Viscoelastic properties of wood materials characterized by nanoindentation experiments

Abstract

International audienceThe viscoelastic properties of the cell wall of the tropic hardwood Carapa procera are investigated by means of nanoindentation tests. Three types of nanoindentation tests are undertaken: creep, continuous stiffness measurement (CSM) and nanoscale dynamic mechanical analysis (Nano-DMA), corresponding to the increased loading rate and so the response of wood cell wall to the loading in a relatively large time scale. It is found that the creep rate is dependent on the applied stress and the relation can be described by the rule of power law. Regarding the dynamic properties (i.e., storage modulus and damping coefficient) in the frequency range of 10-240 Hz, it is shown that the storage modulus increases monotonically, while the damping coefficient decreases. By using the traditional dynamic mechanical thermal analysis as a reference method, the phase transition behavior of wood cell wall can be successfully characterized by the Nano-DMA in a large frequency scale. A dependence of the storage modulus and damping coefficient on the penetration depth is quantified by the CSM tests

Effect of Phenol Formaldehyde Resin Penetration on the Quasi-Static and Dynamic Mechanics of Wood Cell Walls Using Nanoindentation

“…After modification, the E ′ gradually increased first and then remained stable or even decreased with an increase in resin concentration, reaching the maximum of 28.71 GPa and 26.85 GPa with a concentration of 20% and 15% for the outer and inner layer, respectively. The higher E ′ of cell wall may be due to the inhibitions of the main chain movements after being penetrated by PF monomers [42,43]. Except for the physical filling of PF monomers in the nanovoids within the cell walls, the interconnected networks formed within the microfibrils by chemical reaction are another influence factor [44].…”

Quasi-static and dynamic nanoindentation to determine the influence of thermal treatment on the mechanical properties of bamboo cell walls

“…Bamboo products always show significant viscoelastic effects under oscillation stress or stain condition, and these effects are frequently in focus ( Molenaar and Dijkstra 1999 ;Obataya et al 2000 ;Guang and Zhang 2006 ;Huang and Jiang 2008 ;Jiang et al 2009 ). Dynamic nanoindentation can reveal the viscoelastic properties of materials at the small scale ( Odegard et al 2005 ;White et al 2005 ;Chakravartula and Komvopoulos 2006 ;Herbert et al 2008 ) and the viscoelastic properties of wood cell walls ( Zhang et al 2012 ). For this purpose, various instrumental setups can be used, and corresponding data can be analyzed to obtain the frequency domain measurements at ambient temperatures.…”

Frequency-dependent viscoelastic properties of Chinese fir (Cunninghamia lanceolata) under hygrothermal conditions. Part 1: moisture adsorption

“…Plot of viscoelastic parameter vs. frequency appears as a reverse-like temperature scan (Menard 2002). The collections of frequency-dependent viscoelastic data as a function of temperature are also commonly obtained for exploring the effect of frequency on temperaturedriven changes in the material (Amada and Lakes 1997;Jiang et al 2010;Zhang et al 2012;Li et al 2015). From the viewpoint of molecular chain movement, smaller-scale molecular movements are involved at higher testing frequencies.…”