Biobased Composites of Sisal Fiber Reinforced Polypropylene

1 Biobased Composites of Sisal Fiber Reinforced Polypropylene 

1 Mechanical and Dynamic Mechanical Properties of Sisal PP Composites 

The mechanical properties of virgin PP, treated and untreated sisal PP composites, as a function of fiber loading, are presented in Table 9.3 [71]. It is evident that the mechanical properties of the composites increased linearly with the increase in fiber loading from 6.8 to 21%. Tensile strength increased to about 64%, whereas flexural and impact strengths increased to about 

Fiber Vol% Tensile Strength (MPa) Tensile Modulus (MPa) Impact Strength (J/m) 

The variation of die swell ratio De/D (where De and D are the diameters of the extrudates and die) of virgin PP, untreated and treated composites is represented in Table 9.5 [74]. It is evident that the swell ratio of the virgin matrix decreased with the incorporation of fibers. This is probably attributed to the distribution of fibers within the PP matrix which results in stress transfer from matrix to the fiber, thereby retarding the elastic recovery of the material [75]. Furthermore, the treated composites displayed a lesser die swell, thus confirming enhanced fiber-matrix adhesive strength. However, the swell ratio increased with the shear rate, which is probably due to the decrease of normal stress and elastic recovery at low shear rates. 

---