Mechanical Characterization Of Bamboo Fibers With Nanoindentation Technology

The objective of this paper is to study the bamboo of different ages, stem heights, walls. The relative Crystallinity and MFA of bamboo were investigated to support to explain the effects of different ages, stem heights, walls of bamboo. Nanoindentation and Nano-Dynamic Mechanical Analysis were used to acquire the viscoelasticity properties of different ages, stem heights, walls of bamboo fibers cell wall. The results showed that:(1) With increasing age, Their microfibril angle were 8.14 o,9.31 o,8.66 o from 2 to 6-year-old, respectively, their microfibril angle increased first, then decreased from 2 to 6-year-old. The crystallinity with increasing age showed a decreasing trend. From bottom to top, the microfibril angle decreased from bottom to top, the microfibril angle of 1m, 3 m and 5m were respectively 9.07 o, 8.66 o and 7.81 o. The crystallinity showed an increasing trend from bottom to top. In the bamboo wall direction(radial), from outside to inside, the crystallinity decreased, the middle and the outside were not obvious clearly. The maximum and minimum of bamboo microfibril angle were 10.87 o and 8.66 o, the maximum of microfibril angle was at the outer position.(2) The REM and hardness of bamboo fiber bamboo secondary cell wall with increasing age showed a decreasing trend. The REM value was 23.23GPa、21.35GPa、19.57 GPa, the hardness was 0.67GPa、0.59GPa、0.49 GPa from 2 to 6 year.The REM and hardness of bamboo fiber bamboo secondary cell wall with different stem height showed an increasing trend first, then turned to decrease, the REM value was 22.83GPa、19.57GPa、23.86 GPa, the hardness was 0.58GPa、0.49GPa、0.53 GPa respectively from the bottom to the top. The REM and hardness of bamboo fiber bamboo secondary cell wall showed an increasing trend, from inside to outside. The REM value was 20.65GPa、19.57GPa、17.82 GPa, the hardness was 0.54GPa、0.49GPa、0.44 GPa from inside to outside.(3) The Er’ of bamboo fiber cell wall in different ages rose with increasing load frequency. At the same loading frequency, 2-year-old bamboo’s Er’> 4 year old bamboo’s Er ’> 6 years old bamboo’s Er’, While the Er " reduced with increasing frequency, at the same loading frequency, the Er" of 2-year-old of was more than those of 4-years-old and 6-year-old. The Er’ of different bamboo stem height increased with increasing loading frequency. Under the same loading frequency, the Er’ of 1 meter was more than those of 3 meter and 5 meter.,The Er " decreased with increasing load frequency, at the same loading frequency, there were no obvious difference among the 1, 3 and 5meters’ Er". The Er’ in different parts of the bamboo wall increased with increasing load frequency. The Er’ of the outer part was slightly larger than those of the inside and middle part. The Er " decreased with increasing load frequency with different bamboo walls, Under the same load frequency, the Er" was no obvious difference from outer to inside part.