A Study On Starch Based Fully Biodegradable Materials

The compatibility between starch and PBAT is poor, especially starch is difficult to beplastified, which has affected the application of composites. This paper adopted plasticizersuch as glycerol and B2, reinforcing agent such as talc and CaCO3, bulking agent such asB8and B12, hydrophobic modification agent such as KH-550and KH-570, modifying thecomposites. The effect of modifying agent content on mechanical properties, rheologicalproperties, crystallization behavior, microstructure and hydrophobic properties wereinvestigated, and TPS/PBAT composites with better properties were prepared.The experimental results indicated that complex plasticizer, B8and B12couldimprove mechanical properties substantially and their best content was17.5wt%,0.1wt%and8wt%, respectively (based on starch). When1wt%content (based on gross) CaCO3was added, the tensile strength could reach12.13MPa which had improved15.2%.Coupling reagent could also improve mechanical properties. When0.5wt%content (basedon starch) KH-550was added, the tensile strength could reach12.36MPa while elongationat break was100.84%.The torque and rheological properties of materials were investigated by torquerheometer. The experimental results suggested that the balance torque and shear viscositydecreased with the addition of plasticizer content. B8and B12could affect the torque andrheological properties of materials. The shear viscosity decreased with the addition of B12.CaCO3and talc presented the opposite effect on torque and rheological properties. With theaddition of CaCO3, the torque and rheological properties increased to some extent.Moreover, the kinds and content of coupling reagents had a significant effect on the torqueand rheological properties.The crystallization behavior was investigated by X-ray. The results indicated that theXRD peak became lower with the addition of plasticizer, B8and B12. Reinforcing agenthad less effect on crystallization behavior. But the degree of crystallization decreased withthe increase of the coupling reagent KH-550content, and the degree of crystallizationfirstly decreased and then increased with increase of KH-570.The experimental results suggested that plasticizer, B8and B12were conductive toimprove the interfacial compatibility by SEM analysis. Because of the–OH on the surfaceof CaCO3, which had a better dispersion, at the same time few pores were produced. Moreover, the proper content of coupling reagent could not only plastify composites, butalso improve interfacial compatibility.The water resistance of composites was detected by contact angle and waterabsorption. It was found the water resistance decreased with the addition of plasticizer, talcand CaCO3, but it increased with the addition of B8, B12and coupling reagent. When0.5wt%KH-570(based on starch) was added, water absorption was12.87%which hadlowerd35.5%, so it could improve hydrophobic significantly.