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  • Physics  (517)
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  • 1982  (552)
  • 1
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    Chichester, West Sussex : Wiley-Blackwell
    Mathematical Methods in the Applied Sciences 4 (1982) 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 2
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 33-73 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: One considers an elastic halfspace with depth (x1) dependent density Q and Lamé moduli (λ,m̈). Impulsive stresses τli = δ(x2, x3)δ(t) for x1 = 0 are applied with displacement responses ui = gi(t, x2, x3) at x1 = 0 (i = 1, 2, 3). Let vi(t, x1) = ∫∫uidx2dx3 (i = 1, 2 is enough) and set w(t, x1) = ∫∫x2u1dx2dx3. One obtains a system of 3 differential equations for v1, v2, and w to which the spectral techniques of inverse scattering theory are applied as in [25]. The inverse problems for the uncoupled vi can then be solved to produce 2 functions A1 and A2 involving (Q, λ, μ) as functions of “bound” variables y1 and y2 containing (Q, λ, μ), between which a relation then is determined. Analysis of the coupled equation for w then leads to a Fredholm integral equation whose solution provides an additional relation between (Q, λ, μ) from which (Q, λ, μ) can be determined as functions of x1. The integral equation is reduced to a Volterra type equation by results and techniques of transmutation and then solved by a modification of standard techniques. A number of features and results of independent mathematical interest arise from the transmutation theory.
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  • 3
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 123-130 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The Maxwell equations are formulated as an evolution equation in a suitable chosen Hilbert space involving a densely defined closed skew-Hermitian operator which generates a unitary group. A Crank-Nicolsen-Galerkin approximation is then established and convergence is shown by arguments from the theory of approximation of groups of operators.
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  • 4
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 143-163 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: By using the method of averaging, we give a complete Hopf bifurcation diagram when the differential equation has more than one parameter. The method is applied to a system of parabolic equations with nonlinear coupling on the boundary. This set of equations is a mathematical model which describes the normalized concentrations of substances in a solution produced by two enzymes.
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  • 5
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 243-258 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The buckling of a beam or a plate which is subject to obstacles is typical for the variational inequalities that are considered here. Birfurcation is known to occur from the first eigenvalue of the linearized problem. For a discretization the bifurcation point and the bifurcating branches may be obtained by solving a constrained optimization problem. An algorithm is proposed and its convergence is proved. The buckling of a clamped beam subject to point obstacles is considered in the continuous case and some numerical results for this problem are presented.
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  • 6
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 15-18 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In the paper we prove the existence and uniqueness of solutions of the overdetermined elliptic system \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\left( {\rm A} \right)} & {{\rm rot }\upsilon {\rm = }\omega } & {{\rm div }\upsilon {\rm = 0}} & {\upsilon \cdot {\rm }\bar n|_{\partial \Omega } = b} \\ \end{array} $$\end{document} where b, ω are given functions, in a domain Ω C R3 with corners π/n, n = 2, 3, … The proof is divided on two steps, we construct a solution for the Laplace equation in a dihedral angle π/n, using the method of reflection and we get an estimate in the norms of the Sobolev spaces in some neighbourhood of the edge. In the dihedral angle system (A) reduces to the Dirichlet and Neumann problems for the Laplace equation. In the next step we prove the existence of solutions in the Sobolev spaces Wpl(Ω) using the existence of generalized solutions of (A).
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  • 7
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 230-242 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The solvability of a boundary value problem for a nonlinar elliptic partial differential equation in a plane, bounded, multiply connected domain is investigated. The solution of the problem is equal to unknown constants on inner components of the boundary. We want to determine these constants so that the solution satisfies the so-called trailing conditions. The results have immediate applications in hydrodynamics.
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  • 8
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 259-271 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The nonlinear potential problem Δ φ = -r2m 0, n = m is studied with r ≥ 0, n ε (½, ∞), m ε (-1, ∞) and n m 〉 0.With various additional conditions we have regular and singular solutions which can be studied explicitly by homology transformation. It is proved that if m - n + 1 = 0 the solution with φ(0) = 1, ≠ (0) = 0 is radiusstable. Numerical analysis of a number of cases with m - n + 1 = 0 yields the same conclusion.
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  • 9
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 286-290 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Introducing the concept of a supercontinuous operator, we obtain a general convergence theorem for Galerkin approximations. Under the stronger assumption that N is a monotone operator with N(0) = 0, we show norm convergence of the unique Galerkin approximations to the unique solution.
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  • 10
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 317-353 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The generalized Feller equation is a linear, autonomous, parabolic equation of a positive space variable and a time variable. Its coefficients are power functions of the space variable, and they depend on four parameters. In general, the equation is singular at the origin and at infinity. It contains as special cases the special Feller equation, the Kepinski equation, and the standard heat equation. The main objective of the present paper is to establish series expansions of solutions of the generalized Feller equation in terms of the elements of two sequences of particular solutions. The elements of one of these sequences are particular initial condition solutions. The two sequences are biorthogonal. The main result is that a solution does have the desired expansion property if and only if it has the Huygens property in some neighborhood of the origin of the time variable.
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  • 11
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 354-381 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The problem of stress determination in the area of cut-outs in circular cylindrical shells at given loads is of great interest in industrial practice. This work deals with a mixed boundary value problem of a differential equation derived according to the theory of shallow shells. On part Ct1 of the boundary, the displacements are given, whereas the stresses are specified on the remaining part Ct2. Starting from the Betti-Maxwell principle and with the aid of the fundamental solutions for unit loads and unit displacements, integral representations can be derived for the displacement functions as well as the stress functions.The problem is then transformed into an equivalent system of Fredholm integral equations of the first kind with logarithmic kernels as the main part. As the integral equations together with the auxiliary conditions form a strongly elliptical system of pseudo-differential operators, the Galerkin method converges. Assuming that curves Ct1 and Ct1 do not have points of intersection and that the data are sufficiently regular, the required functions are approximated by cubic splines and, for simplicity's sake, the integral equation system is solved by approximation with a collocation method. In view of the complicated terms of the kernel functions, the kernels are split into a regular and a singular part, the regular part being in turn replaced by cubic splines. The remaining integrations are done numerically by means of Gaussian quadrature formulae. The applicability of the method is demonstrated with the example of a cylinder under internal pressure.
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  • 12
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 451-453 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 13
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 272-285 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Semilinear elliptic systems of partial differential equations related to ecology are studied, with Dirichlet boundary conditions. Monotone sequences of functions which satisfy scalar equations are constructed so that they will converge to upper and lower bounds for the solutions of the systems. In case a related system has a unique positive solution, then these sequences will converge to the solution of the original system. Applications of the monotone sequences to uniqueness and stability are also given.
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  • 14
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 291-306 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We consider two vibration problems containing a small parameter → 0: a) Vibration of an elastic, slightly compressible body, and b) acoustic vibration of a slightly viscous compressible barotropic fluid in a vessel.The asymptotics of eigenvalues for problem a) is studied by using a uniformly convergent expansion of the stiff type. After a re-scaling of the spectral parameter, the problem b) reduces to an analogous problem, and we prove that, as ε → 0, infinitely many eigenvalues converge to 0 (which is an eigenvalue of infinite multiplicity of the corresponding inviscid acoustic problem).
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  • 15
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 382-396 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: This paper is concerned with spline methods in a reproducing kernel Hilbert space consisting of functions defined and harmonic in the outer space of a regular surface (e.g. sphere, ellipsoid, telluroid, geoid, (regularized) earth's surface). Spline methods are used to solve interpolation and smoothing problems with respect to a (fundamental) system of linear functional giving information about earth's gravity field. Best approximations to linear functionals are discussed. The spline of interpolation is characterized as the spline of best approximation in the sense of an appropriate (energy) norm.
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  • 16
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 415-424 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The theory of Rayleigh functionals for non-linear eigenvalue problems T(λ) u = 0 is extended to cases where the functional is defined only on a proper subset. The theory applies to problems which do not satisfy an overdamping condition and yields a minimax characterization of eigenvalues. Applications to damped free vibrations of an elastic body are discussed.
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  • 17
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 1-14 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper we prove the existence and uniqueness of solutions of the leakage problem for the Euler equations in bounded domain Ω C R3 with corners π/n, n = 2, 3… We consider the case where the tangent components of the vorticity vector are given on the part S1 of the boundary where the fluid enters the domain. We prove the existence of an unique solution in the Sobolev space Wpl(Ω), for arbitrary natural l and p 〉 1. The proof is divided on three parts: (1) the existence of solutions of the elliptic problem in the domain with corners \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm rot }\upsilon {\rm = }\omega {\rm, div }\upsilon = 0,\upsilon \cdot \bar n||_{\partial \Omega } = 6 $$\end{document} where v - velocity vector, ω - vorticity vector and n is an unit outward vector normal to the boundary,(2) the existence of solutions of the following evolution problem for given velocity vector \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \omega _t + \upsilon ^\kappa \omega _x \kappa - \omega ^\kappa \upsilon _x \kappa = F \equiv {\rm rot }f \\ \omega |_{t = 0} = \omega _0,\omega |_{s1} = \eta \\ \end{array} $$\end{document}(3) the method of successive approximations, using solvability of problems (1) and (2).
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  • 18
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: A study and the solution of an extension of the classical Sommerfeld half-plane problem which leads to a pair of integral equations of the Wiener-Hopf type is given. The method of solution is function theoretic in character and employs a combination of the ideas of Wiener and Hopf and Carleman.
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  • 19
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 131-142 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We study the problem \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} { - \Delta u = \lambda H({\rm u - 1)}} & {{\rm in }\Omega } \\ {u = g} & {{\rm in }\partial \Omega } \\ \end{array} $$\end{document}(H is the Heaviside unit step function) in spherical domains Ω of arbitrary dimension. When g = 0, there are two branches of radial solutions; for small nonzero g there are solutions near the corresponding radial solution. Moreover, the set where μ = 1 is in all cases an analytic hypersurface.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 19-32 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The theory of part I is applied to prove several existence and non-existence results for special cases. If N = 3, a global classical solution of P° exists, if ϕ ≥ 0 has rotational symmetry. If N ≥ 4, global classical solutions of P° do not always exist.
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  • 21
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 98-122 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The aim of this work is to give theoretical justification of several types of finite element approximations to the initial-boundary value problems of first order linear hyperbolic equations. Our approximate scheme is obtained by the piecewise linear continuous finite element method for space variable, x, and the Euler type step by step integration method for time variable, t. An artificial viscosity technique, up-stream type methods are considered within the frame work of L2-theory. The convergence and the error estimate of the approximate solutions to the true one are discussed.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 91-97 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The ‘anti-dynamo’ theorems for poloidal magnetic fields with axisymmetry and plane symmetry are generalized to the case of a compressible and time-dependent flow in a fluid with arbitrary conductivity.
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  • 23
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 164-193 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper we study the application of boundary integral equation methods for the solution of the third, or Robin, boundary value problem for the exterior Helmholtz equation. In contrast to earlier work, the boundary value problem is interpreted here in a weak sense which allows data to be specified in L∞ (∂D), ∂D being the boundary of the exterior domain which we assume to be Lyapunov of index 1. For this exterior boundary value problem, we employ Green's theorem to derive a pair of boundary integral equations which have a unique simultaneous solution. We then show that this solution yields a solution of the original exterior boundary value problem.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 206-229 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The stability, convergence, and consistency properties of the steady-state multigroup model are investigated for submultiplying slab media. These concepts are defined in a Banach space setting in which the norm of the angular flux is the collision density integrated over phase space. It is shown that the multigroup approximations are stable and are both consistent with, and convergent to, the transport equation under the conditions that the maximum fluctuations in the total cross section and in the expected number of secondary particles, arising from each energy level, tend to zero as the energy mesh becomes finer. A concluding discussion deals with pathologies of the multigroup approximation for situations in which these fluctuations do not tend to zero as the norms of the energy partitions. The results in this paper complement the time-dependent results of Belleni-Morante and Busoni for isotropic slabs and the results of Nelson for steady-state rod media.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 307-316 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: A boundary value problem is considered for an equation of mixed type in a rectangle. An energy method is used to prove uniqueness for appropriate boundary conditions. Similar considerations for the adjoint problem allow one to prove the existence of a generalized solution to the problem. It is also shown that the energy method leads naturally to a finite element method. The method is described for a special case and convergence is shown for the resulting numerical procedure.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 397-414 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We consider acoustic waves in domains with boundaries, coinciding with two parallel planes outside a sufficiently large sphere. Several results on spectral properties of the Laplace operator in such domains are derived and used to prove uniqueness and existence of a solution of the Dirichlet boundary value problem for the reduced wave equation under additional restrictions. In particular, a class of domains is described for which no eigenvalues are present.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 425-432 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Lower bounds for the real parts of the points in the spectrum of elliptic equations \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \Delta u + au_x + b{\rm u}_{\rm y} = - \lambda u{\rm in G} \\ {\rm u|}_{\partial {\rm G}} = 0 \\ \end{array} $$\end{document} are derived. These bounds, depending only on the diameter L of the domain G and on the maximum norm M of the coefficients a, b, are optimal. They are always positive and thus the spectrum is bounded away from the imaginary axis. This result is then used to prove an “anti-dynamo theorem” for magnetic fields with plane symmetry in the case of a compressible steady flow surrounded by a perfect conductor.
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    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
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    Topics: Mathematics
    Notes: We consider solutions z of the Cauchy-problem for hyperbolic Euler-Lagrange equations derived from a general Lagrangian f(x, y, z; zx, zy) in two independent variables x, y. z is supposed to be an extremal of the corresponding variational problem. Visualizing z as a surface in R3 we give a geometric interpretation of Lewy's well-known characteristic approximation scheme for the numerical solution of second order hyperbolic equations by approximating z via a polyhedral construction built up from subunits which consist of two characteristic triangles having one side in common but lying on different planes in R3. Utilizing ideas from Cartan-geometry one can (in an appropriate sense) introduce the “mean curvature” of these subunits and it is seen that this curvature vanishes (up to terms of higher order). That is a highly plausible result for the polyhedral approximation of “minimal surfaces”.
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  • 29
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: For singularly perturbed one-dimensional convection-diffusion equations, finite element approximations are constructed based on a so-called approximate symmetrization of the given unsymmetric problem. Local a-posteriori error estimates are established with respect to an appropriate energy norm where the bounds are proved to be realistic. The local bounds, called error indicators, provide a basis for a self-adaptive mesh refinement. For a model problem numerical results are presented showing that the adaptive method detects and resolves the boundary layer.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 433-449 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We consider an unbounded, elastic non homogeneous material with periodic structure. It is shown that the solution of the equations of motion can be expanded in eigenfunctions of periodic operators. The Bloch expansion is used to prove that when the wave-length is long compared to the period of the structure (related to a small parameter ε), the first term of the exact solution expansion, in powers of ε, is the solution of the equations obtained in homogenization theory. The case of a long memory linear viscoelastic material is then studied.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 497-509 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Data processing is an important tool in airspace surveillance and air traffic control today. In this paper the problem is treated how to reconstruct a flown trajectory from its correlated radar plots subject to a certain knowledge of the aircraft manoeuverability and the radar measurement statistics. A variational approach leads to a generalized smoothing spline method. Simulation results are presented.
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 194-205 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We consider the existence of a nontrivial solution of the following equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \begin{array}{*{20}c} {} & {u_{tt} + u_{xxxx} + g(u) = 0} & {(x,t) \in Q = (0,\pi ) \times (0,2\pi )} \\ \end{array} \\ \begin{array}{*{20}c} {(0)} & {u(0,t) = u(\pi,t) = u_{xx} (\pi,t) = 0,t \in (0,2\pi )} & {} \\ \end{array} \\ \begin{array}{*{20}c} {} & {u(x,0) = (x,2\pi ),} & x \\ \end{array} \in (0,\pi ) \\ \end{array} $$\end{document} where g is a nondecreasing function defined on R1, satisfies g(O) = O, and some other additional conditions.Our results and methods are quite similar to those associated with recent work on the nonlinear wave equation [1]-[8]: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \begin{array}{*{20}c} {u_{tt} - u_{xx} + g(u) = 0} & {(x,t) \in 0} \\ \end{array} \\ \begin{array}{*{20}c} {u(0,t) = u(\pi,t) = 0} & {t\varepsilon (0,2\pi )} \\ \end{array} \\ \begin{array}{*{20}c} {u(x,0) = u(x,2\pi )} & {x\varepsilon (0,\pi )} \\ \end{array} \\ \end{array} $$\end{document} .
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  • 33
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper the three-dimensional perturbation flow induced by a rotating and oscillating blade row which operates in a subsonic flow in axial direction of an annular channel is studied. The velocity potential is reduced to the infinite Hilbert space vector of Fourier coefficients of an eigen-function expansion with respect to vanishing normal derivatives on both cylinder walls. These coefficients satisfy an infinite set of ordinary differential equations of second order after an application of a one-dimensional Fourier transform in axial direction.Several canonical two-part mixed boundary value problems are then investigated by reduction to “infinite two-by-two-Wiener-Hopf functional systems”. In case of strong factorizability of certain matrix-operator-valued functions on the line these systems may be solved explicitely. Criteria for the factorization are not given here.
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  • 34
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 510-528 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In the paper a boundary value problem is studied for the equation of mixed typek(y)uxx + uyy + r(x, y)u = f(x, y) in the rectangular domain {(x, y)| -1 〈 x 〈 +1, yc 〈 y 〈 yH} with yc 〈 0, yH 〉 0, k(y) = sign y|y|m, m 〉 0 (and more generally for a function k = k(y) with k(O) = 0, k(y)y 〉 O for y ≠ O). Specific for the stated problem is that no data are prescribed on the line {(x, yc), -1 〈 x 〈 +1}. It is proved that the formulated problem is well-posed in the sense that there is at most one quasi-regular solution and that a generalized solution exists. The energy-integral-(abc-)method is used to show uniqueness and to obtain an apriori estimate for the solution of the adjoint problem whence the existence statement follows.
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  • 35
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    Mathematical Methods in the Applied Sciences 4 (1982), S. 549-571 
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: New condition numbers and stability constants for the numerical behaviour of Cramer's rule and Gaussian elimination for solving two linear equations in two unknowns under data perturbations and rounding errors of floating-point arithmetic are established. By these means fundamental error estimates and stability theorems are proved. The error estimates are illustrated by a series of numerical examples.
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  • 36
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1-13 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Light scattering patterns are calculated for imperfect three-dimensional spherulites with fluctuations in the twist angle. The fluctuations are described in terms of a parameter characterizing the distance correlation function. Cases are considered in which (i) the principal axis of the scattering element makes a constant angle with the radius but there is disorder in the twist angle about the axis, and (ii) there is combined twist disorder and orientation disorder of the scattering elements. Calculations suggest that the disorder in the twist angle may lead to a decrease in the higher-order variation of scattered intensity with scattering angle and deviation from the four-leaf-clover-type scattering characteristic of a perfect spherulite at lower scattering angles. On the other hand, disorder in orientation has little effect on the scattering pattern.
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  • 37
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 49-63 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An experimental study of the tensile properties, tear strength, hysteresis, and swelling ratio of model composite elastomeric compounds consisting of polybutadiene filled with glass beads has been carried out as a function of the size of the beads. The diameter of the beads ranged from 25 to 1000 μm and the volume fractions examined were 0.16, 0.092, and 0.048. Mechanical properties of the filled elastomers were functions of the loading (separation distance), the particle size (surface area/volume), and the elastomer-filler systems studied.
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  • 38
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 99-106 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reasons have been advanced why in some cases concentrated-polymer-solution viscosity measurements are not a suitable method for determining the degree of association of groups attached to polymer chains. These are based on the finite lifetimes of associates compared with the finite lifetimes of the entanglements, which are the major contributors to concentrated-polymer-solution viscosities. The validity of these reasons has been checked in a system where the degree of association of polymer chains can be measured spectroscopically. It was found that the viscosity of these solutions was considerably less than that calculated by the concentrated-solution viscosity equation for solutions of polymers of the average molecular weight expected from the spectroscopically found degree of association.
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  • 39
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 117-130 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(p-phenylene sulfide) (PPS) is a melt- and solution-processible polymer which on treatment with AsF5 forms a blue-black material with a conductivity of 1-10 Ω-1 cm-1. Thermopower measurements indicate that the resulting polymer is p type, consistent with partial oxidation of the PPS by the AsF5. The rate and extent of this doping process prove to be particularly sensitive to the degree of crystallinity of the starting polymer. There is also evidence of crosslinking of the polymer chains during the reaction with AsF5. The details of both the chemistry and physics of the doping of PPS and several of its derivatives are presented.
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  • 40
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 131-139 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The temperature dependence of the reactivity ratio r2 (subscript 2 for styrene) is reported for 1-and 2-vinyl naphthalenes, 4-halogeno-1-vinyl naphthalenes, 2- and 3-vinyl phenanthrenes, and o-methylstyrene. The monomers are classified with respect to In (1/r2) and ΔH # and ΔS# (the differences in activation parameters for homopropagation and crosspropagation). It is shown that the reaction is entropically controlled. It appears that there is no correlation between stabilization energy (ΔE)rs and ΔH# and that the correlation with In(1/r2) is only apparent. The origin of this lack of correlation is analyzed and a new index of reactivity is proposed; its correlation with ΔH# is quite satisfying.
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  • 41
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 191-203 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of polycaprolactone (PCL) with chlorinated polyethylenes (PECls) having chlorine contents of 25, 30, 36, 42, and 48% by weight were prepared and studied by differential scanning calorimetry and small-angle light scattering (SALS). It was found that blends made with PECls containing 30% or more chlorine are completely miscible with PCL (a single glass transition temperature Tg is found) while the PCL/PECl(25) blends are immiscible. PCL crystallizes in the miscible blends at any composition and it has an enthalpy of fusion which decreases only slightly with PECl content. Blends in the PECl composition interval of 0-80% are spherulitic, as shown by SALS, but a rodlike morphology is found at the 85% composition and dispersed crystals are observed at higher compositions. It is suggested that the k parameter of the Gordon-Taylor equation can be taken as a measure of the strength of the specific interaction between PCL and PECl. Low values of k (0.26 and 0.35) are found for PCL/PECl blends but a higher value of k (0.51) has been reported for PCL/poly(vinyl chloride) (PVC) blends, indicating a stronger interaction in the latter mixtures. In agreement with these findings poly(α-methyl-α-n-propyl-β-propiolactone) and poly(valerolactone) are not miscible with PECl, whereas they were previously shown to be miscible with PVC.
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  • 42
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 225-233 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The authors describe small-angle neutron scattering measurements of the screening length ζ in polyacrylamide-water gels. Although these are inhomogeneous systems, the screening length is clearly observable and is in good numerical agreement with the relation E = 3kT/4πζ3, where E is the longitudinal elastic modulus of the gel obtained from measurements of the intensity of qu-asielastically scattered light. Static light scattering observations reveal a larger-scale (ca. 30 nm) superstructure in the gel.
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  • 43
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 259-268 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of copolymerizing small amounts of an ionic moiety (0-7 mol %) into the backbone of a polycondensation polymer have been investigated by a combination of linear viscoelastic, steady-shear, and extensional testing. At a constant viscosity in dilute solution, both the zero-shear-rate viscosity and the maximum relaxation time in the melt increase monotonically with an increase in the ionic character. These effects are present after the data are normalized to remove the increase in the glass transition temperature Tg with increased ionic content. Large-strain, steady-shear flow experiments showed that the viscoelastic memory of the melt is affected by ionic content. An increase in ion content causes a decrease in the effect of strain on the memory function. This effect is not apparent in extensional flow experiments, which indicate that the ionic content does not affect the response if the tests are conducted at a constant temperature above Tg.
