Studies on the biaxial stretching of polypropylene film. V. Orientation mechanism of the one-step biaxially stretched film

The molecular orientation behavior during one-step biaxial stretching in air of a quenched, low crystalline film differs from that of a slightly crystallized, highly crystalline film. In the case of a quenched film a plot of ?Δn_ss versus \documentclass{article}\pagestyle{empty}\begin{document}$ 1/\sqrt {va} $\end{document} is composed of three intersecting straight lines with different slopes, ?Δn_ss and v_A being the birefringence with respect to the normal to the film surface and the degree of stretching in area, respectively. On the other hand, ?Δn_ss of crystalline film changes somewhat differently. It does not increase up to fairly high stretching ratio. When a film with surface layers of different crystallinity was stretched biaxially, the relations between ?Δn_ss and \documentclass{article}\pagestyle{empty}\begin{document}$ 1/\sqrt {va} $\end{document} for the two surface layers differ, that is, a surface layer of low crystallinity shows a change of ?Δn_ss for the two surface layers differ, that is, a surface layer of low crystallinity shows a change of ?Δn_ss like that of a quenched film type and the surface layer of higher crystallinity, follows the behavior typical of highly crystalline film. However, a commercial film having different crystallinites on the two surface layers exhibits another type of ?Δn_ss change, which may be ascribed to the stress remaining frozen in the film in the manufacturing process. In addition, it is found that an Abbé refractometer can give the refractive indices of both the upper and lower surface layers of a film when the film structure is not the same on both surface layers.     

Studies on the biaxial stretching of polypropylene film. III. Electron microscopic observation of the one-step biaxial stretching of isotactic polypropylene spherulites

Polypropylene films of various isotacticities and crystallinities were stretched biaxially in one step in air at 140–152°C or polyaxially in poly(ethylene glycol) at 130–160°C, and the morphological changes were studied by electron microscopy (replica). In the initial stage of stretching, with v_A = 1.4, the spherulites of one of the films used for the experiment were broken both from the centers and boundaries, and those of another film were broken mainly from the center. This difference in the deformation behavior seems to be characteristic of the film properties and independent of the method of stretching, although the factors involved are still unknown. On further stretching (v_A = 22), well annealed spherulites were broken into many small blocklike fragments with unfolded fibrils running among them, particularly at the low stretching temperature (140°C), and fibrillation proceeded at the expense of the residual fragments. In the case of quenched or slightly crystallized material, the fragments were dendritic and divided into finer and finer fibrils on stretching. At elevated temperature, however, even for well annealed spherulites, the deformation behavior resembles that of the quenched material, and at a high degree of stretching the spherulites take on the fibrillar net structure in every case. In films containing a high amount of atactic fraction, radial, tangential, and boundary cracking occurred more easily, and broad fibrils were observed across the cracks.     

Volumetric, viscometric and refractive index behavior of some α-amino acids in aqueous tetrapropylammonium bromide at different temperatures

Densities, ρ, viscosities, η, and refractive indices, n _D, of glycine (Gly), DL-alanine (Ala), DL-valine (Val) (0.05, 0.10, 0.15, 0.20, 0.25 mol kg^?1), and L-leucine (Leu) (0.02, 0.05, 0.10 mol kg^?1) in water and in 0.20 mol kg^?1 aqueous tetrapropylammonium bromide (TPAB) have been measured at 298.15, 303.15, 308.15, and 313.15 K. The density data have been utilized to calculate apparent molar volumes, ?_v, partial molar volumes at infinite dilution, ?_v°, and partial molar volumes of transfer, ? _v°(tr) of amino acids. The viscosity data have been analyzed by means of Jones-Dole equation to obtain Falkenhagen coefficient, A, and Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δµ₁°*, and solute, Δµ₂°*, and enthalpy, ΔH*, and entropy of activation, ΔS*, of viscous flow. The refractive index data have been used to calculate molar refractivity, R _D, of amino acids in aqueous tetrapropylammonium bromide solutions. It has been observed that ?_v°, B-coefficient and Δµ₂°* vary linearly with increasing number of carbon atoms in the alkyl chain of amino acids, and they were split to get contributions from the zwitterionic end groups (NH₃ ⁺, COO^-) and methylene group (CH₂) of the amino acids. The behavior of these parameters has been used to investigate the solute-solute and solute-solvent interactions as well as the effect of tetrapropylammonium cation (C₃H₇)₄N⁺ on these interactions.     

Stress-optical behavior of cycloaliphatic polyesters

Stress-strain-birefringence measurements were carried out on elastomeric networks of poly(oxymethylene-1,4-cis-cyclohexylenemethyleneoxysebacoyl) at several temperatures between 5 and 80°C. The dependence of both the birefringence Δn and the true stress f/A on temperature was found to be linear for T > 30°C; for T < 30°C an anomalous increase in the birefringence and a sharp decrease in the stress was observed. This behavior suggests that crystallinity is developed in the strained networks at low temperatures, and the crystallites are oriented in the direction of the elongation. Values of the optical configuration parameter Δa ranged from 9.15 to 8.28 in units of 10²⁴ cm³ in the temperature range studied. The value at 40°C of 10²⁴Δa, obtained from experiments performed on swollen networks, amounted to 7.47 cm³. These results suggest that intermolecular interactions enhance the birefringence of the strained networks. The quantities Δa and d In Δa/dT were calculated by using the valence optical scheme. Although the calculations reproduce the temperature coefficient fairly well, the theoretical values of Δa are smaller than the experimental ones. The agreement between theory and experiment is better assuming that the CH₂CH₂? COOCH₂ segment is freely rotating.     

Dimerisation and complexation of 6-(4′-t-butylphenylamino)naphthalene-2-sulphonate by β-cyclodextrin and linked β-cyclodextrin dimers

This study shows that stereochemical factors largely determine the extent to which 6-(4′-t-butylphenylamino)-naphthalene-2-sulphonate, BNS^?  and its dimer, (BNS^? )₂, are complexed by β-cyclodextrin, βCD, and a range of linked βCD dimers. Fluorescence and ¹H NMR studies, respectively, show that BNS^?  and (BNS^? )₂ form host–guest complexes with βCD of the stoichiometry βCD.BNS^?  (10^? 4 K ₁ = 4.67 dm³ mol^? 1) and βCD.BNS₂ ^2 ?  (10^? 2 K ₂′ = 2.31 dm³ mol^? 1), where the complexation constant K ₁ = [βCD.BNS^? ]/([βCD][BNS^? ]) and K ₂′ = [βCD. (BNS^? )₂]/([βCD.BNS^? ][BNS^? ]) in aqueous phosphate buffer at pH 7.0, I = 0.10 mol dm³ at 298.2 K. (The dimerisation of BNS^?  is characterised by 10^? 2 K _d = 2.65 dm³ mol^? 1.) For N,N-bis((2^AS,3^AS)-3^A-deoxy-3^A-β-cyclodextrin)succinamide, 33βCD₂su, N-((2^AS,3^AS)-3^A-deoxy-3^A-β-cyclodextrin)-N′-(6^A-deoxy-6^A-β-cyclodextrin)urea, 36βCD₂su, N,N-bis(6^A-deoxy-6^A-β-cyclodextrin)succinamide, 66βCD₂su, N-((2^AS,3^AS)-3^A-deoxy-3^A-β-cyclodextrin)-N′-(6^A-deoxy-6^A-β-cyclodextrin)urea, 36βCD₂ur, and N,N-bis(6^A-deoxy-6^A-β-cyclodextrin)urea, 66βCD₂ur, the analogous 10^? 4 K ₁ = 11.0, 101, 330, 29.6 and 435 dm³ mol^? 1 and 10^? 2 K ₂′ = 2.56, 2.31, 2.59, 1.82 and 1.72 dm³ mol^? 1, respectively. A similar variation occurs in K ₁ derived by UV–vis methods. The factors causing the variations in K ₁ and K ₂ are discussed in conjunction with ¹H ROESY NMR and molecular modelling studies.     

