Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: 8/25/2008
Publication Date: 9/8/2008
Citation: Bajwa, S., Holt, G.A., Bajwa, D., Coffelt, T.A., Nakayama, F.S. 2008. Evaluation of two agricultural residues as ligno-cellulosic filler in polymer composites [abstract]. Association for the Advancement of Industrial Crops Conference, September 7-11, 2008. New Crops and Bioproducts Development. p. 36.
Technical Abstract: Rationale: Agricultural residues refer to the waste stream coming from agricultural production and processing operations. These materials are often rich in ligno-cellulosic fibers, but offer no significant value at present. The processing plants usually pay for disposal of these waste streams, however, these waste materials are rich in ligno-cellulosic fibers, and hence may offer value as fillers in ligno-cellulosic polymer composites (LCPC). Wood plastic composites (WPC) are the common type of LCPC, where wood is used as the fiber filler. Objective: The objective of this study was to evaluate the potential of two agricultural residues, cotton gin waste and guayule waste, as fiber fillers in LCPC.Method: An experiment was conducted by manufacturing LCPC with five fiber fillers, including cotton burr or carpels (CB), cotton burr mixed with 2% of second cut linters (BL), cotton burr mixed with 30% of guayule whole plant (GW), cotton burr mixed with 30% of guayule bagasse (GB), and oak as control (CL). All materials were ground to a size of 20-40 mesh. The formulation of the LCPC was 50% ligno-cellulosic fiber filler, 40% HDPE, 6% lubricant, and 4% mineral filler. The treatments were replicated 5 times. The oven dry fiber filler and other ingredients were weighed, hand mixed, and extruded with a twin-screw extruder through a 1" x 1/4" die. The extruded samples were water cooled, conditioned for approximately 3 months, and then tested for physical and mechanical properties. Results: The LCPC made from cotton and guayule-based fibers showed lower specific gravity and higher water absorption than wood. Strength properties such as MOE, MOR and hardness were lower and nail withdrawal strength was higher for LCPC made from agricultural residues, compared to wood. They also exhibited much lower coefficient of linear thermal expansion compared to the wood-based samples. All the four mixes made from agricultural residue showed good potential as an alternative filler for natural fiber composites. When the four residue-based treatments were compared to each other, the GW had superior physical properties comparable to wood, while GB had better strength properties. Conclusion: Both cotton burr and guayule fibers have good potential as fiber fillers in LCPC.