摘要:

AbstractA review containing 83 references on the chemistry aspects (mechanism and structure–property relationships) for IPN synthesis is presente

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350201

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractFlory–Huggins interaction parameters, λ, were determined for a series of probes in an amine cured epoxy resin matrix (433–493 K) and its precursors (324–363 K) by inverse gas chromatography (IGC). Hildebrand–Scatchard theory was combined with Flory–Huggins theory in order to estimate infinte dilution solubility parameters (δ2) for the matrix and its precursors at 298 K. It was shown that the value of the solubility parameter for the cured resin matrix lies between those of its precursors. Compared to the majority of published work, an unusual aspect of this application of IGC is that solubility parameters have been determined when the stationery phases are (i) small molecules and (ii) a highly crosslinked polymer. Moreover, all possible attempts have been made to ensure equilibrium conditions between probe and stationary phase, and compensation for asymmetry of peak profile has been applied in determining δ2. The solubility parameters estimated by IGC are in good agreement with those calculated by o

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350202

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractPrevious work has shown that the inverse gas chromatography (IGC) method combined with Flory–Huggins and solubility parameter theories could be used to quantify interactions in an amine cured epoxy resin matrix. In the present communication the same procedures have been adopted for an anhydride cured epoxy resin matrix. The solubility parameter at 298 K thereby obtained for the cured resin was 20–6 (MPa)1/2, which lies between the corresponding values of 18.8(MPa)1/2and 22.5 (MPa)1/2for the precursors, viz. Epikote 828 (an epoxide resin) and phthalic anhydride, respectively. It was noted that great care must be exercised regarding choice of solvent used for deposition of phthalic anhydride on a glass bead support because of reaction to phthaclic acid. Similar consderations apply to the choice of probes u

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350203

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractInverse gas chromatography has been used on two types of coated glass fibre over a range of temperatures. Interaction parameters, χ, extrapolated to 298K yielded values for the solubility parameter, δ, of 20.1 (MPa)1/2and 23.5(MPa)1/2. After removal by combustion of the coatings, a higher value was yielded for the δ of glass. The findings, in conjunction with values of 19.8(MPa)1/2and 20–6(MPa)1/2for an amine cured epoxy resin and phthalic anhydride cured epoxy resin, respectively, provide a useful guide to the appropriate combination of cured resin matrix with coating with respect to optimum interfacial interac

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350204

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractSpontaneous current emission (SCE) has been studied in sandwiched different electrode configurations [metal(1)–undoped/doped ethyl cellulose (EC)–metal (1)/(2)] as a function of heating rate, film thickness and dopant concentration in the temperature range 40–200°C. The magnitude and direction of current depend on the combination of electrode metals. SCE thermograms for the Al undoped/doped EC–AI system exhibit two well resolved transition at 110 and 160°C in opposite directions to each other. The phenomena related to these transitions are explained in terms of creation of field at the interfaces and field produced in the bulk of the material. No negative direction transition was observed for electrode systems like Ag–Ag, Pb–Pb, Sn–Sn and Au–Au except for a shoulder of a peak around 100°C. When dissimilar electrode systems (i.e. Al–undoped/doped EC–Ag/Pb/Sn) are used, the current rises and then saturat

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350205

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractRandom copolymers ofN‐vinylcarbazole (VC) and alkylstyrenes with variable molar content of VC (first series) or variable size of alkyl substituent (second series) were characterized by the heat capacity measured at normal pressure in the temperature interval 203–523 K, as well as by measurements of specific volume and thermal diffusivity in the temperature interval 303–523 K and in the pressure range 30–100 MPa. It was established that the increase of thermal mobility of chain repeating units with the molar ratio of hexylstyrene (in the first series) or with the alkyl chain length (in the second series) manifests itself as a shift to lower temperatures of the glass transition temperature, as well as an increase of heat capacity, thermal diffusivity and effective number of external degrees of freedom per chain repeating unit from the Simha–Somcynsky reduced equation of state. The inadequacy of the simple diad additivity scheme for a quantitative description of structure–property relationships for the copolymers studied is

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350206

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractPoly(ether urethane) (PEU)–nylon 6 A–B–A triblock copolymer was synthesised. Correlation of blood compatibility with morphological and surface energetic properties of the block copolymer film was investigated. The block copolymer film exhibited a suppressing effect on thrombus formation and it is suggested that controlling the crystallite size of the nylon 6 block in the block copolymer by regulating the copolymer composition is an important factor in the antithrombogen

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350207

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe synthesis of poly(dimethylsiloxane) (PDMS) by anionic polymerization of octamethylcyclotetrasiloxane (D4) in aqueous emulsion using an emulsifying agent acting also as initiator (benzyldimethyldodecylammonium hydroxide) is described. Stable emulsions of α,ω‐dihydroxy PDMS with an easily controlled molar mass (up to 15 000), a low polydispersity index and high yields were obtained. The amount of cyclics formed (essentially D4to D7) is lower than that observed in bulk. Kinetics analysis and computerized simulations are in good agreement with a reaction scheme involving simultaneous polyaddition/polycondensation processes. At high monomer consumption, polycondensation predominates leading to a broadening of the molecular weight distribution (MWD). The apparent rate constants of initiation, propagation and condensation at various temperatures and the corresponding activation energies were determi

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350208

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe melting behaviour and the morphology of poly(ethylene terephthalate) crystallized from the melt are reported. In general, dual or triple melting endotherms are seen, and single endotherms are seen when the samples are crystallized above 215°C for long times. The location of the uppermost endotherm was found to be constant belowTc= 230°C, and above that temperature the location depends onTc. Therefore, we have shown that samples of PET which are crystallized aboveTc= 230°C contain perfect crystals only; belowTc= 230°C, they contain perfect and imperfect crystals. Scanning electron microscopy showed that the perfect crystals are the dominant lamellae in the spherulitic structure, while the imperfect crystals are the subsidiary lamellae in the spherulitic structure, The amorphous regions are located between individual lamel

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350209

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractInverse thin layer chromatography is used to characterise the chemical interactions that occur on polyaniline that has been electrochemically deposited on to a support. Amino acids are used as the molecular probe species by which the retention behaviour can be related to particular chemical interactions. The mobile phase is also varied, with respect to its polarity and pH, in order to add a further dimension to the qualitative information that is obtained. Anion exchange interactions are found to be the dominant interaction type. However, the behaviour seems to be different to that which occurs on conventional anion exchange materials. The behaviour was dependent upon the number of negative sites and also their spatial arrangement. A configurational‐selective ionic interaction with the polaron lattice of the polyaniline is proposed. The response of the anion exchange behaviour to a change of pH suggested that protonated sites remained within the polymer, even at high pH values (c9

ISSN:0959-8103    

DOI:10.1002/pi.1994.210350210

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY