Physical structure and mechanical properties of polyamide/bamboo composites

The main objective of this work is to process innovative bamboo flour (BF)-reinforced polymer composites. In this context, polyamide 11 (PA 11) is used as technical matrix. Moreover, BF is treated with tetraethyl orthosilicate (TEOS) playing the role of coupling agent. SEM observations show no influence of TEOS on the affinity. The composites were analysed by DSC and DMA, in comparison with neat PA 11. DSC analyses of PA 11/BF highlight that there is no significant modification of the percentage of crystallinity upon introduction of BF whatever the treatment is. Concerning the amorphous phase, only a slight shift of the glass transition of PA 11 from 35 A degrees C (PA 11) to 38 A degrees C (PA 11/BF composites) is recorded. This shift can be explained by physical bonds at the interface PA 11/BF. DMA analyses allow us to explore the role of BF fillers onto the properties of PA 11/BF composites. The first observation is a slight improvement of the shear modulus G' when the concentration in TEOS increases. The beta relaxation at -80 A degrees C is associated with the mobility of the complexes free amide groups/water molecules. There is no shift of the peak due to the presence of BF fillers. The magnitude and width of the relaxation increase with BF and also with TEOS treatment. These observations highlight the increase of hydrogen-bonded water in various sites of the vitreous state. The alpha relaxation is associated with the anelastic mobility liberated at the glass transition. For PA 11/BF composites, it is constituted by two components: the lower-temperature one due to neat polyamide and a higher-temperature one associated with PA 11/BF amorphous domains with a lower thermal conductivity.