摘要:

Controlled‐ingredient‐distribution mixing technology has been exploited in a study of the covulcanization of an SBR‐NBR blend. The technique of differential solvent (or oil) swelling is applied to indicate the existence or absence of interfacial bonds between the SBR and NBR rubber phases. The analysis of swelling based on the fact that (1) NBR is hardly swollen in ASTM #2 oil, while SBR is highly swollen; and (2) the swelling restriction of the SBR‐rich compounds due to the presence of NBR is analogous to the swelling restriction of elastomer networks containing reinforcing fillers. The results on oil swelling, tensile properties, tear strength, and also flex crack growth resistance all indicate that interfacial bonds between the NBR and SBR phases can be achieved by appropriately controlling the distribution of black and other ingredients in the individual rubber phases.

ISSN:0148-6055    

DOI:10.1122/1.549753

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

摘要:

In this article we present tables of values of the climbing constantβ̂=3α1+2α2,whereα1andα2are the parameters of the second‐order approximation to the stress in a slow, slowly varying flow of any simple non‐Newtonian fluid. The parameterβ̂arises in the analysis of rod climbing, and it is proportional to the height of climb in slow steady flow. A method is presented for computing the first normal stress difference and the extensional viscosity at low rates of deformation, usingβ̂alone. This method is useful for all fluids whose unknown second normal stress is nonpositive at low rates of shearing.

ISSN:0148-6055    

DOI:10.1122/1.549754

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

摘要:

An impulse approach to linear viscoelastic behavior is developed that enables one to separate elastic from viscous response. The method relates the total stress impulse to the final state of deformation for viscoelastic fluids and to the total strain impulse for viscoelastic solids. Interestingly for solids, the relationships only involve elastic contributions and for fluids only viscosity terms enter the relationships. It appears that this method will be very useful in material characterization and can be used to follow the development of equilibrium elastic properties in thermosetting systems.

ISSN:0148-6055    

DOI:10.1122/1.549755

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

摘要:

A parallel plate rheometer has been developed for the study of nonlinear viscoelastic phenomena in molten plastics. By making use of a novel shear stress transducer, the effects of instrument friction and edge phenomena on the stress determination are eliminated. This makes possible the study of the response of a melt to large, transient deformations involving large shear rates. The new rheometer was evaluated by studying the response of a polyisobutylene to interrupted shear at 22°C.

ISSN:0148-6055    

DOI:10.1122/1.549756

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

摘要:

The rheology of xanthan solutions is strongly influenced by molecular association and aggregation. The relationship between rheological behavior and molecular association has been studied using dynamic oscillatory measurements, step‐shear‐rate measurements, and optical birefringence. For solutions with concentrations of 0.5% wt or below, weak association—possibly through hydrogen bonding—leads to nonlinear behavior in dynamic oscillatory measurements at high strain. For concentrations of 1% and above, liquid crystalline domains are formed and the time required to approach a steady viscosity value at low shear rates is quite long.

ISSN:0148-6055    

DOI:10.1122/1.549757

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

摘要:

A single 200‐μm particle is injected into a 0.25% w/w solution of a commercial polyisobutylene(Mv=1.5×106)in a polybutene solvent, held between a plate and a 21‐cm disc. When rotation of the disc at 5.7 rpm is begun with a disc‐plate separation of 5.4 mm, the particle initially located at a distancer5.1 cmmigrates away from the axis with about the same speed. This sharp reversal in the direction of migration with such a small change in the initial location is not expected on the basis of any current theory. Increasing the rate of rotation or decreasing the disc‐plate separation increases this criticalrfor reversal, while doubling the particle radius had no significant effect.

ISSN:0148-6055    

DOI:10.1122/1.549773

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

摘要:

Dynamic mechanical properties of systems of a styrene‐butadiene‐styrene triblock copolymer (cSBS) inn‐tetradecane (C14) were examined as a function of concentration and temperature. Since the solvent C14 dissolves B blocks but precipitates S blocks, gels with quasinetwork structure composed of rigid S domains connected with B blocks are formed at room temperature. Such a gel exhibits rubberlike linear viscoelasticity under small‐amplitude oscillation. When the temperature is raised, the rubbery gel changes to a plastic fluid with viscoelasticity, and further to a viscoelastic liquid. Each of these transitions takes place within a relatively narrow temperature range. The critical temperature for the rubbery‐to‐plastic transition depends only slightly on the cSBS concentration, while that for the plastic‐to‐viscous transition depends strongly on the concentration. These results are interpreted in terms of the temperature and concentration dependences of the stability of the microdomain structure existing in the system.

ISSN:0148-6055    

DOI:10.1122/1.549774

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

摘要:

Unsteady flow of polymer liquids following sudden imposition of pressure gradient or bulk velocity in a slit has been considered. Theoretical results, obtained by numerical methods, are based upon the Leonov constitutive equation. For a constant bulk velocity, predictions indicate an overshoot in the pressure before attainment of a steady‐state value. Depending on the bulk velocity, this overshoot may noticeably exceed the steady‐state value. The presence of a pressure overshoot has been observed in extrusion experiments. Theoretical and experimental results for a constant pressure gradient show a successive maximum and minimum in bulk velocity before reaching a steady‐state value. By using a rheo‐optical technique, the time‐dependent gapwise birefringence distribution has been measured following an imposed pressure gradient. The latter experimental results have been found to be in good agreement with theoretical predictions.

ISSN:0148-6055    

DOI:10.1122/1.549775

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549776

出版商:The Society of Rheology    

年代:1984

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549777

出版商:The Society of Rheology    

年代:1984

数据来源: AIP