Effect of organomodified montmorillonite concentration on tensile and flow properties of low-density polyethylene–thermoplastic corn starch blends

Abstract

In this study, low-density polyethylene (LDPE)–thermoplastic corn starch blends containing various amounts of organomodified montmorillonite (OMMT, 0.5–3 part per hundred (phr) resins) were prepared using a twin screw extruder. A 3-wt% LDPE-grafted maleic anhydride was used as a compatibilizer. The tensile, flow and water absorption properties of all the samples were measured by means of standard methods. Intercalated structures were achieved in all the samples, based on the x-ray diffraction and transmission electron microscopic results. Increasing levels of clay also led to the higher gallery distance of silicate layers (i.e. 32.5–34.5 Å). Furthermore, increment in ultimate tensile strength (UTS) and Young’s modulus ( E) as well as decrement in elongation at break ( ∊b) were obtained with increase in clay loading. The sample containing 1 phr nanoparticles showed 20% and 63% increase in UTS and E when compared with the reference sample, respectively. However, ∊b of this sample decreased by 17%. In addition, the flow property measurements indicated that as shear rate and the clay content increased, the apparent viscosity of all the samples decreased and increased, respectively. Finally, the presence of OMMT led to decrease in the melt flow index (MFI) of the samples. The MFI values also decreased with increasing the OMMT concentration. It is believed that the samples prepared in this work may biodegrade after exposure to the environment.