Mechanical and thermal behaviour of bamboo flour-reinforced XLPE composites

In the present work, the influence of natural fillers (bamboo flour/BF) on crosslinked polyethylene (XLPE) has been discussed. The main difficulty for the preparation of the composites is to establish adhesion between hydrophilic natural fillers and hydrophobic matrix. Consequently, coupling agent (CA) as silane must be added to promote interface. In this work, different amounts of tetraethyl orthosilicate (TEOS) were used as coupling agent and SEM images allow us to control the quality of the interface. Differential scanning calorimetry (DSC) shows that the XLPE crystallinity is unmodified upon the introduction of BF. The absence of transcrystallinity is important for preserving the ductility of composites. The dynamic mechanical analyses (DMA) highlight an optimum of shear modulus for a TEOS content of 5 mass% (CA5). Above this amount, the mechanical properties are reduced. These results were confirmed by the SEM observations which highlighted the decrease in the interface between the XLPE and BF. Furthermore, neither the introduction of BF nor the treatment with TEOS exerts an influence on the relaxation temperature: there is no plasticization. The combination of DSC/DMA allows us to show that higher viscoelasticity favouring impact strength is observed in XLPE/BF CA5 composites.