{"title":"Stress-Optical Relationship for Particle Dispersion Systems","authors":"Y. Kawai, Eiko Tamura, T. Shikata, Tadashi Inoue","doi":"10.1678/RHEOLOGY.40.79","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.40.79","url":null,"abstract":"Simultaneous measurements of complex modulus and complex strain-optical (birefringence) coefficient were performed for silica particle suspensions in order to clarify the stress-optical relationship. The dynamic modulus was found to be described with three Maxwell models. The strain-optical coefficient changed its sign form positive to negative with increasing frequency, suggesting the coefficient was composed of two relaxation modes. The relationship between stress and birefringence were found to be described with the modified stress-optical rule, composed of two relaxation modes. The fast mode having negative birefringence was assigned to the anisotropic distribution of particles due to deformation. The slow mode having positive birefringence was tentatively assigned to the aggregation of particles. Although the examined particle dispersion system was not ideal it was strongly suggested that the stress-optical rule would hold valid for the ideal hard particle dispersion systems.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"1 1","pages":"79-83"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83141674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Fukao, Takehide Terasawa, Yuto Oda, Kenji Nakamura, Daisuke Tahara
{"title":"Glass Transition and Aging Dynamics in Single and Stacked Thin Polymer Films","authors":"K. Fukao, Takehide Terasawa, Yuto Oda, Kenji Nakamura, Daisuke Tahara","doi":"10.1678/RHEOLOGY.40.121","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.40.121","url":null,"abstract":"stacked thin films of polystyrene (PS) and poly(2-chlorostyrene) (P2CS) were investigated using differential scanning calorimetry and dielectric relaxation spectroscopy. The glass transition temperature T g of as-stacked thin films of PS has a strong depression from that of the bulk samples. However, after annealing at high temperatures above T g , the stacked thin films exhibit glass transition at a temperature almost equal to the T g of the bulk system. The dynamics of the α-process of stacked P2CS thin films show a time evolution from single thin film-like dynamics to bulk-like dynamics during the isothermal annealing process. The relaxation rate of the α-process becomes smaller with increase in the annealing time. The time scale for the evolution of the α-dynamics during the annealing process is very long compared with that for the reptation dynamics. At the same time, the temperature dependence of the relaxation time for the α-process changes from Arrhenius-like to Vogel-Fulcher-Tammann dependence with increase of the annealing time. The aging dynamics of P2CS thin films with thickness less than 10 nm were also investigated using dielectric relaxation spectroscopy. The imaginary part of the dielectric susceptibility ε \" for P2CS thin films with a thickness of 3.7 nm increased with an increase in isothermal aging time, while this was not the case for P2CS thin films thicker than 9.0 nm. This anomalous increase in ε \" for the ultrathin films is strongly correlated with the presence of a mobile liquid-like layer within the thin films.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"76 1","pages":"121-128"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87423127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Behavior of Vapor-Deposited Molecular Glass and Supercooled Liquid Obtained through Glass Transition from the Glass","authors":"K. Ishii, H. Nakayama","doi":"10.1678/RHEOLOGY.40.129","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.40.129","url":null,"abstract":"In this paper, we briefly overview first the preceding studies on molecular glasses prepared by vapor deposition on a cold substrate, and then explain our recent studies on such molecular glasses and the supercooled liquids (SCLs) obtained from these glasses through glass transition. Glasses of some of alkylbenzene derivatives prepared at the deposition temperatures ( T d s) much lower than the glass transition temperature ( T g ) show a large excess volume, and undergo a relaxation accompanied with a volume shrinkage in a narrow temperature region just below T g when the temperature was raised with a constant rate. These samples also undergo a relaxation in the SCL states from a low-density unstable SCL to another SCL. On the other hand, glasses of the same alkylbenzene derivatives prepared by the deposition at T d s close to T g show a molar volume smaller than that expected for the equilibrium SCLs of these compounds, and undergo a relaxation accompanied with a volume expansion in a narrow temperature region just below T g . Some of these samples undergo a relaxation in the SCL states showing a gradual expansion in the volume. We discuss such differences in the behavior of vapor-deposited molecular glasses and SCLs in relation to non-equilibrium and local molecular conformations in the samples.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"55 1","pages":"129-136"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85014977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Anazawa, T. Tsuda, Hiroshi Yoshiba, T. Narumi, N. Fujisawa, T. Yamagata, T. Hasegawa
{"title":"Pressure Drop in Entrance Flows from Cavity to Slot of Viscoelastic Fluids inside Slot Die","authors":"T. Anazawa, T. Tsuda, Hiroshi Yoshiba, T. Narumi, N. Fujisawa, T. Yamagata, T. Hasegawa","doi":"10.1678/RHEOLOGY.40.91","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.40.91","url":null,"abstract":"In this work, entrance flows of viscoelastic fluids from a cavity to a slot in a slot die coating were investigated experimentally and numerically. Aqueous solutions of polyethylene glycol (PEG) and polyethylene oxide (PEO) mixtures, having viscoelasticity and Newtonian viscosity, were tested in order to clarify the effects of viscoelastic characteristics to the excess pressure drops at the entrance. The measured excess pressure drop changes corresponded to the flow pattern changes from a Newtonian-like flow pattern to vortex generation and growth patterns in an asymmetric entrance flow with a submillimeter slot. Numerical predictions of the transitions in the flow patterns and the pressure drops were also made utilizing exponential Phan-Thien-Tanner (EPTT) model with a finite element method. The predictions qualitatively indicated the increase in excess pressure drop and the vortex generation and growth.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"600 1","pages":"91-99"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74724130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}