A Study on Shrinkages During the Carbonization of Bamboo

Shrinkages have been investigated by means of measuring yields of solid products of carbonized bamboo and the variety of dimension in the carbonization process of bamboo,under the heat treatment temperature from 200 ℃ to 900 ℃.The paper focuses on the feature of shrinkages and the relationship between the shrinkages,moisture and polymer components in bamboo.The results show that,(1)By thermal conversion of bamboo,the rule of shrinkages in various directions show a similar way as that of the weight loss.From 200 ℃ to 400 ℃,shrinkages are most drastic.(2)Shrinkages of bamboo in various directions show an anisotropic feature.At a fixed carbonization temperature,according to a sequence of exterior tangential,radial,interior tangential,axial,the value of shrinkage increase continuously,which in axial direction below 200 ℃ is zero.(3)Below 400 ℃,cellulose,especially those in ordered regions,not only determines the orientation of shrinkages but also has a most significant influence on the degree of shrinkages in various directions.(4)Above 400 ℃,graphitization of bamboo charcoal possibly plays a more and more important role in shrinkages in its various directions.(5)Below the range from 300 ℃ to 350 ℃,raw bamboo or some internodes with the higher moisture perform the higher shrinkages.