ISSN:0959-8103    

DOI:10.1002/pi.4990280102

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA new theory enabling the surface energy of a solid to be expressed as a quantitative energy spectrum has recently been proposed. This theory was tested on clean and contaminated polyvinyl chloride (PVC) surfaces which yielded remarkably different spectra. Electron spectroscopy for chemical analysis (ESCA) confirmed that peak energies could be correlated with specific molecular groups exposed at the surface.

ISSN:0959-8103    

DOI:10.1002/pi.4990280103

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractDurability of adhesively bonded aluminium joints was investigated for both stressed and unstressed joints exposed to environments of air, distilled water, 0.5% sodium chloride solution and 5% sodium chloride solution. Testing involved the use of marine grade aluminium, two acrylic adhesives and two epoxy resin adhesives. Surface preparation consisted of a solvent wipe degreasing procedure. The acrylic adhesives used in this study displayed greater bond durability than cpoxy resins. Results also reaffirmed that the combination of stress and environmental exposure is more detrimental to bond durability than environmental exposure alone. The combined effects of stress and dilute salt solution were found to be more detrimental to adhesive bond durability than stress combined with distilled water, or concentrated salt solution. Two possible causes of bond deterioration considered were corrosion of the aluminium adherend and instability of the interface. Either of these explanations could account for the observed results; however, more work is required to verify these theories.

ISSN:0959-8103    

DOI:10.1002/pi.4990280104

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractKaolinite filler surfaces were modified by both surface adsorption and surface reaction. Their subsequent wetting and adhesion properties were determined by measurement of the contact angle of the powders by the Washburn technique using three probe liquids that spanned molecular polarity. Surface modification by adsorption utilized the kaolinite surface acidity to polymerize styrene. Surface reaction involved reaction of kaolinite hydroxyl groups with aryl diisocyanates and subsequent termination with a series of alcohols of increasing complexity.It was shown that kaolinite surfaces could be modified to produce surfaces of controlled hydrophobicity that could exceed that of conventionally silanated kaolinite. The ability of phases to spread and wet these filler surfaces was analysed in terms of the thermodynamic functions—spreading coefficientS12and spreading pressure

ISSN:0959-8103    

DOI:10.1002/pi.4990280105

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractStudies have been carried out on KrF excimer laser light (EX), X‐ray or electron beam (EB) induced polymerization of 10,12‐pentacosadiynoic acid (PDA) Langmuir‐Blodgett (LB) films in relation to molecular density or molecular arrangement of the films using X‐ray diffraction analysis, infrared (IR) spectroscopy and Raman spectroscopy. The molecular arrangement or density of the PDA LB films was controlled by subphase conditions when the films were built up, such as pH, temperature of a subphase or salt concentration in the subphase. Polymerization sensitivity of the PDA LB film was affected by the arrangement or molecular density. On low density (A type) films the polymerization occurred by irradiation with EX, X‐ray or EB, but on high density (B type) films the polymerization occurred only when the irradiation was carried out by high energy beams such as X‐ray or EB. Decomposition of polymerized films was observed further by excessive irradiation of EX or X‐ray, but not on the B type films. It was revealed by X‐ray diffraction analysis that in the A type film, the PDA molecules bent to a larger extent than those in the B type film and the polymerization proceeded topochemically, that is, the thickness decreased little after EB irradiation in a helium atmosphere. On the other hand, in the B type film, the thickness decreased by about 10% as a result of EB irradiation. By IR reflection‐absorption (RA) and Raman measurements, it was confirmed that conjugated diacetylenic bonds disappeared and conjugated double and new conjugated triple bonds appeared after high energy beam irradiations. These results support the supposition that 1,4‐polymerization, i.e. polydiacetylene type polymerization, occurs easily in the A type film and 1,2‐ or 3,4‐polymerization, i.e. polyacetylene type polymerization, occurs in the B type film, and that the polymerized A type film was decomposed at the polydiacetylenic bond when the irradiation continued further. It was also shown that the polyacetylene type polymer was obtained only when the B type film was irradiated wi

