Polymer Engineering and Science articles from October 2004

Polymer Engineering and Science archives from October 2004

Die lines in plastics extrusion: film blowing experiments and numerical simulation.
October 1, 2004... INTRODUCTION Extrusion is the most important unit operation in the plastics processing industry. It is a convenient way to continuously manufacture lengths of complex cross section to strict dimensional tolerances, mechanical properties...

A method to predict triaxial residual stresses in plastic pipes.
October 1, 2004... INTRODUCTION Thermoplastic products are generally formed from molten polymer and often cooled in a nonuniform way. It is well known that the processing of plastic parts can lead to residual stresses in the final product. Extruded MDPE...

Starch-filled ternary polymer composites. II: room temperature tensile properties.
October 1, 2004... INTRODUCTION Rigid fillers, such as granular starch, are added to polymers to improve certain physical properties, such as dimensional stability and stiffiness (1). They often also have the added benefit of reducing cost. However, some...

Processing of ultra-high molecular weight polyethylene by hot isostatic pressing, and the effect of processing parameters on its microstructure.
October 1, 2004... INTRODUCTION Ultra-high molecular weight polyethylene (UHMWPE) is usually processed in the form of rods, sheets or final products by the application of heat and pressure directly to the polymerized powder (virgin resin). Common processing...

Thermal properties and crystallization behavior of polyolefin ternary blends.
October 1, 2004... INTRODUCTION Isotactic polypropylene (PP) has been used for various applications because of its low cost and ease of processing. However, because of its poor impact strength especially at low temperature, PP has been blended with various...

Flow and heat transfer simulation of injection molding with microstructures.
October 1, 2004... INTRODUCTION In recent years, a number of polymer-based micro-components have been fabricated by combining various lithography techniques and injection molding methods for optical and biomedical applications (1). There are two types of...

A study on the characteristics of antiplasticized polycarbonates and their optical disk substrates.
October 1, 2004... INTRODUCTION Recently, storage media with large capacities for digital information have become necessary, with the development of satellite digital broadcasting or broadband communication of the Internet. Particularly, optical disks such...

Effect of the core-shell impact modifier shell thickness on toughening PVC.
October 1, 2004... INTRODUCTION Impact modifiers are generally compounded into rigid polyvinyl chloride (PVC) to improve toughness while retaining other critical performance properties necessary to achieve demanding application requirements (1-7). The modes...

Bubble nucleation and growth in polymer solutions.
October 1, 2004... INTRODUCTION Bubble nucleation and growth in polymer-gas solutions (1, 2) and in polymer solutions with a volatile component (3) are very important in the production of foamed materials (4) and microcellular plastics (5, 6). Microcellular...

Dynamics of foam growth: bubble growth in a limited amount of liquid.
October 1, 2004... INTRODUCTION The problem of bubble growth is of great importance in the polymer processing industry. It can be found in polymer melt devolatilization and also in the production of polymeric foam materials. In the first process, low...

Melt rheological behavior of starch-based matrix composites reinforced with short sisal fibers.
October 1, 2004... INTRODUCTION In recent years, natural fiber-reinforced thermoplastic composites have found wide use in structural and nonstructural applications exploiting several advantages over more traditional glass fibers (1-7): biodegradability,...

Measurement and prediction of diffusion coefficients of supercritical C[O.sub.2] in molten polymers.
October 1, 2004... INTRODUCTION Supercritical C[O.sub.2] has been used in a variety of industries, such as the food, pharmaceutical, chemical, and plastics industries. Much of the initial research on supercritical C[O.sub.2] (sc-C[O.sub.2]) focused primarily...

A temperature-dependent adaptive controller. Part I: controller methodology and open-loop testing.
October 1, 2004... INTRODUCTION Plastics are becoming increasingly popular for a wide range of engineering applications. Advancements in material science technology have made it possible to develop new classifications of plastics based on weight, thermal...

A temperature-dependent adaptive controller. Part II: design and implementation.
October 1, 2004... INTRODUCTION Design of controllers can be challenging since they must not only provide robust control within a defined operating range, but also must also satisfy criteria involving the controller performance and the close-loop dynamics....

Rheology and processing of BaS[O.sub.4]-filled medical-grade thermoplastic polyurethane.
October 1, 2004... INTRODUCTION Barium sulfate (BaS[O.sub.4])-filled thermoplastic polyurethane is widely used in the medical device industry. Barium sulfate is radiopaque and is usually given to patients in a "barium meal" as a means of imaging the...

Runner balancing by a direct genetic optimization of shrinkage.
October 1, 2004... BACKGROUND Runner Balancing The injection molding process is capable of producing a large number of thermoplastic parts from a multiple-cavity mold in a single cycle. The runner system, which conveys the plastic from the injection...

A parallel coextrusion technique for simultaneous measurements of radial die swell and velocity profiles of a polymer melt in a capillary rheometer.
October 1, 2004... INTRODUCTION The properties of a polymer melt are a combination of the properties of an elastic solid and a viscous fluid. During processing the viscous nature is the dominant characteristic. However, the elastic character is still...

The effects of polymer additives on the operating windows of slot coating.
October 1, 2004... INTRODUCTION Coating flow appears to be of both fundamental and practical interests. One of the most important early theoretical works on coating flow was the analysis on dip coating by Landau and Levitch (1). Pitts and Greiller (2) first...

Viscoelastic changes and cell opening of reacting polyurethane foams from soy oil.
October 1, 2004... INTRODUCTION Depleting oil resources and dependence on other nations for oil has led to concerns over the price of raw materials used to manufacture polyurethanes. Modified soy-based vegetable oil polyols have been successfully...

Influence of molecular weight on strain-gradient yielding in polystyrene.
October 1, 2004... INTRODUCTION Mechanical properties of polymers are usually measured by applying load to large specimens, whose size often is chosen according to some standard. In many application areas, typical dimensions are much smaller than those of...

Cold forging method for polymer microfabrication.
October 1, 2004... INTRODUCTION Polymeric materials have considerable advantages in microfabrication because of their versatile properties and mass production capability. There has been much work worldwide during the past decade on adaptation of conventional...

Kinetics and modeling of the diffusion-controlled diallyl terephthalate polymerization.
October 1, 2004... INTRODUCTION Diallyl terephthalate (DAT), an isomer of diallyl phthalate (DAP) monomer, is considered a promising engineering plastic material. The monomer has low toxicity and high reactivity for homopolymerization and copolymerization...