Location: Functional Foods Research Unit
Title: Evaluation of the mechanical and thermal properties of coffee tree wood flour - polypropylene composites Authors
|Reifschneider, Louis -|
|Lopez-Nunez, Juan Carlos -|
Submitted to: BioResources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 2, 2014
Publication Date: June 11, 2014
Citation: Tisserat, B., Reifschneider, L., Lopez Nunez, J.C., Hughes, S.R., Selling, G.W., Finkenstadt, V.L. 2014. Evaluation of the mechanical and thermal properties of coffee tree wood flour - polypropylene composites. BioResources. 9(3):4449-4467. Interpretive Summary: Coffee is an important food commodity in the world economy. Unfortunately, coffee trees must be frequently replaced due to disease and climate problems. An enormous amount of biomass is yearly generated by this crop, which is currently under-utilized. There is a great need to identify and commercialize new ligno-cellulosic sources to be used in wood plastic composites (WPC). In this study, we evaluated the physical properties of WPC made with coffee tree fiber. Coffee wood fiber was found to provide a superior filler/reinforcement in WPC compared to other bio-materials and will provide an inexpensive commercial filler source in the future.
Technical Abstract: Columbian coffee trees are subject to frequent replacement plantings due to disease and local climate changes which makes them an ideal source of wood fibers for wood plastic composites (WPC). Composites of polypropylene (PP) consisting of 25% and 40% by weight of coffee wood flour (CF) and 0% or 5% by weight of maleated PP (MAPP) were produced by twin screw compounding and injection molding. Injection molded test specimens were evaluated for their tensile, flexural, impact, and thermal properties. Composites containing MAPP had significantly improved tensile and flexural properties compared to neat PP or composites without MAPP. Comparison of the mechanical properties obtained with coffee wood flour to other more conventional wood fillers indicates CF can produce bio-composites with excellent mechanical properties. Izod impact resistances of all composites were significantly lower than neat PP although WPC containing MAPP were superior to WPC without MAPP. Bio-based fiber composites made by mixing CF in equal portions with other fiber sources were evaluated to determine the compatibility of using CF with other sources of filler materials. The alternative fillers consisted of Osage orange wood, pine wood, or Camelina press cake. Soaking of tensile bars of the various CF blends in distilled water for 35 days may alter their color and mechanical properties and result in weight gain. Differential scanning calorimetery and thermogravimetric analysis were conducted on the neat PP and bio-composites to evaluate their thermal properties as they relate to potential degradation during conventional thermoplastic resin processing.