Program Overview and Workflow

As the world moves increasingly towards bio-based technologies, it is necessary to address the barriers impeding wide-spread use of biopolymers and biocomposites. These involve a new set of challenges for the polymer and composites world, including the high cost of biopolymer synthesis, biopolymer property limitations, incompatibility of hydrophilic/hydrophobic surfaces in biofiber reinforced polymers, and inadequate translation of biofiber properties to the biocomposite. Attacking these inter-related biomaterial challenges requires an integrated, cross-disciplinary approach. The chart above illustrates the integration and flow of activities in the CNAM-Bio Center. There are two main programs within the center: Polymer Biosynthesis and Bioprocessing and Biopolymer/Biocomposite Processing and Manufacturing. The processing and manufacturing group uses both commercially available biopolymers and center-derived microbial biopolymers and nanocellulose.

Program Elements

1. Biopolymers from agricultural waste biomass

  • Identify and/or engineer thermophilic microbial strains that can efficiently breakdown lignocellulose without expensive pretreatment and produce biopolymers (primarily polyhydroxyalkanoates, PHAs).
  • Take advantage of the faster kinetics of high temperature processing enabled by utilization of thermophiles.
  • Increase biopolymer yields using genome editing, electrocatalytic, and electrochemical approaches.
  • Scale-up bioreactor production of PHAs to kilogram quantities for utilization in polymer processsing studies (item 5).

2. Biopolymers from methane

  • Develop recombinant strains to produce PHAs from unpurified methane at high yields.
  • Scale-up bioreactor production of PHAs to kilogram quantities for utilization in polymer processsing studies (item 5).

3. Engineering biopolymer properties

  • Characterize the rheological, microstructural, thermal and mechancial properties of the microbial PHAs produced.
  • Engineer polymer structure (monomer composition, side chain structure, etc.), and resulting properties, through genetic engineering strategies.
  • Provide interactive input to the polymer processing investigations (item 5).

4. Nanocellulose from biomass

  • Eliminate the use of strong, high-cost solvents for extraction of nanocellulose from biomass, reducing processing costs and enhancing nanocellulose quality.
  • Produce targeted enzyme cocktail for removal of lignin, pectin and xylan via a thermopilic microbe found to efficiently degrade biomass.
  • Assess dispersion properties of the nanocellulose in polymers and biopolymers (see also item 6).

5. Biopolymer processing

  • Study polymer processing of new biopolymers and design effective processing conditions for extrusion, injection molding, thermoforming, etc.
  • Explore polymer blends and effects of additives.
  • Provide interactive input to the biopolymer property engineering studies (item 3).

6. Biocomposite processing and manufacturing

  • Apply CNAM’s DiFTS process to the production of natural fiber (flax, hemp, bamboo….) thermoplastic polymer and biopolymer composites, with detailed exploration of processing variables and resulting mechanical and impact properties.
  • Use processing flexibility of the CAPE Lab’s Thermoplastic Impregnation Machine (CAPE-TIM) to produce high-quality, continuous-fiber thermoplastic tapes/sheets from natural fiber yarns and fabrics, with both biopolymers and petroleum-based polymers.
  • Systematically evaluate fiber/polymer interface, wet-out, and interfacial failure characteristics.
  • Evaluate innovative and commercial sizing formulations for enhanced  interfacial adhesion.
  • Explore processing and properties of nanocellulose-reinforced biopolymers and mutiscale (natural-fiber/nanocellulose) reinforced biopolymers (with focus on nanocellulose produced  in item 4).
  • Explore hybrid (natural and synthetic) fiber combinations.

7. Advanced characterization

  • Apply TEM, SEM, FTIR, Raman, LC-MS, AFM, EDX, WAXS, XPS, PALM, Micro X-Ray CT, rheometry, DMA, DSC, TGA, and other techniques.
  • Combine scanning probe, fluorescence, and electron microscopies to elucidate the nanoscale architecture of lignicellulosic substrates.
  • Combine PALM with AFM to map nanomechanical and spatio-chemical distributions of bioactive components of lignocellulosic substrates and associated biopolymers.
  • Use advanced characterization techniques to help elucidate biological pathways for biopolymer biosynthesis.
Cellulose degrading bacteria on ligncellulosic substrate (Sani Lab, SD Mines)
Fluorescence emission from PHA in thermophilic microbes stained with Nile red (left), and TEM images of PHA (dark regions) in thermophilic microbes (center and right). (Sani Lab, SD Mines)
Proposed development of recombinant PHA-producing methanatroph strains
Injection molding and compression molding at the CAPE Lab facility, SD Mines
CAPE-TIM Thermoplastic Impregnation Tape and Strand Line at the CAPE Lab facility, SD Mines
Atomic Force Microscope image, Photo-activated Localization Microscope (PALM) image and tomographic reconstruction (based on TEM images) of cellulose nanofibrils (left) dressed with carbohydrate binding molecules (CBMs) expressing a fluorescent protein (middle) or CBMs linked to quantum dot labels (right), revealing nanoscale architecture and molecular organization. Images are from a collaboration between SD Mines (Smith and Ahrenkiel) and NREL Bio-Energy Center.