Current Research

Dr. Clemons' research seeks to overcome technical limitations currently preventing the expanded use polymer composites made with fillers and reinforcements derived from wood or other natural fibers or discover new types of composites made from them. These composites constitute a broad class of materials that range from composites of recycled plastics, wood flour, and various additives to high-performance composites from engineering polymers and nanocellulose, for example.

Though some of these composites (e.g., early wood-flour-filled thermosets – “bakelite”) have been around since the early 1900's, current research usually involves dynamic market segments or rapidly emerging technology areas such as biopolymers or nano-scale fillers and reinforcements that may lead to composites with very different characteristics (e.g., transparency) than those that have been historically produced.

Major research objectives include:

• Understanding and optimizing the influences of constituent materials on the behavior of wood-polymer composites and cellulose nanocomposites
• Developing and optimizing composite preparation methods
• Relating microstructure and morphology to composite behavior
• Using wood-polymer composite technology as a tool to restore damaged ecosystems and promote resource sustainability

Research Interests

• Cellulose nanocomposites
• Materials science and processing of composites from wood or other natural fibers and plastics
• Microstructural influences on composite performance
• Durability of wood-plastic composites
• Composites from recycled materials

Why This Research is Important

Expanding the use polymer composites made with fillers and reinforcements derived from wood or other natural fibers have the potential to impact a variety of forest service and societal goals. These composites could offer significant outlets for wood-based materials from manufacturing residues, recovered post-consumer wood-based materials, and other recycled and underutilized forest-based resources in cost effective, durable products, for example. They also offer an opportunity for reducing the non-renewable content of petroleum-based plastics by adding a sustainable reinforcement. Discovering new technologies or applying emerging ones to wood-based composites could create high-performance and high-value composites that could make wood more competitive with other materials, move wood into entirely new markets, or favorably influence the economics of the biorefinery platform, for example.

Education

• University of Wisconsin, Madison, Ph.D. Materials Science 2000
• University of Wisconsin, Madison, M.S. Forestry 1990
• University of Wisconsin, Madison, B.S. Chemical Engineering 1988

Professional Organizations

• Society of Plastics Engineers, Member

Featured Publications & Products

• Caulfield, Daniel F.; Clemons, Craig; Rowell, Roger M. 2010. Wood thermoplastic composites.
• Clemons, Craig M. 2010. Wood flour.
• Clemons, Craig M.; Stark, Nicole M. 2009. Feasibility of using saltcedar as a filler in injection-molded polyethylene composites.
• Clemons, Craig M.; Sabo, Ronald C.; Hirth, Kolby C. 2011. The effects of different silane crosslinking approaches on composites of polyethylene blends and wood flour.
• Steckel, Vera; Clemons, Craig Merrill; Thoemen, Heiko. 2007. Effects of material parameters on the diffusion and sorption properties of wood-flour/polypropylene composites.
• Clemons, Craig M.; Ibach, Rebecca E. 2004. Effects of processing method and moisture history on laboratory fungal resistance of wood-HDPE composites..
• Clemons, Craig M.; Caulfield, Daniel F.; Giacomin, A. Jeffrey. 1999. Dynamic fracture toughness of cellulose-fiber-reinforced polypropylene : preliminary investigation of microstructural effects.

Patents

• Zhu, JunYong; Sabo, Ronald; Clemons, Craig. 2014. Method for Integrated Conversion of Lignocellulosic Material to Sugars or Biofuels and Nano-Cellulose.

