DYNAMIC MECHANICAL THERMAL ANALYSIS OF MOSO BAMBOO (Phyllostachys heterocycla) AT DIFFERENT MOISTURE CONTENT

Abstract

aBamboo is a type of biomass materials that has great potential as a bioenergy resource in China. The thermal-mechanical behavior of bamboo plays an important role in the formation process of pellets. To investigate the effect of moisture content (MC) on thermal-mechanical behavior of bamboo, the storage modulus and loss factor of moso bamboo was determined using dynamic mechanical thermal analysis (DMTA) from -50 to 150 o C. The experimental results showed that the general feature of bamboo thermal-mechanical properties with temperature is similar to other cellulosic materials, and they are affected by MC. A substantial decrease of storage modulus over the entire temperature range implies that bamboo underwent a glass to rubber transition. Bamboo, at lower MC, has a higher storage modulus, which decreases the mechanical strength of pellets. The loss factor exhibited two major transitions for all samples. There was an α-transition (α 1 ), attributed to glass transition of lignin, peaking in a higher temperature range. The second major relaxation (α 2 ), located in a lower temperature range, was attributed to glass transition of hemicelluloses. Activating lignin and hemicelluloses using moisture and temperature in the temperature range of glass transition can be very helpful to achieve durable particle-particle bonding.

Investigation of changes in compressed moso bamboo (Phyllostachys pubescens) after hot-press molding

“…The bamboo materials with 12 and 16% MC exhibited two transitions: one transition centred around 100 °C (α 1 ); and the other between 30 and 60 °C (α 2 ). Similar results have been previously observed by Liu et al [22] who found that α 1 transition occurred around 80 °C and α 2 transition around 30 °C for moso bamboo with 8 and 12% MC. The α 1 and α 2 transitions are probably linked to the glass-rubber transition of lignin and hemicelluloses, respectively.…”

“…Over the entire temperature range, the bamboo with a higher MC generally had a lower E′ value, indicative of a lower relevant stiffness. Liu et al [22] also found the storage modulus decreased with water content increase. This phenomenon confirmed the expected role of water as having a plasticizing effect on the bamboo.…”

“…At low temperature region, the kinetic energy of material molecules is very low, with motion occurring only in some small units such as side and branched chains. High temperature could result in crystallization or ordering of the molecules, causing the substantial decrease of E′ [22]. It should be noted that, for sample with 16% MC, the E′ gradually increased from around 100 °C.…”

Fire analysis of load-bearing bamboo structures

“…As with other lignocellulosic materials, bamboo compounds undergo a glass transition or phase change at relatively low temperatures. Liu et al (2012) have suggested that hemicellulose reaches its glass transition temperature between 10°C and 30°C. However, the glass transition of lignin, which occurs at 65°C -83°C, is what significantly leads to the initial reduction of the bamboo strength and stiffness (Liu et al, 2012).…”

“…Liu et al (2012) have suggested that hemicellulose reaches its glass transition temperature between 10°C and 30°C. However, the glass transition of lignin, which occurs at 65°C -83°C, is what significantly leads to the initial reduction of the bamboo strength and stiffness (Liu et al, 2012). Various authors (Ramage, Sharma, Shah, & Reynolds, 2017;Reszka & Torero, 2016) suggest that lignin suffers a significant loss of stiffness at temperatures between 65°C and 85°C.…”