摘要:

AbstractCoextrusion flows of polymer solutions and melts to produce polymeric sheets are studied employing (a) the Lubrication Approximation Theory for a quick determination of interface development and pressure drops for each material; and (b) the Finite Element Method, which uses au‐v‐p‐T‐hformulation for the velocities, pressures, temperatures, and interface location and solves in the flow domain the full conservation and constitutive equations. The determination of the interface is part of the solution process. Simulations have been carried out for several cases of two‐layer coextrusion of polymer solutions (Oppanols, i.e., polyisobutylenes) and compared with experimental data available in the literature. A three‐layer coextrusion case is also studied with a barrier ethylene vinyl alcohol and an adhesive layer tying a polystyrene layer, and the results are compared with experimental data. For low flow rates, the interface location agrees closely with experiments. For high flow rates, a tendency for encapsulation occurs, which cannot be captured by the present purely viscous two‐dimensional simulations. © 1993 John W

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe advent of CAE (computer‐aided engineering) technology for injection molding and related processes is having a rapidly growing impact on the molding industry. Proper use of this technology has enhanced engineers' capability in handling all aspects of the molding process and has been proven to benefit both productivity and product quality. However, while CAE can serve as a powerful tool to help engineers make rational engineering decisions, it is by no means a panacea for solving all molding problems. The viability of CAE packages depends heavily not only on the scientific principles and numerical methods used for developing the software, but also on the reliability of the input data such as material properties and process conditions. This article discusses the state‐of‐the‐art of the technology with an emphasis on simulations of latest innovations in injection molding. A three‐layer approach that systematically integrates and efficiently utilizes various CAE tools to solve design problems at different levels of sophistication is also presented. © 1993 by John Wiley

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAn integrated finite element process simulator has been developed for modeling the injection, compression, and resin transfer molding processes for polymeric materials. The similarities among the three processes permit consolidation of the models into an integrated software package with low maintenance and ease of future extension. An introduction to the integration algorithm embedded in the process simulator is followed by models for injection, compression, and resin transfer molding. The validation of the injection molding portion of the integrated simulator is then addressed by comparing pressure history and filling patterns between the simulator predictions and experimental data. Tooling, processing, and quality issues—such as gating and venting design, weldline locations, and pressure and closing force requirements—are illustrated by two examples, a 3‐D fan blade and a ribbed box. © 1993 John Wiley&Son

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractPolypropylene (PP) powder was extruded in the presence of peroxide and multifunctional monomers at varying concentrations. With increasing peroxide concentration, MFI increased almost linearly, whereas hardness, modulus, and impact strength decreased, and the results were interpreted in terms of decreased molecular weight and its distribution by chain scission. On the other hand, triacrylate type multifunctional monomers (PETA and TMPTA) reduced the MFI of PP upon extrusion, and led to increase of Tm and Tc followed by increased modulus, yield strength, and elongation as well. TAIC and PBQ exerted effects smaller than triacrylate type. When the multifunctional monomers were added to the 0.01 phr peroxide containing system, MFI decreased below that of peroxide, and increased above that of multifunctional monomer of the same concentration, and synergistic physical properties were generally obtained, especially at low content of coagent. However, at higher peroxide concentration (0.05 and 0.1 phr) MFI increased with PETA and TMPTA, and decreased with PBQ. In general, increase and decrease of MFI were respectively followed by the decrease and increase of modules, strength, and impact strength as well. © 1993 John Wiley&Sons, Inc

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA theoretical investigation using the failure tensor polynomial criterion was carried out to study the effect of off‐diagonal failure tensor components on the limit behavior of symmetric fiber reinforced laminates under both mechanical and hygrothermal loading. In spite of obvious similarities in the mathematical expression of numerous failure criteria based on the tensor polynomial theory, their predictions may be substantially different depending on loading conditions and on the choice of stress‐interaction terms. Although these predictions for unidirectional fiber reinforced laminae under biaxial loading do not exhibit remarkable differences, this is not the case for multidirectional laminates. Comparison of theoretical predictions with experimental data from in‐plane loaded cross‐ply Graphite/Epoxy laminates proved the reliability of the so‐called generalized elliptic paraboloid failure surface criterion, assuming the existence of a safe triaxial loading path which may depend on the anisotropy of the medium and its suitability for use in structural design applications. © 1993 John Wiley

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe solid state processing technique is used for processing of a variety of polymers such as ultra high molecular weight polyethylene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyether etherketone, and polyphenylene sulfide. The solid state processing involves cold compaction of polymeric powders followed by sintering at temperatures above their melting point. The properties of such products are influenced by the powder characteristics and a number of process parameters encountered during the compaction and sintering processes such as compaction pressure, rate of compaction, sintering temperature, and time. The understanding of the physical processes involved in solid state processing of polymers is essential for defining the parameters to obtain the product with desired properties. In this review, the various aspects of solid state processing are discussed with reference to the physical processes. © 1993 John Wiley&Sons, Inc

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe “Incremental Draw Process” (“IDP”)“Incremental Draw Processing”* and “IDP”* are trademarks and designations for fiber orientation and elongation processes owned and patented by M. V. Sussman, Ph.D., P.E., and licensed through Arthur D. Little Enterprises, Acorn Park, Cambridge, MA 02140.is a newly commercialized technique that controls stress and temperature profiles during high speed drawing of synthetic polymer fibers. Fiber is drawn on a single pair of shaped rolls through a large number of small draw increments within a compact space. Draw zone length and residence time are increased substantially, allowing time for morphological change. Stress relaxation between draw increments and adjustment of temperature, tension, and rate of deformation (draw) at each draw increment more effectively control stress induced crystal growth and amorphous orientation. Ultra‐orientation, improved tensile modules high tenacity, low break elongation, and low boil‐off shrinkage have been produced. Because rates of plastic deformation during drawing are drastically reduced, high fiber throughput speeds are possible, allowing direct coupling to high speed spinning lines.Commercial applications include both textile and ultra‐high strength industrial fiber production. Limited drawing of liquid crystal fibers has been demonstrated. © 199

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis article is the second part of a survey of developments in the open literature during 1991 on subjects related to the injection molding of fiber‐reinforced thermoplastics. Topics discussed include injection molding machines, screw design, process control systems, modeling, product design, mold design and manufacture, characterization techniques, and applications of composites. Although these technological advances are broadly applicable to the processing, design, and manufacture of thermoplastics generally, they are essential to the enhanced engineering, fabrication, and utilization of fiber‐reinforced thermoplastics. © 1993 John Wiley&Sons,

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY