Effects of crystallinity and supermolecular formations on the interfacial shear strength and adhesion in GF/PP composites

Aim of this study was to screen the morphological effects on the interfacial shear strength (i) in glass fibre (GF) reinforced isotactic polypropylene (iPP) model composites. i was determined by a modified single fibre pull-out technique. It was established that the relation between i (5–6 MPa) and the yield stress of the iPP (y30 MPa) is at about 1:6 and that the i values were not influenced by the mophological superstructure set under isothermal crystallization conditions. Increased i was only observed when specimens were produced non-isothermally, by quenching (i9 MPa). This improvement could not be related to thermal shrinkage stresses. The enhancement in i was attributed to better wetting and improved adhesion due to the enlarged amorphous PP (aPP)-phase. A schematic adhesion model considering the wetting behaviour of aPP and iPP was proposed.     

Cooperative inclusion of sodium 1-pyrenesulfonate by γ-cyclodextrin

Summary The interaction of -cyclodextrin(-CD) with sodium 1-pyrenesulfonate(PS) was studied spectrophotometrically. -CD was found to cause much larger decrease in the absorption maxima of PS than -CD. The fluorescence spectra of PS in the presence of -CD showed excimer emission, while those of PS with -CD showed only monomer emission, indicating that -CD forms 12 (-CDPS) complexes in which two PS molecules are included in the -CD cavity in a face-to-face fashion. The binding isotherm showed a sigmoidal curve. The association constants were estimated by computer simulation of the binding curve. The 12 (CDPS) complex was found to be much more stable (K=10⁶ M^–1) than the 11 complex (K=1 M^–1). At high concentration of -CD another -CD cooperates in binding two PS molecules, resulting in the formation of a 22 complex.     

Synthesis of monocarboxylic polyoxyethylenes

Summary The various methods of synthesis which can be used to prepare -carboxy polyoxyethylenes are reviewed. The synthesis and the purification of -methoxy -carboxy polyoxyethylenes ( ) are reported. The process consists of the reaction of halogenoacetic acids with an -methoxy -sodium hydroxylate polyoxyethylene followed by a purification by extraction. ,-dimethoxy and -methoxy -ethyl carboxylate polyoxyethylenes were synthesized.     

Temperature programmed oxidation of Cu/ZnO catalysts with N2O: an attempt for characterization of copper catalysts

For characterization of the surface structure of metallic copper formed on the support, temperature programmed oxidation (TPO) with N₂O was carried out over various Cu/ZnO catalysts. Four peaks of the N₂ formation (, , and ) were observed at 223, 400, 545 and 600 K in the TPO runs. The average copper crystallite size estimated from the sum of the amount of - and -peaks agreed fairly with those determined by X-ray diffraction and transmission electron microscopy. It was concluded that - and -peaks resulted from the oxidation of metallic copper atoms on the steps, corners and/ or defect sites, and on the flat sites of the surface of copper crystallites, respectively, while - and -peaks resulted from the bulk oxidation of copper.     

Calorimetric,X-ray and infra-red investigations on poly(hexamethylene adipamide)

Summary In dependence on crystallization conditions three ranges with different crystal structure and heat of fusion were found by DSC,WAXS,and IR for unoriented PA 6.6 samples of densities between 1.10 and 1.17gcm^–3: Range I:_I triclinic, _c ^I =1.225 gcm^–3,H _M ^I = 235 Jg^–1. Range II:_II triclinic, _c ^II =1.165 gcm^–3, H _M ^II =185 Jg^–1. Range III:Continuous variation from _c ^I ,H _M ^I to _c ^II , H _M ^II . _a=1.095 gcm^–3 is independent of crystallization. conditions. The transition between _I and _II is probably due to changes of the chain conformation.     

Weak Gel Behaviour of Poly(vinyl alcohol)-Borax Aqueous Solutions

Thermal transition of PVA-borax aqueous gels with a PVA concentration of 60 g/L and a borax concentration of 0.28 M was investigated at temperatures ranging from 15 to 60C using static light scattering (SLS), dynamic light scattering (DLS), and dynamic viscoelasticity measurements. Three relaxation modes, i.e. two fast and one slow relaxation modes, were observed from DLS measurements. Two fast relaxation modes located around 10^–310¹ sec, with one fast mode (_f1) being scattering vector q-dependent and the other fast mode (_f2, with _f2>_f1) being q-independent. The _f1 mode was attributed to the gel mode whilst the _f2 mode could be due to the hydrodynamics of intra-molecular hydrophobic domains formed by uncharged segments of polymer backbones. The slow relaxation mode with relaxation time located around 10¹10³ sec in DLS data was due to the motion of aggregated clusters and was observed only at temperatures above 40C. The amplitude and relaxation time of slow mode decrease as temperature is increased from 40 to 60C. At temperatures below 40C, no slow relaxation mode was observed. The SLS measurements showed PVA-borax-water system had fractal dimensions D _f2.4 and D _f2.0 as temperature was below and above 40C, respectively. The simple tilting test indicated gel behaviour for the PVA-borax aqueous system at temperatures below 40C with a creep flow after a long time exposure in the gravity field. But the dynamic viscoelasticity measurements demonstrated a solution behaviour for PVA/borax/water at temperatures below 40C, the critical gel point behaviour for G() and G() was not observed in this system as those reported for chemical crosslinked gels. These results suggest that the PVA-borax aqueous system is a thermoreversible weak gel.     

Stress and recovery maxima in LDPE melt elongation

Summary By means of a new tensile rheometer for polymer melts, stress-strain curves () and the elastic recovery _R() of a low density polyethylene melt were measured up to total strains =7, i.e. stretch =1097, at 150°C and two strain rates, =0.03 and 0.1 s^–1. Tensile tests up to very high strains e give relevant results only if the test performance is characterized by quality parameters which are defined and given in this paper. The test results show a maximum in a as well as in _R at about =5.5. Hence, in the range of investigated, a rheologically steady-state of flow does not exist.     

Ethynylene-disilanylene copolymers

Polymers of structure (SiR₂SiR₂-C C-SiR₂SiR₂-C C) _n , in which ethynylene units alternate with disilylene units, have been prepared by two routes: (a) condensation of dichlorodisilanes with dilithium derivatives of 1,2-diethynyldisilanes and (b) ring-opening polymerization of strained cyclic disilanylene-acetylnes, (SiR₂SiR₂C C)₂. The polymers display UV absorption near 240 nm indicative of – conjugation between the Si₂ and the C C moieties. Polymers with R=R=n-Bu or R=n-Bu, R=Ph, undergo solid-state transitions to form liquid crystalline mesophases resembling those observed for many poly(silylenes). Single crystals were obtained for the polymer with R=R=CH₃, by precipitation from dilute cyclohexane solution. The solid-state properties and structures of this family of polymers are discussed.This paper was presented at the Second International Topical Workshop, Advances in Silicon-Based Polymer Science.     

Electrochemical behaviour of viologen-cyclodextrin inclusion complexes. The case of non-alkyl group substituted viologen

The electrochemical behavior of non-alkyl substituted viologen, 4,4-dibenzyl bipyridinium (BzV), 4,4-dicyanophenyl bipyridinium (CyV) and -,-,-cyclodextrin (, , -CD) was studied using cyclic voltammetry and a spectroelectrochemical method. It was found that BzV and Fe(CN) ₆ ^4– formed a charge-transfer (CT) complex with a ratio of 21 and the colour of the solution faded with the addition of an electrolyte. This behaviour is the same as in then-heptyl viologen and ferrocyanide system [1]. BzV, -CD and -CD formed an inclusion complex only in the reduced state, whilst BzV and -CD formed an inclusion complex in both the oxidized and the reduced state. An EC scheme in which a chemical reaction follows an electrochemical reaction was considered to predominate in the BzV and -, -CD systems, while a CE scheme in which a chemical reaction preceded an electrochemical reaction predominated in the BzV and -CD system. On the other hand, CyV was found to form an inclusion complex with -, -, -CD in both the oxidized and the reduced states. therefore a CE scheme was considered to predominate in the CyV--, -, -CD systems.     

Determination of optical purity of substituted β-lactones

An octakis (3-O-butyryl-2,6-di-O-pentyl)--cyclodextrin capillary gas chromatographic column was used to determine the optical purity of seven different -lactones, having substituents in - or -position, and DL-lactide. The resolving power varied from one lactone to another. The optical purity values determined by GC were in agreement with those obtained from NMR spectroscopy or optical rotation.     

Electrosynthesis of 4,4′-dinitroazobenzene on PbO2 electrodes

Parameters which affect the electrosynthesis of 4,4-dinitroazobenzene from p-nitroaniline on platinum and PbO₂ electrodes were investigated and optimum conditions were determined. Maximum conversion efficiency for electrosynthesis was 95% with a pure -PbO₂ electrode. It was found that the electrocatalytic activity of a PbO₂ electrode depends upon its / ratio and its degree of crystallinity. The effects of the added base and water on the conversion efficiency were also elucidated.     

Chemical effects in commercial and laboratory mixtures of ‘reactive’ phosphate rock and acidulated fertilisers

The chemical analyses of different size fractions of a variety of commerical and laboratory prepared samples of partially acidulated phophate rocks and mixtures of reactive phosphate rock and single superphosphate (called LONGLIFE in New Zealand) have been studied. Whereas only minor chemical segregation effects have been observed for partially acidulated products quite a large bias has been established for LONGLIFE materials, and more especially commercial samples, where larger proportions of phosphate rock were found in the lower size fractions. This inhomogeneity was considered to arise from poor mixing of components and subsequent inconsistent granulation; more stringent rejection criteria for undersize material would greatly assist in improving the product quality. Chemical deactivation of the phosphate rock residue in LONGLIFE materials was also observed; this can be partially explained by a selective reaction of the reactive phosphate rock component with acid still present at the time of mixing with the single superphosphate component.     

Characterization of some organic poly(aminiumphosphate)s

Summary Metachromatic reactions of MB and AO are studied with poly(aminium phosphate)s. The main band() at 665 m and 492 m for MB and AO are shifted to 580 m and 455 m respectively (-bands). The metachromatic values at different concentrations of poly(aminium phosphate)s are also reported. The dye association for MB with these polymer derivatives is investigated conductometrically as well. It is observed that MB can be at the most bind with the phosphate residue of polymer upto 11 molar ratio. The polymeric nature was further established by paper chromatographic technique in Terry's, Ebel's & Pfrengle's solvents.     

Porous mullite ceramics through diphasic gels of large boehmite and small silica particles

Mullite formation process has been studied in stoichiometric mullite (3Al₂O₃·2SiO₂) diphasic gel containing large boehmite (1 m) and small silica (10 nm) particles. It has been found that initial mullitization did not take place inside the silica phase (cristobalite), but took place in the defect -alumina phase. -alumina was stabilized by silica when the temperature was below 1350°C. At temperatures above 1350°C, mullite crystallized directly. It was suggested that silica diffused into the pores (<1.8 nm) of -alumina and prevented the collapse of -alumina pore structure. On the other hand, when silica was not present, the pore structure of -alumina collapsed and -alumina crystallized at 1100°C. Porous mullite ceramics were obtained by using special diphasic gels containing large boehmite and small silica particles.     

The estimation of the residual capacity of sealed lead-acid cells using the impedance technique

The problem of estimating the residual usable energy of a lead-acid cell has been intensified by the introduction of fully sealed units. These rely on the recombination of gaseous oxygen produced during overcharge at the positive electrode with the active material at the negative electrode. This introduction has removed the possibility of electrolyte density measurements, third electrode measurements and restricted residual capacity assessments to the two cell terminals. A method for this process is described using a parameter based on a characteristic frequency. The parameter is also a useful measure of cell ageing.Nomenclature R _SOL Ohmic resistance of cell () - Charge-transfer resistance of positive and negative electrodes () - CL Double-layer capacitance of both positive and negative electrodes (F) - Warburg diffusion (S^–1/2) - C _EXT External series capacitor in analogue Fig. 5 (F) - R _EXT External resistor in parallel withC _EXT in the anologue circuit Fig. 5 () - IND Inductor in Fig. 5 representing the geometrical effects of the cell at high frequencies (Henries) - R _IND External resistor in parallel with IND in the analogue circuit Fig. 5 () - Roughness factor allowing for the porosity of both electrodes     

Catalytic oxidation of methanol to methyl formate over silver – a new purpose of a traditional catalysis system

Catalytic reaction was performed in the unregarded temperature region over silver catalysts with long catalytic lifetime for the conversion of methanol to methyl formate. O-saturated or O-saturated silver catalysts were studied individually to identify the roles of O, O in the oxidative esterification of methanol over an unsupported polycrystalline silver catalyst. A synergic process is proposed based on the coexistence of -oxygen species and -oxygen species on the surface of polycrystalline silver at about 573 K.     

Silphinene Sesquiterpenes as Model Insect Antifeedants

Silphinene sesquiterpenes are established chrysomelid antifeedants. In this work, nine silphinene analogs, 11-acetoxy-5-angeloyloxysilphinen-3-one (1), 11-acetoxy-5-tigloyloxysilphinen-3-one (2), 11-acetoxy-5-iso- butyryloxysilphinen-3-one (3), 11-hydroxy-5-angeloyloxysilphinen-3-one (4), 11,5-dihydroxysilphinen-3-one (5), 11,5-diacetoxysilphinen-3-one (6), 5,11-diisobutyryloxysilphinen-3-one (7), silphinen-3,5,11-trione (8), and O-methyl-5-epicantabrenolic acid methyl ester (10), and a presilphiperfolane sesquiterpene (9) were tested against several divergent insect species, including the lepidopteran Spodoptera littoralis, the chrysomelid Leptinotarsa decemlineata, and five aphid species, and their antifeedant effects were compared with those of picrotoxinin, a GABA-antagonist, and thymol, an allosteric modulator for insect GABA receptors. All insects tested responded to at least one silphinene analog and/or GABA antagonist. Compound 3 and thymol were effective antifeedants against all species tested except S. littoralis, with varying potencies according to their feeding ecologies. The toxicity of these compounds was species-dependent and did not correlate with their antifeedant effect.     

Synthesis of new metal-containing side-chain monomers and polymers

New metal-containing vinyl monomers, hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hexyl-6-oxy-{4-[4-(4-ferrocenoyl phenyl)phenyl]benzoyloxy}methacrylate, and the corresponding homopolymers and random copolymers with hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate were synthesized. The compounds were characterized by¹H NMR; their thermal behavior was investigated by means of differential scanning calorimetry. Monomers and polymers containing the ferrocene unit melt at lower temperatures than those derived from the cyclopentadienyl managanese tricarbonyl moiety. The melting temperatures of the monomers and polymers ranged from 399 to about 515 K, Both monomers and polymers failed to exhibit mesogenic behavior. Values ofM _n,M _w,M _w/M _n, and degree of polymerization were obtained by gel permeation chromatography. TheM _n ranged from 16,500 for the copolymer containing hexyl-6-oxy-{4-[4-(4-ferrocenoyl phenyl)phenyl] benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio to 26,000 for the copolymer containing hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio.M _w/M _n ranged from 1.6 in the case of the copolymer containing hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio to 2.2 in the case of poly(hexyl-6-oxy{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate).     

Iron-ruthenium catalyst for the water-gas shift reaction

Iron-ruthenium catalysts prepared by impregnation of calcination products of -, , -and -iron oxide-hydroxides with either ruthenium chloride or ruthenium red were tested for the activity for the water-gas shift reaction. The effect of support, ruthenium containing impregnation agent and thermal treatment on catalyst performance was discussed.     

Sex pheromone chemistry of the western spruce budwormChoristoneura occidentalis Free

SCOT capillary Chromatographic and SCOT capillary chromatographic-mass spectrometic analyses of gland washes and effluvia of virgin femaleChoristoneura occidentalis Free, have been conducted with both a diapausing and nondiapausing strain of this insect. The following compounds were identified in gland washes and effluvia in both strains:E andZ11–14Ald,E andZ11–14Ac,E andZ11–14OH and 14Ald, 14Ac, and 14OH. The average aldehyde: acetate: alcohol ratio found by analysis of single glands by virgin females (nondiapausing strain) was 170.73. Analysis of virgin female effluvia gave this ratio as 1038 (diapausing strain: %Z=8, 11, 15, respectively) and 1036 (nondiapausing strain: %Z=8, 11, 12, respectively). The saturated components were generally 1–2% of theE isomer in each case. Comparisons of EAG responses of bothC. occidentalis andC. fumiferana toE11–14Ald,E11–14Ac andE11–14OH were made. Correlations with both laboratory and field data previously published were also made betweenC. fumiferana andC. occidentalis.Lepidoptera: Tortricidae.