Kinetics of Methyl Iodide Tribosorption on the Solid-Phase Salt KI

It was found that the tribosorption of methyl iodide from the gas phase of a closed reactor onto a matrix of KI is described by the rate equation for a reversible first-order reaction v _g – v _{, g} = mv _ts ^* exp(–_td D _sp), where v _g and v _{, g} are, respectively, the current and equilibrium amounts of methyl iodide in the gas phase; v _ts ^* is the equilibrium amount of methyl iodide tribosorbed per gram of salt; m is the mass of potassium iodide; _td is a constant, which characterizes the efficiency of tribodesorption (_td = 0.011 ± 0.005 g/J); and D _sp is the specific dose of mechanical energy absorbed by the KI powder. The value of v _ts ^* monotonically increased with increasing equilibrium partial pressure of methyl iodide and reached a maximum value of 25 mol/g. The lower limit of the constant _td, which characterizes the efficiency of tribosorption, was estimated at 0.1 g/J.     

On the Role of Surface Forces in Contact Interaction between Elastic Sphere and Hard Surface

The works preformed earlier were reviewed briefly, and the new problem of the contact interaction between the elastic sphere and hard surface was formulated. The solution of a problem to the generalized surface force and its contact and noncontact components was obtained. The specific case of the obtained solution, when the separation = 0, was considered. The existence of two states of contact interaction between the elastic sphere and hard plane was revealed at = 0: (i) the stable state, at contact with the neck of radius a ₁= , where Ris the sphere radius, = (1 – )/(E), Eis the modulus of elasticity of the sphere, is its Poisson's coefficient, and () is the specific energy of adhesion of the surfaces at the lowest possible separation between these surfaces; and (ii) the unstable (metastable) state, at contact with radius a ₂= 0, i.e., at the point contact between the sphere and the plane. In this case, however, the stable contact with the neck at 0 when the modulus of elasticity E , i.e., at the interaction between the hard sphere and hard plane, is also degenerated into the point contact. It was shown that at the point contact, the contact component F _s ^"of the generalized surface force F _svanishes, whereas the noncontact component F _s ^"acquires the value F _s ^"= F _s= 2R() equal to the force of adhesion.     

Influence of substituents on rate constants for recombination of tertiary peroxy radicals

A linear correlation between the logarithm of rate constant (2k_t) for recombination of tertiary peroxy radicals (ROO)^* and ^* constants of substituents R was found to be 1g 2k_t=lg 2k _t ^° . The calculated values are 1g 2k _t ^° =4.59±0.08 and ^*=5.56±0.35.

---

I (2k_t) (ROO) R: 1g 2k_t=lg 2k _t ^° . , 1g 1g 2k _t ^° =4,59±0,08 =5,56±0,35

     

On the Jovanovic model of adsorption

Summary The effect of the hydrostatic pressure exerted by bulk phases on adsorbed phases depends on the mobility of adsorbed phase and on the topographical distribution of adsorption energy. It is shown in this paper that the Langmuir's equation applies also to adsorption of fully mobile hard discs, on heterogeneous surfaces having fully random topographical distribution of adsorption energy. The effects of the hydrostatic pressure are discussed also in the case of heterogeneous surfaces exhibiting patchwise topographical distribution of adsorption energy.

Symbols

Roman Letters a parameter in the Jovanovic isotherm - A fraction of total surface covered - A ₁ fraction covered of sites having a given adsorption energy - A _j fraction of surface covered as evaluated from the Jovanovic adsorption isotherm - b,b _t parameters in various versions of the Langmuir isotherm - B number of adsorption sites on an adsorbent surface - H enthalpy of adsorption - F free energy of adsorption - k Boltzmann's constant - K, K _j ,K _L parameters in various versions of adsorption isotherms - m mass of the adsorbate molecule - N number of adsorbed molecules - N ₀ monolayer capacity in mobile adsorption - N ₁ local adsorption isotherm - N _t overall adsorption isotherm - p pressure of gas phase adsorbate - q canonical molecular partition function for mobile admolecules - q _st isosteric heat of adsorption - R gas constant - S surface area of adsorbent - S ₁ surface area of sites having a given adsorption energy - S ^* minimum change in the external variable S - T absolute tempetature - T _t frozen temperature Greek Letters Greek Letters parameter of the adsorption isotherm - isothermal-isobaric partition function - adsorption energy - area occupied by one adsorbate molecule - area of box of uniform adsorption energy - chemical potential - v frequency of vibrations of admolecules - range of variation of - () distribution of adsorption energy With 2 figures and 1 table     

Particle behaviour in shear and electric fields

Summary The interactions between two equal rigid conducting spheres in a Newtonian dielectric liquid in combined shear and electric fields are analyzed. The forces and torques, the translational and rotational velocities, and the resulting trajectories of the spheres are calculated for various ratios of the electric field strength to shear rate.The conditions under which the spheres can capture one another are deduced from which capture cross-sections, capture frequencies, and capture efficiencies are calculated, leading to a second order rate equation for capture at low particle concentrations.It is demonstrated that on capture the spheres should come into physical contact in a finite time. However, it is conjectured from previous experiments that dielectric breakdown is apt to occur in the interparticle gap because of the high electric field intensification; when this occurs, complications may be expected which are different in static and alternating electric fields.Closely related to the two sphere problem is the interaction of a rigid conducting sphere with a rigid conducting plane wall; this is discussed in the Addendum.

---

Zusammenfassung Die Wechselwirkungen in gleichzeitig angelegten Scherströmungen und elektrischen Feldern zwischen zwei kleinen, gleiche, festen, leitenden, und in einer Newtonschen Flussigkeit schwebenden Kugeln sind untersucht werden. Die Krafte und Drehmomente, die Translations- und Rotationsgeschwindigkeiten, und die resultierenden Trajektionen der Kugeln werden für verschiedene Verhaltnisse der elektrischen Feldstärke und Schergeschwindigkeit berechnet. Entwickelt werden die Kugelanlagerungsbedingungen, wovon sich die Anlagerungsquerschnitte, die Anlagerungsgeschwindigkeiten, und die Anlagerungseffektivwerte ableiten lassen; dies führt zu einer Anlagerungsgleichung zweiter Ordnung bei geringer Teilchenkonzentration. Es wird gezeigt, daß die Kugeln sich physisch berühren sollten nach Ablauf einer bestimmten (endlichen) Anlagerungszeit. Jedoch, wie es sich aus vorhergehenden Experimenten ergab, dielektrischer Kurzschluß erfolgt im Kugelzwischenraum auf Grund der hohen elektrischen Feldverstarkung; folgendermaBen konnen Komplikationen erwartet werden, die sich für statische Felder und Wechselfelder verschieden ausarten mussen. Die Wechselwirkung zwischen einer kleinen, festen, leitenden Kugel und einer festen, leitenden, flachen Wand ist ein Sonderfall des Zwei-Kugel-Problems; dies wird im Addendum beschrieben.

---

Nomenclature a, b ^*,c, d, e, f ^*,g, b hydrodynamic force and torque coefficients - a ^* b sinb - b sphere radius - B, C; B₀, C₀; C^E trajectory constants whenf=0 (B0,C0); when 0<f< and 2 (B ₀ 0,C ₀ 0) ; whenf= and 2. - C^* orbit constant of a touching doublet - e _i particle fixed unit vectors,i=1, 2, 3, (fig. 1) - E;E ₀ local electric field strength; uniform field applied to the particle-free medium. Normal type designates scalar quantities - E ₃ ^* E _DB E/E ₀; dielectric breakdown strength of medium - f electrohydrodynamic parameter defined in [28] - f _c;f _c ^E collision frequency per unit volume; capture frequency per unit volume - f _i ^E ;f _i ^r ;f _i ^S ;f _i ^t force coefficients of a sphere near a wall due toE ₀; to rotation; to shear; to translation - f(), h() trajectory functions for f=0 defined in [1] and [2] - F _i;F _i ⁰ electric force coefficients (i =1 to 10) defined in [12] and [13] when spheres have potential Vj; when Vj=0. - F ^E ,F ^r ,F ^S ,F ^t forces acting on a sphere near a plane wall - F _i ^E (j) electric force component alongx _i ^' on spherej =1, 2. - g _i ^r ,g _i ^S ,g _i ^t torque coefficients on a sphere near wall - G shear rate - k capture rate constant defined in [44] - K dielectric constant of medium - n integer (n 0) - n ₀;n ₂ number concentration ofsuspension of single spheres; of captured doublets - P _ij coefficients of electric induction - P(r _p ) orientation function of a rigid conducting prolate spheroid - q ₂,q ₃ defined in [66] - Q _j ;Q _j ^* net charges on spherej = 1, 2; charges induced on spherej =1, 2 if as earthed - r;r _p centre-to-centre distance between spheres; axis ratio of spheroid - S _m () functions defined in [48]m = 1,2 - S _ij pure shear (deformation) tensor components - T period of rotation of doublet about ₁ axis whenf < 1 - T ^E ;T ^E ;T ^*E contact time of two spheres; a sphere and a wall; = (2₀ KE ₀ ² / 3)T ^E - T ^r ,T ^S ,T ^t torques on a sphere near a wall - u undistrurbed flow velocity - U;U(j) particle velocity of sphere near wall; of spherej - V _j electric potential of spherej - w _j ;W ₁ ^* dimensionless electric potential of spherej; of sphere 1 whenQ ₁ =0 - x _i ;x _i ;x ₃ ^* space-fixed coordinates defined in figure 1; particle-fixed coordinates alonge 1; = (2₀ KE ₀ ² /3G) ₃ - cos²₂ - Y _n ;Z _n functions defined in [17d]; in [17e] Script symbols A(),B(),L(),D(),E() functions defined in [23] - (F); (F ^(E ); (F ^(s ) general force-torque vector; in an electric field; in shear - L _i () velocity coefficients of two spheres in an electric field,i=1 to 4     

Symmetry and other properties of second-order phenomenological coefficients and thier significance in a chemical system

Using a second-order phenomenological equationJ _i = _j L _ij X_j + _{j, k} L _ijk X_j X_kand assuming that the system is at a state near equilibrium, it has been shown that the symmetry ofL _ijk is retained with respect to the permutations of suffices i j and k Furthermore, using the second-order flux equations, the thermodynamic stability criterion is expressed. The symmetry is shown to be retained in a reaction scheme representing the emplate model. The significance of the stability criterion as expressed by the higher-order phenomenological coefficients is discussed.     

Physicochemical Properties of Ampicillin and Amoxicillin as Biologically Active Ligands with Some Alkali Earth,Transition Metal,and Lanthanide Ions in Aqueous and Mixed Solvents at 20, 30, and 40<Superscript>∘</Superscript>C

The acid-base equilibria of ampicillin and amoxicillin were investigated in pure water and different solvent + water mixtures (solvent = methanol, ethanol, acetone, dimethylformamide, and dimethyl sulfoxide) at a constant ionic strength (I = 0.1 mol-dm^–3 KNO₃) and organic solvent volume fractions of 10, 20, and 30%. The effect of temperature on these equilibria was studied at 20, 30, and 40C. Thermodynamic functions of these ligands were calculated and discussed in terms of G, H, and S. The number of ionizable protons was determined using conductometric titrations. The formation constant of the complexes, which form by reaction of the ligands with Mg(II), Ca(II), Zn(II), Cu(II), Ni(II), Co(II), Ce(III), Pr(III), Eu(III), Gd(III), Ho(III), Er(III), and Yb(III), are determined. The relative stability of the alkali earth, transition, and lanthanide elements are compared with each other and discussed in terms of the ionic radius and the electronic structure of the outer shell of that ion. The results obtained are discussed in terms of macroscopic properties of the mixed solvents and the possible variation in microheterogenity of the solvation shells around the solute.     

Dynamics of the formation and decay of C2(a 3II u,v″=0) radical in a pulse discharge in methane

The plasma of a pulse discharge (0.05 J/cm³) in methane at low pressure (200 Pa) is studied. The dynamics of formation and decay of C₂(a³II_u, v=0) is monitored using a stroboscopic laser absorption method. It was found that substantial amounts of C₂, 10¹⁵ cm^–3, arise with a 1-µs delay after the current pulse.Notation _v absorption coefficient - wave number, cm^–1 - e electron charge - c velocity of light - h Planck's constant - m _e mass of electron - N _v concentration of molecules in the vibrational level v - f oscillator strength - l plasma column length - q _vv Franck-Condon factor - S _JJ Hönl-London factor - Q _rot rotational partition function - F(J) rotational term, cm^–1 - I _sig signal beam intensity - I _ref reference beam intensity - higher state index - lower state index - decay constant     

A Simplified version of the Pariser-Parr-Pople treatment of π-electron systems

The semi-empirical configuration interaction treatment due to Pariser and Parr and to Pople has been modified by reducing the set of electronic interaction integrals to ₁₁ and ₁₂ and by limiting the number of configurations to 10. Hückel MOs are used as basis functions. The dependence of the resonance integral _v on the interatomic distance R _v is simulated by making _v a quadratic function of the Hückel bond orders P _v .

---

Zusammenfassung Eine Modifikation des semiempirischen CI-Verfahrens von Pariser, Parr und Pople wurde zur Behandlung von -Systemen herangezogen. Als Vereinfachung wurde der Grad der CI-Matrix auf zehn beschränkt und von den Elektronenwechselwirkungsintegralen nur ₁₁ und ₁₂ berücksichtigt. Hückel-MOs wurden als Basisfunktionen verwendet. Die Abhängigkeit des Resonanzintegrals _v vom interatomaren Abstand R _v wurde durch den Ansatz von _v als quadratische Funktion der Hückel-Bindungsordnung P _v angenähert.

---

Résumé Le procédé semi-empirique de l'interaction de configuration selon Pariser, Parr et Pople a été modifié en réduisant l'ensemble des intégrales d'interaction électronique à ₁₁ et limitant le nombre des configurations à 10. Les fonctions de base sont des orbitales moléculaires selon Hueckel. La dépendance entre l'intégrale de résonance _v et la distance interatomique R _v est simulée en posant que _v est une fonction quadratique des ordres de liaisons P _v selon Hückel.

     

Apparent molal volumes and heat capacities of some 1:1 electrolytes in anhydrous methanol at 25°C

A flow calorimeter and flow densimeter have been used to measure volume specific heats and densities of solutions of LiCl, LiBr, NaCl, NaBr, KF, KBr, Kl, CsF, and Bu₄NBr in anhydrous methanol at 25°C. The concentrations ranged from approximately 0.01m to close to saturation in some cases. Apparent molal heat capacities _cp and volumes _v have been evaluated and extrapolated to infinite dilution to obtain _cp ^o and _v ^o . Nearly all the heat capacities in methanol are negative. However, with the exception of the lithium halides and Bu₄NBr they are more positive than heat capacities of the corresponding salts in water. The dependence of the heat capacities on ionic radii is generally opposite in methanol solutions from that observed for aqueous solutions. In agreement with others, the _v ^o data indicate that electrostriction in methanol solutions is greater than in aqueous solutions.     

Dinuclear Complexes Contributing to Softness of Metal Acceptors

Since emf measurements with amalgam electrodes have been used, in most studies of the stabilities of complexes between soft metal acceptors and halide ions a series of investigations of the kinetics of electrode reactions were accomplished with halide systems of metal ions in the Groups 11 and 12 in aqueous and/or DMSO solutions. The aim was to establish which complexes contribute to the exchange current density, i _o. Such measurements are found to be a very sensitive method for identifying dinuclear complexes that can display much higher charge transfer rate constants than mononuclear complexes can. From these results it can be stated that hard acceptors do not show any tendency to form dinuclear halide complexes, whereas soft acceptors are apt to do so. This fact leads to the conclusion that dinuclear complexes have a strong internuclear bond. In determinations of the overall stability constant _j of a complex ML _j there is an influence from a complex M₂L _j with a constant _j , resulting in the substitution of _j for ( _j + 2a _{j j} ), where a _j = [M] when the ligand number n = (C _L – [L])/C _M has the value j. An approximate value of the association constant, K _ass, of the internuclear bond can be calculated from _j if _j is known. On the basis of these measurements the most probable types of the internuclear bonds are discussed.     

