Mosab Kaseem

Thermoplastic starch blends: A review of recent works

The aim of this review is to discuss the recent developments in thermoplastic starch blends. Starch has been considered as an excellent candidate to partially substitute synthetic polymer in packaging, agricultural mulch and other low-cost applications. Recently, the starch granules were plasticized using different plasticizers under heating and shearing, giving rise to a continues phase in the form of a viscous melt which can be processed using traditional plastic processing techniques, such as injection molding and extrusion. This kind of starch composites is called thermoplastic starch. Unfortunately, thermoplastic starch presents some drawbacks, such as low degradation temperatures, which make it difficult to process, poor mechanical properties and high water susceptibility. Much work has been carried out to overcome these drawbacks, including the combination of thermoplastic starch with other polymers, aiming at lowering the cost and enhancing the biodegradability of the final product.

Rheological and mechanical properties of polypropylene/thermoplastic starch blend

Starch as an inexpensive and renewable source has been used as a filler for environmentally friendly plastics for about two decades. In order to improve the compatibility between hydrophilic starch granules and hydrophobic polypropylene (PP), glycerol used as a plasticizer for starch to enhance the dispersion and the interfacial affinity in thermoplastic starch (TPS)/PP blend. In this study, PP was melt blended with thermoplastic starch (TPS) using a single screw extrusion process and molded using injection molding process to investigate the rheological and mechanical properties of these blends. TPS viscosity measurements were performed on the single screw extruder. Rheological properties were studied using a capillary rheometer and the Bagley’s correction was performed. Mechanical analysis (stress–strain) was performed using Testometric M350-10KN. The rheological properties showed that the viscosity of TPS decreases with increasing glycerol content in TPS. Also, it was found that PP/TPS blends are pseudo plastic in nature and the flow activation energy of the blends is greater than that of PP. Mechanical results showed that strain at break of the blends is lower than that of PP, whereas the Young’s modulus of the blends is higher than that of PP.

On-Line Rheological Measurements and Mechanical Properties of Acrylonitrile-Butadiene-styrene/Corn Starch Composite

In this work, rheological and mechanical properties of acrylonitrile–butadiene–styrene/corn starch composites (ABS/starch) were studied. The composites were prepared using a laboratory-scale, single-screw extruder. Rheological properties were determined using the single-screw extruder, apparent shear rate (γ a ), apparent shear stress (τ a ), apparent viscosity (η a ), non-Newtonian index (n), and flow activation energy at a constant shear rate (E γ) and constant shear stress (E τ). Mechanical properties in terms of tensile tests were performed using Testometric M350-10KN, stress at break, strain at break, and Youngs modulus were determined. Rheological results showed that the composites are pseudo plastic in behavior, and the apparent viscosity of the composites increases with increasing starch content above the additive rule, which indicates a partial compatibility in the composite. It was also found that the flow activation energy of the composite increases with increasing starch content. The mechanical results showed that the strain at break of the composite decreases sharply by the presence of starch, whereas the Youngs modulus increases with increasing starch content.

Preparation and studying properties of thermoplastic starch/acrylonitrile–butadiene–styrene blend

In this work, blends of acrylonitrile–butadiene–styrene (ABS) and thermoplastic starch (TPS) were prepared by using a single screw extruder (SSE), the starch was plasticized in the single screw extruder by using glycerol as a plasticizer. The blends were characterized by studying rheological and mechanical properties. The rheological results indicated that ABS/TPS blend melts were pseudo plastic and exhibited shear–thinning behavior, and the viscosity of the blend decreased with increasing glycerol content. Also the values of flow activation energy at a constant shear stress (Eτ) of ABS1/TPS25G blend were determined, and it was found that Eτ increased with increasing shear stress. Die swell measurements of the blend showed that die swell ratio increases with increasing shear stress and glycerol content in the blend, while it decreases with increasing L/R. Mechanical results showed that, the values of stress at break and strain at break decreased with increasing TPS content in the blend, which was attributed to the immiscibility between TPS and ABS.