A rotational rheometer with a drag‐cup torque transducer

Berry, G. C.; Wong, C.-P.

doi:10.1002/pol.1975.180130909

Cited by 16 publications

(8 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this equation, ε is a parameter whose value depends on the type of branching and solvent–polymer interaction. It has been suggested that ε has a value of 1/2 for star polymers, 3/2 for combs with large backbones and short branches and 0.7 for a multiarm stars . For random branching, a value of 0.75 is often used, and the average number of branches per macromolecule, m, is calculated from this ratio using the equation:

g = \frac{6}{m} true[\frac{1}{2} {true(\frac{2 + m}{m} true)}^{0.5} \ln true(\frac{{true(2 + m true)}^{0.5} + m^{0.5}}{{true(2 + m true)}^{0.5} - m^{0.5}} true) - 1 true]

…”

Section: Resultsmentioning

confidence: 99%

Molecular, rheological, and thermal study of long‐chain branched polypropylene obtained by esterification of anhydride grafted polypropylene

Guapacha

Failla

Vallés

et al. 2014

J of Applied Polymer Sci

View full text Add to dashboard Cite

Long‐chain branched polypropylene was prepared using reaction in the molten state in the presence of glycerol and a linear polypropylene functionalized with maleic anhydride (PPg). The concentration of glycerol in the melt was varied in the range from 0.1 to 5 wt % to obtain different levels of branching. FTIR spectroscopy results indicate that the OH groups of glycerol react with the anhydrides on the PPg chains giving place to ester groups. The presence of long‐chain branches in the molecular structure of PPg was confirmed using multiple‐detection size‐exclusion chromatography and rheology. These techniques demonstrate that the level of branching increases with glycerol concentration and that the modification of PPg produces materials with a bimodal distribution of polymer species. Moreover, some of the highly modified materials display gel‐like behavior. The materials also display thermo‐rheological complexity and enhanced activation energy at low frequencies. The crystallization study shows that both the anhydride groups in PPg and the LCBs have opposite nucleating effects. PPg presents the largest activation energy of crystallization and its value decreases with the concentration of glycerol for a given level of crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40357.

show abstract

g = \frac{6}{m} true[\frac{1}{2} {true(\frac{2 + m}{m} true)}^{0.5} \ln true(\frac{{true(2 + m true)}^{0.5} + m^{0.5}}{{true(2 + m true)}^{0.5} - m^{0.5}} true) - 1 true]

…”

Section: Resultsmentioning

confidence: 99%

Molecular, rheological, and thermal study of long‐chain branched polypropylene obtained by esterification of anhydride grafted polypropylene

Guapacha

Failla

Vallés

et al. 2014

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Rheological data were obtained with a rotational rheometer described elsewhere. 17 The rheometer, which employs a drag-cup torque transducer and cone-and-plate platens, can be used to determine the creep, recovery, and steady-state flow properties by methods discussed in the reference cited. In experiments described here a cone with angle 2' and radius 1.89 cm was used throughout.…”

Section: Methodsmentioning

confidence: 99%

“…Typically, Q is nearly unity for T , K < 1, but P may not approach unity until much smaller T , K , depending on the polymer. The approximation (17) which appears to apply for T , K not too large3J0 (see below), suggests that the decrease in P ( T , K ) with increasing T , K is associated with the retardation times contributing to R,("". Thus where h ( X i~) is some (here unspecified) function that is zero for small X~K and increases to nearly unity more or less sharply for X~K > 1.…”

Section: Jo(t/7c) R O [ $ (~/ T )mentioning

confidence: 97%

Strain criterion in nonlinear creep and recovery in concentrated polymer solutions

Nakamura

Wong

Berry

1984

J. Polym. Sci. Polym. Phys. Ed.

View full text Add to dashboard Cite

Transient and steady‐state rheological data are reported for several anionic polystyrene solutions in tritolylphosphate (1. 6 < cM/ρMc < 7). Here c is the concentration of the solution, M is the molecular weight, ρ the density of the undiluted polymer, and Mc the molecular weight between entanglements as determined from zero‐shear viscosity. The polystyrene used had Mw = 410,000 and Mw/Mn < 1.06. Data are also given for solutions of polyisobutylene and poly(vinyl acetate) with larger Mw/Mn. The results give a critical strain γ′ ∝ c−1 such that linear viscoelastic behavior was obtained in a simple shear deformation with shear less than γ′. A simplified version of the constitutive equation of Bernstein, Kearsley, and Zapas is used with an empirical strain function F (γ) which contains γ′ as a parameter to discuss transient and steady‐state behavior in terms of the distribution of relaxation (or retardation) times determined for linear viscoelastic responce. Features of the dependence of the steady‐state viscosity ηk, recoverable compliance Rk, the first‐normal stress function Nk(1) on shear rate k are discussed in terms of F (γ) and the distribution of relaxation times to conclude that the latter plays a dominant role in the behavior observed in the range of k usually studied. The results predict that the reduced functions ηk/η0, Rk/R0, and Nk(1)/N0(1) should depend on η0R0k, and that the functional form depends markedly on the distribution of relaxation times, at least in the range η0R0k < 102. Comparison with the mechanistic model of Doi and Edwards shows a similar F (γ) but substantial differences in the reduced functions caused by a very narrow distribution of relaxation times in the model.

show abstract

“…The eddy-current torque transducer is identical to that described in Ref. 2. A principal motivation in this design is the advantage of an electrodeless, low-inertia rotor that does not introduce residual stress.…”

Section: Introductionmentioning

confidence: 99%

“…Rheometers permitting the use of a specified stress history afford several advantages, including the capabilities to conduct creep and recovery tests in both the linear and nonlinear response regimes and to assess the existence of yield behavior for very small stress levels. The design criteria for the rheometer described below include (1) operation over a torque range of about lo6, (2)…”

Section: Introductionmentioning

confidence: 99%

A rotational rheometer for rheological studies with prescribed strain or stress history

Berry

Park

Meitz

et al. 1989

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

A rheometer utilizing an eddy‐current torque transducer and an air‐bearing suspension is described. The rheometer is coupled with a computer‐based data acquisition system and permits studies of shear deformation for several strain or stress histories. A sinusoidal stress history is used to determine the shear storage and loss compliances J′(ω) and J″(ω), respectively. Step stress histories are used to determine the shear creep compliance J(t) and the recoverable complaince R(t) or more complicated linear and nonlinear rheological responses related to these. Deformation at constant strain rate is used to determine the stress growth function or the steady‐state viscosity. The rheometer may be used over the temperature range – 10–180°C, with torque from 1 to 106 dyn cm, and is adaptabel to use with a variety of sample geometrical shapes (e.g., cone and plate, parallel plate, etc.). Examples of measurements on on viscoelastic fluids and on gels below their yield strain are given.

show abstract

A rotational rheometer with a drag‐cup torque transducer

Cited by 16 publications

References 19 publications

Molecular, rheological, and thermal study of long‐chain branched polypropylene obtained by esterification of anhydride grafted polypropylene

Molecular, rheological, and thermal study of long‐chain branched polypropylene obtained by esterification of anhydride grafted polypropylene

Strain criterion in nonlinear creep and recovery in concentrated polymer solutions

A rotational rheometer for rheological studies with prescribed strain or stress history

Contact Info

Product

Resources

About