Polymer Engineering and Science articles from March 2005

Polymer Engineering and Science archives from March 2005

Fast and efficient simulation of 3D creeping flow in ducts using a space-marching algorithm.
March 1, 2005... INTRODUCTION Duct flow can be found in almost any polymer processing method. In fact, in most cases, it represents one of the key aspects to achieve the desired final properties, such as the case of blown film, where rectilinear annular...

Long-term performance of environmentally-friendly blown polyurethane foams.
March 1, 2005... INTRODUCTION Polyurethane foams are widely used as thermal insulator materials due to their low thermal conductivity. Otherwise, they are subjected to aging phenomena (i.e., the increase with time of thermal conductivity) that are...

Local mixing effects of screw elements during extrusion.
March 1, 2005... INTRODUCTION In the last decades, interest has steadily grown in the use of corotating twin screw extruders in both food and nonfood applications [1-3]. The extruder is used for various functions, such as mixing, cooking, or chemical...

Rheokinetics and effect of shear rate on the kinetics of linear polyurethane formation.
March 1, 2005... INTRODUCTION Thermoplastic polyurethanes (TPU) are extensively used as high performance elastomers and tough thermoplastics in a wide variety of industrial applications [1, 2]. Two common techniques for production of these polymers are...

Toughening of polybenzoxazine by alloying with urethane prepolymer and flexible epoxy: a comparative study.
March 1, 2005... INTRODUCTION The polybenzoxazines, a novel class of thermosetting polymers, possess some intriguing properties such as high thermal stability, easy processing ability, low water absorption, near zero shrinkage upon curing, and good...

Studies on atom transfer radical emulsion polymerization of n-butyl methacrylate.
March 1, 2005... INTRODUCTION The preparation of well-defined polymers and copolymers by radical polymerization has recently been an area of high interest [1, 2]. Although many systems have been proposed, the two most widely used are nitroxide-mediated...

Phase separation and rheological behavior during curing of an epoxy resin modified with syndiotactic polystyrene.
March 1, 2005... INTRODUCTION The applications of cross-linked thermoset polymers are limited by their brittleness. To increase their toughness, different methods have been developed. For instance, thermosetting resins have been modified with a variety of...

Mechanical behavior of polymethylmethacrylate with molecules oriented via simple shear.
March 1, 2005... INTRODUCTION This article investigates the tensile, fracture toughness, flexural, and ballistic impact properties of polymethylmethacrylate (PMMA) processed by equal-channel angular-extrusion (ECAE) under two different routes: A and C [1]....

Ejection force of tubular injection moldings. Part II: a prediction model.
March 1, 2005... INTRODUCTION In an injection mold, the ejection system must operate in a way that provides a balanced operation without damaging the molding or the ejector components. Hence, during the mold design, the estimation of the ejection forces is...

Constitutive equation of peroxide cross-linking of thermoplastic polyolefin rubbers.
March 1, 2005... INTRODUCTION Peroxide cross-linkability of ethene-propene copolymers (EPM) rubbers has been the subject of several studies in the past, with different experimental techniques, elastomers, and additives [1, 2]. Every polymer/peroxide...

Properties of mLLDPE/LDPE blends in film blowing.
March 1, 2005... INTRODUCTION Film blowing is the main processing of polyethylene. During the past decades, numerous efforts have been devoted to its modeling. However, there is no model that can successfully predict the film blowing process so far. First,...

Mechanical and fracture characterization of 50:50 HDPE/PET blends presenting different phase morphologies.
March 1, 2005... INTRODUCTION Poly (ethylene terephthalate) (PET) and polyethylenes are extensively used in packaging of consumer and industrial products, being the most found in urban waste streams. One of the best ways of reducing urban waste is by...

A flow simulation for the epoxy casting process using a 3D finite-element method.
March 1, 2005... INTRODUCTION Epoxy casting is a widely used technique for the manufacturing of electric insulation parts, such as bushings, switchgear parts, and instrument transformers. During the process, a liquid epoxy resin mixed with a curing agent...

Derivation of optimal processing parameters of polypropylene foam thermoforming by an artificial neural network.
March 1, 2005... INTRODUCTION Using thermoforming in the processing of foamed plastics has the benefits of low cost, good formability, uncomplicated molds, and the capability to build large or thin structures [1, 2]. Despite these advantages, persistent...

Rheology of fiber filled polymer melts: role of fiber-fiber interactions and polymer-fiber coupling.
March 1, 2005... INTRODUCTION Rigid short fiber polymer composites are widely used in industry because of their low cost and high performance. The physical properties of these polymer composites, such as elastic modulus, strength, thermal expansion,...

Effect of morphology on barrier properties of poly(ethylene terephthalate).
March 1, 2005... INTRODUCTION Poly(ethylene terephthalate) (PET) is one of the widely used polymers for packaging, films, and containers. The choice of PET is due to its high impact resistance, clarity, and barrier properties. PET is subjected to thermal...

The rotational molding of a thermotropic liquid crystalline polymer.
March 1, 2005... INTRODUCTION Thermotropic liquid crystalline polymers (TLCPs) exhibit a number of mechanical and physical properties that make them desirable for use in storage vessels for cryogenic or corrosive fluids. TLCPs have demonstrated...

EWF method to study long term fracture properties of cross-linked polyethylene.
March 1, 2005... INTRODUCTION It has been well known for a long time that polyethylene pipes under pressure exhibit a ductile failure at short-term and a brittle failure at long-term. The time [t.sub.B] corresponding to the transition from the ductile to...

Structure optimization of polycaprolactone foams by using mixtures of C[O.sub.2] and [N.sub.2] as blowing agents.
March 1, 2005... INTRODUCTION Polymeric foams represent an important class of materials with important technological applications. Due to their peculiar properties, these materials find wide use when good mechanical properties and low weight need to be...

Errata.(Correction Notice)
March 1, 2005... Erratum to "Polymer Crystallization Kinetics, Master Quotients, Master Curves and Nakamura-Ozawa-Equations of iPP and PTFE," by Markus Lambrigger, published in POLYM. ENG. SCI. 44:2194-2 202, 2004. DOI: 10.1002/pen.20247 The author would...