Numerical and experimental assessment of water absorption of wood-polymer composites

Wood polymer composites (WPC) are sensitive to moisture because of the hydrophilic nature of the wood fibers. The main objective of this study was to improve the dimensional stability of WPCs by coating. Polypropylene and polylactic acid were reinforced by three pulp fibers (kraft, thermomechanical (TMP), and chemothermomechanical (CTMP)) at three fiber contents (50, 60, and 70% w/w). The resulting WPCs were coated using two commercial coatings, epoxy and acrylic. Kraft fiber WPCs were less sensitive to moisture than TMP and CTMP WPCs. These differences were explained by the crystallinity of the kraft fibers and their better interfacial adhesion to the polymers. The epoxy coating proved to be more effective than the acrylic coating and significantly reduced the water absorption and the thickness swell for all formulations. Negative relationships between the contact angle and water absorption were obtained. These relationships depend on the fiber content and type, the matrix nature, and the coating.

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Regarding some mechanical properties of terrace board made of wood-polymer composites with different filler

Ukrainian Journal of Forest and Wood Science ◽

10.31548/forest2021.02.003 ◽

2021 ◽

Vol 12 (2) ◽

pp. 33-39

Author(s):

N. V. Buiskykh

Keyword(s):

Mechanical Properties ◽

Water Absorption ◽

Polymer Composites ◽

Modulus Of Elasticity ◽

Abrasion Resistance ◽

Physical And Mechanical Properties ◽

Wood Waste ◽

Bending Modulus ◽

Wood Polymer ◽

Wood Polymer Composites

One of the areas of wood waste processing is their use in the production of wood-polymer composites (WPC). The relevance of wood-polymer products is due to the wide range of applications and qualities of this material. WPC does not rot, is not damaged by insects and fungi, does not contain harmful binders. Products from the duodenum do not crack, do not gouge, are waterproof, which makes them an excellent material for manufacturing a terrace board. However, the terrace board must have certain mechanical qualities, which will allow it to be used in fairly harsh conditions - under the action of humidity, UV radiation and under a certain load. This study aimed to determine the main physical and mechanical properties (density, strength at static bending, modulus of elasticity, water absorption, hardness, abrasion resistance, changes in linear dimensions with changing atmospheric environment) samples of terrace board manufacturing from duodenum with different fillers. Samples from a hollow terrace board, which were filled with polyethylene (PE) and polyvinyl chloride (PVC), were used for the study. Based on experimental studies, it was found that the density of both samples is quite high, close to the maximum; the difference is not significant, but when examining microslices under a microscope in samples with PE as a binder, a larger number of voids is observed, indicating the presence of excess moisture or lack of mineral fillers. It may also indicate the destruction of the polymer. It was determined that a number of other important indicators such as strength at static bending, modulus of elasticity, water absorption, abrasion resistance were the best in the samples with a filler of polyvinylchloride. The greatest difference was in the bending strength index and was 35%. It was also found that the hardness of both samples were equivalent. However, the modulus of elasticity of the sample with a filler with PE exceeded the performance of the sample with a filler with PVC by almost 2.5 times. Thus, based on the research, it is possible to identify a number of clear relationships that indicate that theuse of polyvinylchlorideas a binder significantly improves the physical and mechanical properties of the terrace board based on wood-polymer composite. The results of the research will solve the problem of improving the strength characteristics of wood-composite material to expand the range based on wood waste Keywords: density, hardness, modulus of elasticity, water absorption, abrasion resistance.

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Water absorption of wood-polymer composites of savewood

E3S Web of Conferences ◽

10.1051/e3sconf/20199702043 ◽

2019 ◽

Vol 97 ◽

pp. 02043

Author(s):

Tatyana Matseevich ◽

Andrey Matseevich ◽

Andrey Askadskii

Keyword(s):

Water Absorption ◽

Polymer Composites ◽

Wood Flour ◽

High Water ◽

Partial Replacement ◽

Mineral Filler ◽

Wood Polymer ◽

Wood Polymer Composites ◽

Mineral Fillers ◽

Specific Impact

The materials based on wood-polymer composites (WPC) in the form of decking boards are produced, in which wood filler is partially replaced by mineral one. WPC materials manufactured by Savewood using a matrix polymer of polyvinyl chloride (PVC) have good mechanical properties, low abrasion and satisfactory resistance to climatic influences. However, they have relatively high water absorption, the task of reducing which is relevant not only in Russia, but also in other countries where there are constructions of facilities operating in outdoor environmental conditions. The modification of such materials in this work was carried out by replacing part of the wood filler with the mineral filler, which is CaCO3 (chalk). Partial replacement of wood flour with mineral filler resulted in a marked reduction in swelling from 1.25 to 0.01%. In this case, the modulus of elasticity is increased from 2260 to 2880 MPa, tensile strength from 30.5 to values of 16.7 ÷ 32 MPa. The specific impact strength varies from 8.90 to 7.74 kJ/m2. The optimal ratio of wood and mineral fillers is 60/40%.

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Composites made from cellulose-based materials and thermoplastics (usually called wood-polymer composites (WPC) or natural fibre composites (NFC))

10.3403/30266174 ◽

2014 ◽

Keyword(s):

Polymer Composites ◽

Natural Fibre ◽

Wood Polymer ◽

Fibre Composites ◽

Wood Polymer Composites

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Composites made from cellulose-based materials and thermoplastics (usually called wood-polymer composites (WPC) or natural fibre composites (NFC))

10.3403/30266171 ◽

2014 ◽

Keyword(s):

Polymer Composites ◽

Natural Fibre ◽

Wood Polymer ◽

Fibre Composites ◽

Wood Polymer Composites

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Composites made from cellulose-based materials and thermoplastics (usually called wood-polymer composites (WPC) or natural fibre composites (NFC))

10.3403/bsen15534 ◽

2015 ◽

Keyword(s):

Polymer Composites ◽

Natural Fibre ◽

Wood Polymer ◽

Fibre Composites ◽

Wood Polymer Composites

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Rheological Basics for Modeling of Extrusion Process of Wood Polymer Composites

Polymers ◽

10.3390/polym13040622 ◽

2021 ◽

Vol 13 (4) ◽

pp. 622

Author(s):

Krzysztof Wilczyński ◽

Kamila Buziak ◽

Adrian Lewandowski ◽

Andrzej Nastaj ◽

Krzysztof J. Wilczyński

Keyword(s):

Polymer Composites ◽

Process Modeling ◽

Slip Flow ◽

Extrusion Process ◽

Process Conditions ◽

Rheological Models ◽

Wood Polymer ◽

Slip Effects ◽

Process Simulations ◽

Wood Polymer Composites

Wood polymer composites are materials with pseudoplastic and viscoelastic properties. They have yield stress and exhibit slip during flow. Studies on extrusion and rheology, as well as on process modeling of these highly filled materials are limited. Extensive rheological and extrusion modeling studies on the wood polymer composite based on the polypropylene matrix were performed. Viscous and slip flow properties were determined (with Rabinowitsch, Bagley, and Mooney corrections) at broad (extrusion) range of shear rate and temperature, using a high-pressure capillary rheometer. Rheological models of Klein and power-law were used for flow modeling, and Navier model was applied for slip modeling. A novel global computer model of WPC extrusion with slip effects has been developed, and process simulations were performed to compute the extrusion parameters (throughput, power consumption, pressure, temperature, etc.), and to study the effect of the material rheological characteristics on the process flow. Simulations were validated experimentally, and were discussed with respect to both rheological and process modeling aspects. It was concluded that the location of the operating point of extrusion process, which defines the thermo-mechanical process conditions, is fundamentally dependent on the rheological materials characteristics, including slip effects.

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Dielectric Properties of Wood-Polymer Composites: Effects of Frequency, Fiber Nature, Proportion, and Chemical Composition

Journal of Composites Science ◽

10.3390/jcs5060141 ◽

2021 ◽

Vol 5 (6) ◽

pp. 141

Author(s):

Imen Elloumi ◽

Ahmed Koubaa ◽

Wassim Kharrat ◽

Chedly Bradai ◽

Ahmed Elloumi

Keyword(s):

Dielectric Properties ◽

Polymer Composites ◽

Wide Frequency Range ◽

Dielectric Constants ◽

Cellulose Content ◽

Wood Fibers ◽

Low Frequencies ◽

Wood Polymer ◽

Wood Polymer Composites ◽

New Applications

The characterization of the dielectric properties of wood–polymer composites (WPCs) is essential to understand their interaction with electromagnetic fields and evaluate their potential use for new applications. Thus, dielectric spectroscopy monitored the evolution of the dielectric properties of WPCs over a wide frequency range of 1 MHz to 1 GHz. WPCs were prepared using mixtures of different proportions (40%, 50%, and 60%) of wood and bark fibers from various species, high-density polyethylene, and maleated polyethylene (3%) by a two-step process, extrusion and compression molding. Results indicated that wood fibers modify the resistivity of polyethylene at low frequencies but have no effect at microwave frequencies. Increasing the fiber content increases the composites’ dielectric properties. The fibers’ cellulose content explains the variation in the dielectric properties of composites reinforced with fibers from different wood species. Indeed, composites with high cellulose content show higher dielectric constants.

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