The growth of poly (ethylene oxide) (PEO) spherulites was observed synchronously with a polarized optical microscope, which was equipped with a video detector, and so the whole growing process of the PEO spherulites was dynamically recorded as a movie. There was a series of concentric diffractive bands on the surface of the PEO spherulites; furthermore, the diffractive banding did not exist until at least two independent PEO spherulites came into contact with each other. However, the formation of the diffractive banding on the PEO spherulites was also related to the crystallization conditions. It was concluded qualitatively that the diffractive banding formed more easily at the crystallization temperature with a high degree of supercooling, and this was explained in kinetic terms.

The special thermosensitive copolymer with lower critical solubility temperature near human heat of 37℃ in aqueous solution has been prepared successfully by copolymerizing N-isopropylacrylamide (NIPAM) and N-isopropylmethacrylamide (NIPMAM) randomly at an appropriate monomer ratio. The self-association behavior of the poly[NIPAM-ran-NIPMAM] copolymer has been studied by dynamic laser light scattering (DLLS) at a concentration higher than the critical concentration of the self-association calculated from viscosity data according to cluster theory. The effect of the concentration and temperature on the self-association behavior in water has been discussed respectively.

Two distinct single-chain particles of poly(N-isopropylacrylamide) (PNIPAM) in the state of loose coil and compact globule, have been prepared successfully below and above the lower critical solution temperature (LCST) in extreme dilute aqueous solution by the freeze-drying method, respectively. During the preparation of the compact globular single-chain sample, the surfactant of sodium n-dodecyl sulfate (SDS) was added into the system to prevent aggregation of globular single chains formed at a temperature above the LCST. After all the coil has been transformed into the compact globular particle, the SDS molecules were removed by dialysis. The glass transition temperature (T g) of the two single-chain samples has been measured by di

The phenomena of reduced viscosity bending up and sometimes appearing a maximum in extremely dilute concentration regime of polymer solution are resulted from the concentration reduction due to adsorption of polymer onto the glass capillary wall. A quantitative theoretical description of this effect based on Langmuir adsorption isotherm is given. Applying the deduced formula to fit Ohrn’s precisely measured reduced viscosity data of polystyrene, linear and branched polyvinyl acetate solutions for three viscometers with different capillary radius gave satisfactory results. The radius dependence of the effective adsorption layer thickness of these polymers indicates it consists of two parts, that is a true adsorption layer and a repulsion layer between anchored chains on the capillary surface and flowing chains in solution. The reduced viscosities of an ultrahigh molar mass polyethylene oxide sample in aqueous solution were measured both by an ordinary glass viscometer and by a viscometer constructed with a polytetrafluoroethylene capillary. The former exhibits a maximum due to adsorption and the later possesses the typical behavior of slipping flow. After correction for solute adsorption and slippage, respectively, the two sets of data coincide well and gave a common linear reduced viscosity plot down to extremely dilute concentration regime.

An investigation was carried out into the cure kinetics of carbon nanofibers (CNF)/epoxy composites, composed of tetraglycidyl-4,4 -diaminodiphenylmethane (TGDDM) resin and 4,4 -diaminodiphenylsulfone (DDS) as a curing agent. The experimental data for both neat system and CNF/epoxy composites revealed an autocatalytic behavior. Analysis of DSC data indicated that the presence of carbon nanofibers had only a negligible effect on the cure kinetics of the epoxy. Kinetic analysis was performed using the phenomenological model of Kamal and two diffusion factors were introduced to describe the cure reaction in thelatter stage. Activation energies and kinetic parameters were determined by fitting experimental data. Comparison between the two diffusion factors was performed, showing that the modified factor was successfully applied to the experimental data over the whole curing temperature range.