Publications

• Clemons, Craig ; Sabo, Ronald . 2021. A Review of Wet Compounding of Cellulose Nanocomposites.
• Zheng, Ting ; Clemons, Craig M.; Pilla, Srikanth . 2021. Grafting PEG on cellulose nanocrystals via polydopamine chemistry and the effects of PEG graft length on the mechanical performance of composite film.
• Zheng, Ting ; Clemons, Craig M.; Pilla, Srikanth . 2020. Comparative Study of Direct Compounding, Coupling Agent-Aided and Initiator-Aided Reactive Extrusion to Prepare Cellulose Nanocrystal/PHBV (CNC/PHBV) Nanocomposite.
• Ibach, Rebecca E.; Clemons, Craig M.; Stark, Nicole M. 2020. Long-term field exposure of wood-plastic composites processed on a commercial-size extruder.
• Clemons, Craig ; Reiner, Rick . 2020. Preparation of cellulose nanocrystal-polyoropylene masterbatches by water-assisted thermokinetic mixing.
• Dunlop, Matthew J.; Clemons, Craig ; Reiner, Richard ; Sabo, Ronald ; Agarwal, Umesh P.; Bissessur, Rabin ; Sojoudiasli, Helia ; Carreau, Pierre J.; Acharya, Bishnu . 2020. Towards the scalable isolation of cellulose nanocrystals from tunicates.
• Zheng, Ting ; Zhang, Zhan ; Shukla, Srishti ; Agnihotri, Shubh ; Clemons, Craig M.; Pilla, Srikanth . 2019. PHBV-graft-GMA via reactive extrusion and its use in PHBV/nanocellulose crystal composites.
• Stelte, Wolfgang ; Barsberg, Søren T.; Clemons, Craig ; Morais, João Paulo Saraiva; de Freitas Rosa, Morsyleide ; Sanadi, Anand R. 2018. Coir fibers as valuable raw material for biofuel pellet production.
• Ibach, Rebecca E.; Hadi, Yusuf Sudo; Clemons, Craig M.; Sulaeman, Yusuf . 2018. Termite resistance of wood-plastic composites made with acetylated wood flour, coupling agent or zinc borate.
• Peng, Jun; Zhang, Huilong; Zheng, Qifeng; Clemons, Craig M.; Sabo, Ronald C.; Gong, Shaoqin; Ma, Zhenqiang; Turng, Lih-Sheng. 2017. A composite generator film impregnated with cellulose nanocrystals for enhanced triboelectric performance.
• Ibach, Rebecca E.; Clemons, Craig M. 2017. Long term durability of wood-plastic composites made with chemically modified wood.
• Ibach, Rebecca E.; Clemons, Craig M.; Chen, George C. 2017. The use of new, aqueous chemical wood modifications to improve the durability of wood-plastic composites.
• Clemons, Craig. 2016. Nanocellulose in spun continuous fibers: A review and future outlook.
• Peng, Jun; Walsh, Philip J.; Sabo, Ronald C.; Turng, Lih-Sheng; Clemons, Craig M. 2016. Water-assisted compounding of cellulose nanocrystals into polyamide 6 for use as a nucleating agent for microcellular foaming.
• Sabo, Ronald C.; Elhajjar, Rani F.; Clemons, Craig M.; Pillai, Krishna M. 2015. Chapter 15: Characterization and Processing of Nanocellulose Thermosetting Composites.
• Zhang, Jingzhi; Laguna, Andrea; Clemons, Craig; Wolcott, Michael P.; Gleisner, Rolland; Zhu, J.Y.; Zhang, Xu. 2015. Effect of Hot-Pressing Temperature on the Subsequent Enzymatic Saccharification and Fermentation Performance of SPORL Pretreated Forest Biomass.
• Zhang, Chunmei; Zhai, Tianliang; Sabo, Ronald; Clemons, Craig; Dan, Yi; Turng, Lih-Sheng. 2014. Reinforcing Natural Rubber with Cellulose Nanofibrils Extracted from Bleached Eucalyptus Kraft Pulp.
• Peng, Jun; Ellingham, Thomas; Sabo, Ron; Turng, Lih-Sheng; Clemons, Craig M. 2014. Short cellulose nanofribrils as reinforcement in polyvinyl alcohol fiber.
• Zhang, Chunmei; Dan, Yi; Peng, Jun; Turng, Lih-Sheng; Sabo, Ronald; Clemons, Craig. 2014. Thermal and Mechanical Properties of Natural Rubber Composites Reinforced with Cellulose Nanocrystals from Southern Pine.
• Agarwal, Umesh; Sabo, Ronald; Reiner, Richard; Clemons, Craig; Rudie, Alan. 2013. Chapter 1.4: Spatially Resolved Characterization of CNC-Polypropylene composite by Confocal Raman Microscopy.
• Clemons, Craig M.; Rowell, Roger M.; Plackett, David; Segerholm, B. Kristoffer. 2013. Chapter 13:Wood/Nonwood Thermoplastic Composites.
• Clemons, Craig; Sedlmair, Julia; Illman, Barbara; Ibach, Rebecca; Hirschmugl, Carol. 2013. Chemically imaging the effects of the addition of nanofibrillated cellulose on the distribution of poly(acrylic acid) in poly(vinyl alcohol).
• Srithep, Yottha; Sabo, Ronald; Clemons, Craig; Turng, Lih-Sheng; Pilla, Srikanth; Peng, Jun. 2012. Effect of Material Parameters on Mechanical Properties of Biodegradable Polymers/Nanofibrillated Cellulose (NFC) Nano Composites.
• Stelte, Wolfgang; Clemons, Craig; Holm, Jens K.; Ahrenfeldt, Jesper; Henriksen, Ulrik B.; Sanadi, Anand R. 2012. Fuel Pellets from Wheat Straw: The Effect of Lignin Glass Transition and Surface Waxes on Pelletizing Properties.
• Yalcin, Baris; Amos, Steve E; D Souza, Andrew S; Clemons, Craig M; Gunes, I Sedat; Ista, Troy K. 2012. Improvements in processing characteristics and engineering properties of wood flour-filled high density polyethylene composite sheeting in the presence of hollow glass microspheres.
• Javadi, Alireza; Srithep, Yottha; Pilla, Srikanth; Clemons, Craig C.; Gong, Shaoqin; Turng, Lih-Sheng. 2012. Microcellular poly(hydroxybutyrate-co-hydroxyvalerate)-hyperbranched polymer-nanoclay nanocomposites.
• Srithep, Yottha; Turng, Lih-Sheng; Sabo, Ronald; Clemons, Craig. 2012. Nanofibrillated cellulose (NFC) reinforced polyvinyl alcohol (PVOH) nanocomposites: properties, solubility of carbon dioxide, and foaming.
