Studies on the stretching of polypropylene film. I. Two-step biaxial stretching

A polypropylene film was stretched at 100–160°C., quenched to room temperature, and then restretched at the same temperature perpendicularly to the first stretching. The reorientation behavior was investigated by using optical and x-ray methods. During the restretching the monoaxial orientation caused by the stretching is converted into a new monoaxial orientation through a balanced state, where n_pp = n_ps < n_ss. The more or less parallel orientation to the film surface of the polypropylene molecules, brought about by the first stretching, proceeds further on restretching. n_ss is a linear function of the degree of stretching in area v_A. The inclination of this line is independent of the type of deformation, stretching, or restretching, provided the temperature is kept constant. At 160°C. the plot of n_ss versus thickness is less steep than it is at 100 or 130°C. The overall reorientation apparently proceeds according to Kratky's first deformation law. The x-ray pattern of a res?tretched film is a four-point diagram which indicates the existence of a pair of reorientation axes inclined symmetrically against the stretching axis. The inclination grows larger with restretching, and the axes merge into the restretching axis at extreme restretching. This phenomenon is less pronounced when the restretching is carried out at higher temperatures. The density of the restretched film is determined mainly by the stretching temperature, but extreme restretching has a tendency to lower it very slightly.     

Studies on the stretching of polypropylene film. II. Polyaxial stretching

Polypropylene film was stretched polyaxially at 100–160°C., and the orientation behavior was studied by means of optical and x-ray method. The molecular chains oriented progressively to the film surface with an increase in stretching area v_A in the range 1–16, and the (040) selective uniplanar orientation developed at the extreme stretching. The plot of orientation versus v_A was less steep when the stretching was carried out at higher temperature, but the final degree of orientation was independent of the temperature, because the final v_A increased with temperature. At 160°C. premelting occured to such a degree that the high stretching and, consequently, the high orientation could not be obtained. The orientation of the amorphous chains was always behind that of the crystalline region. In the initial stage the polyaxial stretching was not as effective in attaining high biaxial orientation as the two-step biaxial stretching, but the final orientation was the same in both types of stretching because v_A reached a value of 16 in the polyaxial stretching while it was only 2 in biaxial stretching.     

Studies on biaxial stretching of polypropylene film. X. High-temperature x-ray and optical study of type III orientation

Change of orientation and crystalline state of uniaxially stretched polypropylene film during subsequent restretching with the film width unrestrained was studied by means of x-ray, optical, and calorimetric methods. Uniaxially stretched film immediately after 5 min of preheating at 130°C barely suffers premelting. When the preheating temperature rises above 150°C, the premelting proceeds gradually and the x-ray pattern becomes a halo around 160°C, which, however, returns nearly to the original crystalline pattern after cooling to room temperature. The fraction premelted in the preheating amounts to about ½–? under the condition yielding type III orientation at room temperature, as previously reported. The 130°C restretching brings type II orientation already at that temperature, similar to what has been observed at room temperature. When the restretching is performed above 155°C, the crystalline pattern remaining after the preheating converts to a halo during the restretching, which, however, converts again to the crystalline pattern of type III orientation when it is rapidly cooled. This suggests that the restretching at higher temperatures breaks up lamellae into smaller-sized crystallites. Upon cooling, the smaller-sized crystallites reorganize lamellae, the deformed lattice recovers its ordinary state, and the pulled-out chains crystallize into intermolecular crystallites, aligning in the direction of restretching. Concurrently, disorientation proceeds fairly rapidly at such high temperatures, hence, type III orientation cannot be observed even at room temperature unless the film is quickly cooled after restretching. It is concluded that type III orientation results from restretching when thermal motion of the chains within the crystalline phase becomes so violent that the unfolding occurs easily as compared with lamellar rotation.     

Studies on biaxial stretching of polypropylene film. IX. Melting behavior of biaxially stretched film in one step

Melting temperature of a film biaxially stretched in one step in air at 152 or 140°C increases with increase of vA, whereas heat of fusion and density decrease with increase of vA, where vA is the degree of stretching in area. The rapid decrease in density occurs for vA > 10. Extrapolation of the plot of the density versus vA^?1/2 gives a value of 0.870 g/cm³ at infinite vA, which has been reported as the amorphous density of isotactic polypropylene by Farrow. This is so because the fine structure of the film becomes more and more amorphous with further stretching and reaches completely amorphous state at infinite vA. The temperature of stretching has a strong effect on the thermal behavior of a film; a low stretching temperature (140°C) brings about lower melting temperature, heat of fusion, and density. Crystallinity after melt press has not so large an effect on the melting behavior as the stretching temperature. Melting temperature and the shape of the thermogram also depend on the heating rate. There is an appropriate heating rate depending on vA which gives the minimum melting temperature. With stretched samples, a small side peak or a shoulder appears at a relatively low temperature in the thermogram when a high heating rate is used.     

