Microstructural And Micromechanical Properties Of Thermo-treated Bamboo Cell Wall

The objective of this paper is to study 6-years-old bamboo cell wall after heat-treatment. The chemical component and structural properties of the heat-treated bamboo cell wall with 130 oC, 150 oC, 170 oC and 190 oC for 2h, 4h and 6h were investigated. Atomic force microscopy and nano-indentation technology were conducted to test and analyze the effect of heat treatment temperature and time on the nano quasi static mechanics of bamboo cell wall. Based on the nano-indentation test, nano creep properties of heat-treated bamboo cell wall by lengthening duration time. Frequency was taken as a fact to investigated nano dynamic mechanics properties by nano-DMA. The results showed that:(1) The α-cellulose and holocellulose content of heat-treated bamboo cell wall decreased with increase of temperature and time when the heat treatment temperature above 150 oC. Lignin content increased with increasing of temperature and the heat-treated time had little effect on lignin content.(2) The effect of heat-treated temperature and time on the microfibrils angle of bamboo cell wall was not sufficiently obvious. At the low temperature level, the microfibrils angle of bamboo cell wall reduced gradually with the increasing of time, and had little change above 170 oC. The crystallinity of heat-treated bamboo cell wall had a trend of increasing with the increasing of temperature and time, especially above 170 oC.(3) Hardness and elastic modulus of heat-treated bamboo cell wall got higher and higher while temperature increasing and slowed down after the temperature above 170 oC. Duration time of heat treatment do not had an obvious effect on hardness of bamboo cell wall. When temperature below 170 oC, elastic modulus increased gradually with time increasing.(4) Compared with control samples, creep ratio of heat-treated bamboo samples reduced. Creep ratio changed obviously when temperature above 190 oC,and it increased with time increasing. As the temperature reached to 190 oC, strain rate of heat-treated bamboo cell wall was lower than that of control samples obviously, especially at the phase of first 50 s.(5) Compared with control samples, storage modulus of heat-treated bamboo cell wall was much higher while loss modulus became lower. And storage modulus got increased with frequency increasing while loss modulus reduced. Heat treatment time hadan irregular effect onstorage modulus and little influence on loss modulus.