Chapter 4

Chapter 4 CONCLUSIONS AND RECOMMENDATIONS

In creation of thermoplastic starch materials, starch should be melted and plasticized in the presence of a plasticizer, high temperature, and shearing. Blends of sago starch and glycerol (20% and 40% w/w) with a constant amount of moisture were fed using different temperatures per formulation (90°C and 110°C). The extrudates produced were tested for tensile strength at break, biodegradability, and disintegration in water. Results of the tensile strength testing at break have shown that at lower glycerol content, the tensile strength testing at break decreased as the barrel temperature for extrusion increased. Such observation can possibly be attributed to the possible volatilization of the plasticizers at higher temperatures of extrusion, causing less interference in chain-chain secondary bonding of starch bonds. Meanwhile, at higher glycerol content, an opposite effect was observed, that is, the tensile strength at break increased as the barrel temperature for extrusion increased. It could be that the plasticizers interfered with chain-chain secondary bonding to a great extent. At higher temperatures, a possible volatilization of the plasticizers was also suspected, allowing to a certain extent the antiplastification effect produced in high plasticizer contents. The tensile strength at break of the various treatments were significantly different from each other, as observed from the generated p-value of 0.0323. Using Turkey’s HSD post hoc test, it was found out that in terms of tensile strength at break, samples containing 20% glycerol extruded at 90°C and 110°C were significantly different with each other. Similarly, samples containing 40% glycerol extruded at barrel temperatures 90°C and 110°C were significantly different with each other. The biodegradation of the TPS samples have shown no significant signs of biodegradability during the observation period. No significant mass changes were detected;

36 nor were alterations in the visual appearance observed. Similarly, the results in the test for disintegration in water have shown that all the TPS samples were not disintegrated in water. The results of the degradation and disintegration tests suggest that the sago starch-glycerol formulations produced a thermoplastic starch material using this extruder-cooker. It was initial proof of the success of the plasticizing ability of this fabricated machine. The following investigations are further recommended: •

A sheeting machine is needed to conveniently evaluate tensile strength and other physical properties.

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A more accurate instrument is needed to measure the physical properties of the produced material.

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Further biodegradation studies should be done with regards to degradability, or observation periods be extended to determine the complete biodegradation pattern of the produced materials.