摘要:

A new finding is reported that the long range ordered structure is formed in the induction period before the crystallization, when poly(ethylene terephthalate) (PET) is annealed just above the glass transition temperature. This ordering process can be interpreted in terms of the spinodal decomposition type phase separation phenomenon.

ISSN:0094-243X    

DOI:10.1063/1.42457

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We demonstrate that there exists a large anomaly in both real and imaginary parts of complex shear modulus near the phase‐separation line of a semidilute polymer mixture, reflecting entanglement effect. The temporal change in complex shear modulus during phase separation has also been successfully observed by a real‐time measurement. The behavior will be discussed on the basis of the structure‐property relationship.

ISSN:0094-243X    

DOI:10.1063/1.42458

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Ordering process of lamellar microdomains of poly(styrene‐block‐butadiene‐block‐styrene) (SBS) triblock copolymers in melts has been studied using small‐angle X‐ray scattering (SAXS). The SAXS profiles were analyzed by means of the theoretical calculation based on the one‐dimensional paracrystal model so as to characterize quantitatively how the lamellae which were formed through coalescence of cylindrical microdomains ordered. As a result of the analysis, it was found that the distribution of the interlamellar distance and the thickness distributions of polystyre (PS) and polybutadiene (PB) lamellae decreased, whereas the interlamellar distance and the interfacial thickness did not definitely change with time.

ISSN:0094-243X    

DOI:10.1063/1.42354

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Crystallization process and the phase structure formed in PEO/PPMA blends were measured by differential scanning calorimetry (DSC) and small angle X‐ray scattering (SAXS). The half time of the crystallization t1/2increased by blending PMMA and with PMMA molecular weight increased. 2 &thgr; at which the scattered intensity showed the maximum became small by blending PMMA and decreased with PMMA molecular weight increased.

ISSN:0094-243X    

DOI:10.1063/1.42355

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We demonstrate that under deep levels of quench condition a double‐well‐shaped phase diagram leads to unusual pattern formations in a polymer/water mixture. In a low polymer concentration, we find an anomalous phase composed of moving droplets without coarsening. It may be the first example ofa phase stabilized dynamically and not thermodynamically.

ISSN:0094-243X    

DOI:10.1063/1.42356

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We have found a long‐range, soft collision among droplets accompanying a large deformation of droplet shape in the late‐stage phase separation of a polymer mixture sandwiched by two glass plates. There are two possibilities which are responsible for the phenomenon: (1) a preferential wetting of the minority phase to glass and the resulting attractive interaction or (2) diffusion interaction through a weak diffusion field around a droplet.

ISSN:0094-243X    

DOI:10.1063/1.42357

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

When heterogeneous polymers such as diblock copolymers form a microdomain phase, an imposed strain gives rise to stress from two sources, and several mechanisms of stress relaxation. The release of stress by disentanglement is strongly influenced by the effective confinement of the junction points to the domain boundaries and by the stretching of the chains. Using accepted notions of entangled chain kinetics, it is argued that the relaxation time for sliding stress is exponential in the chainlength to the 7/9 power. A method for calculating the frequency‐dependent dynamic modulus is sketched. Despite the slow relaxation implied by these mechanisms, it appears possible to create domains of high energy.

ISSN:0094-243X    

DOI:10.1063/1.42358

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We use the generalized hydrodynamic method in order to describe the macroscopic dynamics of polymeric side‐chain liquid crystals. The hydrodynamic method uses only general symmetry arguments and irreversible thermodynamics to establish phenomenological dynamic equations. In the present case this method has to be generalized by taking into account not only the true hydrodynamic variables, but also some slow relaxational variables, which are slow enough to be relevant for the usual hydrodynamic frequency range.

ISSN:0094-243X    

DOI:10.1063/1.42359

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A microscopic theory for viscosity and particle‐diffusion of the particle‐dispersions in polymers is presented. The theory is based on the scheme of ‘‘microscopic boundary layer,’’ which appropriately combines the statistical mechanical description of the microscopic response in particle‐polymers interface with the continuum mechanical description of the collective response in the polymer background beyond the interface. While the resulting theories in large particle limit correctly recover the continuum mechanical results for intrinsic viscosity and particle diffusivity, the theories for small particles show significant deviation from the continuum results and reasonable dependence on interface structure.

ISSN:0094-243X    

DOI:10.1063/1.42360

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A simple transient model is introduced to describe the dynamics of physically crosslinked networks in which junctions are sufficiently weak to break and recombine in thermal fluctuations. The time‐evolution equation under arbitrary macrodeformation is derived for the creation and annihilation of the junctions. On the basis of this equation, stress‐strain relation under shear and elongational deformation is detailed. On longer time scales than the junction breakage time, the total number of effective chains decreases as time—resulting in an intranetwork flow.

ISSN:0094-243X    

DOI:10.1063/1.42361

出版商:AIP    

年代:1992

数据来源: AIP