Yonglie Chen

UV curing behavior of Methacrylated hyperbranched poly(amine-ester)s

Methacrylated hyperbranched poly(amine ester)s as oligomers in radiation curing resins have a lower viscosity and a higher cure speed. Their viscosity was reduced sharply when an amount of a monomer was added or the temperature was increased. Their polymerization rate and final conversion of the double bond differ with the variation of the chemical structure of the end group, molar mass, and monomer content.

Synthesis and characterization of UV-curable waterborne polyurethane–acrylate ionomers for coatings

A new kind of ultraviolet (UV)-curable waterborne polyurethane–acrylate (PUA) ionomer, prepared from toluene diisocyanate (TDI), polyethylene glycol (PEG), dimethylolpropionic acid (DMPA), triethylamine (TEA), and 2-hydroxyethyl methacrylate (HEMA), was synthesized by the modified prepolymer mixing process in which water serves as a chain-extender and dispersant. Fourier transform infrared (FTIR) spectra demonstrated the formation of the PUA ionomers both in dispersions and in their corresponding cured films. Surface tension of the PUA dispersions decreased as the DMPA-to-PEG mole ratio increased. The investigation of rheological behavior of the PUA dispersions suggested that all the dispersions belong to pseudoplastic fluid and display the characteristic of common polymer dispersions. Differential scanning calorimetry (DSC) analysis showed that the increasing DMPA-to-PEG mole ratio may result in a higher Tg and a broader transition zone for the hard segment. The results of TGA for the PUA-cured films indicated good thermal stability with no appreciable weight loss until well above 200°C. Measurement of physical properties showed that all the PUA-cured films exhibited excellent adhesion, gloss, flexibility, and impact strength, as well as pendulum hardness, depending upon hard segment content.

Photopolymerization kinetics of dendritic poly(ether–amide)s

Abstract The UV-curable dendritic poly(ether–amide)s (DPEA) with different chemical structures of end-groups were synthesized and their photopolymerization kinetics were studied by Photo-DSC. The effects of chemical structures of end-groups, photoinitiator concentration, and co-monomer content on the UV curing rate and the final unsaturation conversion of these dendritic poly(ether–amide)s were investigated. The pendulum hardness and thermal stability of the UV-cured films were also studied.

Photoinitiated copolymerization of acrylamide and styrene in oil-in-water microemulsion

This article describes the copolymerization of acrylamide with styrene in oil-in-water microemulsion, using dodecyl betaine as emulsifier and a-hydroxy-a,a- dimethyl acetophenone or a,a-dimethoxy-phenyl acetophenone as photoinitiator. Re- sults indicated that the photoinitiation of polymerization occurs at the interface be- tween the oil phase and the water phase and that the polymerization occurs in the microemulsion droplet. Particle size increased with increasing polymerization time. The copolymer chain consisted of isolated acrylamide units randomly distributed among styrene groups. q 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2543-2549, 1997

Photoinitiated radical copolymerization of vinyl ether and maleate system

The photoinitiated radical copolymerization of difunctional vinyl ether/ unsaturated polyester containing maleate has been studied by differential photocalorimetry. The copolymerization kinetics were found to be affected by various factors, such as the composition, the photoinitiator concentration, the light intensity and the presence of oxygen. No temperature effect on the copolymerization was found. The mixture of vinyl ether and unsaturated polyester containing maleate was studied by fluorospectrophotmetry and the existence of a complex of electron donor-acceptor was detected.

Studies of Nanocrystalline Phase and Residual Amorphous Phase of FeCuNbSib Alloy Using TG(M) Technique

The σ—T and dσ/dT—T curves of the FeCuNbSiB amorphous alloy, which are the relationship between the total saturated magnetic moment per unit mass σ and temperature, are investigated by magnetic thermogravimetry analysis (TG(M)) technique. It is found that the crystallization process of the samples can be divided into five stages. The studies of samples annealed in temperature range of 480–610°C for 1h show that when the annealing temperature (Ta) is less than 540°C, the quantity of nanocrystalline α-Fe(Si) phase increases evidently with Ta, and the Curie temperature (TC) of residual amorphous phase also increases linearly with Ta, i.e. TC=0.52Ta+91.7°C, with correlation coefficient γ=0.98. The variation of volume fraction of α-Fe(Si) nanocrystalline phase or residual amorphous phase with Ta is measured by TG(M) technique.