Studies on the biaxial stretching of polypropylene film. VII. Refractive index of film measured with abbé refractometer

The refractive index of a film measured with an Abbé refractometer differs often depending on which surface of the film faces the refracting prism of the refractometer. This phenomenon was elucidated by using well-characterized films especially prepared for the purpose. The experimental results led to the conclusion that the measurement with an Abbé refractometer gives the refractive index of the film surface facing the refracting prism independently of the refractive index distribution within the film. The importance of this conclusion is stressed in relation to the structural studies of polymer films, especially of biaxially stretched films.     

Preparation and characterization of biaxially oriented polypropylene film with high molecular orientation in the machine direction by sequential biaxial stretching

Novel approach of applying the ternary polymer blend of long‐chain branched polypropylene (LCB‐PP), conventional polypropylene (PP), and hydrogenated polydicyclopentadiene (hDCPD) has been employed to tensilize biaxially oriented polypropylene (BOPP) film in the machine direction (MD) by successive sequential biaxial stretching method. It is found that the addition of LCB‐PP improves the MD stretchability of the BOPP film of PP/hDCPD blend. Depending on the content of LCB‐PP, LCB‐PP/PP/hDCPD ternary blend could be biaxially stretched up to the MD stretching ratio (MDX) of 12 without film breakage whereas that of PP (conventional BOPP film) resulted in the MDX up to 6. This excellent MD stretchability enabled to tensilize the BOPP film in the MD, where Young's modulus in the MD could be increased up to 4.9 GPa, twice higher than that of conventional BOPP film. The orientation of total molecular chains and that of crystalline molecular chains were evaluated by in‐plane distribution of refractive indices and wide‐angle X‐ray diffraction, respectively. The results are discussed from the viewpoint of deformation behavior during stretching process. Moreover, the resultant film had a dimensional stability substantially equivalent to that of conventional one, in spite of the higher stretching ratio, and an improved moisture barrier property. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

邻菲咯啉衍生物钌配合物的制备及性能研究

钌-邻菲咯啉配合物已经广泛应用于电化学、光化学领域,以羟基苯基并[4,5]-邻菲咯啉（Hpip）为配体,合成二氯化三羟基苯基并[4,5]-邻菲咯啉钌（Ru（Hpip）3Cl2）。应用红外、紫外和荧光光谱对产物进行表征,用循环伏安法考察其电化学行为,研究pH、氧对其荧光强度的影响。结果表明Ru（Hpip）3Cl2在玻碳电极上有准可逆的电化学行为,在溶液中其对氧的响应倍数（I0／I）高达11．9。     

Bis[4-(methylthio)phenylmethyleneaminophenyl] disulfide, 2-[4-(methylthio)phenyl]-2,3-dihydro-1,3-benzothiazole,and its nickel(II) and cobalt(II) complexes: Synthesis,adsorption on gold surface and electrochemical characterization

2-[4-(Methylthio)phenyl]-2,3-dihydro-1,3-benzothiazole (1) and bis[4-(methylthio)phenylmethylene-aminophenyl] disulfide (2) were synthesized. Novel coordination compounds of Ni(II) and Co(II) with 2-[4-(methylthio)phenylmethyleneamino]thiophenol, M(1)₂ (M=Co (3); M=Ni (4)), were prepared by reacting 1 with M(OAc)₂·6H₂O or MCl₂·6H₂O in EtOH solution. The structure of 2 was proved by X-ray crystallography. Electrochemical behavior of 1–4 in CH₃CN solution and at the surface of a gold electrode was studied by cyclic voltammetry. The modification of the electrode by ligand 1 and its complexes with Ni²⁺ and Co²⁺ is described in detail. Two procedures were used to obtain a self-assembled monolayer of a metal complex on the gold surface: the adsorption of prepared coordination compound 3 or 4 on the electrode and the initial modification of the electrode with ligand 1 followed by the formation of a coordination complex between the ligand adsorbed on the electrode and a metal salt occurring in solution. On the basis of the electrochemical data, it was found that the structure of complexes formed on the surface differs from that of the complexes produced in solution.     

Studies of the electrodeposition of palladium from baths based on [Pd(NH3)2X2] salts. I. [Pd(NH3)2Cl2] baths

Spectroscopic techniques are used to confirm the chemistry of solutions of [Pd(NH₃)₂Cl₂] in aqueous NH₄Cl at various pH. In addition, potential sweep and step methods at rotating and stationary disc electrodes (both vitreous carbon and freshly plated palladium) are used to investigate palladium deposition from a standard electroplating bath, [Pd(NH₃)₂Cl₂] in NH₄Cl/NH₃ (pH 8.9). The relative importance of oxygen reduction, hydrogen absorption and hydrogen evolution as competing cathode reactions under various conditions is defined and the advantage of strong convection for high rate plating is demonstrated.     

