Modeling the hygrothermal creep behavior of wood plastic composite (WPC) lumber made from thermally modified wood

2019 ◽  
Vol 33 (8) ◽  
pp. 1109-1124 ◽  
Author(s):  
Murtada Abass A Alrubaie ◽  
Roberto A Lopez-Anido ◽  
Douglas J Gardner ◽  
Mehdi Tajvidi ◽  
Yousoo Han
Keyword(s):  
Flexural Strength ◽  
Power Law ◽  
Creep Behavior ◽  
Viscoelastic Behavior ◽  
Creep Recovery ◽  
Wood Plastic Composite ◽  
Power Law Model ◽  
Plastic Composite ◽  
Thermally Modified Wood ◽  
Modified Wood

The viscoelastic behavior of an extruded wood plastic composite (WPC) made from thermally modified wood under hygrothermal treatment was studied and modeled. Multiple three-point bending creep/recovery tests were carried out using a dynamic mechanical thermal analyzer (DMTA) equipped with a submersible clamp. WPC specimens with a 15-mm span were subjected to two initial applied stresses; 9% and 14% of the flexural strength in 30 min of creep and 30 min of creep recovery under the combined effects of temperature (25°C, 35°C, and 45°C) and water immersion (saltwater (SW) and distilled water). A dry condition WPC control was used to compare the hygrothermal effects with respect to the control conditions. The WPC material in this article exhibited a linear viscoelastic behavior under the effect of temperature, whereas a nonlinear viscoelastic behavior was observed under immersion conditions. A power law model is considered a useful model to describe the creep behavior of WPC specimens with a 15-mm span in the control and the SW conditions and at 45°C. A power law model was used to describe 180-day creep deflection of WPC lumber beams with an 853-mm span subjected to 12 MPa of the flexural strength in four-point bending at 50% relative humidity and at 21°C. The power law model predicts that the WPC lumber will reach a flexural strain in outer fiber of 1% in approximately 150 years.

scholarly journals Flexural Creep Behavior of High-Density Polyethylene Lumber and Wood Plastic Composite Lumber Made from Thermally Modified Wood

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 262 ◽  
Author(s):  
Murtada Abass A. Alrubaie ◽  
Roberto A. Lopez-Anido ◽  
Douglas J. Gardner
Keyword(s):  
Creep Behavior ◽  
Creep Deformation ◽  
High Density Polyethylene ◽  
Creep Compliance ◽  
High Density ◽  
Wood Plastic Composite ◽  
Creep Stress ◽  
Plastic Composite ◽  
Thermally Modified Wood ◽  
Modified Wood

The use of wood plastic composite lumber as a structural member material in marine applications is challenging due to the tendency of wood plastic composites (WPCs) to creep and absorb water. A novel patent-pending WPC formulation that combines a thermally modified wood flour (as a cellulosic material) and a high strength styrenic copolymer (high impact polystyrene and styrene maleic anhydride) have been developed with advantageous viscoelastic properties (low initial creep compliance and creep rate) compared with the conventional WPCs. In this study, the creep behavior of the WPC and high-density polyethylene (HDPE) lumber in flexure was characterized and compared. Three sample groupings of WPC and HDPE lumber were subjected to three levels of creep stress; 7.5, 15, and 30% of the ultimate flexural strength (Fb) for a duration of 180 days. Because of the relatively low initial creep compliance of the WPC specimens (five times less) compared with the initial creep compliance of HDPE specimens, the creep deformation of HDPE specimens was six times higher than the creep deformation of WPC specimens at the 30% creep stress level. A Power Law model predicted that the strain (3%) to failure in the HDPE lumber would occur in 1.5 years at 30% Fb flexural stress while the predicted strain (1%) failure for the WPC lumber would occur in 150 years. The findings of this study suggest using the WPC lumber in structural application to replace the HDPE lumber in flexure attributable to the low time-dependent deformation when the applied stress value is withing the linear region of the stress-strain relationship.

scholarly journals Modeling the Long-Term Deformation of a Geodesic Spherical Frame Structure Made from Wood Plastic Composite Lumber

2020 ◽  
Vol 10 (14) ◽  
pp. 5017
Author(s):  
Murtada Abass A. Alrubaie ◽  
Douglas J. Gardner ◽  
Roberto A. Lopez-Anido
Keyword(s):  
Service Life ◽  
Creep Strain ◽  
Power Law ◽  
Frame Structure ◽  
Model Parameters ◽  
Wood Plastic Composite ◽  
Power Law Model ◽  
Flexural Stress ◽  
Plastic Composite

