摘要:

AbstractFilm embossing is a mechanical process in which a flat film is transformed into an embossed product. During the process, thermal and stress fields are applied to the polymer, causing changes in the microstructure and physical dimensions of the material. The engineering analysis of the process requires the study of various aspects relating to the characterization of the microstructure before and after embossing. A variety of experimental techniques were employed to characterize the properties and microstructure of embossed films in relation to: crystallinity, orientation, mechanical properties, and dimensions of the embossed films. Mathematical models were also developed to predict the temperature, stress, and deformation in the plastic films during embossing. The thermal treatment of the plastic film was shown to be the most significant factor in the process. The important aspects influencing the thermal treatment include the radiation heater temperature, preheat roll temperature, line velocity, and film thickness. In general, the heat transfer mathematical model predictions were in agreement with the experimental data. The stress and deformation analysis suggested that the embossing pressure and the rubber layer on the backup roll are significant factors in determining the dimensions and stress distribution in the nip region. © 1992 John Wiley&Sons, Inc

ISSN:0730-6679    

DOI:10.1002/adv.1992.060110301

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

年代:1992

数据来源: WILEY

摘要:

AbstractA computer simulation program has been developed for the rotational molding of plastics. The predictions obtained from this program in terms of heating/cooling rates and overall cycle times have been compared with experimental molding trials with a range of plastics. It is shown that the computer model predicts accurately the real situation for a wide range of processing conditions. In particular, the program allows the effects of oven efficiency, mold material, mold wall thickness, and molded part thickness to be assessed quantitiatively. The article presents information on heat transfer coefficients that are applicable during rotational molding and typical cycle times for a wide range of process conditions. © 1992 John Wiley&Sons, Inc

ISSN:0730-6679    

DOI:10.1002/adv.1992.060110302

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

年代:1992

数据来源: WILEY

摘要:

AbstractAn approach to modify a thermoplastic polymer's cost–property profile is through polymer blends and glass reinforcement. An experimental design for a thermoplastic polymer formulation was done using RS/Discover® and EChip®. Here, two crystalline thermoplastic polymers have been compounded with fiber glass to reduce cost and maintain useful melt processing properties and physical properties. Using RS/Explore and EChip software, the results were analyzed by regression analysis and the results summarized in contour plots. The ease of use and resultant format of the data analysis from these software packages are compared. A total of 10 responses were measured and analyzed in this experiment and multivariate data analysis was incorporated where appropriate. © 1992 John Wiley&Sons,

ISSN:0730-6679    

DOI:10.1002/adv.1992.060110303

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

年代:1992

数据来源: WILEY

摘要:

AbstractA generalized Eulerian‐Lagrangian approach is used to study the compression molding of viscoelastic polymers. The complete, unsteady, two‐dimensional equations of motion are used in the analysis. The White–Metzner model is used to describe the constitutive behavior of the material. The solution is obtained using a mixed Galerkin finite element method. An automatic remeshing scheme is introduced to reduce the mesh distortion during the solution procedure. Results for the pressure and force required in mold closing are presented for the isothermal filling of a rectangular cavity. © 1992 John Wiley&Son

ISSN:0730-6679    

DOI:10.1002/adv.1992.060110304

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

年代:1992

数据来源: WILEY

摘要:

AbstractThermoplastic epoxy resins have some special applications. In this study, the diglycidyl ether of bisphenol‐A and three different monoamines—butylamine, hexamine, and dodecylamine—at different epoxy–amine ratios were used to make epoxy resins. Relative viscosity, hardness, Vicat softing temperature, volume resistivity, and refractive index were investigated. As amine contents approach the equivalent value, these properties reach the maximum value except the refractive index, which decreases continously with increasing amine content. When the carbon number of amines increases, the properties decrease except volume resistivity. Refractive index values vary with composition, suggesting a possibility of producing epoxies with a desired refractive index for optical applications. © 1992 John Wiley&S

ISSN:0730-6679    

DOI:10.1002/adv.1992.060110305

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

年代:1992

数据来源: WILEY

摘要:

AbstractDuring a routine extrusion compounding of a polymer blend of polyarylate resin and ethylene/acrylate rubber, an unexpected powdery product instead of a cohesive mixture was obtained. Also, the 20% rubber component was not well dispersed in the final product. This process problem was studied by simulation with a laboratory internal mixer following the procedure discussed by Shih. The powder formation was successfully reproduced. From the results of continuous video monitoring and analyses of the intermediate samples collected during the simulation experiments, we found that the progression of mixing from solid pellets to a cohesive mixture in a batch mixer or a twin‐screw extruder needs to “climb over” a prolonged transition state where the plastic polyarylate was dispersed in the 20% rubber. The finding led to two successful solutions to the powdering problem. A “phase‐inversion” mechanism is proposed to explain the observed morphological changes. This mechanism appears to have wider applicability in the processing of polymer blends. © 1992 John Wil

ISSN:0730-6679    

DOI:10.1002/adv.1992.060110306

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

年代:1992

数据来源: WILEY