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Modeling and Simulation of a Biopolymer
Processing in a Single Screw Extruder
U. Romero Ortiz, A. López Villa and R.O. Vargas Aguilar
Abstract
Modeling and numerical simulation of a biopolymer processing in a single
screw extruder is developed. Polylactic acid (PLA) is one of the natural polymers
proposed as a substitute for synthetic polymers because of the similarity in physical
properties as well as processing conditions. The PLA behaves as a shear thinning
fluid, in order to involve this feature the Power Law model is used as a constitutive
equation and the temperature dependent viscosity is also considered. The model is
validated comparing typical flow curves of a Newtonian fluid generated by the model
with results previously reported in the literature. Finally, the drag flows and pressure
flows are analyzed, the effect of the power index and the flow curves for Newtonian
and non-Newtonian fluids are compared.
1 Introduction
Polymer extrusion is a process that offers advantages over most plastic transformation
processes and with an economic cost with respect to any other. The single screw
extruder is the most common equipment in the polymer industry. It can be part of an
injection molding unit and found in numerous other extrusion processes, including
blow molding, film blowing, and wire coating (Bird et al.
1960
).
Environmental concerns have led over the past years to growing over new solution
for plastics, “green plastics” have been motivated by two specific goals: reduc-
ing dependence of plastic production on petroleum supplies and developing solu-
tions to plastic waste accumulation. The development of biodegradable polymers
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