|BAJWA, DILPREET - North Dakota State University|
|BAJWA, SREEKALA - North Dakota State University|
Submitted to: Polymer Degradation and Stability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2015
Publication Date: 7/13/2015
Citation: Bajwa, D., Bajwa, S., Holt, G.A. 2015. Impact of biofibers and coupling agents on the weathering characteristics of composites polymer degradation and stability. Polymer Degradation and Stability. 120:212-219. DOI:10.1016/j.polymdegradstab.2015.06.015.
Interpretive Summary: The use of natural fibers to manufacture composites used for building materials, automotive parts, and consumer goods is a growing trend as companies seek to be more eco-friendly. However, all natural fibers do not behave the same and some fiber characteristics have a negative impact on the composties they are used as an ingredient. This study evaluated the use of two coupling agents with cotton burrs, guayule bagasse (biomass remaining from extracting resin from the guayule plant) and oak wood flour (an industry standard that has been extensively researched). The three biofibers were blended and the coupling agents added independently. The objective was to see if the coupling agents enhanced mechanical properties, thermal stability, and/or weathering performance to 2,200 hours of UV exposure. Results revealed that the coupling agents did not positively impact water absorption, color steadfastness, or surface texture.The sturctural and mechanical properties were impacted more by the blends of natural fibers than the coupling agents.
Technical Abstract: This paper explores the ultraviolet (UV) weathering performance of high density polyethylene (HDPE) composites with different biofiber fillers and coupling agent. Biofiber polymer composite (BFPC) material samples were prepared using oak, cotton burr and stem (CBS) or guayule bagasse as fiber source HDPE as resin, and two different coupling agents. Weathering variables included exposure to UV radiation and moisture cycles for up to 2200 h. Each variable can degrade BFPC matrix independently or synergistically. The impact of weathering was measured through the changes in the surface matrix, mechanical properties and thermal stability of BFPC as a function of biofibers types and coupling agents. The coupling agent treated composites showed significant color shift (change in E) and variable surface degradation. Water absorption of the weathered samples continued to increase after 10 days of immersion. Flexural stiffness, strength and impact properties of weathered samples decreased regardless of fiber type or coupling agent. Linear thermal expansion of weathered composites was not affected by coupling agents. Overall oak fiber based composites performed better than CBS and guayule based fibers.