The long-term deformation of a geodesic spherical frame structure with a diameter of 20 m made from wood plastic composite (WPC) lumber (struts) is described using the Norton-Bailey power law model to predict the service life creep behavior (the creep strain ( ε c r )) of the WPC. The Norton-Bailey power law model parameters, A the power law multiplier, n the stress order, and m the time order, were obtained from experimental four-point bending flexural creep measurements of WPC lumber subjected to three levels of flexural stress: 7, 14, and 29% of the ultimate flexural strength for 200 days. The parameters obtained from the experiments showed good agreement to the model of the WPC lumber in flexure. The Norton-Bailey power law parameters were then implemented to describe the long-term deformation of the spherical frame structure. The limit of failure was considered when the WPC creep strain reaches the value of 1%. However, the FEA predicted the maximum creep strain to be 20% of the failure strain. This modeling approach is considered useful to describe and predict the long-term deformation of aquacultural structures made from viscoelastic materials during the envisioned service life (10 years) based on experimental creep data for the members that form the structure.

The Dynamic Viscoelastic Behavior of Wood-Plastic Composites

2013 ◽  
Vol 815 ◽  
pp. 639-644 ◽  
Author(s):  
Pei Ying Liu ◽  
Zhi Hong Jiang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Storage Modulus ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Peak Frequency ◽  
Wood Plastic Composite ◽  
Plastic Composite ◽  
Positive Effect

Wood-plastic composite is a kind of viscoelastic materials. This paper presents the dynamic viscoelastic behavior of WPCs at different temperature, frequency and bamboo flours levels. The storage modulus decreased with the rise of temperature, the loss modulus and tanδ increased as temperature increased but decreased after reaching the peak. Frequency had a little influence on storage modulus and loss modulus, but the glass transition temperature increased with the increase of frequency, while the tanδ decreased. The glass transition temperature of this kind WPCs is about 85°C. The addition of bamboo flours had a positive effect on the dynamic viscoelastic behavior. From the results above, the activation energy of the WPCs was measured using an Arrhenius relationship to investigate the interphase between the wood and plastic.

Experimental investigation of the hygrothermal creep strain of wood–plastic composite lumber made from thermally modified wood

2019 ◽  
Vol 33 (9) ◽  
pp. 1248-1268 ◽  
Author(s):  
Murtada Abass A Alrubaie ◽  
Roberto A Lopez-Anido ◽  
Douglas J Gardner ◽  
Mehdi Tajvidi ◽  
Yousoo Han
Keyword(s):  
Creep Strain ◽  
Water Immersion ◽  
Creep Recovery ◽  
Short Term ◽  
Creep Response ◽  
Plastic Composites ◽  
Thermally Modified Wood ◽  
Term Creep ◽  
Modified Wood ◽  
Short Term Creep

The hygrothermal effect on the short-term creep behavior of extruded thermally modified wood fiber–high-strength styrenic copolymer plastic composites (wood–plastic composites (WPCs)) was investigated on specimens preconditioned for 1 month under water immersion (distilled water (DW) and saltwater (SW)). These specimens were then tested in the same conditions for short-term creep and creep-recovery response using a submersible clamp. The short-term creep tests of WPC specimens (that are immersed in water as a function of different temperatures) have not yet been reported in previous studies. The objective of this study was to determine whether the hygrothermal creep response of WPC material evaluated through water immersion differs from the creep response published in the literature for other environmental exposure conditions. The experiments included measuring 30 min of creep and 30 min of creep recovery on the specimens immersed in SW and DW at two different levels of flexural stresses (9% and 14% of the flexural strength) and three temperature values (25, 35, and 45°C). The average creep strain recovery (%) of the specimens was higher for the specimens immersed in SW during testing than the control specimens. The WPC material is considered to have a potential use in structural applications in environments where the temperature is below 45°C because of the following factors: the low deformation under the short-term sustained loading, the decrease in the deformation rate with respect to the increase in load duration, maintaining the modulus of elasticity over a range of temperatures from 25°C to 45°C under sustained load, and the ability to recover more than 69% of the average creep strain under water immersion when the loading source is removed. The creep strain fractional increment (CSFI) of the WPC in this study under all conditions was 13% which is 86% lower than the CSFI of the WPCs reported in previous studies.

scholarly journals Experimental Study on the Flexural Creep Behaviors of Pultruded Unidirectional Carbon/Glass Fiber-Reinforced Hybrid Bars

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 976 ◽  
Author(s):  
Hiran Mayookh Lal ◽  
Guijun Xian ◽  
Sabu Thomas ◽  
Lei Zhang ◽  
Zhonghui Zhang ◽  
...  
Keyword(s):  
Power Law ◽  
Creep Behavior ◽  
Beam Theory ◽  
Power Law Model ◽  
Fiber Reinforced ◽  
Freeze Thaw ◽  
Glass Fiber Reinforced ◽  
Service Period ◽  
Structural Applications ◽  
Glass Carbon

