Manufacture and Mechanical Behavior of Green Polymeric Composite Reinforced with Hydrated Cotton Fiber

Composites using natural fibers as reinforcement and biodegradable polymers as matrix are considered environmentally friendly materials. This paper seeks the mechanical and morphological characterization of a biocomposite of polyurethane (PU) derived from a blend of vegetable oils doped with alumina trihydrate (ATH) and reinforced with hydrated cotton fiber fabric (HCF). The comparison and study were performed based on the properties of the: (i) pure PU; (ii) PU doped with ATH containing 30% of the final mass (PU+30%ATH); (iii) composite of PU reinforced with 7 layers of cotton fiber fabric (PU+7CF); (iv) composite of PU+30%ATH reinforced with 7 layers of CF (PU+30%ATH+7CF); (v) composite of PU+30%ATH reinforced with 7 layers of hydrated cotton fiber fabric (PU+30%ATH+7HCF). The mechanical properties obtained according to the tensile test for the composite PU+30%ATH+CF with fibers oriented at 0° showed a significant increment in tensile strength (60 MPa) and the modulus of elasticity (4.7 GPa) when compared to pure PU (40 MPa) and (1.7 GPa) respectively. PU+30%ATH also presented a rising tensile strength (31 MPa) and Young modulus (2.6 GPa). For the composite with addition of water, results presented a significant decrease in strength (31.3 MPa) and stiffness (0.9 GPa) than the composite with no water. Electron microscopy (SEM) analyses exhibited that the samples with addition of water showed the presence of large amounts of pores and the lower interaction between matrix and fiber. These results may explain the lower mechanical properties of this material. DOI: http://dx.doi.org/10.30609/JETI.2019-7576