Thermoplastic silicone elastomer lubricant in extrusion of polypropylene wood flour composites

Hristov, Velichko; Vlachopoulos, J.

doi:10.1002/adv.20090

Cited by 19 publications

(16 citation statements)

References 28 publications

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“…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: Wood Polymer Composites Characterization With Pressure-drmentioning

confidence: 99%

“…Several studies focused on the choice of the most suitable additives to obtain a product with optimal physical and mechanical performance. The most important additives of WPCs are coupling agents and lubricants [ 48 , 53 , 58 , 61 , 63 , 64 , 67 , 68 , 73 ].…”

Section: Wood Polymer Composites Characterization With Pressure-drmentioning

confidence: 99%

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

Mazzanti

Mollica

2020

Polymers

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“…showed that the torque and melt pressure during extrusion and the apparent shear viscosity measured by capillary rheometer gradually decreased with the increase of lubricant content in the WPC formulation. Hristov and Vlachopoulos used a low concentration of 1 wt % thermoplastic silicone elastomer in the extrusion of WPC to reduce or even completely eliminate the surface tearing and increase the extrusion speed. Chen et al .…”

Section: Introductionmentioning

confidence: 99%

“…The study by Adhikary et al 23 showed that the torque and melt pressure during extrusion and the apparent shear viscosity measured by capillary rheometer gradually decreased with the increase of lubricant content in the WPC formulation. Hristov and Vlachopoulos 24 used a low concentration of 1 wt % thermoplastic silicone elastomer in the extrusion of WPC to reduce or even completely eliminate the surface tearing and increase the extrusion speed. Chen et al 25 found that the torque of the Pithecellobium Clypearia Benth Fiber (PCBF)/recycled Acrylonitrile-Butadiene-Styrene (ABS) composite decreased with an increase of the TPW604 lubricant content.…”

Section: Introductionmentioning

confidence: 99%

Effects of lubricants on the rheological and mechanical properties of wood flour/polypropylene composites

Dai

Wang

Zhang

et al. 2019

J of Applied Polymer Sci

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The lubricant is an indispensable agent used in wood plastic composites (WPCs) to improve the processing flowability, especially with high wood content. Here, the effects of different lubricating systems on the rheological and mechanical properties of wood flour/polypropylene (WF/PP) composites are investigated. Additionally, several theoretical models are used to describe the rheological behavior. The results show that stearic acid (SA), semirefined paraffin wax (Wax), and zinc stearate (ZnSt) can decrease the equilibrium torque, complex viscosity, relaxation time, and flow activation energy of the composite melts. Compared to a single lubricant, the combination of Wax and SA lubricants exhibits lower values and the composite with 3 wt % SA and 1 wt % Wax has the best lubricating effect. The synergistic effect of the combined SA and Wax lubricants further decreases the interactive force between the molecules, indicating that multifunctional lubricating systems play a predominant role in WPCs and improve the overall processing properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47667.

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“…The design of a new product and corresponding extrusion die, must take into account several issues namely, achievement of balanced flow [2][3][4], avoidance of rheological defects, maximization of the production rate [5][6][7] and maintenance, or increase, of the product quality [1]. Profiles like window frames and catheters, are some of the applications that involve the most complex cross-section geometries produced by extrusion.…”

Section: Introductionmentioning

confidence: 99%

Design of complex profile extrusion dies through numerical modeling

Gonçalves

Carneiro

Nóbrega

2013

Journal of Non-Newtonian Fluid Mechanics

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The achievement of a balanced flow is one of the major tasks encompassed in the design of profile extrusion dies [1]. For this purpose numerical modeling codes may be a very useful aid. The research team involved in this work has been working during the last decade on the development of numerical tools to aid the conception of extrusion dies [1,2]. The design code developed so far carries out the automatic search of a final geometry via an optimization routine coupled with geometry and mesh generators and a 3D computational fluid dynamics (CFD) code based on the finite volume method (FVM). This CFD code is able to model the flow of polymer melts in confined channels, but is inadequate to deal with complex geometries, since it is limited to structured meshes. This work describes the recent efforts made to enlarge the scope of the design procedures, that are currently focused on the development of a modeling code able to deal with unstructured meshes. This code solves the continuity and linear momentum conservation equations, with generalized Newtonian fluids, using a SIMPLE based approach. This paper describes the developed numerical modelling code and its employment in a case study that involves the design of a medical catheter extrusion die, focused on the search of a balanced flow distribution. The results obtained show that the developed numerical code is able to deal with complex geometrical problems, being thus a valuable tool to aid the design of extrusion dies to produce complex profiles.

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Thermoplastic silicone elastomer lubricant in extrusion of polypropylene wood flour composites

Cited by 19 publications

References 28 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

Effects of lubricants on the rheological and mechanical properties of wood flour/polypropylene composites

Design of complex profile extrusion dies through numerical modeling

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