The effect of oil heat treatment on biological, mechanical and physical properties of bamboo

Abstract

Bamboo is now widely used in construction, papermaking, textile, furniture and other fields because of its renewable, fast-growing, high-strength, high-yield and easy processing. However, compared with wood, bamboo and bamboo products are more vulnerable to damage by fungi and pests. An effective and eco-friendly method is urgently needed to improve their physical and chemical properties, decay resistance and anti-mildew properties, and hydrophobic properties. Here, bamboo was heated with methyl silicone oil. The effect of different temperatures (140 °C–200 °C) and different times (2 h–6 h) on the properties of bamboo was studied systematically, including chemical composition, physical and mechanical properties, surface wettability, decay resistance and anti-mildew property. No starch granules were observed inside the parenchymal cell lumen of bamboo specimen heat treated at 200 °C for 6 h. And with the increase of heat treatment temperature and time, the content of cellulose and hemicellulose decreases gradually while relative content of lignin increases due to its better thermal stability. Accordingly, the surface wettability decreases due to the changes of the surface functional groups and micro-morphologies. Under the condition of oil heat treatment at 160 °C for 2 h, the compressive strength parallel to grain of bamboo samples reach the maximum of 109.52 MPa. With further increase of heating temperature, the corresponding compressive strength decreases. The resulted bending strength and MOE both display similar changing trend. However, the optimal parameter is at 180 °C for 2 h, with the highest bending strength and MOE values of 142.42 MPa and 12,373.00 MPa, respectively. Finally, the decay resistance and anti-mildew property are dramatically enhanced with increased heat treatment temperature and time. All the corresponding changing mechanisms are investigated in depth and in detail. Our results provide comprehensive process parameters and micro-mechanism for the performance of oil heat treatment of bamboo, which can be used to guide the actual production.

Change in Micro-Morphology and Micro-Mechanical Properties of Thermally Modified Moso Bamboo

“…Unfortunately, some physical properties of bamboo are decreased due to the disruption of hydrogen bonds when the treatment temperature is above 180 °C. Changes in chemical composition, density, EMC, and mechanical properties of thermally modified wood have been intensely investigated at the macro scale [ 14 , 15 , 16 ]. In addition, micro-morphology and nanomechanical properties of thermally modified bamboo have been less intensely analyzed at the nano-scale.…”

Determination of the Effects of Superheated Steam on Microstructure and Micromechanical Properties of Bamboo Cell Walls Using Quasi-Static Nanoindentation

“…To be specific, when the treatment temperature is at 160 • C, there is no significant change of mass loss in comparison to no treatment (p > 0.05). However, the treatment severity makes a positive contribution to the mass loss of moso bamboo when the treatment temperature is over 170 • C. According to previous literature [4][5][6][7], the decomposition of hemicellulose begins at 180 • C, and with the increasing decomposition of hemicellulose, more acetic acid is released.…”

“…At 150 • C, the TM can effectively minimize hygroscopicity, shrinkage, and swelling qualities. The considerable breakdown of hemicellulose at 180 • C or above positively contributes to anti-fungi capabilities [6,7]. Conventional heat treatment media, such as oil, heat air, and high frequencies, can lead to the loss of moisture content in Moso bamboo, which can cause cracks on the bamboo surface.…”

The Influence of Saturated Steam on Moso Bamboo Quasi-static Micromechanical Properties: Nano-Scale Evaluation

“…In conclusion, the loss modulus decreased significantly. Enhanced frequency contributed negatively to the loss tangent, this is due to the shorter molecular chain rearrangement time resulting in the stiffening of material (Yang et al 2020;Hao et al 2021).…”