Slip behavior of high-density polyethylene at small shear stresses in the presence of esterified polyethylene glycol

Abstract

Viscoelastic instabilities in polymer melts can be mitigated using polymer processing aids (PPAs) that impose slip between melts and substrates. In this study, the effect of a newly synthesized esterified polyethylene glycol (PEG) on the slip behavior of a high-molecular-weight high-density polyethylene at small shear stresses was investigated. Rheological measurements were employed to capture the dependence of slip velocities on shear stress and calculate extrapolation lengths and friction coefficients. Our findings showed that the incorporation of PEG-based PPA increased slip velocities while an increase at temperature suppressed slip. At 190 °C, there was a strong slip zone at shear stresses smaller than 9 kPa for all samples with and without PEG. In this zone, the extrapolation length showed ascending and descending behavior while its values were almost constant beyond this zone. The incorporation of PEG-based PPA at 190 °C doubled the extrapolation length from 300 to 600 μm and amplified its variation in the first zone. The study of the slip behavior at 210 °C revealed that the samples did not experience the first zone. They showed a second zone with extrapolation lengths well below 100 μm, signifying the presence of a weak slip regime. This study highlights the importance of PPAs in altering the slip mechanisms for high-molecular-weight polymer melts.

Effect of blend composition on the adhesion strength of EVA‐g‐MA/LLDPE‐g‐MA films to epoxy substrates

“…The morphologies of these blends can range from simple, two‐phase structures, such as droplets or fibrils embedded in a continuous matrix, to multi‐phase structures, such as co‐continuous or bicontinuous networks 26 . The morphology of partially miscible polymer blends is important as it can strongly influence the mechanical, 27 rheological, 28,29 and thermal properties of the material 30 . The addition of a second phase can remarkably alter the crystallinity of polymers by promoting or inhibiting the crystallization, 20 depending on their properties and the processing conditions 31–35 .…”

Evaluation of Layer Adhesion and Uniformity in Poly(lactic acid) and Thermoplastic Starch Multilayered Films

“…Besides the impact of compatibilization, layers are processed in molten states to form adequate interfacial layers. During the formation processes, the shear rate determines the flow strength and residence time of the layers within heated zones in a common block. , Also, the viscosity ratio at the processing conditions is another parameter that can potentially influence the interfacial adhesion and layer uniformity. , The aforementioned studies do not provide information regarding the effect of material and processing parameters such as shear rate and viscosity ratio on the final layered films properties, including the adhesion strength and layer uniformity.…”