Thermal and mechanical performances of bamboo strip

Abstract

Bamboo strips extracted from Phyllostachys viridiglaucescens, grown in Europe, were analysed to assess their thermal and mechanical properties for composites application. Thermal stability of the European bamboo was studied by Thermogravimetric Analysis (TGA) and compared to the one of species grown in Oceania. An evolution of the chemical composition along the radial direction of the Phyllostachys bamboo was identified by TGA. The inner part of culms shows a higher proportion of hemicelluloses, while the percentage of crystalline cellulose is higher in the outer portion. This evolution of the composition was used to interpret the original data recorded by Dynamic Mechanical Analysis (DMA) of the strips. Glassy tensile modulus founded by DMA increases from the inner part of the culm (6.8 GPa) to the outer part (9.9 GPa). The variation of the cellulose content along the radius of the bamboo culm is related to this increase and shows a good correlation with thermal behaviour. The dynamic relaxations in the shear mode reveal the existence of two secondary relaxation modes sensitive to water. In the order of increasing temperatures, they have been assigned to the mobility of methylol groups and to heterogeneities of the polymeric matrix. By combining Differential Scanning Calorimetry (DSC) and DMA, the response of the viscoelastic transition of bamboo strips, at 210 °C, was evidenced for the first time. Bamboo strips behave as a unidirectional composite reinforced by technical fibres; its particularly high shear glassy modulus (2.3 GPa) deserves to be emphasised.

Continuous Bamboo Fibers/Fire-Retardant Polyamide 11: Dynamic Mechanical Behavior of the Biobased Composite

“…On the high-temperature side, the increase of energy loss might have been due to the viscoelasticity of bamboo fibers. This hypothesis is supported by previous data recorded on bamboo strips obtained from the same bamboo species, reported by Richmond et al [56]: They observed by DMA in the tensile mode a viscoelastic relaxation peak at 200 °C.…”

Physical and dynamic mechanical properties of continuous bamboo reinforcement/bio-based epoxy composites

“…This value is particularly high compared with the glassy modulus of the matrix (1.8±0.1 GPa). In a previous work, the Young's modulus of the same bamboo strips than the ones used in composites was measured : 10±2.4 GPa [34]. The major point on figure 9 is that, in the elongation mode, the contribution to the Young's modulus of the bamboo reinforcement is predominant.…”

“…The restriction comes from the processing temperature, which is limited by the thermal stability of natural fibres. It has been shown that the temperature should be below 200 °C to avoid any thermal degradation of the natural reinforcements [34]. Such limitations favour thermosets.…”

“…Two kinds of reinforcement were studied: bamboo fibres (BF) and bamboo strips (BS). Bamboo strips were characterized in a previous study [34]. Accordingly, the best properties are obtained from strips extracted at the periphery of bamboo culm while the location of strips along the culm length has no influence.…”

“…Bamboo strips (BS) were extracted by a purely mechanical process by Cobratex. With dimensions of 0.3 mm thick and 5 mm width, those reinforcements show a Young's modulus of 10 GPa and a tensile strength of 210 MPa [34].…”