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The interlayer phase coherence in Bi 2 Sr 2 CaCu 2 O 81y was quantitatively determined in a wide field range by using the Josephson plasma resonance (JPR). At the first-order transition (FOT), a novel frequency-independent JPR with sharp resonance width is found, indicating a jump in the interlayer phase coherence. Above the FOT, sample-moving magnetization measurements show an anomaly consistent with the report by Fuchs et al. [Phys. Rev. Lett. 80, 4971 (1998)], where the interlayer phase coherence shows no anomaly. These results suggest the decoupling nature of the FOT, and can rule out the existence of the vortex line liquid state.

Polystyrene latex samples have been synthesised from an oil-in-water (o/w) emulsion of the monomer using ultrasonic irradiation as the initiation source. No added chemical initiators were used in any of the reactions. The free radicals formed from the cavitation process under the action of the ultrasound are sufficient to initiate the polymerisation. In the current study, the effects of varying the input intensity of the ultrasound were investigated. A marked increase in the monomer conversion rate as a function of time was seen as the power was increased. Despite this increase in conversion rate, the increasing intensity did not affect the resultant latex particle sizes. In all cases, the particle diameters at the conclusion of a polymerisation were seen to be in the range of 40 to 50 nm. The effects of changing the concentration of surfactant in the polymerisation medium and of changing the temperature were also probed. Increases in both were seen to lead to an increased rate of conversion at a fixed input intensity. Again, the particle diameters were invariant as a function of changing conditions. The small particle sizes and high conversion rates are thought to be due to a continuous nucleation process that is caused by the scavenging of free radicals throughout the polymerisation by freshly formed small oil droplets.

The curing kinetics and morphology of an interpenetrating polymer network (IPN) formed from an epoxy resin (DGEBA) cured by an imidazole (1-MeI) and a dimethacrylate resin (bisGMA), cured by low-and hightemperature peroxide initiators (TBPEH and DHPB, respectively) have been studied by temperature-ramping DSC, isothermal near-infrared (NIR), DMTA and small-angle neutron scattering (SANS). bisGMA and DGEBA are polar and chemically similar thermosetting resins which should enhance the miscibility of their IPNs. The phase structure was controlled by varying the curing procedure: the order of gelation of the components is dependent on the choice of low-and high-temperature initiators for bisGMA and this affects the morphology formation. In the cure of the bisGMA/TBPEH:DGEBA/1-MeI system, the dimethacrylate cures first. For isothermal cure studies at 80 • C, the final conversion of the epoxy is reduced by high crosslinking of the methacrylate groups in the IPN causing vitrification before full cure. The dimethacrylate conversion is enhanced due to plasticisation with unreacted DGEBA, and its cure rate is increased due to accelerated decomposition of TBPEH initiator by 1-MeI. SANS revealed that phase separation occurs in these IPNs with domains on the scale of 6-7 nm. In the cure of the bisGMA/DHBP:DGEBA/1-MeI system, the epoxy cures at a similar rate to that of the methacrylate groups. For isothermal cure studies at 80 • C, similar final conversions of the epoxy have been observed except for the 75:25 IPN. The cure rate of the methacrylate groups in the IPN is increased also due to accelerated decomposition of DHBP initiator by 1-MeI, and the extent of accelerated decomposition for DHBP is stronger than that in the TBPEH-based systems. SANS studies revealed that this system is more homogeneous due to the rapid formation of the dimethacrylate gel in the presence of the preformed epoxy network which interlocks the networks at low degrees of methacrylate conversion.

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