• Javadi, Alireza; Srithep, Yottha; Clemons, Craig C.; Turng, L-S.; Gong, Shaoqin. 2012. Processing of poly(hydroxybutyrate-co-hydroxyvalerate)-based bionanocomposite foams using supercritical fluids.
• Agarwal, Umesh P.; Sabo, Ronald; Reiner, Richard S.; Clemons, Craig M.; Rudie, Alan W. 2012. Spatially Resolved Characterization of Cellulose Nanocrystal-Polypropylene Composite by Confocal Raman Microscopy.
• Clemons, Craig M.; Sabo, Ronald C.; Kaland, Michael L.; Hirth, Kolby C. 2011. Effects of silane on the properties of wood-plastic composites with polyethylene-polypropylene blends as matrices.
• Stelte, Wolfgang; Clemons, Craig; Holm, Jens K.; Sanadi, Anand R.; Ahrenfeldt, Jesper; Shang, Lei; Henriksen, Ulrik B. 2011. Pelletizing properties of torrefied spruce.
• Srithep, Yottha; Javadi, Alireza; Pilla, Srikanth; Turng, Lih-Sheng; Gong, Shaoqin; Clemons, Craig; Peng, Jun. 2011. Processing and characterization of recycled poly(ethylene terephthalate) blends with chain extenders, thermoplastic elastomer, and/or poly(butylene adipate-co-terephthalate).
• Olsson, S.; Ostmark, E.; Ibach, R.E.; Clemons, C.M.; Segerholm, K.B.; Englund, F. 2011. The Use of Esterified Lignin for Synthesis of Durable Composites.
• Stelte, Wolfgang; Clemons, Craig; Holm, Jens K.; Ahrenfeldt, Jesper; Henriksen, Ulrik B.; Sanadi, Anand R. 2011. Thermal transitions of the amorphous polymers in wheat straw.
• Clemons, Craig. 2010. Composites from wood and plastics.
• Clemons, Craig. 2010. Elastomer modified polypropylene polyethylene blends as matrices for wood flour plastic composites.
• Pilla, Srikanth; Kramschuster, Adam; Lee, Jungjoo; Clemons, Craig; Gong, Shaoqin; Turng, Lih-Sheng. 2010. Microcellular processing of polylactide-hyperbranched polyester-nanoclay composites.
• Clemons, Craig M. 2010. Natural fibers.
• Javadi, Alireza; Srithep, Yottha; Lee, Jungjoo; Pilla, Srikanth; Clemons, Craig; Gong, Shaoqin; Turng, Lih-Sheng. 2010. Processing and characterization of solid and microcellular PHBV/PBAT blend and its RWF/nanoclay composites.
• Agarwal, Umesh P.; Sabo, R.; Reiner, Richard S.; Clemons, Craig Merrill; Rudie, Alan W. 2009. Raman analysis and mapping of cellulose nanocrystal-polypropylene composite.
• Lei, Yong; Wu, Qinglin; Clemons, Craig M.; Guo, Weihong. 2009. Phase structure and properties of poly(ethylene terephthalate)/polyethylene based on recycled materials.
• Clemons, Craig. 2008. Raw materials for wood-polymer composites..
• Lei, Yong; Wu, Qinglin; Clemons, Craig M.; Yao, Fei; Xu, Yanjun. 2007. Influence of nanoclay on properties of HDPE/wood composites.
• Clemons, Craig Merrill; Sanadi, Anand R. 2007. Instrumented impact testing of kenaf fiber reinforced polypropylene composites: effects of temperature and composition.
• Lei, Yong; Wu, Qinglin; Clemons, Craig M. 2007. Preparation and properties of recycled HDPE/clay hybrids.
• Clemons, Craig; Stark, Nicole. 2007. Use of saltcedar and Utah juniper as fillers in wood plastic composites.
• Ibach, Rebecca E.; Clemons, Craig M.; Schumann, Rebecca L. 2007. Wood-plastic composites with reduced moisture : effects of chemical modification on durability in the laboratory and field.
• Ibach, Rebecca E.; Clemons, Craig M. 2006. Effect of acetylated wood flour or coupling agent on moisture, UV, and biological resistance of extruded woodfiber-plastic composites.
• Winandy, Jerrold E.; Clemons, Craig M.; Stark, Nicole M.; Muehl, James H.; Williams, R. Sam. 2005. Evaluation and process development of salt cedar and juniper biocomposites as tools to utilize exotic and invasive species and restore native ecosystems.
• Clemons, Craig M.; Caulfield, Daniel F. 2005. Natural fibers.
• Clemons, Craig M.; Caufield, Daniel F. 2005. Wood flour.
• Caulfield, Daniel F.; Clemons, Craig; Jacobson, Rodney E.; Rowell, Roger M. 2005. Wood thermoplastic composites.
• Stark, Nicole M.; Matuana, Laurent M.; Clemons, Craig M. 2004. Effect of processing method on surface and weathering characteristics of wood-flour/HDPE composites.
• Clemons, Craig Merrill; Ibach, Rebecca E. 2003. Application of laboratory fungal resistance tests to solid wood and wood-plastic composite.
• Ibach, Rebecca E.; Clemons, Craig M.; Stark, Nicole M. 2003. Combined ultraviolet and water exposure as a preconditioning method in laboratory fungal durability testing.
• Stark, Nicole M.; Matuana, Laurent M.; Clemons, Craig M. 2003. Effect of processing method on accelerated weathering of wood-flour/HDPE composites.
• Clemons, Craig; Caulfield, Daniel; Giacomin, A. Jeffrey. 2003. Impact toughness of cellulose-fiber reinforced polypropylene : influence of microstructure in laminates and injection molded composites.
• Ibach, Rebecca E.; Clemons, Craig M. 2002. Biological resistance of polyethylene composites made with chemically modified fiber or flour.
• Clemons, Craig M.; Ibach, Rebecca E. 2002. Laboratory tests on fungal resistance of wood filled polyethylene composites.
• Clemons, Craig. 2002. Wood-plastic composites in the United States : the interfacing of two industries.
• Stark, N. M.; White, R. H.; Clemons, C. M. 1997. Heat release rate of wood-plastic composites.
• English, Brent; Clemons, Craig M.; Stark, Nicole; Schneider, James P. 1996. Waste-wood-derived fillers for plastics.