Direction of the action of glycosidases fromLimnaea stagnalis on the carbohydrate groups of the (Fc)5 region of immunoglobulins M

The action of the combined glycosidases fromL. stagnalis on the carbohydrate groups of two monoclonal immunoglobins M (Waldenström's disease) — IgM_El (I) and IgM_Ser (II) — has been studied by the semiquantitative evaluation of densitograms of glycopeptides after their separation by disc electrophoresis in polyacrylamide gel. The accessibility of the oligosaccharide groups (OGs) to the action of the glycosidases according to the positions of the OGs in a particular domain of the (Fc)₅ region of a IgM decreases for (I) in the sequence C3 C4 > hinge, and for (II) in the sequence hinge > C4 > C3. The difference in the accessibilities of the OGs (I) and (II) is apparently explained by differences in the conformations of (I) and (II). A hypothesis has been put forward concerning the possibility of the partial degradation of (II) by the accompanying proteases.N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 371–375, May–June, 1984.     

Transformed steroids

Conclusions The addition of thioacetic acid to the ⁵ bonds of 16- and 16-mercapto-3-hydroxypregn-5-en-20-one 3,16-diacetates (II) and (III) under radical conditions gives not only trans-diaxial addition products-6,16- and 6,16-dimercapto-3-hydroxy-5o;-pregnan-20-one 3,6,16-triacetates (IV) and (V) -but also cis-addition products-6,16- and 6,16-dimercapto-3-hydroxy-5-pregnan-20-one 3,6,16-triacetates (VI) and (VII).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 405–411, February, 1969.     

Abhängigkeit der freien Enthalpie-Änderung von der Netzebenenzahl bei Bildung von Mikroparakristallen

Zusammenfassung Das anhand vieler sorgfältiger Reflexprofilanalysen abgeleitete ^*-Gesetz läßt sich auch thermodynamisch verstehen, wenn man die Fragilität der Valenzwinkel durch ein entsprechendes MuldenpotentialU einführt. Dies liefert in dem Ausdruck für die ÄnderungG der freien Enthalpie bei Teilchenbildung neben den bekannten, von der Teilchengröße unabhängigen zwei Termen für freie Oberflächenenergie und freie VolümenthalpieG _v einen dritten, mit der ZahlN der Netzebenen wachsenden Summanden. Diese sog. Volum-StörenthalpieA ₀g² N ist also auch abhängig von der relativen statistischen Varianzg der Abständed von Gitterbausteinen benachbarter Netzebenen. Durch Einführung des ^*-Gesetzes ergibt sich die Beziehung ¦G_v¦ /A ₀ K()=0.06 mitK()=356 g² /¯ d¦G_v¦=1–1–. Im Grenzfall=1 ist die kritische Keimgröße gleich der mittleren statistischen Größe der Mikroparakristalle. Dieser Fall wird für Metallschmelzen diskutiert.=0 stellt den anderen Grenzfall der Kristallbildung dar.Herrn Prof. Dr. K. Kobayashi zum 70. Geburtstag zugedacht.     

Some perspectives on the modeling of plasma jets

A mathematical representation is developed describing the temperature and the velocity profiles and mixing in a plasma jet discharging into ambient air. In the model, realistic allowance is made for turbulent behavior, the temperature-dependent property values, and also for the boundary conditions, including entrainment. The more precise definition of the boundary conditions, mixing, and entrainment are thought to be important novel features of this work. The theoretical predictions were found to be in good agreement with measurements reported by Vardelle regarding the behavior of a nitrogen plasma, but the agreement was less satisfactory for an argon plasma jet. Possible reasons for the discrepancy are discussed.Notation C ₁,C ₂,C _D constants inK- turbulence model - h enthalpy - H ₁ length of integration region - H ₂ width of integration region - K turbulent kinetic energy per unit mass - m mass concentration of plasma - Q _f mass flow rate of plasma gas for flat inlet profiles - Q _P mass flow rate of plasma gas for parabolic inlet profiles - P _w torch power - r radial coordinate - R ₀ internal radius of torch exit - S source term for dependent variable - S _R radiation loss per unit volume of plasma - T _a ambient temperature - T _m maximum temperature - T _t torch tip temperature - u velocity inz-direction - u _{C 1} velocity at and in the direction of the symmetry axis of the flow - u _m velocity of plasma atr=0 andz=0 (maximum velocity) - u axial direction velocity difference across the width of the mixing region - v velocity in r direction - Y radial width of the mixing region - z axial coordinate - density - , _e, _t molecular, effective, and turbulent viscosities, respectively - dissipation rate of turbulence energy - thermal efficiency of plasma torch - Prandtl/Schmidt number forh, K, , andm Visiting Fulbright Scholar and Associate Professor of Chemical Engineering, on leave from the Institute of Chemical Engineering and Technology, Punjab University, Lahore-20, Pakistan.     

Heat of fusion and specific volume of poly(ethylene terephthalate) and poly(butylene terephthalate

Summary Concerning the relation between the experimental heat of fusion H* and the specific volumev of PETP a considerable uncertainty exists in literature. For PBTP obviously no data have been reported. The present paper reports H* andv measurements for undrawn PETP and PBTP samples which have been crystallized from the glassy state or from the melt at different temperatures for different periods of time.For PETP a linear relation is obtained: H* = 1411–1886v (Jg^–1). Published values for the specific volumev _c of the PETP crystal range from 0.660 to 0.687 cm³g^–1. Ifv _c = 0.660 cm³g^–1 is accepted, a heat of fusion M _m = 166 Jg^–1 is obtained for the PETP crystal.For PBTP also a linear relation is found: H* = 1296–1628v (Jg^–1). Withv _c = 0.71 cm³g^–1 one obtains H _M = 140 Jg^–1 as the heat of fusion of the PBTP crystal. The specific volumev _a of amorphous PBTP (H* = 0) is 0.796 cm³g^–1 which is much higher than the hitherto used values of 0.781–0.782 cm³g^–1. The reason for this difference is thatv _a cannot directly be measured, because the low quasi-static glass temperature of 15 °C enables quenched PBTP to undergo cold crystallization at 20 °C.

---

Zusammenfassung Hinsichtlich des Zusammenhangs zwischen experimenteller Schmelzwärme H* und spezifischem Volumenv von PETP bestehen in der Literatur beträchtliche Diskrepanzen. Für PBTP wurden bislang offensichtlich keine Ergebnisse veröffentlicht. In der vorliegenden Arbeit werden Messungen von H* undv für unverstreckte PETP- und PBTP-Proben mitgeteilt, die unterschiedlich lange bei ver-schiedenen Temperaturen aus dem Glaszustand oder aus der Schmelze kristallisiert wurden.Für PETP ergibt sich die lineare Beziehung: H* = 1411–1886v (Jg^–1). Literaturwerte für das spezifische Volumenv _c des PETP-Kristalls schwanken zwischen 0.660 und 0.687 cm³g^–1. Nimmt manv _c = 0.660 cm³g^–1 als richtig an, so erhält man als Schmelzwärme des PETP-Kristalls H _M = 166 Jg^–1 = 32 kJ mole^–1.Auch für PBTP erhält man eine lineare Abhängigkeit: H* = 1296–1628v. Mitv _c = 0.71 cm³g^–1 ergibt sich als Schmelzwärme des PBTP-Kristalls H _M = 140 Jg^–1 = 31 kJ mole^–1. Das spezifische Volumen des amorphen PBTP beträgt _a = 0.796 cm³g^–1 und ist erheblich größer als der bisher angenommene Wert von 0.781 cm³g^–1. Die Ursache fÜr diese Diskrepanz liegt darin begündet, daßv _a nicht direkt gemessen werden kann, weil wegen der niedrigen quasi-statischen Glastemperatur von 15°C bei abgeschrecktem PBTP die Kaltkristallisation bei 20°C bereits einsetzt.

---

---

With 7 figures and 3 tables

---

Dedicated to Professor Dr. Matthias Seefelder on the occasion of his 60th birthday     

On the closed form of Wigner rotation matrix elements

The closed forms of some rotation matrix elementsd _{m m} ^j (/2) are presented. The closed forms of summation involved two binomials and some special hypergeometric functions are also obtained. The MAPLE V program which calculates d _{m m} ^j (), dm,. (/2) and the help file are given in appendix.Supported in part by the Chiu Feng-Chia research Fund. Thanks are due to the Board of Trustees Chairman Dr. Ying-Ming Liao as well as the Trustee Dr. Charles Chiu-Hsiong Huang and President Dr. Ted C. Yang of Feng-Chia University, Taichung, Taiwan, ROC.     

Elastizitätsmodul und Dichte von kaltverstrecktem und druckbehandeltem Polyäthylen

Zusammenfassung Proben aus Polyäthylen hoher Dichte wurden bei Raumtemperatur mit verschiedenen Geschwindigkeitenv _ver auf einer Zugprüfmaschine verstreckt. Beiv _ver 10 mm/min beobachtet man eine fast isotherm verlaufende inhomogene Deformation, die zu Verstreckungsgraden=8–13 und mittleren Dichten = 0.80 g/cm³ in den verstreckten Probenbereichen führt. Die bei höherenv _ver bis zu 50 mm/min eintretende adiabatische Erwähnung ergibt höhere Verstreckungsgrade=13–18 und geringere Dichten = 0.64 g/cm³. Es existiert kein natürlicher Verstreckungsgrad. Der Dichteabfall mit zunehmendem kann durch eine Gerade repräsentiert werden; der ElastizitätsmodulE ergibt eine mit zunehmende Kurve.Nach einer Druckbehandlung der Proben mit 5600 bar bei Raumtemperatur erreichte ihre Dichte fast wieder den Anfangswert vor der Verstreckung, wobei keine Abhängigkeit von oder anderen Parametern zeigte. Der ModulE hatte zugenommen, aber nicht proportional zur Dichte. Der Vergleich von undE verstreckter Proben vor und nach der Druckbehandlung weist auf den Netzwerkcharakter von kaltverstrecktem Polyäthylen hin.Herrn Prof. Dr. K. Ueberreiter zum 70. Geburtstag gewidmet.     

Preparation and characterization of a series of poly(acrylamide-co-acrylates), with a copolymer composition between 0–96.3 mol-% acrylate units with the same degree and distribution of polymerization

A series of linear poly(acrylamide-co-acrylates) (PAAm/AAcNa) has been prepared covering a copolymer composition between 0 and 96.3 mol% acrylate units, which have the same degrees of polymerization and chain length distributions. Measurements of viscosity and light scattering have proven that maximum coil dimensions of PAAm/ AAcNa in salt solutions are achieved at about 67 mole-% AAcNa. This so-called maximum behaviour was researched by measuring the radius of gyration, second virial coefficient, molecular weight, preferential solvation, viscosity and absorption bands of the copolymer series. Thus, an increase in the possible ways of arranging AAcNa-AAm-AAcNa units (via H-bonds) will lead to extended coil dimensions and therefore influence the viscosity. In addition, it can therefore be concluded from all these results that the maximum behaviour is real and not influenced by the different distributions of the samples. The copolymer composition can be easily determined by infra-red spectroscopy by use of a proposed relation.Abbreviations A₂ second virial coefficient (mole · cm³ · g^–2) - AAm acrylamide - AAcH acrylic acid - AAcNa sodium acrylate - c polymer concentration (g · cm^–3) - salt concentration (g · cm^–3), (Val · cm^–3) - C _LS critical concentration obtained by light scattering (g · cm^–3) - d _[] viscosity equivalent diameter of a sphere (nm) - E extinction - FW _s formula weights of salt - g _s gram of salt - g _p gram of polymer - GuaCl guanidinium chloride - h ^21/2 root mean square end-to-end distance (nm) - K optical constant for unpolarized incident light (mole · cm² · g^–2) - M molarity (mole · 1^–1) - M _w weight average molecular weight (g · mole^–1) - N _L Avogadro constant 6.023 · 10²³ mole^–1 - P _n number average degree of polymerization - P _w weight average degree of polymerization - PAAm poly(acrylamide) - PAAcH poly(acrylic acid) - PAAcNa poly(sodium acrylate) - PAAm/AAcNa poly(acrylamide-co-sodium acrylate) - R _[] Rayleigh ratio of the scattering at angle (cm^–1) - R _G ² _Z ^1/2 root mean square average radius of gyration (nm) - R _[] viscosity equivalent radius of a sphere (nm) - T temperature (°C), (K) - u excluded volume (cm³ · g^–1) - V molar volume (cm³ · mole^–1) - V _s partial specific volume - X mole fraction - (NH₂) oscillation of deformation - extinction coefficient - ₀ zero shear viscosity (Pa · s), (mPa · s) - _red reduced viscosity (cm³ · g^–1) - [] intrinsic viscosity (cm³ · g^–1) - _a constant of preferential solvation (g · g^–1) - ₀ wavelength of light in vacuo (nm) - chemical potential - v _as stretching vibration - scattering angle (°)