Processing And Characterization Of Polycaprolactone (PCL) : Sago Starch Blends As Biodegradable Polymers

Tahir, Nur Hazwani (2016) Processing And Characterization Of Polycaprolactone (PCL) : Sago Starch Blends As Biodegradable Polymers. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

Biodegradable polymers undergo chain cleavage at the polymer chains as a result of the action of microorganisms and/or enzymes. The rate of the degradation may vary from hours to years depending on the molecular structures of the polymers. Polycaprolactone (PCL) is one of most-known biodegradable polymers. However, PCL is expensive and limited in resources. This study, therefore, attempted to blend PCL with naturally abundant sago starch at varied mass compositions to lower the cost and increase biodegradability. The blends were prepared by using solvent casting method which involved two main processes; dissolution of PCL and sago starch in chloroform and solvent evaporation of the blends obtained. The blends tend to shrink as sago starch increased suggesting that sago starch was an excellent filler that can be incorporated easily into the PCL polymer matrix phase. The thermal properties were measured by Differential Scanning Calorimeter (DSC). The melting temperatures and latent heats of fusion of the PCL/sago starch blends ranged between 64.92-67.07 °C and 27.97-51.21 kJ/kg, respectively. Based on DSC curve, it can be concluded that no significant change in the thermal properties indicates no chemical reaction occurred between sago starch molecules and PCL chains. The mechanical properties of the blends were measured by tensile machine of 50 kN load with constant crosshead speed of 50 mm/min. The strength and ductility of the blends were found to decrease with increasing starch content. For example, the ultimate tensile strength and elongation % at break for PCL 50 wt %/sago starch 50 wt % were 1.35 MPa and 156%, respectively, which were lower than that of pure PCL (ultimate tensile strength = 3.94 MPa, elongation % at break = 1528 %. The addition of starch to PCL, however, seems to increase the tensile Young’s modulus of the blend suggesting that blends became stiffer with increasing starch contents. The biodegradability of PCL/sago starch blends was verified by soil burial biodegradation test which following ASTM 988-12 standard. The sample films were buried in a multilayer substrate consisting of mineral bed/soil mixture and left for 10 days. The mass loss of the sample films were ranged between 80-90 %. The sample with high starch contents found to degrade faster than that of pure PCL. The polyethylene film that was used as a control in this test did not degrade at all. Based on their biodegradability, mechanical and thermal properties, it can be concluded that these PCL/sago starch blends possess properties that make them technically and economically viable as biodegradable polymers that can be applied in various applications particularly in the field of packaging, biomedical and agricultural.

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