• Peltola, Heidi
• Jetsu, Petri
• Pääkkönen, Elina

Abstract

In the study, two wood fibre types, bleached softwoodkraft pulp (BSKP) and thermomechanical pulp (TMP) withfibre lengths of 2.28 and 1.40 mm, respectively, weremelt processed with poly(lactic acid) (PLA) using atwin-screw extruder to fibre content of 30 wt-% andinjection moulded. In addition, three wood flour (WF)types especially targeted for wood plastic composites(WPC's) with average particle sizes of 915, 500 and 150?m were selected as wood fillers and processed with sameparameters. Microscopic analysis as well as macroscopicimages showed very uniform fibre dispersion in BSKP andTMP fibre composites, whereas with wood flours clearirregular particle sizes and shapes were visible. Elasticmodulus was increased with all the wood component types,but a clear reduction of impact strength and tensilestrength were seen in wood flour composites, a phenomenontypical to polymer fillers. The reinforcement capabilityof wood fibres comes apparent by detecting an increasedmaterial ductility and strength when wood in fibre formis used as reinforcement. In addition, water absorptionremained lower when fibres were used instead of woodflours. Thus, the use of wood fibres in WPC's instead ofconventional wood flours offers improved materialproperties, uniform appearance with colouringpossibilities and all together, an enhanced bio-basedmaterial for added-value products.

Topics

• dispersion
• polymer
• strength
• composite
• wood
• ductility