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  • 44
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 297-305 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For some fibers, such as the nylon monofilaments studied here, quantitative information may be obtained from scanning electron micrographs of fracture surfaces. On these surfaces the segment of the cross section that supports the load at the instant of rupture is seen distinctly, and its area can be measured. Normalizing breaking load by this area provides a breaking stress characteristic of the final supporting segment. “Ultimate” breaking stresses calculated in this way indicate (i) For notched filaments, the ultimate breaking stress is almost constant with notch depth and also with strain rate. (ii) For un-notched filaments, there is an increase of breaking load with strain rate, due in part to the extent of the slow cleavage that precedes failure; however, the ultimate breaking stress increases as rate of strain decreases. These two findings are incompatible with mechanisms of failure based on growth of microcracks by heat- and stress-activated chain breakage. A possible explanation involves rearrangement of microfibrils within the fiber which alters their strength distribution. (iii) The apparent strength reduction on wetting nylon filaments in water is due to a faster rate of growth of the slow-cleavage area; the ultimate breaking stress is unchanged, except at high rates of strain.
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  • 45
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 327-344 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The existence of local order in two epoxy resins of the diglycidyl ether of bisphenol-A (DGEBA) type has been investigated using Rayleigh scattering and Brillouin spectroscopy. The resins differ in their molecular weight distributions and their relative concentrations of epoxide and hydroxyl groups. The complementary use of both techniques in elucidating the thermal behavior of local order is illustrated, and the use of the latter technique to study thermal acoustic phonons and hypersonic relaxation is discussed. Both techniques independently show that molecular aggregates exist in each resin system. The scattering-envelope dissymmetry shows that the resin with the high epoxide/hydroxyl group ratio contains aggregates up to 20 nm in size, and the low-ratio resin exhibits sizes up to 70 nm. These aggregates are thermally unstable in the temperature range studied (293-443 K). Dissolution in chloroform shows that these aggregates are reduced in size and that further structural changes occur which are dependent on solvent concentration. Aggregate volume fractions were determined for a range of aggregate size. Brillouin spectroscopy indicated that both resins exhibit hypersonic relaxation in the temperature range studied. The complex longitudinal moduli of the resins were superimposable under a WLF temperature transformation comparable to the difference in their static glass transition temperatures. Molecular aggregate size, number, and stability are related to the epoxide/hydroxyl ratio of the resins and the degree of intermolecular hydrogen bonding.
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  • 46
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A single master logarithmic stress relaxation curve of reduced modulus as a function of reduced time is established for a styrene-butadiene rubber (SBR) system, accounting for the effects of crosslinking density, temperature, and time. The results from recent tests involving uniaxial and various biaxial strain states at finite strain levels may be represented by a unique strain-energy function W of the Valanis-Landel separable symmetric type, \documentclass{article}\pagestyle{empty}\begin{document}$ W = \sum\limits_{i = 1}^3 {w(\lambda_i)} $\end{document} where the λi are principal extension ratios. These two representations demonstrate that the mechanical response of whole families of elastomeric materials may be predicted once a single member of the family is fully characterized.
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  • 47
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This article proposes a temperature-jump (T-jump) approach for characterizing the kinetics of volume recovery in glassy materials. The kinetic characterization is based on the Kovacs-Aklonis model. This incorporates a retardation-time spectrum which shifts according to both the temperature and the instantaneous volume. The proposed experiments involve measuring the change in recovery rate caused by an abrupt temperature jump. Although an analogous procedure has been used to determine the activation energy for linear viscoelastic creep, the analysis for volume recovery is complicated by its inherent nonlinearity. Nevertheless, accounting for the nonlinearity by a reduction of the time scale permits the T-jump results to be analyzed. In particular, the T-jump approach can be used to: (i) test a particular functional form for the shift factor and (ii) determine the previously unmeasurable parameter x, which defines the relative importance of the temperature dependence and the volume dependence in this function. In addition, numerical simulations indicate that the proposed method can be implemented in the laboratory.
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  • 48
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 457-472 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin films of a polyester of lactic and glycolic acid were prepared to give controlled amounts of disk spherulites. The spherulite contents ranged from zero to 100% and were accurately measured. The stress-strain properties of the films were then determined at 60°C, i.e., about 20°C above the glass transition temperature Tg. The mechanical behavior varied quite systematically with spherulite content and displayed little dependence on spherulite size. It was found that much of the mechanical data could be reasonably well described by a simple composite model. In addition, the yield strain as well as the strain to break could be principally coupled to the deformation of only the amorphous phase. SEM and optical microscopy studies supported the above conclusion, also demonstrating that the isolated spherulites adhered well to the amorphous matrix and behaved as stress concentrators in the system when the deformation temperature was above Tg.
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  • 49
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bimodal networks consisting of very short and relatively long poiydimethylsiloxane (PDMS) chains were studied from 30 to -52°C in an attempt to elucidate the anomalous increases in modulus [f*] exhibited by such elastomeric materials at high elongations. Temperature was found to have very little effect on (i) the elongation at which the upturn in [f*] becomes discernible, (ii) the elongation at which rupture occurs, and (iii) the total increase in [f*] up to the rupture point. The standard force-temperature (“thermoelastic”) plots were linear, but gave values of the energetic contribution to the total force which were significantly smaller than those universally obtained on unimodal, long-chain PDMS networks. Birefringence-temperature relations were also found to be linear, and yielded values of the optical-configuration parameter and its temperature coefficient which were in satisfactory agreement with the corresponding values reported for unimodal PDMS networks. These results indicate that even at very low temperatures the observed increases in modulus (and consequent improvements in ultimate strength) are due to non-Gaussian effects arising from limited chain extensibility, rather than from intermolecular reinforcing effects such as strain-induced crystallization.
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  • 50
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 557-560 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 51
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 561-578 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Neutron scattering data for melt-crystallized polyethylene have been analyzed in order to clarify to what extent the chain folding is randomly reentrant. No attempt has been made to specify the molecular conformation in every detail, and the emphasis is on distinguishing between different classes of conformation. The most random folding corresponded to a model where the folding is imposed solely by the criterion of the chain segments moving the least possible distance during the crystallization process (a “freezing-in” model). This has been shown not to be compatible with published data. For this model analytic calculations are possible based on the projection of a three-dimensional Gaussian distribution onto a plane. A subunit model is then proposed which requires substantial local rearrangement of the chain as it folds during crystallization, but where the distribution of the subunits within the whole molecule is imposed by the preexisting Gaussian chain of the melt. Arguments based on space filling considerations are invoked, with the postulate of a surface structure which is neither crystalline nor truly amorphous. Anything approaching a random switchboard model (e.g., the freezing-in model which we consider) is contrary to both space filling considerations and to the comparison of observed and calculated neutron scattering. The analytical calculation which was performed for the freezing-in model was employed so as to simplify calculations for the subunit model. For scattering intensities over a wide range of scattering angle it is deduced that only the structure within the subunit need be considered. Numerical computer calculations involving only a small number of stems were then carried out for a number of different subunit structures, and some general features are noted which restrict the type of model which can explain the data. As in previously published analyses, a very high proportion of adjacent folds is not compatible with the results. A row model for the stems within a molecule can achieve good agreement, either with straight rows or with a certain amount of “stagger” incorporated. Up to about 40% of the folds could be adjacent. Models based on two-dimensional random walks did not give good agreement.
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  • 52
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 623-632 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When two shear deformations γ1 and γ2 are successively applied to an entangled polymeric system, a composite temporary network is formed. In this article a simple method is proposed for evaluating separately the contributions from the component networks of different deformations, γ1 + γ2 and γ2, to the observed shear and normal stresses. The method is applied to literature data for a polystyrene solution. It is revealed that the entangled chain segments formed between the applications of two deformations relax very rapidly, while those formed prior to the first deformation do not relax for quite a long time. The result is in accord with the conjecture based on the tube model of entanglement that the chain ends lose their orientation as the chain creeps out of an oriented tube.
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  • 53
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 651-658 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A novel method for investigating the morphology of multiphase polymers is discussed. In this procedure, inherent differences in secondary and backscattered electron emission from the various components rather than topographical variations are used to produce image contrast. The combined use of various selective stains and energy-dispersive x-ray analysis to accentuate and positively identify individual phases is discussed. The effects of coating thickness and type and changes in accelerating voltage on image quality are also described.
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  • 54
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 743-750 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The characteristic ratios of stereoirregular polybutadiene and polyisoprene have been evaluated by a combination of intrinsic viscosity and light-scattering measurements under θ conditions. The polydienes were synthesized by anionic polymerization and thus had near-monodisperse molecular weight distributions and were of uniform microstructure. The polybutadiene C∞ was found to be 5.1, which is in good agreement with the Abe-Flory predictions. However, the value of 5.1 for polyisoprene is somewhat higher than prediced by theory.
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  • 55
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 773-775 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 56
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin films of spin-probed and spin-labeled poly(methyl methacrylate) (PMMA) have been examined by electron spin resonance (ESR) at X-band frequency (9.2 GHz) and at various temperatures. Direct spectral evidence is presented to indicate that the composite ESR spectra observed in a certain temperature range originate from two states of distinctly different mobility, one with slow motions corresponding to a glassy state and the other with fast motions corresponding to a liquidlike state. The coexistence of these two states at temperatures considerably below the glass transition temperature can be explained as a result of the effect of free volume in a solid polymeric glass.
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  • 57
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 783-791 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An expression for local composition which describes nonrandom interactions between unlike molecules in polymer solutions is proposed. This expression makes the nonrandom model compatible with the one-fluid hypothesis and satisfies the limits of randomness when experimental conditions evolve in such a way. Data on several binary systems are studied using this model which represents simultaneously activity and heat-of-mixing data.
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  • 58
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 837-844 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Molecular aggregation of the aromatic polyimide poly(4,4′-oxydiphenylene-pyromellitimide) is influenced by the initial imidization temperature and by cold drawing. The effect of molecular aggregation in polyimides on their mechanical properties has been investigated. The density of a polyimide in which molecular aggregation gives an amorphous state is increased slightly by cold drawing. On the other hand, if molecular aggregation leads to a heterogeneous two-phase structure, the density is decreased by cold drawing. With increasing initial imidization temperature, the α absorption peak in dynamic tensile measurements becomes broader and smaller, and shifts to a higher temperature. From analysis of correlations between molecular aggregation and mechanical properties, it is concluded that the mode of molecular motion corresponding to the α dispersion in polyimide is a long-range cooperative motion of the main chain which is associated with the glass transition.
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  • 59
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 893-898 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Exact expressions are derived for the spinodal, critical conditions, and separation factor of a ternary solution consisting of a pure solvent and two monodisperse homologous polymers in which the Flory-Huggins interaction parameter χ depends separately on the concentrations of the polymer components. The results allow one to see the difference from previous expressions obtained with χ depending on the total concentration of the polymer, and are expected to be useful for experimental determination of the Gibbs free energy of ternary solutions.
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  • 60
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 929-930 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 61
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 953-959 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reorientational relaxation of 9-cyananthracene fluorescent label molecules has been measured in bulk polybutadiene and solutions with cyclohexane by a fluorescent depolarization technique. The procedure adopted consists in the incorporation of an Arrhenius temperature dependence of the orientational relaxation time in the Perrin equation, thus obviating the necessity of an independent determination of the intrinsic polarization ratio P0 and enabling one to obtain the preexponential factors and the activation energies of the reorientational relaxation times. The most noteworthy result in our view is the validity of the Arrhenius equation for the effective microviscosity as opposed to the validity of the Fulcher-Vogel-Tamann equation with a glass point of T0 = 136 K for the shear viscosity of a polymer solution (90%).
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  • 62
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 981-987 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A spectrophotometric method was developed for measuring the birefringence of highly oriented synthetic fibers. This method surmounts the low birefringence limit of the standard quartz compensator method and the difficulties in interpretation of the photographic fringe method. A highly oriented aramid fiber gave birefringence values of 0.60-0.75 by this method, compared with 0.25 for polyester and 0.06 for nylon by other conventional methods. The operating principles and excellent results of this new method provide a basis for the extension of routine birefringence characterization to highly oriented fibers.
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  • 63
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1013-1018 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The production of oriented “crystalline” fibers of an atactic polymer, poly{1-[6-(4-biphenylyloxy)hexyloxycarbonyl]ethylene} is reported. The x-ray diffraction is consistent with a two-chain unit cell with a = b = 23.5 Å, c = 6.48 Å, and γ = 120. Although the cell is essentially hexagonal, the absence of screw symmetry along the polymer chain reduces the crystal symmetry to P A packing model consistent with these data is proposed.
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  • 64
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1069-1080 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A systematic study of the sodium and calcium salts of an ethylene-methacrylic acid copolymer is reported. Fourier-transform infrared spectroscopy (in the midinfrared region) is applied to the characterization of structural changes as a function of temperature and time of annealing. In the spectra of calcium ionomers, bands associated with carboxylate dimers are identified and assignments of specific spectral features to multiplets and clusters are discussed. The spectroscopic changes observed in the spectra of sodium ionomers differ somewhat from their calcium counterparts in that a single infrared band attributed to isolated carboxylate groups is observed. Assignments of specific bands to multiplets and clusters can, however, be made in a manner consistent with the interpretation of the spectra of calcium ionomers.
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  • 65
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1107-1128 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The technique of nitric acid etching followed by gel permeation chromatography has been used to determine the crystal length distribution in ultrahigh-modulus polyethylenes. The crystal length distribution has been studied as a function of draw ratio, polymer molecular weight, processing conditions, and annealing. The results confirm that although there is a considerable broadening of the crystal length distribution on drawing, the majority of crystals have lengths less that 500 Å. There are detailed changes in the length distribution due to changes in draw temperature, molecular weight, and annealing which are not always reflected in corresponding changes in the long period determined from small-angle x-ray scattering. Possible reasons for these discrepancies are discussed.
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  • 66
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1129-1141 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crazes have been grown from crack tips in thin films of the following five polymers: polytertbutylstyrene (PTBS), polystyrene (PS), poly(styrene-acrylonitrile) (PSAN), poly(phenylene oxide) (PPO), and poly(styrene-methyl methacrylate) (PSMMA). These polymers represent a wide range of le values, where le is the chain contour length between entanglements. Quantitative transmission electron microscopy has been used to analyze the extension ratio λcraze and displacement profiles for these crazes. From these measurements the craze surface stresses have been computed by using the method of distributed dislocations. This analysis also permits an accurate measure of the level of the applied stress σ∞. These measurements show that the stress necessary for crazing increases as le decreases and that the higher surface stresses present at crack tips generate crazes that have higher λs than isolated crazes in the same polymers. Surface drawing is shown to be the dominant mechanism for craze thickening in all five polymers.
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  • 67
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1175-1192 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Shrinkage of unconstrained low-density polyethylene samples and the retractive stress of samples with ends fixed have been investigated as a function of the annealing time tA and temperature TA on material drawn at room temperature to draw ratios λ between 4 and 6. The shrinkage increases with tA and TA. The retractive stress on a sample annealed with ends fixed goes through a maximum as the sample is annealed and then drops to a limiting value which increases with TA as long as TA is at or below 80°C and rapidly decreases with higher TA. The drop from the maximum to the limiting retractive stress, slow at lower TA and rapid at higher TA, seems to be a consequence of rapid pulling of chain segments out of crystal block in which interfibrillar tie molecules are anchored. This process is facilitated by the high TA, which softens the crystal matrix. At constant end-to-end distance, the contour length of the tie molecules is irreversibly increased, and this causes a reduction in the contribution of the affected tie molecules to the overall retraction stress. Hence one finds a substantially higher retraction stress during first heating than during subsequent cooling and heating of the drawn sample.
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  • 68
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1193-1205 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The birefringence of model structures of ultraoriented polyethylene has been calculated by using the point-dipole concept and the polarizability tensor of the methylene group derived recently by Pietralla. For well-oriented chains the birefringence is determined by the combination of a negative anisotropy of the polarizability tensor of the methylene group and a positive anisotropy of the Lorentz tensor, both with respect to the chain direction. As a consequence it decreases with increasing density. The results are in agreement with experimental values of Mead, Desper, and Porter. In the model the amorphous regions are regarded as a mixture of planar and helical segments arranged in nematiclike bundles which additionally may have a certain distribution of orientation. The birefringence is not much affected by defects which, on the other hand, strongly influence the ultimate mechanical properties.
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  • 69
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1223-1232 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical properties of a series of polyester resins made from a maleic/phthalic anhydride-based unsaturated polyester crosslinked with each of styrene, 4-methyl styrene, 4-ethyl styrene, 4-n-butyl styrene, 4-isopropyl styrene, tertiary butyl styrene, 4-chlorostyrene, and 3,4-dichlorostyrene were studied. The order of the α transition temperatures was as expected from that for the homopolymers, except in the case of the chlorostyrenes, for which dipolar interactions with the polyester chain may be important. The styrene bridges appeared to be involved in a steric interaction (and in the case of the chlorostyrenes, a dipolar interaction) with the β relaxing ester species. It is suggested that both the γ and γ′ relaxations involve similar interactions between the matrix and the relaxing moieties. For the 4-n-butyl styrene resin, an additional relaxation below -170°C was observed, and is ascribed to relaxation of the n-butyl group.
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1233-1247 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This article demonstrates that the neglect of nonlinear effects in the conventional counterion condensation theory for the double layer about a charged cylinder can be significant, especially for phenomena involving intramolecular or intermolecular interactions in dilute solutions. For concentrated solutions the Manning theory derives from a linearized superposition approximation for the potential, in contrast to the cylindrical-cell model, which explicitly treats interactions within an ordered array of parallel cylinders. A new theory which treats interactions explicitly while permitting disorder in two dimensions is presented, and predictions for the osmotic pressure are compared with those from the Manning and cylindrical-cell models.
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  • 71
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1269-1278 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ultrasonic measurements were made on a series of eight crosslinked polyepoxides over the temperature range from 0 to 60°C at a frequency of 2 MHz. From these measurements the bulk (K) and shear (G) moduli were calculated. These data were then analyzed in terms of molecular component properties. Proceeding by analogy with Rao's rule for liquids, the authors found that K is not an additive property but the function U = V(K/ρ)1/2γ is an additive property. Here V is molar volume, ρ is the density, and γ is the Gruneisen parameter (for interchain vibrations). A similar relation was found to hold for shear modulus. In particular, G is not an additive property but W = V(G/ρ)1/2g is an additive property, where g = (1/2α) (∂ InG/∂T)p - 1/2 is the shear analog of the Gruneisen parameter. Using U and W, calculations were made of K and G as functions of temperature for the eight epoxies. These results agree with the measured values within the experimental uncertainty of the measurements.
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  • 72
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1279-1287 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: A rheo-optical investigation has been carried out on a sample of high-density polyethylene (HDPE) in an attempt to examine the nature of the α-relaxation mechanism. Dynamic mechanical and bi-refringence behavior was measured over the frequency range of 0.008-4.3 Hz and temperature range -40 to 100°C. The dynamic mechanical and birefringence data were reduced to a reference temperature of 50°C by a combination of horizontal and vertical superposition. The significance of the vertical shift factor has been discussed extensively in previous papers and is not dealt with here. An Arrhenius plot was made of the log of the horizontal shift factor versus reciprocal temperature for the mechanical and optical data. The mechanical data exhibited three distinct regions, the slopes of which led to activation energies of 70, 90, and 150 kJ mol-1. The temperature at which these dispersions occurred suggested the observation of the β, α1, and α2 relaxation processes. The optical data contained two distinct regions from which activation energies of 55 and 95 kJ mol-1 were obtained. The high-temperature α2 process was not observed in the Arrhenius plot; however, a maximum in K′ and a change in sign of K″ probably reflects a contribution from the α2 relaxation mechanism.
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  • 73
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetic interpretation of the damage produced by heavy ions (3684Kr and 1735Cl from 1 MeV/amu) and γ radiation in cellulose triacetate leads to an exponential dependence on the ion fluence. A comparison of the fading effect produced by heavy ions and γ rays shows that the heavy ions, unlike γ rays, cause irreversible damage. Finally, a nonlinear dependence on the flux of ions and γ rays is found in the kinetics of radiation damage. This result is contrary to the usual assumption that heavy-ion flux, like γ-ray flux, is additive, at least for the fluxes of 109-2 × 1010 ions/cm2s and dose rates of 103-104 Gy/h used in this work.
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  • 74
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1327-1340 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Tracks of heavy charged particles have been observed in cellulose acetate by conventional electron microscopy (100 kV) and by high voltage microscopy (1, 2 MV). The tracks are formed of successive islets following each other at distances of 70-150 Å. With the evolution of the diameter of these zones is shown the existence of a highly perturbed cylindrical volume (diameter 400 Å for the case of krypton) corresponding to regions in which free radicals have been created. The different techniques used do not allow observation of the latent track because of the complications of energetic phenomena: the electron beam current density being limited, the contrast is small and hence the resolution is restricted.
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  • 75
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1289-1311 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Our earlier results on ασ and heavy-ion-radiation damage in cellulose triacetate (CTA) are compared with those of previous authors on UV-and γ-radiation damage in the same material. Thus the common effects of these different methods of irradiation can be distinguished from those characteristic of the radiation employed. With heavy-ion radiation the production of stable radicals is accompanied by C - O cleavage. In the case of 3684Kr (1 MeV/amu) ions, the number of free radicals produced is investigated, without distinguishing the species, by using the scavenger technique in the solid phase, combined with UV spectroscopy. On the other hand, C - O cleavage is observed by IR spectroscopy, with its inherent selectivity. A statistical study shows that the experimental curves representative of the evolution of the optical transmittance ratio before and after irradiation L(N) versus the ion fluence N are of exponential type: $$ L(N) = \alpha e^{\beta N} $$ where β is a parameter related to the volume damaged by a single ion and, therefore, to the latent track size. The latter is approximated by a cylinder whose height is equal to the range of the ion. For 3684Kr8+ (1.1 MeV/amu) the track length is 21 μ. For each type, damages are localized within a radius of 250 Å for free-radical yields, 148 Å for cellulosic chain cleavages, 108 Å for deacetylation, and 100 Å for opening of pyrannosic rings. The track length is 14 μ for 1735Cl6+ (1 MeV/amu), while the radius of the cylinder in which free radicals are produced is only 80 Å.
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  • 76
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1341-1353 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A number of characteristic liquid-crystalline textures can be obtained in binary and ternary systems (i.e., including one or two solvents) based on polystyrene-poly(ethylene oxide) (PS-PEO) and polystyrene-polyisoprene block copolymers. These textures include oily streaks, myelinic figures, and vesicles, all characteristic of a lamellar structure; fan-shaped textures of cylindrical structure; and isotropic domains indicative of a cubic structure. Experimental conditions used to systematically produce the mesomorphic textures are described, and the rather critical solubility conditions which the solvents must meet are indicated. The rules and described procedures should be quite general and applicable to other copolymers as well. Finally, highly unusual examples of “pseudomorphosis” typical of liquid-crystalline textures occurring in bulk upon melting and crystallization of the PEO sequences in PEO-PS copolymers are also reported.
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1355-1364 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electrostatic internal and free energies are calculated for the cell model of a polyelectrolyte solution having two kinds of counterions of the same charge but different size. The calculation is based on the solution of the Poisson-Boltzmann equation obtained previously. The electrostatic contributions to the internal and free energies are presented as functions of valences, radii, and mole fractions of counterions, and their application to interpretation of experimental results is discussed.
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  • 78
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    Notes: Absolute intensity measurements of a dynamic small-angle x-ray scattering from a linear polyethylene were carried out during polymer crystallization from melt in a temperature range of 113.5° to 124.5°C. The mean-square modulation of the electron density over the irradiated volume was evaluated and the feasibility of dynamic experimentation for crystallization kinetic analysis was established. The results provide an absolute value of mass density of the amorphous phase of a semicrystalline polymer at the crystallization temperature.