Experimental and Theoretical Studies of the HeICl Van der Waals Complexes in the Valence and Ion-pair States

The article presents results of experimental and theoretical analysis of the T-shaped and linear HeICl van der Waals complexes in the valence A1 and ion-pair β1 states as well as the HeICl(A1,v_A,n_A←X0⁺,v_X=0,n_x and β1,v_β,n_β←A1,v_A,n_A) optical transitions (n_i are quantum numbers of the vdW) modes). The HeICl(β1,v_β,n_β)→He+ICl(E0⁺, , β1) decay are also studied. Luminescence spectra of the HeICl(β1,v_β=0–3,n_β) complex electronic (ICl(E0⁺,v_E, ) and vibrational ICl(β1,v_β) predissociation products are measured, and branching ratios of decay channels are determined. To construct potential energy surfaces for the HeICl(A1, β1) states, we utilized the intermolecular diatomic-in-molecule perturbation theory first order method. Experimental and calculated spectroscopic characteristics of the A1 and β1 states agree well. Comparison of the experimental and calculated pump-probe, action and excitation spectra shows that the calculated spectra describe the experimental spectra adequately.     

Anionic polymerization of norbornene trisulfide (exo-3,4,5-trithia-tricyclo[5.2.1.02.6]decane)

The anionic polymerization of norbornene trisulfide initiated with sodium thiophenoxide (sodium cation solvated with dibenzo-18-crown-6 ether) was studied. Polymers with high molecular weights were obtained (M _n up to 10⁵, osmometrically). Molecular weights calculated for living polymerization conditions (i.e., one molecule of initiator yields one macromolecule) agree well with M _n measured by osmometry. ¹H-NMR, ¹³C-{¹H}-NMR, and Raman spectra of the polymer are given. Thermodynamics of polymerization in toluene solvent is described. Enthalpy ΔH_ss = ?(1.39 ± 0.17) kcal mol^?1 and entropy ΔS_ss = ?(7.52 ± 0.55) cal mol^?1 deg^?1 coefficients of polymerization were evaluated from the temperature dependence of the equilibrium monomer concentration determined dilatometrically.     

Data on the thermochemistry of azoalkanes

The rate constant of the primary decomposition step was determined for four symmetrical and four unsymmetrical azoalkanes. From the experimental activation energies and some literature enthalpy data, the following enthalpies of formation of radicals and group contributions were calculated: ΔH_? (CH₃N₂) = 51.5 ± 1.8 kcal mol^?1, ΔH_? (C₂H₅N₂) = 44.8 ± 2.5 kcal mol^?1, ΔH_? (2?C₃H₇N₂) = 37.9 ± 2.2 kcal mol^?1, [N_A-(C)] = 27.6 ± 3.7 kcal mol^?1, [N_A-(?_A) (C)] = 61.2 ± 3.1 kcal mol^?1.     

Equilibrium anionic polymerization of 4,7-dioxaoctanal and n-octanal

Equilibrium anionic polymerization of 4,7-dioxaoctanal (DOA) and n-octanal (OA) was carried out in tetrahydrofuran in the temperature range of ?90 to ?68°C, and thermodynamic parameters were evaluated as follows: ΔH_ss = ?4.0 ± 0.1 kcal/mole, ΔS_ss = ?18.4 ± 0.5 cal/mole-deg, and T_c,ss = ?56°C for the DOA system; ΔH_sc = ?3.4 ± 0.1 kcal/mole, ΔS_sc = ?15.7 ± 0.4 cal/mole-deg, and T_c,sc = ?59°C for the OA system. Comparison of these values with those in the cases of β-methoxypropionaldehyde and n-valeraldehyde made it clear that the aliphatic aldehyde having a longer alkyl group polymerizes with smaller changes of enthalpy and entropy and that the polar-substituted aldehydes have higher polymerizability than the corresponding unsubstituted aliphatic aldehydes in the temperature range studied. These effects of substituents are interpreted from the viewpoint of the intermolecular interactions of polar groups in monomers and their polymers.     

Variable temperature multinuclear NMR. Investigation of dimethylformamide exchange on the octakis (N,N-dimethylformamide)-thulium(III) ion

The rate of DMF exchange on [Tm (DMF)₈]³⁺ has been determined by ¹H- and ¹³C-NMR. linebroadening techniques. ¹H-NMR. yields the following solvent exchange parameters; ΔH* = 33.2 (±0.5) kJ mol^?1, ΔS* = 9.9 (±2.4) J K^?1 mol^?1and k (200 K) = 2.94 (±0.09)× 10⁴ s^?1, whilst results from ¹³C-NMR. are similar. No evidence, by ³⁵C1-NMR., was found of contact ion-pair formation when the perchlorate salts were used.     

Interactions of Phenylalanine,Tyrosine and Histidine in Aqueous Caffeine Solutions at Different Temperatures

Densities, ρ, viscosities, η, and refractive indices, n_D of aqueous caffeine (0.5 M) and of solutions of amino acids, l‐phenylalanine (Phe), l‐tyrosine (Tyr) and l‐histidine (His), (0.01–0.05 M) in aqueous‐caffeine have been measured at 298.15, 303.15, 308.15 and 313.15 K. From these experimental data, apparent molar volume, ?_v, limiting partial molar volume, ?^º_ν and the slope, S_v, transfer volume, ?^º_ν,tr, Falkenhagen coefficient, A, Jones‐Dole coefficients, B, free energies of activation per mole of solvent, Δμ^o#₁ and per mole of solute, Δμ^o#₂, enthalpy, ΔH^* and entropy, ΔS^* of activation of viscous flow, and molar refraction, R_m were calculated. The results are interpreted from the point of view of solute‐solvent and solute‐solute interactions in these systems. It has been observed that there exist strong solute‐solvent and weak solute‐solute interactions in these systems. Further, the solute‐solvent interactions decrease, whereas solute‐solute interactions increase with rise in temperature. It is observed that these amino acids act as structure‐makers in aqueous‐caffeine solvent. The thermodynamics of viscous flow have also been discussed.     

Piezoelectricity in oriented films of poly(γ-benzyl-L-glutamate)

Oriented films of poly(γ-benzyl L -glutamate) (PBLG) were prepared by two methods. Films of PBLG cast from chloroform solutions were elongated by rolling at 70°C. A solution of PBLG in methylene bromide was placed in a magnetic field of about 7000 gauss and the solvent was slowly evaporated for a few days until an oriented film was obtained. The real and imaginary components of the complex piezoelectric strainconstant d₂₅^* = d₂₅′ ? jd₂₅″ were determined over the temperature range from ?180°C to +180°C at a frequency of 20 Hz. The constants showed dispersions at about 20°C and about 100°C, where dynamic viscoelastic dispersions were also observed. Degree of crystallinity X_c and degree of orientation II_a of crystallites were determined from x-ray diffraction diagrams. The product X_cII_α and the value of d₂₅′ at room temperature were found to be linearly related, and both showed a maximum at an elongation ratio of 1.5 (the ratio of the final to initial length) for roll-oriented films and at an initial solution concentration of 15% by weight for magnetically oriented films. The largest values of d₂₅′ were approximately 2 × 10^?12 and 4 × 10^?12 coulomb/newton, respectively, at room temperature.     

Thermodynamic Studies of Bi-Univalent Electrolytes. VI. Thermodynamics of Cadmium Acetate from E. M. F. and Calorimetric Measurements

E. M. F. of the Cell, Cd-Hg (2-phase)/CdAc₂(m), Hg₂Ac₂(s)/Hg was measured at 20°, 25°, 30° and 40°C. The standard e. m. f. of the cell, Cd/CdAc₃(m), Hg₂Ac₂(c)/Hg was evaluated as E°=1.1500?11.09×10^?4T+1.06×10^?8T² The thermodynamic data of the reaction, Cd(c) + Hg₂Ac₂(c)=2Hg(l)+Cd⁺⁺(aq)+2Ac^?(aq) at 25°C were estimated as ΔF°=?42,139, ΔH°=?48,698 cal mole^?1 and ΔS°=?22.0 cal deg^?1 mole^?1 at 25°C. The thermodynamic data for the formation of Hg₂Ac₂(s) were evaluated as ΔF_f°=?202.3, ΔH_f°=?154.5 Kcal mole^?1 and S°=72.9 cal deg^?1 mole^?1. From measurements of the heats of solution of CdAc₂·2H₂O in aqueous solution, the relative partial molal enthalpies of cadmium acetate in aqueous solution were estimated.     

Synthesis and Crystal Structures of the First Quaternary Tantalum Thiogermanates,ATaGeS5 (A = K,Rb, Cs)

The new quaternary thiogermanates, ATaGeS₅ (A = K, Rb, Cs) were prepared with the use of halide fluxes and the crystal structures of the compounds were determined by single‐crystal X‐ray diffraction methods. The compounds are isostructural and crystallize in space group P\bar{1} of the triclinic system with two formula units in a cell of dimensions: a = 6.937(1) Å, b = 6.950(2) Å, c = 8.844(3) Å, α = 71.07(2)°, β = 78.56(2)°, γ = 75.75(2)°, V = 387.6(2) Å³ for KTaGeS₅; a = 6.996(3) Å, b = 7.033(3) Å, c = 8.985(4) Å, α = 70.33(3)°, β = 78.12(4)°, γ = 75.63(4)°, V = 399.6(3) Å³ for RbTaGeS₅; a = 7.012(4) Å, b = 7.202(3) Å, c = 9.267(5) Å, α = 68.55(3)°, β = 77.27(4)°, γ = 74.75(4)°, V = 416.2(4) Å³ for CsTaGeS₅. The structures of ATaGeS₅ (A = K, Rb, Cs) are comprised of anionic infinite two‐dimensional {}_\infty^2 [TaGeS₅^–] layers separated from one another by alkali metal cations (A⁺). Each layer is made up of tantalum centered sulfur octahedra and pairs of edge‐sharing germanium centered sulfur tetrahedra. The classical charge valence of these compounds should be represented by [A⁺][(Ta⁵⁺)(Ge⁴⁺)(S^2–)₅]. UV/Vis diffuse reflectance measurements indicate that they are semiconductors with optical bandgaps of ca. 2.0 eV.     

Seltenerdhalogenide Ln4X5Z. Teil 1: C und/oder C2 in Ln4X5Z

Rare Earth Halides Ln₄X₅Z. Part 1: C and/or C₂ in Ln₄X₅Z The compounds Ln₄X₅C_n (Ln = La, Ce, Pr; X = Br, I and 1.0 < n < 2.0) are prepared by the reaction of LnX₃, Ln metal and graphite in sealed Ta‐ampoules at temperatures 850 °C < T < 1050 °C. They crystallize in the monoclinic space group C2/m. La₄I₅C_1.5: a = 19.849(4) Å, b = 4.1410(8) Å, c = 8.956(2) Å, β = 103.86(3)°, La₄I₅C_2.0: a = 19.907(4) Å, b = 4.1482(8) Å, c = 8.963(2) Å, β = 104.36(3)°, Ce₄Br₅C_1.0: a = 18.306(5) Å, b = 3.9735(6) Å, c = 8.378(2) Å, β=104.91(2)°, Ce₄Br₅C_1.5: a = 18.996(2) Å, b = 3.9310(3) Å, c = 8.282(7) Å, β = 106.74(1)°, Pr₄Br₅C_1.3: a = 18.467(2) Å, b = 3.911(1) Å, c = 8.258(7) Å, β = 105.25(1)° and Pr₄Br₅C_1.5: a = 19.044(2) Å, b = 3.9368(1) Å, c = 8.254(7) Å, β = 106.48(1)°. In the crystal structure the lanthanide metals are connected to Ln₆‐octahedra centered by carbon atoms or C₂‐groups. The Ln₆‐octahedra are condensed via opposite edges to chains and surrounded by X atoms which interconnect the chains. A part n of isolated C‐atoms is substituted by 1‐n C₂‐groups. The C‐C distances range between 1.26 and 1.40Å. In the ionic formulation (Ln³⁺)₄(X^?)₅(C^4?)_n(C₂^m?)_1?n·e^? with 0 < n < 1 and m = 2, 4, 6 (C₂^2?, C₂^4? C₂^6?), there are 1 < e^? < 5 electrons centered in metal‐metal bonds.     

