The utilization of thermomechanical pulp fibers in WPC: A review

Thermomechanical pulp (TMP), among other natural fibers, features characteristics that make it a promising candidate for the utilization in polymer composites. This review is providing an overview on the current state of research on TMP reinforced polymer composites. More than 50 references were reviewed. The cited literature is catalogued according to pretreatments, batch or continuous procedures, processing at laboratory or industrial scale, fiber contents, polymer types, coupling agents as well as wood species. The reinforcing potential of TMP utilized in composites is demonstrated. Tensile strength was found to be peaking at a fiber content of around 40 wt %. Fiber morphology is presumed to be an important determinator for composite properties. Specific mechanical energy [kWh/kg] is presented as an indicator suitable to compare the influence of various processes on fiber morphology. Furthermore, the feed-in and dosing issue that generally accompanies the utilization of cellulosic fibers is described and possible solutions are discussed. (C) 2017 Wiley Periodicals, Inc.