ISSN:0959-8103    

DOI:10.1002/pi.4990280106

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractPlastics are popularly regarded as an environmental hazard. Ferric stearate photoinitiated high density polyethylene (HDPE) films manufactured as supermarket shopping bags were found to rapidly photodegrade after exposure to ultraviolet (UV) and visible light irradiation. Our studies confirmed manufacturer's claims that the bags would degrade more rapidly than standard UV stabilised bags. The photodegradable bags had the potential to completely degrade and be resorbed into the biosphere without adverse effects.

ISSN:0959-8103    

DOI:10.1002/pi.4990280107

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractSingle‐mode and multi‐mode planar optical waveguides with low loss were fabricated by spin‐coating thin films of poly(vinyl alcohol) (PVAl) and 4‐dihexylamino‐4′‐nitro‐stilbene (DHANS) doped poly(methylmethacrylate) (PMMA) onto glass substrates, and characterised by theoretical analysis and optical guided‐mode measurements. The optical constants of the waveguides were determined with good accuracy by measuring the coupling synchronised angles and fitting them, via a recursion method, into the waveguide dispersion equations. The number of the guided modes observed in these thin films can be controlled by tailoring t

ISSN:0959-8103    

DOI:10.1002/pi.4990280108

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe results of a review of the patent literature on polymeric flow improvers for distillate fuels showed that a diverse range of polymeric compositions is effective. Ethylene‐containing compositions predominate and of these ethylene‐vinyl acetate (EVA) copolymers are the most common. Ethylene‐vinyl acetate copolymers were synthesised using a high pressure autoclave. The effectiveness of the copolymers varied greatly with the chemical composition of the copolymer. The techniques described in the literature for the determination of the composition of EVA copolymers are summarised and reviewed. A new technique using proton nuclear magnetic resonance was developed. A statistical analysis of the results is pres

ISSN:0959-8103    

DOI:10.1002/pi.4990280109

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA simultaneous dissolution of two lyotropic polyamides, poly(p‐phenylene terephthalamide) (PPTA) and poly(4,4′‐terephthanilidc adipamide) (PTAd), in a concentrated H2SO4(1 to 1.5% wt) produced an isotropic single phase solution. The crystallinity of PPTA/PTAd blends confirmed formation of a mesomorphic polyblend to the molecular level. With increasing concentration, solutions of these PPTA/PTAd blends in 100% H2SO4showed a sequential phase change typical of a single lyotropic polymer. Further, the ternary solution exhibited a wider biphase range than both binary solutions of PPTA/100% H2SO4and PTAd/100% H2SO4. Dry‐jet wet spinning of anisetropic solution of this ternary composition with a PTAd weight fraction less than 0.5 enabled us to obtain PPTA/PTAd blend fibers. Including a PTAd weight fraction of 0.1‐0.15 reduced both the orientation angle and fibrillation. The particular blend fiber with a PTAd weight fraction of 0.15 exhibited a synergistic effect on the mechanical p

ISSN:0959-8103    

DOI:10.1002/pi.4990280110

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe viscoelastic behaviour in the molten state of low density polyethylene‐polybutene 1 blends has been studied according to temperature, shearing stress and shearing rate. Measurements were made with a capillary viscometer for the static properties and a balance‐rheometer system of Kepes for the dynamic properties. Correction of experimental data has been performed and flow activation energies at a constant shear stress determined, whilst elasticity was investigated by means of the Barus factor. Furthermore, an investigation has been performed on variations of the real η′ and imaginary η″ parts of the complex viscosity with regard to the pulsation frequency ω. The Cole‐Cole and the Smyth representations were utilised to determine the Newtonian viscosity ηo, the parameter of distribution of relaxation timehand the average relax

ISSN:0959-8103    

DOI:10.1002/pi.4990280111

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY