Polymer Sci Research Articles

Energy release rate of a single edge cracked specimen subjected to large deformation

The single edge notch specimen (SEN) is commonly used to measure the fracture toughness, or critical energy release rate of soft elastic materials. To measure toughness, an expression for the energy release rate, J, the mechanical energy available for growing the crack per unit area, is needed. Since strains in these fracture experiments can easily exceed several hundred percent, large deformation analysis is needed to calculate J. An approximate formula for J in SEN samples subjected to moderately large deformation was given by Rivlin and Thomas in J Polym Sci 10:291–318. https://doi.org/10.1002/pol.1953.120100303 (1953) and Greensmith in J Appl Polymer Sci 7:993–1002. https://doi.org/10.1002/app.1963.070070316 (1963). However, this formula works only for small crack lengths, for stretch ratio up to two and does not match the linear elastic result in the limit of small strains. In this paper we carry out a series of finite element (FE) simulations to obtain accurate approximations that are valid for all practical crack lengths and strain levels. Our FE result shows that the small crack approximation of by Rivlin and Thomas in J Polym Sci 10:291–318. https://doi.org/10.1002/pol.1953.120100303 (1953) does not work well in the small strain regime, and in particular, result of Greensmith in J Appl Polymer Sci 7:993–1002. https://doi.org/10.1002/app.1963.070070316 (1963) underestimates the energy release rate for stretch ratios less than 1.5.

Detaching Microparticles from a Liquid Surface.

The work required to detach microparticles from fluid interfaces depends on the shape of the liquid meniscus. However, measuring the capillary force on a single microparticle and simultaneously imaging the shape of the liquid meniscus has not yet been accomplished. To correlate force and shape, we combined a laser scanning confocal microscope with a colloidal probe setup. While moving a hydrophobic microsphere (radius 5-10 μm) in and out of a 2-5 μm thick glycerol film, we simultaneously measured the force and imaged the shape of the liquid meniscus. In this way we verified the fundamental equations [D. F. James, J. Fluid Mech. 63, 657 (1974)JFLSA70022-112010.1017/S0022112074002126; A. D. Scheludko, A. D. Nikolov, Colloid Polymer Sci. 253, 396 (1975)] that describe the adhesion of particles in flotation, deinking of paper, the stability of Pickering emulsions and particle-stabilized foams. Comparing experimental results with theory showed, however, that the receding contact angle has to be applied, which can be much lower than the static contact angle obtained right after jump in of the particle.

Drying dissipative structures of the aqueous suspensions of palygorskite and tungstic acid particles

Macroscopic and microscopic dissipative structural patterns during dryness of the aqueous suspensions of palygorskite (PGK, needle-like shaped) and tungstic acid (TA, plate-like) have been studied on a cover glass. The coexistence of the broad ring of the hill accumulated with the particles and the round hills is observed around the outside edges of the dried film and in the center, respectively. These patterns differ from those of the suspensions of spherical particles. Furthermore, the spoke-like patterns, which have been observed for the suspensions of the spherical particles so often, are not observed at all for PGK and TA suspensions. These characteristic macroscopic patterns of PGK and TA are quite similar to those of the fractionated and monodispersed bentonites (plate-like) reported previously Yamaguchi et al. (Colloid Polymer Sci 283:1123, 2005). Wrinkled and/or branch-like fractal patterns are observed in the microscopic scale, which are quite similar to those of bentonites. “Shape information” of the colloidal particles is clarified to be “transferred” to the drying patterns via the convectional and sedimentary patterns during the course of dryness.

Synthesis of zinc sulfide multi-scale agglomerates by homogeneous precipitation–parametric study and mechanism

When zinc sulfide is prepared by homogeneous precipitation from an acid solution of zinc sulfate and thioacetamide in a stirred reactor, it is generally obtained in the form of four-scale agglomerates. This paper is intended to progress in the understanding of the nature of the construction stages of these agglomerates. For this, successive size scales are studied as a function of several operating parameters: pH, concentration in reactants, temperature and stirring rate. Microscopic characterization is performed at different times of the precipitation process. The successive steps of construction of the multi-scale structure aggregates are discussed in the context of the model of Eshuis and Koning, Coll. Polymer Sci. 272 (1994) 1240 and Eshuis et al. Colloid and Surfaces, Physicochemical and Engineering Aspects 151 (1999) 505.