Unidirectional pultruded glass/carbon hybrid fiber-reinforced polymer (HFRP) bars with a diameter of 19 mm have recently been developed for various structural applications. In this study, the creep behavior of HFRP bars caused by bending was experimentally evaluated under different conditions. Our creep study included freeze–thaw preconditioned and unconditioned HFRP bars. The rate of strain and deflection were monitored continuously for a duration of 5000 h. The bars were further tested for creep under the combined effects of mechanical loading and induced thermal cycles, while continuously monitoring the strain rate. Stress levels of 50% to 70% were selected for our creep study. The creep behavior of the bars was analyzed utilizing Findley’s power-law model. On the basis of the linear approximation of Findley’s power law, modulus reductions of approximately 21%, 19%, and 10.75% were calculated for combined freeze–thaw/creep-loaded, freeze–thaw pretreated, and unconditioned HFRP bars, respectively, over a service period of 50 y. The time-dependent deflection of HFRP bars was analyzed by coupling Findley’s power-law model with Euler Bernoulli’s beam theory. The creep deflection intensified by 26.6% and 11.1% for preconditioned and untreated bars, respectively, after a service period of 50 y. The microstructures of HFRP bars was also examined utilizing scanning electron microscopy.

Dispersion of Chrysotile Fibers in Wood-Plastic Composite

2011 ◽  
Vol 347-353 ◽  
pp. 4089-4092
Author(s):  
Sheng Wei Sun ◽  
Jian Lin Luo ◽  
Qiu Yi Li ◽  
Feng Hao
Keyword(s):  
Flexural Strength ◽  
Flame Retardant ◽  
High Speed ◽  
Wood Flour ◽  
Water Mixture ◽  
Wood Plastic Composite ◽  
Hot Press ◽  
Dispersion Method ◽  
Plastic Composite ◽  
Press Molding

Raw chrysotile fiber (ChF) was dispersed in water through surfactant-decoration and vibromill-shearing process. Wood flour (WF) pretreated by the coupler was added into ChF/water mixture while high-speed stirring. After oven-dry, the WF/ChF mixture was filled in polypropylene (ChF/WPC) employing hot-press molding technique. Optical microscopy (OM) was employed to observe the dispersion of ChF in both water and WPC matrix. Mechanical and flame-retardant behaviors of ChF/WPC were further studied to verify the effectiveness of dispersion method of ChF. ChF can be well dispersed in water with SDBS penetrating and vibromill treatment from OM observation. The mechanical and fire-resisting properties of ChF/WPC are improved comparing with the plain WPC, there exists 59.72% increment in flexural strength of ChF/WPC with 10% ChF addition, and 61.97% increment in flammability retardant of ChF/WPC with 15% ChF addition.

Characterizing the mechanism of improved adhesion of modified wood plastic composite (WPC) surfaces

2007 ◽  
Vol 21 (11) ◽  
pp. 1097-1116 ◽  
Author(s):  
Gloria S. Oporto ◽  
Douglas J. Gardner ◽  
George Bernhardt ◽  
David J. Neivandt
Keyword(s):  
Wood Plastic Composite ◽  
Plastic Composite ◽  
Modified Wood

scholarly journals Experimental and Numerical Investigation of Tensile and Flexural Behavior of Nanoclay Wood-Plastic Composite

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2773
Author(s):  
Mohammad E. Golmakani ◽  
Tomasz Wiczenbach ◽  
Mohammad Malikan ◽  
Seyed M. Mahoori ◽  
Victor A. Eremeyev
Keyword(s):  
Tensile Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
Wood Flour ◽  
Flexural Modulus ◽  
Plastic State ◽  
Wood Plastic Composite ◽  
Wood Powder ◽  
Particle Content ◽  
Plastic Composite

In this study, the effect of wood powder and nanoclay particle content on composites’ mechanical behavior made with polyethylene matrix has been investigated. The wood flour as a reinforcer made of wood powder was at levels of 30, 40, and 50 wt.%, and additional reinforcement with nanoclay at 0, 1, 3, and 5 wt.%. Furthermore, to make a composite matrix, high-density polyethylene was used at levels of 70, 60, and 50% by weight. Wood-plastic composite (WPC) specimens were manufactured in injection molding. After preparing the specimens, tensile and bending tests were performed on samples. The mechanical properties such as tensile and flexural strength and flexural modulus were measured. Results showed that nanoclay particle content increases flexural modulus, flexural strength, modulus of elasticity, and tensile strength. The experimental test results show that Young’s moduli increased with the volume of wood flour. The biggest modulus of elasticity was achieved in the samples having 50 wt.% of wood powder. Furthermore, the highest value of tensile strength was achieved at the level of 30 wt.%. The highest flexural strength was for the sample containing 50% wood powder by weight. Additionally, a numerical model was made utilizing the Abaqus software using the finite element method (FEM). Comparing the numerical and experimental results, it was found that they are compatible in the linear-elastic and plastic state of the material. There are no crucial differences between experiment and FEM.

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