ISSN:0730-6679    

DOI:10.1002/adv.1986.060060401

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

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper begins with a brief description of the history of development of PVC plastisol. It, then, presents technical background on the nature of PVC plastisol, covering subjects of particle size distribution and nature of agglomerates, viscosity aging and deagglomeration, rheology of suspension, gelation and fusion, and thermodynamic interaction between polymer and plasticizer. The main part of the paper concerns rheological observation of the gelation and fusion process of PVC plastisol, as the title of the paper indicates. This is a summary of recent work by the authors plus their new work on the effect of plasticizer type. The first half is the investigation of gelation and fusion mechanisms with use of a model plastisol system. Viscoelastic measurements, thermal analyses on the behavior of glass transition, and the scanning electron microscopic examination of the particulate structure were used to support the investigation. The last half considers the effect of the material variables on the gelation and fusion behavior; molecular weight, extractable additives (emulsifiers), agglomerates and fine particles, size of primary particles and plasticizer type are covered. Among these material variables, the plasticizer type has by far the largest influence on the gelation behavior. The observed solvent power is not necessarily in agreement with the thermodynamic interaction parameters found in the literature. It is indicated that a further systematic investigation is necessary to elucidate the nature of the plasticizer–polymer interactio

ISSN:0730-6679    

DOI:10.1002/adv.1986.060060402

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe flow of molten polymers through extrusion dies sets specific problems, usually connected to homogeneous distributions of flow rate and temperature. To overcome these problems, the computation of the flow by numerical techniques may be very useful. In this paper, approximation methods are developed, in order to treat industrial die geometries, without too complex and time‐consuming computation programs. Different examples of results, for the main types of industrial dies, are presente

ISSN:0730-6679    

DOI:10.1002/adv.1986.060060403

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe flow of molten polymers in molds is described by the conservation of mass, momentum, and energy. Several simplifications have been proposed in the last 40 years. The early models were essentially unidirectional approximations. More recently, the Hele–Shaw flow approximation has been used together with the appropriate analytical or numerical methods. Current developments include commercially available computer software based on network models for flow simulation in complex molds and modern sophisticated finite element solution of the complete conservation equations that give insight to fountain flow and small scale phenomen

ISSN:0730-6679    

DOI:10.1002/adv.1986.060060404

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

年代:1986

数据来源: WILEY

摘要:

AbstractProgress in the analysis of the wire‐coating process is reviewed. In particular, the melt flow analysis inside high‐speed, pressure‐type, wire‐coating dies is presented. Early analytical efforts have been based on the lubrication approximation theory under isothermal conditions. Recent advances include full nonisothermal flow analysis using numerical finite element methods. Wire‐coating coextrusion is also reviewed. A need for more experimental data and inclusion of viscoelastic effects in the constitutive models used in the analysis are of primary importance for fu

ISSN:0730-6679    

DOI:10.1002/adv.1986.060060405

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

年代:1986

数据来源: WILEY

摘要:

AbstractExtrudate irregularities, or “melt fracture,” with narrow MWD LLDPE resins occur at low deformation rates, and represent a severe rate limiting factor in commercial blown film fabrication with narrow die gaps. Extensive capillary rheometer measurements for several polymers, and blown film fabrication studies for LLDPE, seem to support an earlier finding that slip in the die land region invariably accompanies the observed extrudate irregularities. Lack of strong chemical forces for adequate adhesion at the polymer/metal interface in the die land region appears to be primarily responsible for the initiation of slip. Improvements in adhesion, by proper choice of the materials of construction and/or adhesion promoters in the resin, virtually eliminate the rate limiting effects of melt fracture in commercial blown film processing, and provide substantial improvements in critical end‐use properties, with

ISSN:0730-6679    

DOI:10.1002/adv.1986.060060406

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

年代:1986

数据来源: WILEY

摘要:

AbstractAn augmented Lagrangian formulation is used to model the nonisothermal, bidimensional flow of a shear‐thinning fluid in a sudden planar contraction by the finite element method. An efficient solution strategy is proposed which enables computations at large Peclet number and for highly nonlinear rheological behavior at a reasonable cos

ISSN:0730-6679    

DOI:10.1002/adv.1986.060060407

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

年代:1986

数据来源: WILEY

ISSN:0730-6679    

DOI:10.1002/adv.1986.060060408

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

年代:1986

数据来源: WILEY

ISSN:0730-6679    

DOI:10.1002/adv.1986.060060409

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

年代:1986

数据来源: WILEY