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1371-1384 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Hydrostatic pressure usually increases the glass transition temperature Tg of a polymer glass by decreasing its free volume; if the pressurizing environment is soluble in the polymer, however, one might expect an initial decrease in Tg with pressure as the polymer is plasticized by the environment. Just such a minimum in the Tg of polystyrene (PS) is observed as the pressure of CO2 gas is increased over the range 0.1-105 MPa from both ultrasonic (1 MHz) measurements of Young's modulus E and static measurements of the creep compliance J. A time-temperature-pressure superposition law is obeyed by PS which allows a master curve for the compliance to be constructed and shift factors to be determined. A master curve for E is then obtained by using the Boltzmann superposition principle. The compliance J reaches a maximum, and E and Tg reach minima, at a CO2 pressure of ca. 20 MPa at both 34 and 45°C, which are above the critical temperature (31°C) of CO2. At the minimum, Tg is 41 at 45°C and 36 at 34°C, the larger depression at 34°C evidently corresponding to the higher solubility of CO2 at the lower temperature. The plasticization effect due to CO2 can be isolated by subtracting the effect of hydrostatic pressure alone from the experimental data. The results leave no doubt that at high pressures CO2 gas is a severe plasticizer for polystyrene.
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1385-1397 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The pressure-volume-temperature (PVT) properties of blends of poly(2,6-dimethyl-1,4-phenylene ether) (PPO) with polystyrene (PS) have been studied experimentally in both the glassy and melt states at 0, 20, 40, 50, 60, 80, and 100% PPO content. In all compositions a strong glass transition was observed varying linearly with composition. For all but the 40% PPO composition this was the only transition, indicating molecular compatibility of the components in these blends. The 40% PPO composition showed a very weak second transition near the glass transition of pure PS. A small amount of phase separation may have occurred in this blend. The data for the glassy and melt states were fitted to an empirical equation of state based on the Tait equation. The volume of the melts at constant pressure and temperature showed a virtually linear dependence on composition. Any negative excess volume of mixing compatible with the data would have to be very small, smaller than expected from previous measurements in the glassy state. Various properties relating to the glassy and melt states and to the glass transition were evaluated and are discussed as a function of composition. It was found that most properties of the glasses could not be modeled by simple functions of composition.
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1399-1408 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A recent theory of multicomponent fluids is applied for the first time to a compatible binary polymer blend. Good accord between the experimental pressure-volume-temperature measurements over the whole range of compositions by Zoller and theoretical predictions obtains. In particular, satisfactory predictions of high pressure from low-pressure information result. From the interplay between experiment and theory, the scaling quantities and thus the characteristic self- and cross interaction parameters are derived. The excess volumes are discussed and estimates of excess enthalpies presented. The theory predicts the actual enthalpy of the components or mixtures once the scaling parameters have been determined by means of volume-temperature data at atmospheric pressure. Enthalpy measurements to test these predictions are highly desirable.
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  • 82
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1409-1425 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Oscillatory flow birefringence (OFB) measurements have been carried out for an extensive series of solutions containing narrow-distribution, atactic, linear polystyrenes PS (10, 000 or 390, 000 Mw) or poly(α-methylstyrene) PMS (400,000 Mw) in a high-viscosity solvent, Aroclor 1248. The concentration ranges examined are such that the concentration dependence is obtained in both the “dilute” and “semidilute” regimes; the data are sufficiently precise to permit extrapolation to obtain for the first time the infinite-dilution properties. Various plotting formats are explored to determine an appropriate extrapolation procedure. The infinite-dilution OFB properties are compared with the bead-spring model (Zimm) theory which predicts quantitatively the frequency dependence of the observed properties for the PS and PMS solutions studied except for the high-frequency regime. The sensitivity and precision of the OFB experiment is such that the extrapolation curves-and the resulting infinite-dilution properties-show substantially less scatter than comparable visco-elasticity (VE) data. There is no evidence of a change in the character of the concentration dependence for the range of concentrations studied.
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1437-1442 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A general equation is derived for the stress response of a linear viscoelastic material to periodic strain excitation at constant strain rates. The energy dissipated in any cycle, especially in a steady-state loop, is discussed. The results can be used to analyze test results in determining mechanical properties of polymers. A simple Maxwell model and a three-parameter Maxwell model are used to illustrate the calculation of stress response and energy dissipation under constant-strain-rate loading.
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1427-1435 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The carbon-13 spin-lattice relaxation times T1 of the crystalline components of four solid ethylene-octene copolymers have been studied as a function of thermal history, branching number, and branching distribution. Slowly cooled samples (1 deg/min from melt to room temperature) exhibited similar or longer T1s with respect to the same sample quench cooled (from the melt into 20°C water). The greater the degree of branching and the more homogeneous the branching distribution, the shorter were the observed crystal lattice T1s. Differences of up to a factor of 3 in T1 were observed for the same sample undergoing the two thermal treatments. Different degrees of branching homogeneity (for the same total number of branches) resulted in differences approaching a factor of 7 for samples with the same thermal history. These variations were attributed to the differing effects of side-chain disruption of the crystal lattice.
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1443-1451 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of data imprecision and baseline uncertainties have been investigated by computer simulation of GPC data from a polymer sample with a truncated log-normal molecular weight distribution. If the data are very accurate, as few as five data points can be sampled without serious error in computed molecular weight averages. The number of data points required is much larger, however, if these are taken at equal increments of molecular weight rather than elution volume. The effects of noise can be counteracted by increasing the sampling frequency. Baseline uncertainties present a more serious problem, especially for broad-distribution samples. If the detected signal is too noisy to permit accurate location of the baseline, errors can be minimized by using a second, more sensitive detector to determine the peak start and end. It is very difficult to estimate M̄z and higher molecular weight averages accurately if the noise level is greater than 0.5%.
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  • 86
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1453-1464 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The pressure-volume-temperature (PVT) relationships of bisphenol-A polycarbonate, polyarylate, and phenoxy were studied at pressures to 1800 kg/cm2 and in both the glassy and melt states. Earlier data on polysulfone are included in the analysis and discussion of the results. All four polymers contain the bisphenol-A residue in their repeat unit, together with a moiety of varying complexity, and are therefore somewhat related. At the glass transition, equations of the Ehrenfest type hold, provided the pressure dependence of the glass transition temperature is defined from the line obtained by intersecting the quasiequilibrium PVT relationship of the glass with the equilibrium PVT surface of the melt. The Prigogine-Defay ratio r = ΔκΔCp/TgVg(Δα)2 at P = O is unity within experimental error for all four polymers. The melt data were fitted successfully to the Simha-Somcynsky theory. Molecular parameters deduced from the reducing parameters vary in a reasonable manner among these four related polymers, lending support to the foundations of the theory.
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  • 87
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1485-1496 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The aliphatic polyamides nylon 6 and 6,6 have been cold drawn by using the new concept of reversible plasticization with NH3. Two aspects were investigated: the effect of NH3 plasticization on the stress-strain behavior of nylon 6,6, and the extent of NH3 absorption as determined by x-ray analysis for the structurally simpler nylon 6. X-ray analysis shows that ammonia is absorbed preferentially by the amorphous phase and that the plasticization has a significant effect on the unit-cell orientation, the small-angle void scattering, and the interplanar spacings between sheets of hydrogen-bonded chains. The effect of plasticization was seen in the lower yield stress, the higher draw ratio (up to 8X) and tensile modulus (10 GPa) not attainable with unplasticized specimens.
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  • 88
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1465-1484 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystalline morphology, or supermolecular structure, of poly(ethylene oxide) has been studied as a function of molecular weight and crystallization conditions. Molecular weight fractions, covering the range 6 × 103 to 1 × 107 are used over the range of accessible temperatures for isothermal crystallization as well as for a large set of controlled nonisothermal crystallization conditions. A morphological map is constructed from these studies and compared with the literature results. Prior reports were primarily confined to low molecular weights, which restricted the generalization of the findings. In the present work, as a consequence of the extended molecular weight range, conditions are established for the systematic development of several different, well-defined, organized super-molecular structures as well as for highly crystalline but disorganized systems. Strong similarities are found between the results for poly(ethylene oxide) and previous reports for linear polyethylene. A generalization for all chain molecules is suggested.
