Jun-ichi Takimoto

Crystallization kinetics of polypropylene under high pressure and steady shear flow

Abstract We investigate the simultaneous effect of pressure P and shear flow on the crystallization process of polypropylene using a modified pressure–volume–temperature measurement system that has been developed in our laboratory. We focus on the inverse of half-conversion time 1/ t 1/2 that is defined by the inverse of the time when the relative crystallinity of system reaches to one half. It is found that the pressure dependence of the quantity 1/ t 1/2 can be expressed by a shifted degree of super-cooling Δ T ( P ) by pressure. We also find that 1/t 1/2 (T,P, γ ) under both pressure and shear flow can be described by a sum of 1/t 1/2 (T,P, γ =0) under no shear and a linearly increasing term with shear rate γ .

Stochastic Aspects of Bridging Bonds of Induced Structure of Electro-Rheological Fluids in Shear Flow

The bridging of electrodes by clusters of polarizable elements occurs to be a dominant feature of the response of certain electrorheological fluid suspensions and liquid polymeric blends to the imposed electric field. The evolution of the bridging structure in deformation and flow is described as a stochastic process and identified with the macroscopic flow behavior. The effect of structure is introduced into the rheological equation providing its non-linear modification. The comparisons are presented showing how the proposed rheological equation describes rheological characteristics measured at steady shearing flow and start-up shearing flow.

THE CONTRIBUTION OF COLUMNAR STRUCTURE TO THE STRESS IN ER POLYMERIC BLENDS IN A SHEAR FLOW

The bridging of electrodes by the columns of highly viscous polymer is dominant feature of the response of most electro-rheological liquid polymeric blends to the imposed electric field. To link the columnar structure and its deformation to the macroscopic shear stress, the transitory process of structure reorganization is described as a stochastic process determining rheological properties of the blend. The shear stress predictions are compared to the experimental data for steady and start up shear flows. The data support the assumption that only viscous deformation prevails in shear flow.

Primitive Chain Network Model for Entangled Polymer Blends

The primitive‐chain network model for Brownian simulation of entangled polymers is extended so as to include the case of polymer blends. Predictions for the phase diagram and for the linear viscoelastic response appear consistent with earlier works.

Generalization of the Ohta‐Kawasaki Theory for Microphase Separation of Block Copolymer Melts

The Ohta‐Kawasaki theory for the microphase separation of the diblock copolymer melts has been generalized to study arbitrary block copolymer melts and blends. The results of the simulation with the generalized theory were compared with those of the self consistent field (SCF) theory and it has been shown that they give qualitatively the same result.