The development of laminar morphology in a co-rotating twin screw extruder

Abstract

Laminar morphology of high‐density polyethylene (HDPE)/polyamide‐6 (PA‐6) blends was obtained, for the first time, in a co‐rotating twin screw extruder. The morphology analysis in the interior of the adapter, which connects the extruder with a slit die, revealed that, under specific processing conditions, it is possible to produce layers of PA‐6 in the end of the screw zone of the extruder. The micrographs of the extruded final products showed distributed layers across the sample thickness and along the flow direction. The effect of design and processing variables such as adapter angle, die gap, temperature profile, feed rate, and screw speed on the final product morphology were evaluated. In this research, blends were obtained with toluene permeability reduced by up to 113 times from the permeability of the matrix alone. This value is 2.5 times better than the best value reported for products of single screw extrusion. Mechanical tests showed that the HDPE/PA‐6 extrudates maintain stiffness and tensile strength values comparable to those of polyethylene. In order to obtain products with optimum balance between the permeability and the mechanical properties, a statistical analysis was carried out. It produced useful information regarding the important processing and design factors that affect the product properties. © 1999 John Wiley & Sons, Inc. Adv Polym Techn 18: 89–108, 1999

Rubber‐toughened PLA blends with low thermal expansion

“…In general, the rheology foundation to produce polymer blend with microlayer structure is the flow of binary phase, in which the melt viscosity and elasticity ratio are the most important 30. We have confirmed that a polymer blend owning the morphology with the plastic as the dispersed phase and the rubber as the matrix is benefit to form the co‐continuous microlayer structure during injection molding 26.…”

Thermoplastic rubber/PP elastomers toward extremely low thermal expansion

“…However, in this study, the domain size in EOR/PP blends was larger than those in other blends, which may be ascribed to viscosity. In general, the rheology foundation to produce polymer blend with microlayer structure is the flow of binary phase, in which melt viscosity and elasticity ratio are the most important parameters . Higher viscosity of the matrix phase can delay the break‐up time after shear deformation, thereby favoring lamellar orientation .…”

Compatibilization of Poly(styrene‐acrylonitrile) (SAN)/Poly(ethylene) Blends via Amine Functionalization of SAN Chain Ends

“…This change in morphology results in a higher tortuosity within the blend which significantly reduces the permeability, and almost achieves the permeability of a coextruded nylon sheet. [1,20,21] Poly(styrene-ran-acrylonitrile), SAN, has excellent grease and chemical resistance as well as high gas barrier properties due to the polarity of the acrylonitrile monomer. [22] For this reason it would make an excellent barrier material within a PE blend.…”

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