In this communication we wish to report a new technique to inter-convert numerically linear viscoelastic functions. Customarily such computations are accomplished through the distribution of relaxation times [l-41. Difficulties encountered in such methods have been dis-cussed [3,5]. Our technique circumvents the use of distribution of relaxation times by resorting to linear programming (LP). Because of its importance in operations research, standard LP routines are readily available in any computer library. Thus calculations may be accomplished with minimal efforts in further programming. In this work, we have used ALPHAC, an LP routine developed at the Univer-sity of California Computer Center. The method is simple to use, requires relatively few data points, and yields rather accurate re-sults. cable to systems of linear equations [6]. The classic problem of LP Linear programming is a numerical optimization procedure appli-cable to systems of linear equations [6]. The classic problem of LP

AbstractThe hydrophilic behavior including water absorption, swelling, and dielectric spectrum of pure HSPAN as well as HSPAN/PVA blends are investigated. The HSPAN/PVA membranes still absorb a considerable amount of water. The effect of water upon mechanical properties is also investigated for these membranes. Formalization of membrane enhances mechanical properties and reduces weight losses during swelling with much loss in the water absorption ability of PVA. This kind of blend shows promise as material for hydrophilic membranes.

A chemorheological equation of state for the stress relaxation of elastomers has been derived. This equation of state provides a general relationship between stress ratio and aging time.

AbstractA simple equation is proposed to calculate the shear‐rate‐dependent viscosities of entangled polymers and particle suspensions. The rate‐dependence of the viscosities is attributed to changes in certain structural parameters associated with the fluids, such as entanglement density or degree of particle agglomeration. The state of these structural parameters for fluids subjected to a given shear flow is determined by two competing process, i.e., structural breakdown and reformation, which in steady How arc in a state of dynamic equilibrium. For the polymer systems structural degradation and reformation are tantamount to entanglement loss and creation, whereas for the suspensions they are correlated with the particle breakup and flocculation. The regeneration process is driven by thermal diffusion and is assumed to be independent of shear rate. The degradation process is caused primarily by the imposed shear and is assumed to be proportional to the shear rate to a power m (0

The Rouse-Bueche-Zimm molecular theory of viscoelasticity has been extended to compute the relaxation time spectra of radial block and graft copolymers of various configurations and compositions. The basic assumption of the model is that the effect of foreign blocks and grafts on the relaxation spectrum is attributable to differences in the friction coefficients and submolecular chain dimensions from those of the host chain. In addition, the nearest-neighbor matrix must also be appropriately modified to take into account the nonlinear nature of the chain structure. Relaxation spectra can then be obtained by solving the equation of motion numerically on a computer. The resulting viscoelastic relaxation times of those copolymers are given as a function of copolymer composition, number of side chains, their lengths and the spacings between them. The model is restricted to bulk homogeneous copolymers or those copolymers dissolved in appropriate solvents to preclude microphase separation.

AbstractThe current, and rather incomplete, understanding of the role of amorphous contribution to the Grüneisen functions of semicrystalline polymers is reviewed. There are two kinds of Grüneisen functions. The microscopic mode Grüneisenr parameter is a measure of the volume dependence of lattice frequencies in a solid. Their magnitudes vary with the specific mode. The macroscopic Grüneisen constant relates the mechanical and thermal parameters in solids. It is a weighted average of mode Grüneisen parameters. At a given temperature there is only one Grüneisen constant for a material. Because the various experimental techniques often favor certain lattice modes, there is a great variation in the literature values of Grüneisen functions for polymeric solids., For semicrystalline polymers, the degree of crystallinity and thermal history also affect the measured magnitudes. In this work a unified derivation of the existing equations will be given. Current theoretical models for the Grüneisen constants are described. The available literature data on Grüneisen constants of semicrystalline polymers, principally polyethylene, will be discussed.

The plasma polymerization of ethane has been studied in the frequency range of from 50 Hz to 13.56 MHz. The rate of polymer deposition is strongly dependent on frequency, with significantly higher rates being observed at frequencies below 6 MHz. The effects of frequency can be interpreted in terms of a mechanism that assumes that polymer is formed by the reaction of surface free radicals, created by the bombardment of the growing polymer by charged species, with gas phase free radicals, formed by collisions of energetic electrons with monomer molecules.

Journal of Polymer Science: Polymer Letters EditionVolume 17, Issue 9 p. 595-599 Article A kinetic network model for nonlinear viscoelastic flow properties of entangled monodisperse polymers David Soong, David Soong Department of Chemical Engineering, University of California, Berkeley, Berkeley, California 94720Search for more papers by this authorMitchel Shen, Mitchel Shen Department of Chemical Engineering, University of California, Berkeley, Berkeley, California 94720Search for more papers by this author David Soong, David Soong Department of Chemical Engineering, University of California, Berkeley, Berkeley, California 94720Search for more papers by this authorMitchel Shen, Mitchel Shen Department of Chemical Engineering, University of California, Berkeley, Berkeley, California 94720Search for more papers by this author First published: 6 September 1979 https://doi.org/10.1002/pol.1979.130170909Citations: 12AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume17, Issue96 September 1979Pages 595-599 RelatedInformation

AbstractReverse osmosis membranes prepared by plasma polymerization of allylamine–nitrogen mixtures over a porous substrate were evaluated for the rejection of components present in washwater. The membranes exhibited high rejections for sodium chloride, potassium chloride, detergent, and dextrose. High rejections of urea could be achieved, but only at a sacrifice of water flux. Lactic acid could also be rejected but caused a degradation of the plasma‐deposited layer.

Journal of Applied Polymer ScienceVolume 23, Issue 1 p. 299-302 NoteFree Access Secondary relaxation behavior of some diene polymers Jacob Mathew, Jacob Mathew Department of Chemical Engineering, University of California, Berkeley, California 94720Search for more papers by this authorMitchel Shen, Mitchel Shen Department of Chemical Engineering, University of California, Berkeley, California 94720Search for more papers by this authorThomas F. Schatzki, Thomas F. Schatzki Western Regional Research Center, U. S. Department of Agriculture, Berkeley, California 94710Search for more papers by this author Jacob Mathew, Jacob Mathew Department of Chemical Engineering, University of California, Berkeley, California 94720Search for more papers by this authorMitchel Shen, Mitchel Shen Department of Chemical Engineering, University of California, Berkeley, California 94720Search for more papers by this authorThomas F. Schatzki, Thomas F. Schatzki Western Regional Research Center, U. S. Department of Agriculture, Berkeley, California 94710Search for more papers by this author First published: 1 January 1979 https://doi.org/10.1002/app.1979.070230127Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References 1 R. P. Gupta, J. Phys. Chem., 66, 1 (1962). 2 R. J. Morgan, L. E. Nielsen, and R. Buchdahl, J. Appl. Phys., 42, 4653 (1971). 3 T. F. Schatzki and R. G. Meisenheimer, Shell Development Company Technical Report No. 141, 1963 (obtainable from TFS); J. Mathew, M.S.Ch.E. Thesis, University of California, Berkeley, 1976. 4 G. Kraus, C. W. Childers, and J. T. Gruver, J. Appl. Polym. Sci., 11, 1581 (1967). 5 K. Sanui, W. J. MacKnight, and R. W. Lenz, Macromolecules, 7, 101 (1974). 6 J. K. Gillham and J. A. Benci, J. Appl. Polym. Sci., 18, 3775 (1974). 7(a) T. F. Schatzki, J. Polym. Sci., 57, 496 (1962); (b) Polym. Prepr. Am. Chem. Soc., Div. Polym. Chem., 6, 464 (1965); (c) J. Polym. Sci., C14, 139 (1966). 8 J. Mathew, M. Shen, and T. F. Schatzki, J. Macromol. Sci. Phys., B13, 349 (1977). Citing Literature Volume23, Issue11 January 1979Pages 299-302 ReferencesRelatedInformation

AbstractThe plasma polymerization of C2F4 was carried out in both continuous wave and pulsed rf discharges to establish the effects of reaction conditions on the kinetics of polymer deposition and the polymer structure. ESCA spectra of the polymer show evidence for CF3, CF2, and CH2 groups. Under conditions favoring low deposition rates, the dominant functional group is CF2. At higher deposition rates the concentration of CF2 groups is reduced and a more crosslinked polymer is produced. Both polymer deposition rates and polymer structures were essentially identical when using continuous wave and pulsed rf discharges.

The effect of discharge frequency on the kinetics of plasma polymerization of ethane was studied over the frequency range from 50 Hz to 13.56 MHz, in a tubular reactor at a pressure of 0.5 torr, a flow rate of 20 cm3STP/min and a discharge power level of 10 watts. The discharge voltage and current were also measured at the same time. On the basis of these data, the following polymerization mechanisms are proposed, i. e., ion bombardment in the frequency range from 50 Hz to 50 KHz, electron bombardment from 50 KHz to 6 MHz and free radical and/or ion-electron pair diffusion from 6 MHz to 13.56 MHz. In the region that ion or electron bombardment is the predominant mechanism, most films were cracked, but in the region that the free radical and/or ion-electron pair diffusion are predominant, transparent or colored films were obtained in the relatively wide discharge parameter range. The infrared spectra and dielectric properties of the films formed in the three frequency regions were also measured. The infrared spectrum showed a broad absorption in the wave length region over 8 μm. This absorption depends on the polymerization condition, suggesting the existence of OH and CO as well as unsaturated groups. The dielectric properties are also affected by the condition of polymerization, treatment after film formation, film thickness and so on. In our experimental condition, an appearent loss peak can be observed at a temperature of -30 °C for a measuring frequency of 1 KHz. The activation energy of this loss peak was about 0.68 eV for each sample formed at the different discharge conditions. It is proposed that this loss peak is attributable to γp assigned to the carbonyl group.

Polymers can be obtained by subjecting an organic or organometallic vapor to the plasma created in an electrical glow discharge. By varying the plasma conditions such as pressure, monomer flow rate, power etc., not only films but also powder and oil are formed In this paper we shall consider both the mechanism of polymerization and the influence of reaction conditions upon the rates of polymerization. A kinetic model will be presented, which appears to be in good agreement with experiments. The plasma polymerized materials can be characterized by IR, NMR, ESCA and other analytical techniques. It has been found that the polymer is highly crosslinked, amorphous and often contains functional groups not originally present in the monomer. The electrical properties of these films will also be discussed. Some of the potential applications of plasma polymerized films will be pointed out.