Back SearchTitle: PHENOLIC RESINS (II) - INFLUENCES OF THE CHEMICAL STRUCTURE OF HIGH MOLECULAR WEIGHT MOLECULES ON THEN MECHANISMS OF CROSS-LINKING AND ON THE FINAL STRUCTURE OF THE RESINS
Page Range: p.233-262
Author(s): Bouajila J; Raffin G; Watson H; Sanglar C; Paisse J O; Grenier-Loustalot M F
File size: 318K
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Issue Year: ppc
Volume: 11
Issue No: No. 4
Abstract
Physicochemical characterisation of the structures of phenol oligomers in resols is carried out by fragmenting monomers in LC/UV/MS and LC/UV/MS/MS. Fragmentation mechanisms are related to the numbers and positions of substituents on the aromatic ring and to the types of oligomer junctions. The resols were prepared with differing molar ratios, and were crosslinked using two industrially recommended heat cycles. The progression of resin crosslinking was determined by solid state C NMR (CP/MAS), and the residual percentage of monomers and oligomers was determined in leachates and characterised by LC/UV/MS. Results for crosslinking advancement were then correlated with the various synthesis parameters. 24 refs.
Title: PHENOLIC RESINS (III) - SOLID STATE STRUCTURES AND THERMAL PROPERTIES OF CROSS-LINED PHENOLIC RESINS
Page Range: p.263-276
Author(s): Bouajila J; Raffin G; Watson H; Sanglar C; Alamercery S; Grenier-Loustalot M F
File size: 170K
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Issue Year: ppc
Volume: 11
Issue No: No. 4
Abstract
In order to understand the thermal stability of phenolic resins prepared with different synthesis processes, networks have been characterised using various non-destructive and solid state physicochemical techniques. The thermodynamic properties of the resins were determined by differential scanning calorimetry and by coupling thermogravimetric analysis with infrared absorption spectroscopy. Results obtained with solid state CNMR (CP/MAS) and FTIR were analysed and related to the thermal characteristics of the networks (DSC and TGA/FTIR). The data were correlated with parameters and conditions of syntheses of resols and of the initial prepolymers. 30 refs.
Title: THEORETICAL ANALYSIS OF THE SURFACE STRUCTURE OF TEXTILE-REINFORCED THERMOPLASTICS
Page Range: p.277-290
Author(s): Mitschang P; Blinzer M; Woeginger A
File size: 212K
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Issue Year: ppc
Volume: 11
Issue No: No. 4
Abstract
In order to allow the use of a combination of different materials in a car body, a uniform surface appearance is required. The use of endless fibre reinforced organic thermoplastic sheets in the production of car panels is discussed in terms of the surface quality of the sheets. Surface problems are said to be caused mainly by the print-through of the reinforcing fibres. This article describes the work needed to investigate the material and process parameters influencing the topography of the organic sheets. A finite element has been created which is used to consider the physical behaviour of the matrix and reinforcement during the temperature drop in processing. Non-isotropic characteristics of the textile as well as the time and temperature dependent mechanical behaviour of the thermoplastic matrix are taken into account. 24 refs.
Title: GAS SENSING MATERIALS FROM CARBON BLACK/POLY(METHYL METHACRYLATE) COMPOSITES
Page Range: p.291-300
Author(s): Dong X M; Fu R W; Zhang M Q; Zhang B; Li J R; Rong M Z
File size: 152K
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Issue Year: ppc
Volume: 11
Issue No: No. 4
Abstract
The electrical conductivity of carbon black filled polymethyl methacrylate and its responsiveness to organic solvent vapours is investigated. Carbon black-polymer conductive composites were synthesised by in-situ polymerisation. They exhibited a low electrical percolation threshold. Their electrical resistance was increased drastically when they were exposed to solvent vapours such as chloroform, tetrahydrofuran, and ethyl acetate. The effect of temperature on the vapour responsivity of the composites was also notable. Elevated temperatures accelerated the vapour-induced variation in electrical resistance of the composites. The experimental data also indicated that the composites possessed a good reproducibility of vapour responsivity, suggesting that they could be used as gas sensors. 22 refs.
