Extruded Wood-Flour Polypropylene Composites: Effect of a Maleated Polypropylene Coupling Agent on Filler-Matrix Bonding and Properties

Abstract

Full factorial studies were conducted to determine the effects of a coupling agent (a low molecular weight maleated polypropylene (MAPP)) and other composition and processing variables on the mechanical properties of a wood-flour-filled polypropylene (PP) composite. Effects of MAPP on the bonding between PP and wood veneer were also examined. At less than 1 percent by weight, MAPP produced useful increases in strength and modulus properties of the composite, and this effect was somewhat enhanced by small-particle-size wood flour and multiple extrusions. However, MAPP caused small losses in notched impact energy. High extrusion temperature (190°C to 250°C) had little influence on strength, but it decreased notched impact energy. Peel force between PP and wood veneer was increased by pretreatment with MAPP for aspen, but not for birch, aspen being more porous than birch. The effectiveness of MAPP may therefore be related to its ability to penetrate the wood and form a strongly held hydrophobic layer that is attractive to the PP, thereby increasing both the effective bonding area and mechanical interlocking.

Effects of nanoparticles on the density reduction and cell morphology of extruded metallocene polyethylene/wood fiber nanocomposites

“…The WF was dried at 105°C for 6 h in a vacuum oven to remove any inherent moisture and thereby prevent the deteriorating effects of moisture on the cell structure 12, 13. The dried WF, the base resin (mPE or mPE nanocomposite), and the CA were blended with a K‐mixer14 and then granulated. The PWC granules were then processed in a counter‐rotating twin‐screw compounder [Fig.…”

“…12,13 The dried WF, the base resin (mPE or mPE nanocomposite), and the CA were blended with a K-mixer 14 and then granulated. The PWC granules were then processed in a counter-rotating twin-screw compounder [ Fig.…”

Critical processing temperature in the manufacture of fine‐celled plastic/wood‐fiber composite foams

“…To ensure fine-celled morphology, the volatile contents of WF need to be reduced to a bare minimum, using any of the standard drying techniques, such as online devolatilization, 18,24 oven drying, hot air convective drying, drying in K-mixer, 25 and the like. However, even the dried WF releases additional volatiles when further heated to the processing temperatures of the plastics, which is typically around 200°C.…”

Alkyl ketene dimer modification of thermomechanical pulp promotes processability with polypropylene

“…Indeed, choosing a fiber with a high‐tensile strength, such as jute, does not translate to the overall strength of the composite unless compatibility between matrix and filler has been achieved 19 . In general, the surface of natural‐based fibers is more hydrophilic than the commonly used polyolefins, making compounding during the process and transfer of mechanical stress of the final composite material poor 20–23 . The investigation demonstrates that PP composites utilizing various types of natural fibers without any modification such as hay, lemon, and palm exhibit a reduction in tensile strength, particularly evident when the fiber loading surpasses the range of 20–30 wt% 24 .…”