Effects of the preexisting crystal lamellar structure on the crystallization behavior of the other component were investigated for the blend of poly(oxymethylene)/poly(L-lactide) (POM/PLLA), using DSC, polarizing optical microscopy, SAXS, and dielectric relaxation measurements. In this system, even at a low POM fraction of 10 wt%, POM crystallized first and formed the crystal lamellar structure due to its significantly faster crystallization rate. PLLA, which crystallizes later, was found to crystallize from the unique confined space between the POM crystal lamellae. Despite the restricted space between the POM crystal lamellae, the crystallization rate of PLLA was improved compared to that of bulk PLLA. Analysis of the nucleation rate and spherulite growth rate showed that while the spherulite growth rate was slightly reduced by the presence of the POM crystal lamellae, the nucleation rate was significantly improved, which resulted in the increase of the overall crystallization rate. Furthermore, the dielectric relaxation measurements suggested that the formation of the POM crystal lamellae suppressed the mobility of the amorphous PLLA molecular chains, which is thought to contribute to the increase in the nucleation rate.

In the multi-chain slip-spring, the dynamics of Rouse chains connected by virtual springs called slip-springs that hop along the chain are considered. Although this approach has been proven to reproduce entangled polymer dynamics efficiently, the settings of the artificially introduced slip-springs should be carefully examined. In this study, we discussed the effect of the slip-spring degeneracy by limiting the number of anchored slip-springs on each Rouse bead to zero and one. According to the altered slip-spring statistics, we derived the compensation potential to eliminate the artifact of slip-springs on the chain statistics. With this potential, we performed numerical simulations. The results demonstrated that although we reasonably retain the Gaussian chain statistics, the dynamics deviate from the established entangled polymer dynamics because of the significant slow-down in the chain motion induced by the correlation between different slip-springs. The observed deceleration can be explained by the fact that the movement of slip-springs can be cast into an asymmetric exclusion process.

In aged society, the number of persons with difficulty in mastication and swallowing is increasing, and the aspiration-induced pneumonia is one of the top causes of death in the elderly. Although the detailed mechanism of aspiration is still not well understood, great efforts have been done to prevent the aspiration, and thickening of bolus has been found effective to reduce the risk of aspiration. It was pointed out earlier that excessive thickening reduces the palatability and the intake of fluids leading to dehydration and malnutrition and to formation of the residue as a risk of aspiration. In the present review, the physiological aspects of food oral processing conducted in the mouth by teeth, tongue, saliva have been introduced, and practical evaluation methods of rheological properties used in hospitals and nursing care facilities are described. Viscosity of commonly used polysaccharide-based thickening agents is described in relation with yield stress, thixotropy together with tribological aspects which play important roles in swallowing. To improve the control of texture, new thickening agents and modifying methods of rheological properties are described. Emerging methods to study the swallowing process have been also discussed. Finally, the importance of integration and collaboration of different disciplines is emphasized.

This report briefly describes the articles published in the 50th volume of the Nihon Reoroji Gakkaishi (the Journal of the Society of Rheology, Japan) in 2022. The statistics are that the total number of articles is 54, and the ratio of papers in English is 0.55. The highlight is the invited review articles to the special issue commemorating the 50th volume, which showcase the recent progress and perspective of a wide range of topics by 18 up-and-coming rheologists. The other special issue was dedicated to industrial rheology, in which 6 papers were published mainly for the industrial applications of polymers.