Diaminodiphenyl sulfone is used as a curing agent to obtain an epoxy-resin-based binder with improved thermal stability. The kinetics of curing of this composition is studied by rheokinetic and...

A series of experiments has been carried out in order to construct a master curve generalizing the combined impact of temperature and low viscosity additives on the viscosity of heavy crude oil. The goal was to establish the temperature–diluent concentration relationship to achieve a defined limit of heavy crude oil viscosity suitable for tube transportation. The ultimate viscosity limit was assumed to be 0.2–0.4 Pa·s. Three different industrially acceptable diluents (light oil, light gas oil, and spindle oil) were used for mixing with heavy oil. The viscosities of the mixtures were measured across the whole concentration range at temperatures from –20 to 50 °C. The experimental temperature and concentration dependencies of the mixture viscosity were described by corresponding equations. The data enabled to construct master curves for the determination of temperature–concentration relationships for the suitable viscosity level. The proposed approach can be applied to different heavy crude oil–diluent mixtures.

This work is aimed at developing a kappa-carrageenan (kCR) gel with increased methotrexate (MTX) content. β-Cyclodextrin (βCD), which is able to inclusion complex formation with MTX, has been used to increase the drug concentration in the hydrogel. The rheological behavior of the designed gels was investigated and the influence of MTX and βCD on the viscoelastic properties of kCR gel was studied in detail. The effect of βCD and its concentration on the MTX-releasing rate from the kCR gels was examined. The properties of kappa- and iota-carrageenans loaded with MTX were compared and the differences observed were explained in terms of different binding affinities of MTX to these polymers. The obtained gels provided desirable viscoelastic properties useful for topical application.

We investigate the structure–property relations of the multiblock copolymers of norbornene with cyclododecene synthesized via the macromolecular cross-metathesis reaction between amorphous polynorbornene and semicrystalline polydodecenamer in the presence of the first-generation Grubbs catalyst. By adjusting the reaction time, catalyst amount, and composition of the initial system, we obtain a set of statistical multiblock copolymers that differ in the composition and average length of norbornene and dodecenylene unit sequences. Structural, thermal, and mechanical characterization of the copolymers with NMR, XRD, DSC (including thermal fractionation by successive self-nucleation and annealing), and rotational rheology allows us to relate the reaction conditions to the average length of crystallizable unit sequences, thicknesses of corresponding lamellas, and temperatures of their melting. We demonstrate that isolated dodecenylene units can be incorporated into crystalline lamellas so that even nearly random copolymers should retain crystallinity. Weak high-temperature endotherms observed in the multiblock copolymers of norbornene with cyclododecene and other cycloolefins could indicate that the corresponding systems are microphase-separated in the melt state.