Rheological parameters and characteristics of bamboo in compression perpendicular to grain under hot-pressing process

Bamboo with high specific strength is a renewable biomaterial. Studying the rheological properties of bamboo is helpful to improve the performance and quality of bamboo products. In this paper, four-element Burgers model was applied to describe the creep behavior of moso bamboo (Phyllostachs pubescens) in compression perpendicular to grain under hot-pressing process. The relationship between creep components and experimental factors (temperature, moisture content and stress level) was investigated. More importantly, four rheological parameters in Burgers model were also determined at different temperatures, moisture contents and stress levels. And the effect of experimental factors on rheological parameters was quantitatively explored. The results showed that, when compressive stress was below the yield limit, the amount of three components of creep was proportional to experimental factors, but the increase in temperature and moisture content could reduce the proportion of elastic deformation, and improve the proportion of viscoelastic deformation and viscous deformation. Besides, rheological parameters were insensitive to stress level when temperature and moisture content remained unchanged. But they were greatly affected by temperature and moisture content, presenting a linear inverse proportion to them.