Viscosity of poly(vinyl acetate) and its concentrated solutions

Berry, G. C.; Nakayasu, Haruo; Fox, Thomas

doi:10.1002/pol.1979.180171101

Cited by 30 publications

(15 citation statements)

References 13 publications

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“…The change in x observed here is definite, but less obvious because of no correction of the segmental friction coefficient for the viscosity. The correction would yield a gentler slope in the low‐concentration region of the curve that leads to a sharper crossover in x ,45, 47 but it requires the data of the temperature dependence of viscosity as a function of ϕ. The data without the cumbersome correction are adequate for our purpose in view of the crudity of the discussion here because the correction does not appreciably alter the value of ϕ c 47.…”

Section: Resultsmentioning

confidence: 99%

“…The correction would yield a gentler slope in the low‐concentration region of the curve that leads to a sharper crossover in x ,45, 47 but it requires the data of the temperature dependence of viscosity as a function of ϕ. The data without the cumbersome correction are adequate for our purpose in view of the crudity of the discussion here because the correction does not appreciably alter the value of ϕ c 47. The boundary concentration ϕ c for (η 0 −η s ) is located in the crossover region for the ϕ o dependence for the ratios | C ij / C 10 | ( i , j = 0, 1, and 2) in Figure 6.…”

Section: Resultsmentioning

confidence: 99%

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Multiaxial deformations of end‐linked poly(dimethylsiloxane) networks. III. Effect of entanglement density on strain‐energy density function

Kawamura

Urayama

Kohjiya

2002

J Polym Sci B Polym Phys

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Strain-energy density functions (W) of end-linked polydimethylsiloxane (PDMS) networks with different entanglement densities were estimated as a function of the first and second invariants I 1 and I 2 of Green's deformation tensor on the basis of the quasi-equilibrium biaxial stress-strain data. Entanglement densities in the PDMS networks were controlled by varying the precursor PDMS concentration ( 0 ) is independent of the degree of dilution at network preparation. The contribution of each term in I 1 and I 2 to total energy depends on whether the precursor PDMS solution before end-linking belongs to the concentrated regime 0 Ͼ c where many entanglement couplings of precursor chains exist or the moderately concentrated regime 0 Ͻ c where pronounced entanglement couplings of precursor chains are absent. These results suggest that the rubber elasticity of the end-linked networks is significantly influenced by the entangled state of precursor chains before end-linking, and the extra terms in the estimated W that are absent in the prediction of the classical rubber elasticity theories [W ϭ C (I 1 Ϫ 3)] mainly originate from the effect of trapped entanglements.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Multiaxial deformations of end‐linked poly(dimethylsiloxane) networks. III. Effect of entanglement density on strain‐energy density function

Kawamura

Urayama

Kohjiya

2002

J Polym Sci B Polym Phys

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“…Furthermore, the plateau modulus, GNO, of the polymer system, while being independent of the molecular weight, is reported as scaling with the concentration as G N o 4 7 ( 2 ) where y is reported to be approximately7-10 2.0-2.3. On the other hand, the terminal relaxation time, T d , is re-portedgJ1 to scale as Td {(T,#')MX@z (3) where x is approximately 3.4-3.7, and now the value of z is approximately 1.4.…”

Section: Introductionmentioning

confidence: 99%

Molecular weight and concentration dependences of the terminal relaxation time and viscosity of entangled polymer solutions

Rendell¹,

Ngai²,

McKenna³

1987

Macromolecules

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A new model is presented for entangled polymer solutions which accounts for the observed molecular weight and concentration dependences of the zero-shear viscosity qo and the terminal relaxation time Td. Our development, based upon the coupling model of relaxation, quantitatively describes how relaxation of a primitive mode is modified by coupling through entanglements to its environment. The primitive mode is represented by a Rouse chain of Gaussian submolecules, each of root mean square length u equal to the entanglement distance and each characterized by an entanglement friction coefficient fo. By extending the analyses developed previously for polymer melts, the model predicts that qo 0: f *~l ( 1 -n )~y [~a ( 1 -v ) ] 2 / ( 1 -n ) where 4 is the polymer volume fraction. Here n is the coupling parameter describing the terminal relaxation and y, a , and u are given by GNo 0: @ y , Me 0: 4P, and u a 4-"m. Numerical examples are shown to agree with experiment; e.g., for n = 0.41, y = 2, a = 1, u = 0.6, qo a f*k@.4434. Comparison of the present results is also made to the reptation and scaling theory predictions.

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“…In order to answer the question as to the legitimacy of one or another hypothesis accounting for the dramatic change in the viscous properties of the PFEPh solutions along the C scale, let us calculate the critical concentration C* responsible for the occurrence of an intermacromolecular contacts network in the solutions. For this purpose we will use the approach as described in [37], according to which C* is associated with the coil volumes per unit of M «S2)3/2/M):…”

Section: Rheological Properties Of Concentrated Polybis-trifluoroethomentioning

confidence: 99%

Mesophase State of Polyorganophosphazenes

Kulichikhin¹,

Антипов²,

Borisenkova³

et al. 1994

Partially Ordered Systems

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Earlier it was believed [1] that an ordering at a level exceeding the shortrange order of low molecular liquids cannot exist above the melting point in flexible-chain polymers which do not contain meso genic groups. However, recently, a large number of polymers, for example, polyphosphazene, has been found, which cannot be described in the framework of the traditional classification of liquid crystals. An additional type of mesomorphic state, that of a conformationally disordered crystal, was suggested [2,3].A more common approach is analyzing this type of mesophase as a threedimensional ordered crystal having a different perfection extent along each of its crystallographic dimensions. In order to gain a better insight into this problem, it is necessary to accumulate experimental evidence.Polyorganophosphazenes (PPh) with the following general formula:are of interest from the viewpoint of the meso phase class of polymers [4], since many of the representatives of this class may have an ordering level intermediate between a crystalline and an amorphous state in a broad temperature range [5]. A comprehensive review of earlier works on the structure and properties of PPh was published in [6]. The number of publications on the description of the structure, morphology, and characteristics of the physical transitions and physical-mechanical properties of these polymers has considerably increased in recent years. However, there is no complete information on the structure of PPh, especially in the mesomorphous state. V. P. Shibaev et al. (eds.), Liquid Crystalline and Mesomorphic Polymers

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Viscosity of poly(vinyl acetate) and its concentrated solutions

Cited by 30 publications

References 13 publications

Multiaxial deformations of end‐linked poly(dimethylsiloxane) networks. III. Effect of entanglement density on strain‐energy density function

Multiaxial deformations of end‐linked poly(dimethylsiloxane) networks. III. Effect of entanglement density on strain‐energy density function

Molecular weight and concentration dependences of the terminal relaxation time and viscosity of entangled polymer solutions

Mesophase State of Polyorganophosphazenes

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