Title: THEORETICAL STUDY OF THE RELEASE AND CONSUMPTION OF AN AGENT IN FOOD FROM ACTIVE POLYMER PACKAGING
Page Range: p.301-310
Author(s): Kouali M E; Salouhi M; Labidi F; Brouzi M E; Vergnaud J M
File size: 99K
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Issue Year: ppc
Volume: 11
Issue No: No. 4
Abstract
The use is examined of active packaging for food products in order to extend their shelf life. Active packaging allows for the controlled release of an anti-microbial agent into the food. The packaging used comprises two layers, at lease one with an impermeable polymer which protects the system from the environment, and the other with a polymeric carrier containing the agent, the polymer carrier being bound to the inside of the packaging and in contact with the food. A study is reported which describes the process of the agent release. The agent diffuses through the polymer carrier with a constant diffusivity into the liquid food, with a finite coefficient of convective transfer at the interface. The rate of consumption of the agent resulting from its action on the microorganisms is controlled by a first-order reaction with respect to its concentration in the liquid. Results are expressed in terms of the profiles of concentration of the agent developed through the thickness of the polymer carrier, the kinetics of the agent remaining free in the liquid, and the kinetics of consumption of the antimicrobial agent by the microorganisms. Two new dimensionless numbers are introduced, which take into account the rate of consumption of the agent and either the diffusivity, when the process is controlled by diffusion, or the rate of convection coefficient when it is controlled by convection, in order to clarify the process. 20 refs.
Title: HIGH-TEMPERATURE ADHESIVES BASED ON ALDER-ENE REACTION OF DIALLYL BISPHENOL A NOVOLAC AND BISMALEIMIDE: EFFECT OF BMI STRUCTURE AND NOVOLAC MOLAR MASS
Page Range: p.311-320
Author(s): Gouri C; Nair C P R; Ramaswamy R
File size: 139K
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Issue Year: ppc
Volume: 11
Issue No: No. 4
Abstract
Diallyl bisphenol A formaldehyde novolac (ABPF) resin was cured with four structurally different bismaleimides (BMIs) at high temperatures through an Alder-ene reaction which resulted in thermally stable network polymers. The adhesive characteristics of the different BMI-ABPF systems were evaluated in terms of the lap shear strength on aluminium substrates at varying temperatures up to 250 degrees C. These properties are reported to be not significantly affected by the structure of the BMI. Although the lap shear strength of the BMI-ABPF systems were not particularly high due to the brittle nature of the crosslinked structures, all the systems exhibited remarkably good retention of lap shear strength at high temperatures. By replacing ABPF with its monomeric analogue o,o'-diallyl bisphenol A (DABA), was shown to produce better adhesion, but in a poorer thermo-adhesive profile. A comparison of DMA and thermo-adhesive profiles is said to imply that in the majority of cases, molecular relaxations at higher temperatures are conducive to matrix toughening, resulting in enhanced adhesion properties. 20 refs.
Title: INK-ELIMINATED PAPER SLUDGE FLOUR AS FILLER FOR POLYPROPYLENE
Page Range: p.321-326
Author(s): Qiao X; Zhang Y; Zhang Y
File size: 71K
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Issue Year: ppc
Volume: 11
Issue No: No. 4
Abstract
In this study, a PP copolymer with high impact strength was chosen as the polymer matrix, and ink-eliminated paper sludge flour (IESF) was evaluated as a new kind of filler for the preparation of P composites. The crystal structures, thermal behaviour and mechanical properties of the PP composites obtained were investigated and compared to those for conventionally filled calcium carbonate PP. Experimental results showed that the addition of the IESF filler, not only had positive and negative effects on the crystal growth of the alpha-phase and beta-phase of the PP respectively, but also induced the crystallisation and melting temperatures due to its nucleation regent effect. It was also reported that the nucleation regent effect of IESF was better than that of calcium carbonate for PP crystallisation, and that with the same filler content, the mechanical properties of the IESF/PP composites are better than those of calcium carbonate filled PP, with the exception of impact strength and elongation. 16 refs.
Title: STUDY OF THE PROPERTIES OF PMR POLYIMIDE RESIN/COPPER FOIL COMPOSITES
Page Range: p.327-340
Author(s): Chou S; Lee K-S
File size: 199K
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Issue Year: ppc
Volume: 11
Issue No: No. 4
Abstract
Research was carried out to develop a high temperature laminate for use in electronic equipment based on copper laminate and polyimide film. The use of polyimide film in the composite not only offers improved dimensional stability, but also improves the resistance to high temperatures. A PMR (polymerisation of monomer reactants) polyimide resin was prepared from three monomer reactants: 5-norbornene-2,3'-dicarboxylic anhydride, 3,4'-oxydianiline, and 3,3'4,4-benzophenone tetracarboxylic dianhydride. Composite properties were tested for heat and chemical resistance, and the dielectric constant and dissipation factors were also examined. Results indicate that the PMR laminates synthesised meet the necessary requirements. 11 refs.