: January 1, 1998 through January 1, 1999
RFA: Exploratory Environmental Research Centers (1992) RFA Text | Recipients Lists
Research Category: Center for Clean Industrial and Treatment Technologies (CenCITT) , Targeted Research
Objective:
This project is dedicated to developing technology for establishing a plant where the first truly lignin-based biodegradable plastics can be manufactured. The industrial byproduct lignin for producing these plastics was 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.
Then, through CenCITT funded work, alkylated 100% kraft lignin-based plastics with tensile properties very similar to those of polystyrene were produced. Thus the proposed work has sought to develop feedstocks suitable for injection-molding biodegradable plastic components composed solely 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, could be extrusion-molded into strong plastic components. The compositions of the preparations have been evaluated through chromatographic analyses and molecular weight determinations. The plasticizers sought for use with the new alkylated kraft lignin-based plastics were 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 was centrally important. The final step in making these new biodegradable plastics was to involve spray-drying aqueous suspensions of the kraft lignin derivatives to produce powders that would 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 was fully established during the previous reporting period. In the absence of plasticizers, these new materials exhibited tensile behavior very similar to that of polystyrene.
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 was promoted.
It was then found that removal of the low molecular weight kraft lignin components by ultrafiltration improved the 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 were closest to polystyrene as far as tensile strength (37 MPa), Young's modulus (1.9 GPa) and elongation to failure (2%) were concerned. In regard to the relatively low elongation to failure, alkylated 100% kraft lignin-based polymeric materials were quite brittle and therefore needed to be plasticized or toughened if the goal of injectionmolding useful components from them was to be realized.
For the first time ever, extensive plasticization of alkylated 100% kraft lignin-based polymeric materials was achieved in 1998 with commercially available aliphatic polyesters. By blending with such components at levels ranging to 30 - 40%, alkylated kraft lignin-based polymeric materials were progressively plasticized and exhibited extensive plastic deformation before fracture. The ultimate strains could extend comfortably beyond 60%. The poly(1,4-butylene adipate), poly(1,3-propylene adipate), poly(1,3-propylene succinate), poly(diethyleneglycol adipate) and poly(trimethylene glutarate) used for the purpose did not themselves have any measurable tensile strengths and therefore they acted as true plasticizers, presumably separating the macromolecular lignin chains so as to facilitate chain segmental mobility. A 30% plasticizer content may be higher than desirable from an economic point of view, and so a major effort was mounted to attain adequate degrees of plasticization using only 10 - 15% blend component levels. This part of the enterprise has so far not succeeded.
The final phase of the project has involved extrusion-molding studies with the plasticized alkylated 100% kraft lignin-based polymeric materials. This work has focused upon making tensile test pieces with a Randcastle RC-0250 single screw extrusion-molding unit. Hereby the feasibility of extrusion/injection-molding components and/or parts from these thermoplastic formulations has been clearly demonstrated. However, the configuration of the apparatus employed for the purpose has tended to engender the appearance of voids in the test pieces that have been produced. The cause of the problem is under investigation.
Journal Articles:
No journal articles submitted with this report: View all 10 publications for this subprojectSupplemental Keywords:
RFA, Scientific Discipline, Geographic Area, Sustainable Industry/Business, Midwest, Chemical Engineering, cleaner production/pollution prevention, Sustainable Environment, Chemistry, State, Technology for Sustainable Environment, Civil/Environmental Engineering, Civil Engineering, New/Innovative technologies, Engineering, Environmental Engineering, Minnesota, biodegradable, polbiny acetate, environmentally conscious manufacturing, pulp, lignin, polymers, biodegradable materials, innovative technology, International Falls, Minnesota, plastics, innovative technologies, pollution prevention, polymer designRelevant Websites:
biodegradable plastic, lignin, pulp, fabrication.Main Center Abstract and Reports:
R825370 Center for Air, Climate, and Energy Solutions 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
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
Main Center: R825370
155 publications for this center
36 journal articles for this center