Research Highlights

Highlight	Title	Year
FPL-2014-174	Enhancing High-Performance Plastics with Nanocellulose Forest Service scientists are using nanocellulose to improve the performance of engineering plastics. By applying advanced processing methods, t ...	2014
FPL-2010-011	Improved Composites from Wood Flour and Mixed Plastics In a cooperative project with Louisiana State University, Forest Products Laboratory researchers have used crosslinking technologies, commonly u ...	2010
FPL-2010-026	Increasing the Value of Slash by Use in Oriented Strand Board The project takes a closer look at chunkwood processing first developed in 1977 at the Northern Research Station lab in Houghton, MI. Branches a ...	2010
FPL-2013-148	Nanocellulose Gels Spun Into Continuous Fibers for Use in Advanced Composites Forest Service scientists worked with the University of Wisconsin to spin nanocellulose gels into continuous fibers so that they can be used mor ...	2013
FPL-2014-188	Short Cellulose Nanofibrils Reinforce Aligned Polyvinyl Alcohol Fibers Cellulose nanomaterials have recently gained much attention for their potential use for reinforcing polymers and for use in functional materials ...	2014
FPL-2011-13	Softening of Biomass and Its Effect on Fuel Pellet Production Biomass such as torrefied wood or wheat straw are of increasing interest as fuel but are difficult to pelletize. Researchers are investigating t ...	2011
FPL-2012-12	Wood-Plastic Composites Improved with Glass Adding microsized glass particles to wood-plastic composites creates a less dense but stiffer material for use in a variety of building applicat ...	2012