g-Bae Jun

Blends of polybutyleneterephthalate with ethylene-propylene elastomer containing isocyanate functional group

Abstract Ethylene–propylene elastomer (EPM) grafted with an isocyanate-containing monomer (HI) was blended with polybutyleneterephthalate (PBT), and its morphological, rheological, and mechanical properties were studied. The monomer HI was prepared by the reaction of 2-hydroxylethylmethacrylate and isophorone diisocyanate. The HI was successfully incorporated onto EPM backbone through solution graft reaction with radical initiator. When the PBT was blended with HI-grafted EPM (EHI), the morphologies of the dispersed phase displayed differences with respect to particle size and interfacial adhesion, when compared with those of the PBT/EPM blend. The increase in complex viscosity, storage modulus and impact strength of PBT/EHI blends ensured that the compatibility between PBT and EPM was improved through functionalization of EPM with the isocyanate moiety. These results are mainly due to in situ graft PBT–EPM copolymer that formed through the chemical reaction between the isocyanate group of EHI and hydroxyl or carboxyl end groups of PBT.

Effects of acrylonitrile content on PC/ABS alloy systems with a flame retardant

To investigate the effect of a flame retardant on PC/ABS alloy systems, a reactive-type brominated epoxy resin was used as a flame retardant, and mixed with PC/ABS at various amount using a twin-screw extruder. The rheological, morphologi- cal, mechanical, and thermal properties were investigated as a function of acrylonitrile (AN) content in ABS. The shear viscosity of the PC/ABS blend increased as the AN content in ABS increased. Temperature drastically affected the shear viscosity in the ABS matrix, but not as much in the PC matrix. A blend of PC 50% containing AN 22% is suitable to process because its shear viscosity is low in the high shear rate region and its mechanical properties drastically increase in the beginning of the PC matrix. In addition, gradual increases of heat distortion temperature were observed in the entire range of the PC content.

Monodisperse Micron-Sized Polyaniline Composite Particles for Electrorheological Fluid Material

In order to investigate the electrorheological (ER) behavior of monodisperse colloidal suspensions, polyaniline (PANi) composite particles were synthesized by chemically oxidative polymerization of aniline in the presence of macroporous polymer particles. Particle characterization was carried out by FT-IR spectroscopy, conductometry and scanning electron microscopy. ER proper- ties of PANi composite suspensions under various electric fields were then investigated and consequently found to be dependent on the particle compositions and the applied electric field strength.

Monodisperse micron-sized crosslinked polystyrene particles. VII. Importance of monomer-diffusible surface characteristics of growing particles

Abstract The monodisperse micron-sized polystyrene particles crosslinked with polyether diol diacrylates were produced by a simple dispersion polymerization in an ethanol solution. Unlike conventional divinylmonomers, the polyether diol diacrylates used as a crosslinker showed an excellent effect on maintaining the particle monodispersity even in a moderate crosslinker concentration. It is believed that the monomer-diffusible surface of primary particles played a decisive role in achieving the monodispersity of final particles by suppressing the second nucleation. The importance of monomer-diffusivity was tried to understand systematically in producing the crosslinked micron-sized polymer particles by the dispersion polymerization.

Spherical Polarization Body: Synthesis of Monodisperse Micron‐Sized Polyaniline Composite Particles

A new method to synthesize uniform polyaniline-coated composite microparticles was contrived considering the surface reactivity and porous structure of substrate polymer particles. It was found that the pore diameter together with the epoxy functional group plays a crucial role in controlling the structure of polyaniline shell. The polyaniline composite particles produced in this study are believed to find great applicability in piezoelectronics and as electro-rheological fluids.

Monodisperse Micron-sized Polystyrene Particles by Seeded Polymerization Using Reactive Macrosurfactants

Monodisperse micron-sized polystyrene particles could be prepared through a two-staged seeded swelling and polymerization method using reactive surfactants. The seed was obtained by emulsifier-free emulsion polymerization. To prepare conventional surfactant-free monomer emulsion droplet in swelling process, a tri-block diol diacrylate (t-BDDA), which is poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) tri-block copolymer containing two chain ends capped with acryloyl chloride, was employed as a reactive surfactant instead of conventional surfactants. Thermodynamic consideration of the effect of monomer droplet size and interfacial tension on the swelling process ensured that two-staged monomer swelling could be effectively performed by using t-BDDA as a surface-active macromonomer. From the surface tension measurement and optical microscope observation, it was found that the t-BDDA had a favorable surface activity when the monomer emulsion was prepared under its cloud point. From the X-ray photoelectron spectroscopy, it was found that most of the t-BDDA resided on the final particle surfaces.