摘要:

An investigation was undertaken to study the influence of a bimodal size distribution of particulates on the shear viscosity, primary normal stress coefficient, dynamic viscosity, and storage modulus of filled polymeric systems. As expected, all four rheological properties of the composite systems with a bimodal size distribution of solids were reduced in comparison to the properties of the composite systems with a unimodal size distribution of particulates. In addition, the maximum packing fraction was increased when the modality of the solids mixtures was increased. The present research effort showed that a design equation given by Ouchiyama and Tanaka and used by Gupta and Seshadri allows thea prioriprediction of the maximum packing parameter as a function of particle size and size distribution. Consequently, it was possible to calculate an optimum reduction of rheological properties due to a bimodal size distribution of particulates that was in agreement with experimental results.

ISSN:0148-6055    

DOI:10.1122/1.549991

出版商:The Society of Rheology    

年代:1988

数据来源: AIP

摘要:

A flow visualization technique based on photochromic dyes has been used for the study of polymeric fluids in a number of flow configurations. The technique is based on the activation of the dye by ultraviolet light. This photoactivation results in the apparition of dark marker lines in the midst of the fluid. High‐speed movies can then be digitized and allow us to compute velocities anywhere inside the flow field. The results presented here address more particularly the case of the tubeless siphon. We have measured the velocity profile inside its fluid column for a number of flow conditions, and observed unexpectedly large velocity gradients. Indeed, the axial velocity at the centerline was found to be much greater than the velocity of the free surface at the same axial location. An interesting feature of this flow field is that the velocity profile appears to be a linear function of the radial location over most of the cross‐section of the column.

ISSN:0148-6055    

DOI:10.1122/1.549989

出版商:The Society of Rheology    

年代:1988

数据来源: AIP

摘要:

Material functions of two engineering plastics [a poly(phenylene ether) and a poly(ether imide)] were characterized, including the shear viscosity, first normal stress coefficient, storage and loss moduli, growth and relaxation of shear stress, and first normal stress coefficient and relaxation moduli. The oscillatory shear and relaxation moduli data were employed to determine the temperature‐dependent parameters of Wagner model. Various material functions, which were determined on the basis of this model in conjunction with the fitted parameters agreed reasonably well with the experimental results. The reported data and parameters should facilitate a better understanding of the processability characteristics of these two engineering plastics.

ISSN:0148-6055    

DOI:10.1122/1.549968

出版商:The Society of Rheology    

年代:1988

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549990

出版商:The Society of Rheology    

年代:1988

数据来源: AIP