Noboru Tokita

An Additive Functional Theory of Viscoelastic Deformation with Application to Amorphous Polymers, Solutions and Vulcanizates

An additive hereditary functional theory of viscoelastic deformation has been developed by simplifying the general Green-Rivlin theory by means of interpreting a series of rational experiments on bulk elastomers. Application to simple shear flow is discussed in detail.

Laboratory Simulation of a Factory Extrusion Process by the Die Swell Tester

Abstract The simulation principle (scaling) of the tire tubing process was studied by the “Die Swell Tester”. It was found that once the following three conditions were established, the die swells (ratio of extrudate to die cross section) of factory tubed extrudate were identical to lab scale DS results: namely, (1) same operation temperature, (2) same residence time in die, and (3) same ratio of die length to die diameter (L/D). In order to obtain the same L/D values between the complicated die shape of a factory tuber and the circular die of the DST, it is shown that the hydraulic radii (area/perimeters) must be kept the same. The correlation coefficient between factory extrudate properties and DST values was 99.6%. On the contrary, the Mooney torque ML1 + 4 values did not correlate with the die swell properties of the factory extrudates. Cold shrinkage of cut lengths of factory extrudates was simulated by the use of an extension control attachment to the DST. The theoretical analysis of potential recov...

Analysis of Band Formation in Mill Operation

Abstract A theoretical method has been developed to provide a rational means for preventing improper fast roll banding in drop mill operation. For a given material at a certain mill temperature, the material tends to go to the back roll with a very narrow nip distance. The material will go to the front roll at a certain nip distance as the nip is widened and will return to the back roll as the nip is again narrowed. This nip position is called the Front-Back Transition Point. A dimensionless number, the “Band Formation Index”, N0, is constant at the front-back transition point regardless of the type of mill and is a function of the friction ratio, nip distance at the transition point, and radius of the mill rolls. Applications of the N0 concept to a factory mill operation have been discussed, and practical means to avoid back roll banding and bagging have been described.