Download (PDF 327 KB): https://research.fs.usda.gov/download/treesearch/30664.pdf
Abstract
The characteristics and properties of wood fiber is one of many factors of critical importance to the performance of wood-plastic composites. In commercial thermo-mechanical pulping (TMP) of wood chips to produce fibers, high temperatures (>100°C) are used to separate the fibers during TMP refining. These mechanical pressures and temperatures are usually modulated to achieve the desired fiber characteristics and properties. However, relatively high total electric energy is required to produce these TMP pulps. Recently, an oxalic-acid pretreatment of wood chips prior to TMP refining has been developed. Previous, experiments have found that the energy required in refining after such pretreatment can be dramatically reduced. In addition, other work with medium-density fiberboard made using TMP fiber from oxalic acid-pretreated chips was shown to have enhanced moisture resistance when compared to fiberboard made with non-treated fiber. In the experiments reported in this paper, wood chips were first pre-treated using either oxalic acid- or dialkyl ester oxalic acid-derivatives, then refined into fiber using traditional TMP refining processes. These variously treated fiber groupings were then compounded with high-density polyethylene and injected molded into flexural test specimens (ASTM D790). Wood-plastic composites made using fibers from these oxalic acid- and diethyloxalate-pretreatments were shown to produce wood-plastic composites with similar mechanical performance to that of composites made using untreated control fibers. With further work, oxalic acid- and diethyloxalate-pretreatments may result in a modified wood fiber that has potential to enhance physical properties such as dimensional stability, has virtually no effect on mechanical performance, but greatly diminishes the energy required to refine pine chips into fiber.
Keywords
Composite materials,
testing,
energy consumption,
mechanical properties,
injection molding of plastics,
wood-plastic composites,
oxalic acid,
wood-pulp,
pulping,
polyethylene,
diethyl oxalate,
wood fibers,
red pine,
wood-plastic materials,
thermomechanical pulping,
chips,
pretreatment
Citation
Winandy, J.E.; Stark, N.M.; Horn, E. 2008. Wood-plastic composites using thermomechanical pulp made from oxalic acid-pretreated red pine chips. Global WPC and Natural Fibre Composites Congress and Exhibition : June 18-19, 2008, Kassel, Institut fur Werkstofftechnik, Kunststoff-und Recyclingtechnik : scientific presentations. Szczecin, Poland : PPH ZAPOL Dmochowski, Sobczyk Spolka Jauna, 2008: Pages 1-7
