Rheological properties of wood polymer composites and their role in extrusion

Đuretek, Ivica; Schuschnigg, Stephan; Gooneie, Ali; Langecker, Günter; Holzer, Clemens

doi:10.1088/1742-6596/602/1/012014

Cited by 12 publications

(12 citation statements)

References 12 publications

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“…In the first one, a fluid is forced by an externally applied pressure gradient through a very narrow tube of circular or rectangular uniform cross section. Strictly speaking, one talks about capillary viscometry only when circular tubes are used, while rectangular ones are actually named “slits” [ 33 , 34 , 35 , 36 , 37 ]. In the present paper, we will treat these two different geometries together, referring to them as “pressure-driven viscometers”.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…In the case of WPCs, this is further complicated by the wood fibers playing a role in the viscosity modification as the shear rate increases, for example, due to fiber orientation phenomena [ 56 ]. Slip velocity can also be characterized through pressure-driven viscometers [ 31 , 33 , 35 , 36 , 37 , 43 , 46 , 52 , 54 , 57 , 58 , 59 , 60 , 61 ], and it is well established that it is an increasing function of the wall shear stress.…”

Section: Wood Polymer Composites Characterization With Pressure-drmentioning

confidence: 99%

“…Many papers investigated the effect of wood flour concentration on the shear or apparent viscosity [ 33 , 43 , 49 , 50 , 52 , 54 , 56 , 57 , 59 , 60 , 62 , 63 , 64 , 65 , 66 ]. Everyone agrees that viscosity increases with concentration, regardless of all other factors.…”

Section: Wood Polymer Composites Characterization With Pressure-drmentioning

confidence: 99%

“…Viscosity can be as high as 1–10 kPa s in the case of 50 wt.% wood loading at low shear rates (100 s −1 ). The wood content has also a great influence on the wall slip behavior, with slip velocity increasing with the amount of natural filler [ 33 , 43 , 52 , 54 , 58 , 59 , 60 , 61 , 67 ]. Slip velocity is of the order of 1–10 mm/s at a 200 kPa applied shear stress.…”

Section: Wood Polymer Composites Characterization With Pressure-drmentioning

confidence: 99%

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A Review of Wood Polymer Composites Rheology and Its Implications for Processing

Mazzanti

Mollica

2020

Polymers

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Despite the fact that wood polymer composites are interesting materials for many different reasons, they are quite difficult to shape through standard polymer processing techniques, such as extrusion or injection molding. Rheological characterization can be very helpful for understanding the role played by the many variables that are involved in manufacturing and to achieve a good quality final product through an optimized mix of formulation and processing parameters. The main methods that have been used for the rheological characterization of these materials are capillary and parallel plate rheometry. Both are very useful: rotational rheometry is particularly convenient to investigate the compounding phase and obtain structural information on the material, while capillary viscometry is well suited to understand final manufacturing. The results available in the literature at the moment are indeed very interesting and are mostly aimed at investigating the influence of the material formulation, the additives in particular, on the structural, mechanical, and morphological properties of the composite: despite a good number of papers, though, it is difficult to draw general conclusions, as many issues are still debated. The purpose of this article was to overview the state of the art and to highlight the issues that deserve further investigation.

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Section: Theoretical Backgroundmentioning

confidence: 99%

Section: Wood Polymer Composites Characterization With Pressure-drmentioning

confidence: 99%

Section: Wood Polymer Composites Characterization With Pressure-drmentioning

confidence: 99%

Section: Wood Polymer Composites Characterization With Pressure-drmentioning

confidence: 99%

See 2 more Smart Citations

A Review of Wood Polymer Composites Rheology and Its Implications for Processing

Mazzanti

Mollica

2020

Polymers

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“…Thus, global extrusion models are generally limited to viscous flows. To produce global models for wall-slipping materials it is necessary to develop models both for a plasticating unit and for an extrusion die [23,24,25,26].…”

Section: Introductionmentioning

confidence: 99%

Computer Modeling for Single-Screw Extrusion of Wood–Plastic Composites

et al. 2018

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Abstract:Experimental and theoretical studies have been performed on the single-screw extrusion of wood-plastics composites. Experimental research has been carried out on the flow and melting of polypropylene (PP)-based composites with different wood flour (WF) content in the single-screw extruder. Based on these experimental observations, elementary models of the process phenomena have been proposed and a global model of the process has been developed. This global computer model includes the models of solid conveying, melting dependent on the wood flour content, melt flow in the screw, and melt flow in the die. 3-D non-Newtonian finite element method (FEM) screw pumping characteristics have been applied to model the melt flow in the metering section of the screw. The model predicts the extrusion output, pressure and temperature profiles, melting profile, and power consumption. The model has been validated experimentally. An effect of material slip on the extruder operation has been discussed including both slipping in the screw/barrel surfaces and in the extruding die.

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Effect of fiber and polymer variability on the rheological properties of wood polymer composites during processing

et al. 2018

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We investigated the effects of fiber variability, size and content on the fusion characteristics of wood particlereinforced high-density polyethylene (HDPE). Five types of wood sawdust were used: eastern white cedar, with sapwood, and heartwood treated separately; jack pine divided into wood and bark; and black spruce. Three different fiber length classes were also used. Composite pellets containing wood particles at 25, 35, and 45% by weight with HDPE were made using a corotating twin-screw extruder. The pellets were melted and mixed during 7 min in a torque rheometer at 1808C. We also investigated the polymer variation using HDPE, polypropylen (PP), polyvinyl chloride (PVC), and a blend of (80% HDPE1 20% PP) where wood fiber proportion and length were kept constant. We varied the mixing temperature to reach the melting temperature range of each polymer. Mixing and melting times, maximum torque and stabilized torque were obtained. Adding wood fibers to the HDPE increased processing time and torque energy. At constant fiber length and proportion, torque properties varied with fiber origin. Higher fiber length and proportion increased torque energy and time of stabilization. Thus, using wood fibers with different properties will lead to significant variations in processing, such as in extrusion or injection. The fusion characteristics of wood polymer composite vary among polymers. The PVC showed the highest steady-state torque. The formulation containing a polymer blend of HDPE and PP showed the highest torque energy. This higher torque energy is explained by the interaction of the incompatible polymeric chains of the two thermoplastic polymers. POLYM. COMPOS., 00:000-000, 2018.

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Rheological properties of wood polymer composites and their role in extrusion

Cited by 12 publications

References 12 publications

A Review of Wood Polymer Composites Rheology and Its Implications for Processing

A Review of Wood Polymer Composites Rheology and Its Implications for Processing

Computer Modeling for Single-Screw Extrusion of Wood–Plastic Composites

Effect of fiber and polymer variability on the rheological properties of wood polymer composites during processing

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