Photocatalytic degradation of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] on the layer of TiO2 particles in the batch mode plate film reactor

The photocatalytic degradation of diuron in aqueous solution on TiO₂ layer of a batch mode plate reactor irradiated with ultraviolet sun-bed tubes was investigated. Dependence of the reaction rate on the diuron concentration (in the range of 0·8–8·0×10⁻⁵ mol dm⁻³) and on the light intensity (0·8–2·7×10⁻⁹ einstein cm⁻² s⁻¹) but independence on the flow rate (2·5–3·6 dm³ min⁻¹) were found. A reaction scheme was proposed following the main identified primary [3-(3,4-dichlorophenyl)-1-methyl-1-formylurea and 3-(3,4-dichlorophenyl)-1-methylurea] and secondary [3-(3,4-dichlorophenyl)-1-formylurea and 3,4-dichlorophenylurea] products. © 1998 SCI     

2－（5－溴－2－吡啶偶氮）－5－［（N，N－二羧基甲基）氨基］苯酚的合成及其与钴显色反应的研究

新水溶性显色剂２－（５－溴－２－吡啶偶氮）－５－［（Ｎ，Ｎ－二羧基甲基）氨基］苯酚（５－Ｂｒ－ＰＡＤＣＡＰ）的合成。讨论了试剂与钻（Ⅱ）的最佳反应条件。在ｐＨ６．０，配合物的最大吸收波长为６００ｕｍ，摩尔吸光系数达９．５×１０４。所确立的方法可用于维生素Ｂ１２中钴的测定。     

Second-sphere Coordination of [Pt(bipy)(NH3)2]2+ by Dibenzo-crown Ethers. Solution Spectroscopic Studies and the Crystal and Molecular Structures of [Pt(bipy)(NH3)2.dibenzo-30-crown-10] [PF6]2.0.6 H2O and [Pt(bipy)(NH3)2.dibenzo-24-crown-8] [PF6]2

In addition to hydrogen bonding and Coulombic forces, charge transfer interactions stabilise the 1:1 adducts formed between [Pt(bipy)(NH₃)₂] ²⁺ and a series of dibenzo-3n-crown-n (n = 6–12) ethers as evidenced by ¹H NMR and UV-visible spectra in solution and by X-ray crystal structures (for n = 8 and 10) in the solid state. Mutual diamagnetic (ring current) shielding by the aromatic systems of host and guest results in dramatic upfield shifts of certain aromatic proton resonances on adduct formation, especially when n = 10 or 11. A broad charge-transfer absorption band at 350 nm attains its maximum intensity at n = 11 though stability constant measurements indicate optimum binding when n = 10. X-ray diffraction studies reveal that, when n = 8, only one of the crown ether benzo-rings interacts with the bipyridyl ligand in a charge-transfer sense. However, when n = 10, the macrocycle is sufficiently large and flexible to allow both benzo-rings to enter into stabilising interactions with the bipyridyl ligand such that the platinum complex is encapsulated by the host in a U-shaped cavity.     

A novel effect of bis(6-heptenyl)zinc on the molecular weight and rheologic performance of polypropylene produced by rac-Me2Si[2-Me-4-Ph-Ind]2ZrCl2/MAO

The polymerization of propylene combined with bis(6-heptenyl)zinc (BHZ) catalyzed by rac-Me₂Si[2-Me-4-Ph-Ind]₂ZrCl₂/MAO was investigated. BHZ acts as both a comonomer and a chain transfer reagent, which was verified by ¹H NMR and ¹³C NMR spectra. A novel effect of BHZ on the molecular weight and rheologic properties of the product was explained by the production of LCB.     

Functional display of active bovine adrenodoxin on the surface of E. coli by chemical incorporation of the [2Fe-2S] cluster

The display of heterologous proteins on the surface of living cells bears promising options for a wide variety of biotechnological applications. Up to now, however, cellular surface display was merely restricted to simple polypeptide chains. Here we present for the first time the efficient display of a protein (bovine adrenodoxin) that contains an inorganic, prosthetic group in its active form on the surface of Escherichia coli. For this purpose apo-adrenodoxin was transported to the cell surface and anchored within the outer membrane by the autotransporter pathway. Incorporation of the iron-sulfur cluster was achieved by a single-vial, one-step titration under anaerobic conditions. The biological function of surface-displayed holo-adrenodoxin could be established through adrenodoxin-dependent steroid conversion by two different cytochrome P450 enzymes and the number of functional molecules on the cell surface could be determined to be more than 10(5) per cell. Neither the expression of adrenodoxin nor the incorporation of the chemical iron-sulfur cluster reduced the viability of the bacterial cells.     

