摘要:

AbstractWe describe the computer‐aided engineering analysis of a linearly tapered coat‐hanger die in this paper. The general governing equation for flow distribution inside the die was derived first. On the basis of this equation, we have developed the design formula for a die to deliver uniform flow. In addition, we have also examined the variations of lateral flow uniformities and residence time distributions of polymeric liquids under several different design and operating conditions: (1) using manifolds with non‐circular cross‐sections, (2) adjusting production widths, (3) delivering fluids with different viscosities, and (4) enlarging manifolds for practical production conside

ISSN:0032-3888    

DOI:10.1002/pen.760282302

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe mechanics of the blown film process are studied for Newtonian and viscoelastic models of the polymer melt. Multiple solutions of the governing equations are possible even for the Newtonian fluid, with the existence of more than one steady‐state bubble profile for a given set of operating parameters; steady axisymmetric solutions vanish suddenly at critical combinations of operating variables. Several types of instabilities exist, including one that is analogous to “draw resonance.” The stability of the bubble to infinitesimal disturbances depends on the set of operating parameters that is controlled; control of the bubble inflation pressure is much less stable than control of the amount of inflating air, for example. Heat transfer is stabil

ISSN:0032-3888    

DOI:10.1002/pen.760282303

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effects of the higher alpha‐olefin comonomers on the rheology and processing behavior of linear low density polyethylenes were investigated. Four linear low density polyethylene resins polymerized with butene, hexene and octene comonomers and a low density polyethylene were characterized in terms of their shear viscosity, first normal stress difference, storage and loss moduli, shear stress growth, stress relaxation upon step strain, stress relaxation upon the cessation of steady shear, and uniaxial extensional stress growth material functions. Differences in first normal stress difference, relaxation moduli, damping function parameters, and uniaxial extensional stress growth behavior were noted. The observations were elucidated in terms of the processability considerations in blown film extrusion proces

ISSN:0032-3888    

DOI:10.1002/pen.760282304

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractBlown film samples of linear low density polyethylene resins copolymerized with butene, hexene, and octene were characterized in terms of various mechanical and optical properties which included tensile, impact, tear, puncture, haze, and gloss. The microstructure development aspects were also investigated employing crystallinity and density, infrared dichroic ratio, and birefringence, and focusing on various positions along the circumference of the bubble. The ultimate properties, and the microstructure of the blown film samples, were found to depend strongly on the extent of short chain branching and on the comonomer employed.

ISSN:0032-3888    

DOI:10.1002/pen.760282305

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe pressure drop/flow rate equation for non‐Newtonian fluid flow in channels of irregular cross‐section is determined theoretically by two numerical methods. Two representative non‐Newtonian fluid models, the Ellis and the Herschel‐Bulkley models, have been studied for several commonly encountered non‐circular channels. The empirical methods proposed by Kozicki,et al, and Miller have been analyzed. The validity of their methods is

ISSN:0032-3888    

DOI:10.1002/pen.760282306

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractA new procedure has been developed to measure the temperature distribution of the polymer melts along the screw axis during injection by using a small sheath thermocouple. At the same time, the effects of molding conditions on temperature distribution has been studied. The temperature distribution of the polymer melt along the screw axis during injection can be obtained from the difference between the standard temperature profile and the temperature profile of the polymer melt with unknown and non‐uniform temperature measured under the same rate of injection. The temperature of a polymer melt within a shot is not uniform. The difference between the maximum and the minimum temperature within a shot may exceed 10°C in some cases. There are two major factors which govern the effects of molding conditions on the temperature distribution of the polymer melts during injection. The first is the amount of shear heating in the metering zone. The second is the amount of heat absorbed into the polymer in the compression and feed zon

ISSN:0032-3888    

DOI:10.1002/pen.760282307

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effect of titanate, zirconate, and zircoaluminate coupling agents on the viscosity of zirconia‐polypropylene injection molding blends was investigated. The zircoaluminate did not influence viscosity while the two former additives effected a considerable reduction. The titanate coupling agent also reduced the viscosity of the polymer in the absence of ceramic powder, and was more efficient in this respect, as a flow modifier than dioctyl phthalate. A comparable effect on the ceramic suspension was obtained by adding a species similar in molecular structure to the titanate coupling agent but without coupling abilit

ISSN:0032-3888    

DOI:10.1002/pen.760282308

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760282301

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY