Effect of SiO2 Content on the Extended Creep Behavior of SiO2-Based Wood-Inorganic Composites Derived via the Sol–Gel Process Using the Stepped Isostress Method

Abstract

In this study, methyltrimethoxysilane (MTMOS) was used as a reagent to prepare SiO 2 -based wood-inorganic composites (WIC SiO 2 ) via the sol-gel process, and subsequently, the extended creep behaviors of WIC SiO 2 with weight percent gains (WPGs) of 10%, 20%, and 30% were estimated using the stepped isostress method (SSM). The results revealed that the density of all samples ranged from 426 to 513 kg/m 3 , and no significant difference in the modulus of elasticity (MOE) was noted among all of the samples (10.5–10.7 GPa). However, the MOR of WIC SiO 2 with a WPG of 20% (102 MPa) was significantly greater than that of untreated wood (87 MPa). In addition, according to the result using the SSM, the SSM-predicted creep master curve fitted well with the experimental data for the untreated wood and WIC SiO 2 . This result demonstrated that the SSM could be a useful method to evaluate long-term creep behaviors of wood and WIC SiO 2 . Furthermore, the activation volume ( V *) of the specimens was calculated from the linear slope of Eyring plots, and the resulting V * of all of the WIC SiO 2 (0.754–0.842 nm 3 ) was lower than that of untreated wood (0.856 nm 3 ). On the other hand, the modulus reduction of untreated wood showed 39%, 45%, 48%, and 51% at 5, 15, 30, and 50 years, respectively. In contrast, the modulus reduction of the WIC SiO 2 with a WPG of 10% decreased to 25%, 31%, 35%, and 38% at 5, 15, 30, and 50 years, respectively. Similar trends were also observed for other WIC SiO 2 with different WPGs. Of these, the WIC SiO 2 with a WPG of 20% exhibited the lowest reduction in time-dependent modulus (31%) over a 50-year period. Accordingly, the creep resistance of the wood could be effectively enhanced under the MTMOS treatment.

Long-Term Creep Behavior Prediction of Sol-Gel Derived SiO2- and TiO2-Wood Composites Using the Stepped Isostress Method

“…All SSM tests were performed at 20 °C, which is below the glass transition temperature ( T g ), thus, the Eyring model (Equation (2)) is used to calculate the activation volume in this study [29]. This model was applied to estimate the shift factor (α σ ), which shows the following express rate with the stress level [25,28]:logασ=log(sans-serifε˙sans-serifε˙r)=V*2.303kT(sans-serifσ−σref) where sans-serifε˙ and sans-serifε˙r are respectively the creep rate at the elevated stress (σ) and reference stress (σ ref ), V * is the activation volume, k is Boltzmann’s constant (1.38 × 10 −23 J/K), and T is the absolute temperature.…”

“…In the past few years, the stepped isostress method (SSM), which can evaluate the creep behavior of a single sample by a stepped increase of the stress level [24,25,26,27], was shown to be more beneficial in assessing the creep behavior of low-thermal-conductivity materials (e.g., wood and wood composites) compared to the SIM [28]. A previous study demonstrated that wood treated with methyltrimethoxysilane (MTMOS) could effectively enhance its creep resistance [29]. However, to the best of our knowledge, the effect of different metal alkoxides on the creep behavior of WICs has not been studied using the SSM.…”

Magnetic Properties of FeNi3 Nanoparticle Modified Pinus radiata Wood Nanocomposites

“…Furthermore, wood with a microporous structure can combine a natural porosity scaffold with inorganic/organic compounds. Therefore, many efforts have been devoted to creating functionalized wood by dispersing inorganic and organic components into the wood matrix in order to endow these wood-based materials with new properties, such as biodegradation resistance [2], rheological properties [3], mechanical properties [4,5,6], acoustic properties [7], and magnetic properties [8]. Among these properties, magnetism has recently received much attention.…”