DNA-promoted electrochemical assembly of [Ru(bpy)2dpp] on the ITO electrode by introducing copper(II) ion

The electrochemical assembly of [Ru(bpy)₂dpp]^3+/2+ (where bpy = 2,2′-bipyridine, dpp = 2,3-bis (2-pyridyl) pyrazine) promoted by calf thymus DNA on an ITO electrode based on the introduction of copper(II) ion has been investigated. There exists a diffusion-controlled wave and two prewaves for the complex in the differential pulse voltammetric sweeping process. The formal potential of the high prewave shift ca. 0.530 V negatively compared with that of the diffusion-controlled wave. Dpp ligand with two vacant chelating N sites in the complex can bite Cu²⁺ and the resultant heterometallic complex shows a weakened assembly in contrast to that of [Ru(bpy)₂dpp]^3+/2+ alone. Furthermore, double stranded DNA is able to accelerate the assembly of the ruthenium complex and heterometallic complex generated by chelating with Cu²⁺ by using the ITO surface, the prompted strength of the latter is far stronger than the former. Their assembled mechanism enhanced by DNA is proposed.     

Substituted propyne polymers—part II. Effects of aging on the gas permeability properties of poly[1-(trimethylsilyl)propyne] for gas separation membranes

Poly[1-(trimethylsilyl)propyne] (PTMSP) is an unusual polyyne material which is optically clear, exhibits high solubility in nonpolar organic solvents, and good oxygen compatibility. By contrast, polyacetylene is black, insoluble, and is unstable in oxygen. The long term stability of PTMSP has been determined by a combination of thermal gravimetric analysis (TGA) and permeability test procedures under a number of different isothermal aging conditions. The use of commercial antioxidants at up to 2 weight percent improves the long term stability of PTMSP. The presence of the antioxidant has no effect on the surface fluorination of PTMSP. Testing of PTMSP films for over eight months shows no change in either permeability or selectivity in contrast to previously reported data.     

Mechanistic aspects of polysaccharide complexation by quaternary ammonium salts,based on the reaction of Xanthan gum with [1-14C]cetyltrimethylammonium bromide (Part II)

Complex formation between cetyltrimethylammonium bromide (CTAB) and xanthan gum in Xanthomonas campestris fermentation broth has been further used to exemplify the reaction between carboxy group — containing polysaccharides and quaternary ammonium salts. The variation of the molar ratio of xanthan gum: CTAB in the supernatant with variation of addition of quaternary ammonium salt is one parameter of the reaction which shows a definite relationship. Although this molar ratio in the supernatant is high (> 1) during the initial stages of the reaction, when little precipitation of the polysaccharide is occurring; it appears that the ratio must be below a critical value of about one before the end-point of the complexation reaction can occur. The molar ratio of xanthan gum:CTA in the complex is initially exaggerated due to precipitation of polysaccharide with uncomplexed carboxy groups, but this ratio attains a constant value during the final stages of the reaction. A surprising observation of this study was the evidence obtained that CTAB added to X. campestris fermentation broth in excess of the complexation reaction end-point requirement is associated with the insoluble xanthan gum-CTA complex and is not present in the supernatant. Several possible explanations have been put forward to account for this observation. On the basis of this and another recent study, a detailed model of the mechanism of the complexation reaction between xanthan gum and CTAB in aqueous solution has been proposed. Discussion has been given to the implications and applicability of this particular complexation reaction mechanism.     

Torsional braid as a kinetic tool for the study of the polymerization of viscous materials. II. Catalytic effects in the polymerization of carboxylic acid-terminated polybutadiene prepolymers with tris[1-(2-methyl)aziridinyl]phosphine oxide

The torsional braid technique for studying the polymerization of viscous substances has been extended to a study of the homogenous catalytic behavior of a number of acidic and basic catalysts int he polymerization of carboxy-terminated polybutadiene with tris(methyl aziridinyl)phosphine oxide. No general catalytic behavior was observed. Specific catalysis was observed in the case of lithium oleate, where the gel time was decreased, and in the case of bis(tri-n-butyltin) oxide, where the gel time was increased. The average energy of activation for all of these polymerizations was 13.9 ± 0.5 kcal./mole. This energy of activation and the reaction environment, when compared with the data in the literature, strongly suggest that the explanation that a change in the rate-determining step occurs as a function of the polarity of the reaction medium fails to account for all of the results.