Properties of Wood–Plastic Composites Manufactured from Two Different Wood Feedstocks: Wood Flour and Wood Pellets

Abstract

Driven by the motive of minimizing the transportation costs of raw materials to manufacture wood–plastic composites (WPCs), Part I and the current Part II of this paper series explore the utilization of an alternative wood feedstock, i.e., pellets. Part I of this study reported on the characteristics of wood flour and wood pellets manufactured from secondary processing mill residues. Part II reports on the physical and mechanical properties of polypropylene (PP)-based WPCs made using the two different wood feedstocks, i.e., wood flour and wood pellets. WPCs were made from 40-mesh wood flour and wood pellets from four different wood species (white cedar, white pine, spruce-fir and red maple) in the presence and absence of the coupling agent maleic anhydride polypropylene (MAPP). With MAPP, the weight percentage of wood filler was 20%, PP 78%, MAPP 2% and without MAPP, formulation by weight percentage of wood filler was 20% and PP 80%. Fluorescent images showed wood particles’ distribution in the PP polymer matrix was similar for both wood flour and ground wood pellets. Dispersion of particles was higher with ground wood pellets in the PP matrix. On average, the density of composite products from wood pellets was higher, tensile strength, tensile modulus and impact strength were lower than the composites made from wood flour. Flexural properties of the control composites made with pellets were higher and with MAPP were lower than the composites made from wood flour. However, the overall mechanical property differences were low (0.5–10%) depending on the particular WPC formulations. Statistical analysis also showed there was no significant differences in the material property values of the composites made from wood flour and wood pellets. In some situations, WPC properties were better using wood pellets rather than using wood flour. We expect if the material properties of WPCs from wood flour versus wood pellets are similar and with a greater reduction in transportation costs for wood pellet feedstocks, this would be beneficial to WPC manufacturers and consumers.

Effect of Eco-Friendly Peanut Shell Powder on the Chemical Resistance, Physical, Thermal, and Thermomechanical Properties of Unsaturated Polyester Resin Composites

“…The most common natural filler is wood fiber or flour, which is a waste product in the production of paper [13][14][15]. However, waste rice husks, nut shells, stalks of hemp, sisal, jute, or corn cobs are being used more often [16][17][18].…”

Modification of Laser Marking Ability and Properties of Polypropylene Using Silica Waste as a Filler

“…The device was equipped with a set that allowed it to determine the mass of the samples both in the air and after immersion in a liquid, which was methyl alcohol with a density (ρ L ) of 0. 792 g/cm 3 . The tests were carried out at a temperature of 23 ± 2 • C. The density of individual samples was calculated using the following formula:…”

“…For composition S5, a 2% increase in density (0.924 g/cm 3 ) was recorded. The composition with the highest tested degree of filler (S10) was characterized by a density of 0.95 g/cm 3 . The higher density of composites compared to unfilled PP is unfavorable for application purposes; its consequence may be an increase in the weight of moldings made of this type of material.…”

“…For ecological reasons, raw materials of natural origin are increasingly used as PP fillers. These include, among others, ground wood particles [1][2][3], natural fibers [4], and waste materials, e.g., sunflower husks [5], crushed egg shells [6], and ground rubber from car tires [7,8]. Our previous research [9] describes the mechanical properties of polypropylene composites with 10 and 20 wt% silica content.…”

Thermal, Mechanical, Morphological and Aesthetical Properties of Rotational Molding PE/Pine Wood Sawdust Composites

“…They prove to be good alternatives to inorganic materials and a successful solution for wood polymer composites (WPC) that makes use of organic materials with virgin, recycled or green plastics, reducing dependency on petroleum-based raw materials [ 3 , 7 , 8 , 9 ]. Moreover, they offer the advantages of enhancing acoustic performance, reduced weight, lower production costs and biodegradability [ 10 ]. WPC can be easily processed through typical processing techniques, such as extrusion, injection molding, compression molding or thermoforming and they can also be manufactured like common plastics [ 11 ].…”