The Effect of ultra‐high speed twin screw extrusion on ABS/organoclay nanocomposite blend properties

Abstract

Acrylonitrile butadiene styrene (ABS) nanocomposites containing Cloisite 11 organoclay at 2 wt% were prepared using a 60 L/D ultra‐ high speed twin screw extruder (TSE), with speeds ranging from 400 to 4000 rpm. The purpose of this study was to investigate the effect of high shear melt processing on the intercalation and exfoliation of organoclay in the polymer, as well as the mechanical and rheological properties of the material. X‐ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) results showed better intercalation of the nanofiller with increasing screw speed up to a point, and indicated an exfoliated structure of the nanocomposites extruded at 4000 rpm. Mechanical and rheological testing results indicated that by adding organoclay to ABS, the properties improved with increasing screw speed up to an optimum value of 2000 rpm. However, at the higher screw speeds of 3000 and 4000 rpm, the intense shear history led to a decrease in properties, most likely due to chain scission and molecular weight reduction. Similar trends were observed in rheological properties of the nanocomposite as well. At 2000 rpm, the results indicate that the lowering of the molecular weight due to shear effects is balanced by good intercalation/exfoliation of the organoclay. POLYM. ENG. SCI., 57:60–68, 2017. © 2016 Society of Plastics Engineers

Influence of Processing Conditions on the Preparation of Clay-Based Nanocomposites by Twin-Screw Extrusion

“…This was explained by a degradation of the matrix at high speed, leading to a drop of viscosity and a less efficient exfoliation. Such degradation was also reported by Pistor et al (2015) and, in the domain of very high speeds (1000 -4000 rpm), by Farahanchi et al (2017aFarahanchi et al ( , b, 2018. Chain scissions, reducing the molecular weight and the viscosity, occurred above 400 and 1000 rpm, depending on the severity of the screw profile.…”

Kinetic and process modeling of thermal and mechanical degradation in ultrahigh speed twin screw extrusion

“…Depolymerization and other unintentional conversions along the extruder while running at very high speeds may adversely affect material properties and final product performance. [7] Previous works have studied the thermomechanical degradation of thermoplastics in conventional extrusion processes; however, almost none of these works concern the very high shear stress encountered in modern polymer processes, and most do not attempt to separate thermal and mechanical factors causing degradation. Silvano et al observed decreased viscosity in neat polypropylene as well as PP/montmorillonite nanocomposites when subjected to multiple reprocessing cycles in a TSE.…”

In‐line measurement of residence time distribution in melt extrusion via video analysis

“…Back mixing due to pressure gradients, dispersion by mixing elements, and wall adherence of material on the screw and barrel wall cause nonplug flow behavior during extrusion, resulting in a broader RTD . For reinforced polymers, the mechanical properties strongly depend on distribution of the filler, without damaging the matrix polymer chains . Understanding the RTDs impact on these factors is crucial , especially for scale up .…”