Thermal stability analysis and mechanical performance of Mediterranean lignocellulosic fiber reinforced polypropylene sustainable composites

Abstract

The utilization of the available agro waste to make sustainable materials was recently emphasized to develop better bio-products and sustainable socio-economic environment. This work investigates the effect of reinforcing polypropylene with lemon leaves (LL) and fig leaves (FL) on the overall mechanical performance of the prepared composites considering various reinforcement conditions. The investigations including determining the tensile strength, tensile modulus, elongations at break, flexural and impact properties as well as revealing the thermal characteristics of the fibers to expose their suitability for such bio-based composites. Thermal gravimetric analysis (TGA) and its derivative (DTG) were used to study the thermal stability of fiber composition during manufacturing. The surface morphology of the fibers as well as their polypropylene composites were analyzed using scanning electron microscopy (SEM). Results have revealed that LL positively affects both tensile strength and modulus. The 20 wt% of LL have enhanced the tensile modulus from 1229 MPa to 1321 MPa. However, FL had negative impact on the tensile properties regardless of weight %. FL and LL reduced the flexural strength and impact toughness of PP regardless of weight %. The tensile strength of the 30 wt% lemon leaves-PP composite reaches its highest value at 43.4 MPa. Furthermore, thermal analysis showed that the fibers did not decompose during the manufacturing process. The initial decomposition temperatures of LL and FL were 239 °C and 226 °C, respectively, exceeding the processing temperature of 170 °C. Furthermore, an in-depth comparison of the tensile strength of the studied FL/PP and LL/PP composites with other commonly used PP composites available in the literature was also performed here to demonstrate the potential of Mediterranean fibers and their suitability for green bio-composites.