Stress-Activated Sliding Motion: A Coupled-Potential Model

In a notable study by Julicher & Bruinsma (BPJ 74, 1998), a model was presented describing the motion of an RNAP molecule during an elongation cycle. First, stepping motion of a catalytic (C)-site takes place. This generates stress in the molecule between this (C)-site and a front (F)-site. This stress activates forward sliding of the (F)-site by lowering the activation barrier hindering its motion.Here we look at this RNAP model in terms of a coupled-potential paradigm, taken from an inchworm-like model of a polymer chain. This model describes how stress produced by forward motion of a (C)-like site in the polymer leads to activated sliding of an (F)-like site (Joseph, J Polymer Sci 16, 1978). The (F)-like site has two positions - (1) and (2) - and so possesses a double-well potential. This site is coupled in series to a linear spring - with a single-well harmonic potential. A (C)-like site occupies the spring free end.We find that coupling (adding) these two potentials yields a net potential with the (F)-like site occupying position (1). Also, there is a large activation barrier hindering movement to position (2). However, when the (C)-like site at the spring free end is pulled forward, the stretching of the spring causes the equilibrium position of the harmonic potential minimum to be shifted forward. Coupling of this shifted potential reduces the net potential barrier, and this reduction activates forward sliding motion of the (F)-like site.We conclude that this type of coupled-potential inchworm model yields insight into how stress can activate sliding motion during the RNAP elongation cycle.

Quantitative Deuterium Isotopic Profiling at Natural Abundance Indicates Mechanistic Differences for Δ12-Epoxidase and Δ12-Desaturase in Vernonia galamensis

Quantitative (2)H NMR spectroscopy can determine the natural abundance ((2)H/(1)H) ratio at each site of a molecule. In natural products, variation in these values is related to the reaction mechanisms in the pertinent biosynthetic pathway. For the first time, this novel approach has been exploited to probe for mechanistic differences in the introduction of different functionalities into a long-chain fatty acid. Vernolic acid, a major component of the seed oil of Vernonia galamensis, contains both an epoxide and a desaturation. The site-specific isotopic distribution ((2)H/(1)H)(i) has been determined for both vernolic acid and linoleic acid isolated from the same V. galamensis oil. It is found that the ((2)H/(1)H) ratio of vernolic acid shows a pattern along the entire length of the chain, consistent with linoleic acid being its immediate precursor. Notably, the C13 relates to the C13 of linoleic acid but not to the C13 of oleic acid. Furthermore, the C12 and C13 positions in vernolic acid are less depleted, consistent with a change in hybridization state from sp(2) to sp(3). However, the C11 position shows a marked relative enrichment in the vernolic acid, implying that it plays a role in the epoxidase but not the desaturase mechanism. Thus, although it can be concluded that the catalytic mechanisms for the epoxidase and desaturase activities are similar, marked differences in the residual ((2)H/(1)H) patterns indicate that the reaction mechanisms are not identical.

Fatigue initiation and propagation in natural and synthetic rubbers

Elastomeric matrix composites are usually reinforced by mineral particles such as carbon black and sometimes by long metallic or organic fibers. In the absence of fiber, rubbers can be considered as nanocomposites. In service conditions, the fatigue damage of rubbers is a combination of: (a) mechanical damage; (b) chemical damage; (c) thermal damage. Experience shows that, in cyclic loading, rubbers are damaged to the point of formation of one or several cracks which then propagate. As for metal, it is recommended to study separately initiation of cracks and then their propagation. Generally speaking, the fatigue resistance is affected by chemical transformation such as crystallisation. It means that compression loading is an important factor. To show this effect, an axisymetric hour-glass shape specimen ( D=25 mm) is proposed to test rubbers. A large effect has been found of the mean stress on the fatigue strength depending on the chemical composition of the materials and of crystallisation transformation if it appears. The crack growth rate is studied using linear fracture mechanics as proposed earlier (Rivlin RS, Thomas AG. Rupture of rubber: I. Characteristic energy for tearing. J Polymer Sci 1953;10(3):291). In this case, the strain energy release rate G is substituted for the concept of tearing energy T. The application of fracture mechanics to elastomers generates some difficulties because of the important deformability. In order to apply a tension–compression loading a thick edge notched specimen is recommended with two lateral grooves ( W=150 mm, B=25 mm). For low values of Δ T, a threshold can de defined depending on the R ratio. It is shown that for a high R ratio the fatigue crack would not propagate if the crystallisation transformation is high. In contrast, if R=−1, the threshold disappears. A finite element simulation of stresses and strains is presented in order to get a better explanation of the experimental results.

Ultralow interfacial tensions in water–n-alkane–surfactant systems

The interfacial tensions between water- and oil-rich phases in the presence of microemulsions have been measured for ternary systems of water, n-alkanes, and nonionic alkylpolyglycolether surfactants (CiEj). It is found that the minimum of the interfacial tension curve, which is observed for each system in conjunction with the well-known phenomenon of phase inversion, depends sensitively, but systematically, on the chemical nature of the oil and the surfactant. Specifically, the minimum value of the interfacial tension σ̄ab decreases by 1 order of magnitude on decreasing either the carbon number of the alkane k by 6, or the number of oxyethylene groups j by 3, or by increasing the number of carbon atoms in the surfactant tail i by 2. The numerical values of the interfacial tensions as a function of temperature are presented along with an empirical description previously suggested [R. Strey, Colloid and Polymer Sci. 272, 1005 (1994)]. From the analysis, in terms of bending energy one obtains estimates for the bending and saddle-splay constants. The similar shape of the interfacial tension curves permits a superposition of the data for all 19 systems in support of a scaling relation recently derived [S. Leitao, A. M. Somoza, M. M. Telo da Gama, T. Sottmann, and R. Strey, J. Chem. Phys. 105, 2875 (1996)]. Furthermore, we note a striking coincidence of the numerical values of critical amplitude ratio R=σ0ξ02=0.37 kT in near-critical systems and the product σ̄abξ̄2=0.44(±0.10) kT where ξ̄ is the maximum length scale in the bicontinuous microemulsions.

Spinodal equation for polydisperse polymer solutions

In this paper polydisperse polymer solutions are considered to be described by a class of free-energy functions generalizing the classical Flory-Huggins relation by replacing Huggins’ X -term by a function which is assumed to depend on a finite number of moments of the molar mass distribution. Most free-energy functions used in practice obey this condition. For this class of free-energy functions a spinodal theorem is proved; if the phase considered lies on the spinodal, then a matrix Q is positive semidefinite and its determinant, det Q , equals zero. The calcu­lation of the matrix Q is relatively simple. M. Gordon, P. Irvine & J. W. Kennedy ( J. Polymer Sci . 61, 199 (1977)) and P. Irvine & M. Gordon ( Proc. R. Soc. Lond. A 375, 397 (1981)) showed that the spinodal problem considered may be simplified by replacing the given distribution by a spinodal equivalent distribution consisting of a number of discrete polymer species. For this reason a finite moment problem has to be solved. The theorem proved in this paper results in avoiding the solution of this moment problem and, furthermore, guaran­tees the stability matrix to possess the minimal order.

A pulsed field gradient NMR study of diffusion in semicrystalline polymers: self-diffusion of alkanes in polyethylenes

By means of the pulsed field gradient NMR technique the self-diffusion of six alkanes (from n-butane to n-pentadecane) in three low density polyethylenes and one high density polyethylene differently thermally treated was examined. The concentration dependence could be described very satisfactorily with the free volume theory in the form of Fujita (Adv. Polymer Sci. 3(1961) 1). The parameter B of the diffusants and the fractional free volumef 2 of the polyethylenes were determined from the experimental data. The fractional free volumesf 2 show a strong dependence on the type of polyethylene, the main influence results from the different content of CH3 groups or short chain branches. The diffusion coefficient extrapolated to zero diffusant concentration is proportional to the eighth power of the amorphous content. This strong dependence shows that the free volumes of the amorphous parts of the polyethylenes are intimately connected with crystallinity, both determined by the different degrees of short chain branching. The pre-exponential factor in the free volume expression decreases with increasing amorphous content of the polyethylenes and increases with increasing length of the diffusants. It was found that the spherulite boundaries in the polyethylenes do not act as diffusion barriers.

Experimental evidence that mutual and tracer diffusion coefficients for hemoglobin are not equal

Photon correlation spectroscopy (PCS) has been used to measure the mutual diffusion coefficient Dm for unliganded hemoglobin in the concentration range 0.86 to 15.7 g/dl. The result corrected to water at 20 °C is Dm=Do[1−(0.0057±.0003)c] where Do= (6.75±0.05) ×10−7 cm2/s and c is in units of g/dl. It is shown that Dm can be used with the phenomenological theory of diffusion to predict the tracer diffusion coefficient Dt and that the predictions agree with the results of diaphragm cell measurements [Keller, et al., J. Phys. Chem., 75, 379 (1971)]. In contrast to this, diaphragm cell measurements of Dm do not agree with PCS measurements, with open capillary and free diffusion experiments [Kitchen, et al., J. Polymer Sci. Sym. No. 55, 39 (1976)], or with ultrafiltration measurements [Probstein, et al., J. Phys. Chem. 83, 1228 (1979)]. The evidence indicates that Dm≠Dt for hemoglobin, and that diaphragm cell measurements of Dm are not reliable for proteins. (AIP)

Chain-axis invariant and chain-axis rotation twins in polymer crystals

A detailed treatment is presented of the crystallography of twinning shears which cause the polymer chain axes in polymer crystals to be invariant or to be rotated but undistorted. These chain-axis invariant and rotation twins in polyethylene are considered in detail. The polyethylene twinning mode with twinning elements $$\begin{gathered} K_1 = \{ 102\} ;\eta _1 = \left\langle {20\bar 1} \right\rangle ; K_2 = \{ 100\} ; \hfill \\ \eta _2 = \left\langle {001} \right\rangle and magnitude of shear{\mathbf{ }}g = 0.34 \hfill \\ \end{gathered} $$ is proposed as the twinning mode which is most likely to cause a marked chain axis rotation without causing a change in the orientation of theb axis and only a small change in thickness of crystalline lamellae. These are the requirements ofc-twinning which was used byPietralla (Colloid & Polymer Sci.254, 249–257 (1976) to explain some aspects of the orientation behaviour of polyethylene.

Origin of the γ relaxations in polyethylene and polytetrafluoroethylene (article in J. Polymer Sci. A‐2, 7, 1329, 1969)

Origin of the γ relaxations in polyethylene and polytetrafluoroethylene (article in <i>J. Polymer Sci. A‐2</i>, <b>7</b>, 1329, 1969)

Application of the Hankel transform method in small-angle X-ray scattering for the study of the internal structure of tobacco mosaic virus

A method developed earlier [Fedorov & Aleshin (1966) Vysokomol. Soed. 8, 5016; translated into English in Polymer Sci. USSR (1967) 8, 1657] which permits the determination of the radial electron density distribution function of cylinders on the basis of the small-angle scattering curve, is applied to the study of the tobacco mosaic virus structure. The results obtained are in good agreement with the X-ray structural analysis of TMV. Questions concerning the extrapolation of the experimental curve, the estimation of the obtained resolution of electron density as well as the possibilities of this method are also considered.

Polymerization of epoxyorganosilanes. II. Asymmetric selective polymerization of epoxyorganosilanes

AbstractThe asymmetric selective polymerizationIn PINO's words : stereoselective polymerization, cf. J. Polymer Sci. C 16 (1968) 3265. of epoxyethyltrimethylsilane (ETMS) and of (2.3‐epoxypropoxy)trimethylsilane (EPOS) were studied using a catalyst system formed by an organometallic compound reacted with an optically active reagent. Optically active polymers were obtained in both cases but the asymmetric selectivity of EPOS polymerization was low, considering the weak optical activity of glycidol derived from the hydrolysis of recovered monomer. Concurrently, this experiment permitted us to deduce that dextrotatory EPOS has the same configuration as dextrorotatory glycidol.A polymer of EPOS was submitted to a series of reactions leading to a polymer identical to polypropylene oxide (PPO). The optical behaviour of this polymer, studied in comparison with PPO, also confirmed the relation between the absolute configuration of EPOS and its optical rotation sign. This is the first example, in which the absolute configuration can be determined by utilizing the asymmetric selective polymerization.

Investigation of ionic copolymers by thermal volatilization analysis

Journal of Applied Polymer ScienceVolume 12, Issue 8 p. 1981-1982 NoteFree Access Investigation of ionic copolymers by thermal volatilization analysis M. C. McGaugh, M. C. McGaugh Polyolefins Research Laboratory, Texas Division, The Dow Chemical Company, Freport, TexasSearch for more papers by this authorSherman Kottle, Sherman Kottle Polyolefins Research Laboratory, Texas Division, The Dow Chemical Company, Freport, TexasSearch for more papers by this author M. C. McGaugh, M. C. McGaugh Polyolefins Research Laboratory, Texas Division, The Dow Chemical Company, Freport, TexasSearch for more papers by this authorSherman Kottle, Sherman Kottle Polyolefins Research Laboratory, Texas Division, The Dow Chemical Company, Freport, TexasSearch for more papers by this author First published: August 1968 https://doi.org/10.1002/app.1968.070120817Citations: 5AboutPDF 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 No abstract is available for this article. Reference 1 I. C. McNeill, J. Polymer Sci. A-1, 4, 2479 (1966). Citing Literature Volume12, Issue8August 1968Pages 1981-1982 ReferencesRelatedInformation

Polymerization of propylene oxide with Ziegler‐Natta catalysts

Journal of Applied Polymer ScienceVolume 12, Issue 6 p. 1477-1479 NoteFree Access Polymerization of propylene oxide with Ziegler-Natta catalysts Takayuki Otsu, Takayuki Otsu Faculty of Engineering, Osaka City University, Sumiyoshi-ku, Osaka, JapanSearch for more papers by this authorAkira Akimoto, Akira Akimoto Faculty of Engineering, Osaka City University, Sumiyoshi-ku, Osaka, JapanSearch for more papers by this authorShuzo Aoki, Shuzo Aoki Faculty of Engineering, Osaka City University, Sumiyoshi-ku, Osaka, JapanSearch for more papers by this author Takayuki Otsu, Takayuki Otsu Faculty of Engineering, Osaka City University, Sumiyoshi-ku, Osaka, JapanSearch for more papers by this authorAkira Akimoto, Akira Akimoto Faculty of Engineering, Osaka City University, Sumiyoshi-ku, Osaka, JapanSearch for more papers by this authorShuzo Aoki, Shuzo Aoki Faculty of Engineering, Osaka City University, Sumiyoshi-ku, Osaka, JapanSearch for more papers by this author First published: June 1968 https://doi.org/10.1002/app.1968.070120619Citations: 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 No abstract is available for this article. References 1 J. Furukawa and T. Saegusa, Polymerization of Aldehydes and Oxides, Interscience, New York, 1963. 2 L. E. St. Pierre, in Polyethers, Vol. 1, N. G. Gaylord, Ed., Interscience, New York, 1963. 3 A. E. Gurgiolo, Revs. Macromol. Chem., 1, 39 (1966). 4 R. O. Colclough, G. Gee, and A. H. Jagger, J. Polymer Sci., 48, 273 (1960). 5 E. J. Vandenverg, J. Polymer Sci., 47, 486 (1960). 6 S. Kambara, M. Hatano, and A. Takahashi, Kogyo Kagaku Zasshi, 66, 1132 (1963). 7 A. Takahashi and N. G. Gaylord, J. Polymer Sci. A-1, 4, 2015 (1966). 8 V. A. Kropachev, L. V. Alferova, and N. M. Geller, paper presented at Symposium on Macromolecular Chemistry, Prague, 1965; Preprints, p. 531. 9 T. Otsu, A. Shimizu, and M. Imoto, J. Polymer Sci. A-1, 4, 1579 (1966). Citing Literature Volume12, Issue6June 1968Pages 1477-1479 ReferencesRelatedInformation

High-temperature-resistant fibers. (ACS Symposium, January 1966) : A. H. Frazer (ed.), J. Polymer Sci. Pt. C, (19) (1967) 300 pp. Part I. Organic fibers (10 papers). Part II. Inorganic and metallic fibers (10 papers)

High-temperature-resistant fibers. (ACS Symposium, January 1966) : A. H. Frazer (ed.), J. Polymer Sci. Pt. C, (19) (1967) 300 pp. Part I. Organic fibers (10 papers). Part II. Inorganic and metallic fibers (10 papers)

Molecular weight of onuphic acid.

BiopolymersVolume 6, Issue 4 p. 629-632 Communications to the EdtiorFree Access Molecular weight of onuphic acid F. G. E. Pautard, F. G. E. Pautard Astbury Department of Biophysics, The University, Leeds, EnglandSearch for more papers by this authorH. Zola, H. Zola Astbury Department of Biophysics, The University, Leeds, EnglandSearch for more papers by this author F. G. E. Pautard, F. G. E. Pautard Astbury Department of Biophysics, The University, Leeds, EnglandSearch for more papers by this authorH. Zola, H. Zola Astbury Department of Biophysics, The University, Leeds, EnglandSearch for more papers by this author First published: April 1968 https://doi.org/10.1002/bip.1968.360060416Citations: 2AboutPDF 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 References 1 F. G. E. Pautard and H. Zola, Carbohydrate Res., 3, 58 (1966). 2 F. G. E. Pautard and H. Zola, Carbohydrate Res., 3, 271 (1967). 3 F. G. E. Pautard and H. Zola, Carbohydrate Res., 4, 78 (1967). 4 H. Zola, J. Polymer Sci. A-1, 5, 2707 (1967). 5 F. G. E. Pautard and H. Zola, Proceedings, International Symposium on Solution Properties of Natural Polymers, Edinburgh, 1967, Chemical Society, in press. 6 J. E. Hodge and B. T. Hofreiter, Methods of Carbohydrate Chemistry, Vol. I, R. L. Whistler and M. L. Wolfrom, Eds., Academic Press, New York, 1962, p. 386. 7 J. T. Park and M. J. Johnson, J. Biol. Chem., 181, 149 (1949). 8 B. H. Zimm, J. Chem. Phys., 16, 1099 (1948). 9 J. Lacapere and G. Delaville, Path. Biol., 8, 29 (1960) 10 B. N. Preston, M. Davies, and A. G. Ogston, Biochem. J., 96, 449 (1965). 11 L. T. Muus and F. W. Billmeyer, J. Am. Chem. Soc., 79, 5079 (1957). 12 F. G. E. Pautard, P. G. Kelly, and H. Zola, paper presented at 6th Intern. Congr. Biochem., New York, 1964; Abstracts, 6, 84 (1964). 13 G. N. Graham, P. G. Kelly, F. G. E. Pautard, and R. Wilson, Nature, 206, 1256 (1965). 14 J. E. Scott, in Methods of Biochemical Analysis, Vol. 8, D. Glick, Ed., Interscience, New York, 1960, p. 145. 15 F. G. E. Pautard and H. Zola, unpublished results. Citing Literature Volume6, Issue4April 1968Pages 629-632 ReferencesRelatedInformation

Bidirectional reflectance characteristics of rough, sintered-metal, and wire-screen surface systems.

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