The dynamic and static modulus of elasticity (MOE) between bluestained and non-bluestained lumber of Lodgepole pine were tested and analyzed by using three methods of Non-destructive testing (NDT), Portable Ultrasonic Non-destructive Digital Indicating Testing (Pundit), Metriguard and Fast Fourier Transform (FFT) and the normal bending method. Results showed that the dynamic and static MOE of bluestained wood were higher than those of non-bluestained wood. The significant differences in dynamic MOE and static MOE were found between bulestained and non-bluestained wood, of which, the difference in each of three dynamic MOE (E p , the ultrasonic wave modulus of elasticity, E m , the stress wave modulus of elasticity and E f , the longitudinal wave modulus of elasticity) between bulestained and non-bluestained wood arrived at the 0.01 significance level, whereas that in the static MOE at the 0.05 significance level. The differences in MOE between bulestained and non-bluestained wood were induced by the variation between sapwood and heartwood and the different densities of bulestained and non-bluestained wood. The correlation between dynamic MOE and static MOE was statistically significant at the 0.01 significance level. Although the dynamic MOE values of E p , E m , E f were significantly different, there exists a close relationship between them (arriving at the 0.01 correlation level). Comparative analysis among the three techniques indicated that the accurateness of FFT was higher than that of Pundit and Metriguard. Effect of tree knots on MOE was also investigated. Result showed that the dynamic and static MOE gradually decreased with the increase of knot number, indicating that knot number had significant effect on MOE value.
Cellulose-based electrothermal composites (CETCs) are
a type of
functional material that combines a cellulose substrate with a heat
generator to form multifunctional electrothermal composites with outstanding
mechanical properties, biodegradability, flexibility, and Joule heating
performance. The forms of cellulose include nanocellulose, cellulose
fibers, cellulose paper, and cellulose fabrics. The heat generators
include carbon-based materials (e.g., graphene and carbon nanotubes),
metal nanowires, metal carbides/nitrides, and other conductive polymers.
With the increasing demand for clean energy, comfortable heating,
and green raw materials, CETCs are expected to become one of the most
promising materials used in electric heating products. To provide
the latest research and innovative strategies, this review introduces
the methods used to prepare CETCs; these include vacuum filtration,
freeze-drying, wet spinning, solution casting, coating, in situ polymerization,
and deposition. Additionally, applications and prospects of cellulose-based
electrothermal composites in wearable heaters, soft electrothermal
actuators, deicers and defrosters, and agricultural films are presented.
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