Yields of O2(1Σg+) and O2(1Δg) in the H + O2 reaction system,and the quenching of O2(1Σg+) by atomic hydrogen

The generation of metastable O₂(¹Σg⁺) and O₂(¹Δg) in the H + O₂ system of reactions was studied by the flow discharge chemiluminescence detection method. In addition to the O₂(¹Σg⁺) and O₂(¹Δg) emissions, strong OH(v = 2) → OH(v = 0), OH(v = 3) → OH(v = 1), HO₂(²A′₀₀₀) → HO₂(²A″₀₀₀), HO₂(²A′₀₀₁) → HO₂(²A″₀₀₀), and H O₂(²A″₂₀₀) → HO₂(²A″₀₀₀) emissions were detected in the H + O₂ system. The rate constants for the quenching of O₂(¹Σg⁺) by H and H₂ were determined to be (5.1 ± 1.4) × 10^?13 and (7.1 ± 0.1) × 10^?13 cm³ s^?1, respectively. An upper limit for the branching ratio to produce O₂(¹Σg⁺) by the H + HO₂ reaction was calculated to be 2.1%. The contributions from other reactions producing singlet oxygen were investigated.     

№Determination of Trace Arsenic by Solid Substrate-Room Temperature Phosphorescence Quenching Method Based on the Catalyzed Reaction of H2O2 Oxidizing 9-Hyd roxy-2,3,4,9-tet rahyd ro-1,10-anth raquinone

A new solid substrate-room temperature phosphorescence （SS-RTP） quenching method for the determination of trace As（V） has been developed, based on the facts that 9-hydroxy-2,3,4,9-tetrahydro-1,10-anthraquinone （R） can emit intense and stable SS-RTP on solid substrate, and α,α＇-dipyridyl can activate As（V） catalysis of the reaction of H2O2 oxidizing R to non-phosphorescence compound R＇, which can cause the sharp quenching of SS-RTP. Under the optimum condition, the relationship between the ΔIp of the emitting intensity and 1.60-160 fg·spot^-1 As（V） （corresponding concentration： 0.0040-0.40 ng·mL^-1, sample volume： 0.4 μL·spot^-1） conformed to Beer＇ law. The regression equation of working curve can be expressed as ΔIp= 20.46＋0.5492CAs（v） fig·spot^-1） （r= 0.9995, n = 6）. The limit detection （LD） is 0.27 fg·spot^-1 [As（V） corresponding concentration： 6.8 × 10^-13 g·mL^-1, n=11]. The samples containing 0.0040 and 0.40 ng·mL^-1 As（V） were repeatedly determined for 11 times. RSD are 3.0% and 2.7% respectively. The SS-RTP mechanism was also discussed. R was synthesized in this paper. Meanwhile, the structure was determined by NMR, IR, mass spectra and elemental analysis.     

A Thermodynamic Study of Bromo-Lanthanum (III) Complexes from EMF Measurements

The stability constants (for the formation) of LaBr²⁺ and LaBr₂⁺ ions were obtained potentiometrically at various ionic strengths at 20°, 25°, 30°, and 35°. The molal free energy was given by ΔG°=-2,444.04+2.67T log T+1.39T. The thermodynamic quantities for the formation of LaBr²⁺ were evaluated as ΔH_f° = ?207.9, ΔG_f° = ?199.1 kcal mole^?1 and S° = ?29.5 cal. deg^?1 mole^?1 at 25°.     

The fluorescence of all-trans diphenyl polyenes

The temperature dependence of the fluorescence and fluorescence excitation spectra of all-trans diphenyl hexathene (DPH) and octatetraene (DPO) in six solvents confirms the S₁(¹A_g*) and S₂(¹B_u*) state assignment, and determines their energy difference ΔE. The S₁ fluorescence rate parameter k_F depends on ΔE, the solvent refractive index n, the S₂ (n = 1) fluorescence rate parameter k_F20 (2.23 × 10⁸ s^?1 for DPH, 2.33 × 10⁸ s^?1 for DPO), and the S₂-S₁ coupling matrix element V (745 cm^?1 for DPH, 500 cm^?1 for DPO). The S₁ fluorescence is induced by ¹B_u*-¹A_g* potential interaction (PI), via a b_u vibrational mode (≈ 900 cm^?1), and not by vibronic coupling. The main S₁ radiationless transition, rate parameter k_R, is thermally-activated internal rotation through an angle θ about the central ethylenic bond(s). The PI distorts the S₁ (θ) potential surface and thus influences k_R.