Use of wood fibers in thermoplastic composites: VI. Isocyanate as a bonding agent for polyethylene-wood fiber composites

The aim of this study was to investigate the effect of recycling on polypropylene (PP) and wood-fiber thermoplastic composites (WPCs) using a co-rotating twin-screw extruder. After nine extrusion passes microscopy studies confirmed that the fiber length decreased with the increased number of recycling passes but the increased processing time also resulted in excellent dispersion and interfacial adhesion of the wood fibers in the PP matrix. Thermal, rheological, and mechanical properties were studied. The repeated extrusion passes had minimal effect on thermal behavior and the viscosity decreased with an increased number of passes, indicating slight degradation. The recycling processes had an effect on the tensile strength of WPCs while the effect was minor on the PP. However, even after the nine recycling passes the strength of WPC was considerably better (37 MPa) compared to PP (28 MPa). The good degree of property retention after recycling makes this recycling strategy a viable alternative to discarding the materials. Thus, it has been demonstrated that, by following the most commonly used extrusion process, WPCs can be recycled several times and this methodology can be industrially adapted for the manufacturing of recycled products.

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Quantifying effects of compositional variations on microstructural properties of polypropylene-wood fiber composites by melt rheology and tensile test data

Journal of Composite Materials ◽

10.1177/0021998318786792 ◽

2018 ◽

Vol 53 (4) ◽

pp. 503-514 ◽

Cited By ~ 1

Author(s):

Ali Durmus ◽

Mehmet Ozcan ◽

Ismail Aydin

Keyword(s):

Mechanical Properties ◽

Tensile Test ◽

Wood Fiber ◽

Micromechanical Model ◽

Viscoelastic Behavior ◽

Alkaline Treatment ◽

Fiber Composites ◽

Test Machine ◽

Wood Fibers ◽

Compositional Variations

In this study, melt-state rheological behavior and solid-state mechanical properties of polypropylene-wood fiber composites were investigated in detail depending on compositional variations such as (i) alkaline treatment on wood fibers, (ii) fiber size, (iii) wood fiber content, and (iv) compatibilizer/wood fiber ratio. Composite samples were prepared in a lab-scale co-rotating twin screw extruder by using a maleic anhydride grafted polypropylene as compatibilizer. Morphological features of composites were examined in a scanning electron microscopy. Viscoelastic behavior and mechanical properties of samples were analyzed by performing oscillatory tests in a rotational rheometer and a universal tensile test machine. It was found that the increasing amounts of wood fiber and compatibilizer/wood fiber ratio led to improve melt elasticity and tensile strength. It was concluded that the amount of compatibilizer into composite formulation was the most important compositional parameter compared to size and chemical treatment of wood fibers for improving the physical properties of composites. The Nicolais-Nicodemo micromechanical model showed that the increasing amount of compatibilizer yielded lower parameters which implied better interfacial adhesion between polypropylene and wood fibers.

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Application of Solubility Parameters to Lignocellulosic/Thermoplastic Composites

MRS Proceedings ◽

10.1557/proc-266-155 ◽

1992 ◽

Vol 266 ◽

Author(s):

Don H. White ◽

S. C. Park

Keyword(s):

Physical Properties ◽

Polymer Blends ◽

Wood Fiber ◽

Thermoplastic Composites ◽

Solubility Parameters ◽

Current Interest ◽

Wood Fibers ◽

Good Adhesion ◽

Miscible Polymer Blends ◽

Miscible Blends

AbstractThe usefulness of solubility parameters in identifying miscible polymer blends is reviewed. The use of wood fibers in mixtures of recycled thermoplastics is of current interest. These composites do not require miscible blends of polymers, but must exhibit compatibility in order to have good adhesion and physical properties. The use of solubility parameters to design improved composites is cited. This approach is then applied to wood fiber/polyolefin thermoplastic composites.

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Insight into the Surface Properties of Wood Fiber-Polymer Composites

Polymers ◽

10.3390/polym13101535 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1535

Author(s):

Klementina Pušnik Črešnar ◽

Marko Bek ◽

Thomas Luxbacher ◽

Mihael Brunčko ◽

Lidija Fras Zemljič

Keyword(s):

Polymer Composites ◽

Surface Properties ◽

Wood Fiber ◽

Antioxidant Properties ◽

Skin Layer ◽

Filler Loading ◽

Attenuated Total Reflection ◽

Thermoplastic Composites ◽

Wood Fibers ◽

Pp Composites

The surface properties of wood fiber (WF) filled polymer composites depend on the filler loading and are closely related to the distribution and orientation in the polymer matrix. In this study, wood fibers (WF) were incorporated into thermoplastic composites based on non-recycled polypropylene (PP) and recycled (R-PP) composites by melt compounding and injection moulding. ATR-FTIR (attenuated total reflection Fourier transform infrared spectroscopy) measurements clearly showed the propagation of WF functional groups at the surface layer of WF-PP/WF-R-PP composites preferentially with WF loading up to 30%. Optical microscopy and nanoindentation method confirmed the alignment of thinner skin layer of WF-PP/WF-R-PP composites with increasing WF addition. The thickness of the skin layer was mainly influenced by the WF loading. The effect of the addition of WF on modulus and hardness, at least at 30 and 40 wt.%, varies for PP and R-PP matrix. On the other hand, surface zeta potential measurements show increased hydrophilicity with increasing amounts of WF. Moreover, WF in PP/R-PP matrix is also responsible for the antioxidant properties of these composites as measured by DPPH (2,2′-diphenyl-1-picrylhydrazyl) assay.

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Use of wood fibers in thermoplastics. VII. The effect of coupling agents in polyethylene–wood fiber composites

Journal of Applied Polymer Science ◽

10.1002/app.1989.070370420 ◽

1989 ◽

Vol 37 (4) ◽

pp. 1089-1103 ◽

Cited By ~ 166

Author(s):

R. G. Raj ◽

B. V. Kokta ◽

D. Maldas ◽

C. Daneault

Keyword(s):

Wood Fiber ◽

Fiber Composites ◽

Coupling Agents ◽

Wood Fibers

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A Novel Design for Producing Fine-Celled Foams of Plastic/Wood-Fiber Composites

10.1115/imece2000-1952 ◽

2000 ◽

Author(s):

Ghaus M. Rizvi ◽

Chul B. Park

Keyword(s):

System Design ◽

Cell Morphology ◽

Fiber Composite ◽

Wood Fiber ◽

Fiber Composites ◽

Wood Fibers ◽

Blowing Agent ◽

Composite Foams ◽

Innovative System ◽

Novel Design

Abstract This paper presents an innovative system design for production of plastic/wood-fiber composite foams based on a chemical blowing agent (CBA). Wood-fiber inherently contains moisture, which adversely affects the foam processing and the resultant cell morphology. To improve the cell morphology, the moisture content in the final foam should be minimized. A novel system design is presented for achieving this goal. Undried wood-fibers were processed together with HDPE, CBA and a coupling agent (CA) in a tandem extrusion system. At the interconnection of the two extruders, a vent was provided to purge the moisture into the atmosphere. HDPE/wood-fiber composite foams were produced on this system and on a single extruder without the vent, for comparison. The cellular morphology and volume expansion ratios of the foamed composites were characterized. The foams produced on the newly developed tandem system exhibited significantly improved cell morphology and surface quality.

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