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  • 89
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1497-1502 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rms radii of gyration 〈S2〉1/2 and second virial coefficients Γ2 of five monodisperse polystyrenes (M × 10-5 = 1.6, 2.8, 4.2, 6.6) were measured in isorefractive toluene-poly(methyl methacrylate) (M̄v = 4.0 × 104, 1.6 × 105, and 6.3 × 105) “solvents.” For a given PMMA, the concentration at which the θ condition (defined by Γ2 = 0) was reached was independent of PS molecular weight, but varied inversely with PMMA molecular weight (0.10, 0.056, and 0.023 g/mL, respectively). When this θ condition is reached by adding PMMA to toluene, the radii of gyration are decreased by only about 15%, much less than when it is reached by going to a poor, low-molecular-weight solvent. This reflects the exclusion of PMMA from the PS coils, the internal environment of which is essentially pure toluene.
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  • 90
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1503-1509 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Small- and wide-angle x-ray scattering results for a series of un-neutralized and neutralized sulfonated polystyrenes are presented for the range of sulfonation from 0 to 7.26 mol %. From the small-angle scattering it is shown that above the 3 mol % level for both the zinc and sodium salts, a Bragg spacing (37 Å) and diameter (6.9-8.4 Å) of the scattering unit can be calculated. When the concentration of salt is increased, there is no appreciable change in the latter two measurements. The wide-angle data indicate that the cations do not influence to any large extent the basic intramolecular and intermolecular structure of polystyrene. All the data are consistent with the onset of clustering above a critical ion concentration.
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  • 91
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1525-1531 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Stress-induced crystallization of natural rubber networks is studied. The analysis is carried out using two different experimental techniques and the results are compared. In particular, the microcalorimetric and photoelastic results seem to be in disagreement, but the disagreement can be resolved by assuming that organization phenomena take place even at strains less than the critical value at which thermally detectable crystallization occurs. It is believed that such organization phenomena give rise to highly defective crystallites which behave as nucleation agents in the crystallization process that is induced at larger strains.
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  • 92
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1513-1524 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dilute-solution hydrodynamic data for xanthan biopolymer in water suggest a rodlike molecule of dimensions 15,000 × 20 Å, and molecular weight 2.2 × 106 g/mol. Upon addition of NaCl to this system, the xanthan molecules self-associate to form stable aggregates. The native xanthan conformation can be thermally denatured to a disordered coil which can be stabilized at room temperature in 4M urea. The transition to semidilute solutions is manifested by discrete changes in the concentration dependence of diffusion coefficient and zero-shear viscosity at c ≈ 2.0 × 10-4 g/mL. At higher concentrations c ≥ 1.0 × 10-3 g/mL, the light-scattering and shear-viscosity data are qualitatively but not quantitatively consistent with predictions of the dynamical theory of Doi and Edwards for an isotropic entangled solution of rigid-rod molecules. Measurements of latex sphere diffusion in xanthan-water solution show a sudden retardation at c ≈ 1.0 × 10-3 g/mL, consistent with the cooperative formation of a motionally restricted network of long, thin, rigid fibers. At high shear rates, flow birefringence experiments indicate enhanced ordering of the xanthan chains in the semidilute regime.
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  • 93
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1533-1550 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some of the history of the proposed liquid-liquid transitions Tll and T′ll that have been reported to exist above the glass transition temperature Tg and the role played by the torsional braid analyzer are outlined. Confusion has been created by the failure to clearly distinguish such kinetic phenomena as viscoelastic and dielectric loss processes from thermodynamic transitions. It is shown quantitatively how the log decrement of an oscillating system can exhibit one more peak than is found in the loss tangent-temperature curve of a viscoelastic liquid.
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  • 94
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1551-1564 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A torsional braid analyzer (TBA) has been constructed for an investigation into the behavior of this instrument. An explanation was desired for the presence of the proposed second liquid-liquid transition T′ll peak in the log decrement-temperature curve of a low-molecular-weight polystyrene whose loss tangent increases monotonically as a function of increasing temperature at constant frequency. The response of the TBA was studied as a function of amplitude of oscillation, the nature of the braid, the braid tension, frequency, and the nature of the impregnant. All of the braids examined were shown to be extremely nonlinear in their response. Two peaks in the damping of the composite system as a function of temperature are attributed to the interaction between the impregnant properties and the nonlinear response of the glass fiber braid.
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  • 95
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The liquid-liquid transition Tll has been examined by using differential scanning calorimetry as the tool of measurement. The results presented show that for the case of polystyrene, the Tll event appears to be an artifact caused by the presence of volatile components. Purified samples of polystyrene, polydienes, and poly(1-butene) do not show the Tll transition.
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  • 96
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1575-1583 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosity data available for four anionically polymerized polystyrenes ranging in molecular weight from 1100 to 47,000 for the temperature range Tg to Tg + 100°C have been fitted by computer programs to both the Vogel, Fulcher, Tamman, and Hesse (VFTH) equation and to two optimum intersecting Arrhenius equations. The intersection point has been interpreted as a manifestation of a liquid-liquid transition. The fits to the VFTH equation were in every case found to be far superior. Systematic deviations of the residuals were observed for the best Arrhenius fits which indicate the lack of any validity for such a representation of the data.
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  • 97
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1585-1592 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The determination of the properties of aqueous salt solutions of poly(ethylene oxide) has been extended to cloud-point and θ-temperature measurements in sodium acetate, potassium fluoride, sodium thiosulfate, and potassium phosphate. The Hofmeister series for the decreasing effect of anion species in salting out the polymer is accordingly extended. However, the order of the effect depends on whether it is made on the basis of molar anion concentration the molar concentration of unit anion charge, or the ionic strength. Viscosity measurements on θ and non-θ solutions containing zinc sulfate, potassium fluoride, and potassium phosphate gave polymer dimensions (in addition to limiting viscosity numbers etc.), and characteristic ratios in good agreement with theoretical predictions (Abe and Mark), and enthalpy and entropy parameters χH and χs; the latter values, nominally -0.14 and 0.63, are identical at 298 K for the three salt species.
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  • 98
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1593-1607 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dilute mixtures of poly(ε-caprolactone) (PCL) in poly(vinyl chloride) (PVC), poly(p-iodostyrene) (PpIS) in polystyrene, and deuterated polystyrene (d-PS) in protonated poly(o-chlorostyrene) (PoCIS) were investigated by means of small-angle x-ray scattering and small-angle neutron scattering. The radii of gyration of PCL in PVC and of d-PS in PoCIS were found to be expanded over the θ values by 50 and 30%, respectively. Values of the second virial coefficient were positive although errors prevented definitive evaluation of the interaction parameter. PpIS was found to aggregate, with both the radius of gyration and molecular weight increasing with concentration. Concentrated mixtures of PCL and PVC were also investigated by using the Debye-Bueche correlation function analysis. Correlation distances indicated good mixing throughout the entire composition range.
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  • 99
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1609-1615 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ethylene glycol dimethacrylate (EGDM) was polymerized to provide specimens suitable for three-point bending tests. Fracture surfaces were generally similar to those reported previously for relatively brittle materials such as silicate glasses. Attention was concentrated on linear features which lay in roughly parallel arrays in the direction of crack propagation. Generally the features had a circular cross section which, in a few cases, tapered to a fine point. In other cases partially detached features were observed to have an irregular radius of curvature. The two preceding observations were interpreted as evidence of localized plastic deformation. The linear arrays of surface features were explained by adoption of Preston's mechanism for formation of “stries” in brittle materials. However, this mechanism calls for a characteristic cross section which in the case of poly(EGDM) was replaced by a circular cross section. To account for this difference, localized plastic deformation was invoked.
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  • 100
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    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1617-1622 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low-temperature dielectric loss measurements reveal a tendency of 4-methyl-2, 6-di-tert-butyl phenol (the antioxidant BHT) to associate with various reagents in hydrocarbon media. The affinity with carbonyl groups appears to be particularly appreciable. It is suggested that this may have a bearing on the antioxidant activity of this type of compound.
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